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(1)Michigan Technological University. Digital Commons @ Michigan Tech Michigan Tech Publications 11-1-2019. Open electronics for medical devices: State-of-art and unique advantages Gaurav Pandey Noble Sensors LLC. Ankit Vora Michigan Technological University, avora@mtu.edu. Follow this and additional works at: https://digitalcommons.mtu.edu/michigantech-p Part of the Electrical and Computer Engineering Commons. Recommended Citation Pandey, G., & Vora, A. (2019). Open electronics for medical devices: State-of-art and unique advantages. , 8(11) http://doi.org/10.3390/electronics8111256 Retrieved from: https://digitalcommons.mtu.edu/michigantech-p/1349. Follow this and additional works at: https://digitalcommons.mtu.edu/michigantech-p Part of the Electrical and Computer Engineering Commons.

(2) electronics Review. Open Electronics for Medical Devices: State-of-Art and Unique Advantages Gaurav Pandey 1, * and Ankit Vora 2 1 2. *. Noble Sensors LLC, New York, NY 10010, USA Michigan Technological University, Houghton, MI 49931, USA; avora@mtu.edu Correspondence: gauravpandey11@gmail.com; Tel.: +1-302-722-5676. Received: 30 September 2019; Accepted: 30 October 2019; Published: 1 November 2019.  . Abstract: A wide range of medical devices have significant electronic components. Compared to open-source medical software, open (and open-source) electronic hardware has been less published in peer-reviewed literature. In this review, we explore the developments, significance, and advantages of using open platform electronic hardware for medical devices. Open hardware electronics platforms offer not just shorter development times, reduced costs, and customization; they also offer a key potential advantage which current commercial medical devices lack—seamless data sharing for machine learning and artificial intelligence. We explore how various electronic platforms such as microcontrollers, single board computers, field programmable gate arrays, development boards, and integrated circuits have been used by researchers to design medical devices. Researchers interested in designing low cost, customizable, and innovative medical devices can find references to various easily available electronic components as well as design methodologies to integrate those components for a successful design. Keywords: open electronics; open-source electronics; medical devices; ultrasound; neurological sensors; posture correction; computed tomography; medical infusion pumps; healthcare. 1. Introduction Healthcare technology is a classic case study for the effectiveness of open and open-source electronics. A high degree of precision, robustness, and reliability are necessary for any healthcare device. An analysis by Winter et al. [1] has projected the enormous cost savings (in billions of US$) of an open-source MRI scanner, which is just a small class of all medical devices which can benefit from open electronic hardware. There is a wide range of open-source software [2–14] for medical imaging—mainly for image processing (filtering) and visualization. There is some highly encouraging research [15–21] on artificial intelligence (mainly neural networks and deep learning) for computer-aided diagnostics. Although these research articles on computer aided diagnostics do not necessarily describe open-source software, they are all nevertheless reproducible. Unlike open-source medical software, the field of open-source medical hardware is less developed and less published in peer-reviewed literature. As a recent review by Niezen and co-workers [22] points out, many of the open-source medical device projects are still in nascent stage and unreported in peer-reviewed literature. This is in contrast with the field of open-source medical imaging software; for example, the Medical Imaging Interaction Toolkit (MITK) has been available as an open-source software for almost 16 years now [11]. To take full advantage of the vast developments in the open-source medical software [4–14] and machine learning algorithms [15–21], it is necessary to develop open-source hardware for medical devices. In fact, with the growing popularity of 3-D printing and open computing platforms such as Arduino®and Raspberry Pi, it is possible to come up with open/open-source electro-mechanical designs for medical devices. In this review, we focus mainly on the open electronic components for medical devices. Electronics 2019, 8, 1256; doi:10.3390/electronics8111256. www.mdpi.com/journal/electronics.

(3) Electronics 2019, 8, 1256. 2 of 25. Readers interested in the mechanical aspect of the open-source medical devices can explore some recent studies [23–31] in open-source robotic hands. During the review, we have found that open electronics not only reduce development cost but in some instances, lead to better hardware and a higher performance solution. The advantages of using open electronics platform are the modularity, ease of repair, data sharing, as well as leveraging machine learning. For example, two healthcare devices made by different manufacturers but using the same open-electronics platform can easily share data or upload their data to a common cloud merely by a firmware update. Such seamless data sharing can take full advantage of the progress in machine learning. Open hardware devices can benefit from the numerous open-source software [2–6,12–14] which are very well published in literature. Specifically, recent studies have demonstrated the suitability of Raspberry Pi® [32–34] for artificial intelligence and deep learning. Among the wide range of medical devices, we will further study ultrasound, X-Ray CT, ECG, fluid infusion devices, wearable and posture detection medical devices in particular. This review will serve as a guideline for researchers selecting electronic components for rapid prototyping. While most of the open electronic components are available on popular hobbyist websites such as Sparkfun®, Adafruit®etc. Researchers can also leverage the readily available and professionally designed “demo boards” or “evaluation boards” or “development boards” that can be found on major electronics retailers such as Mouser®, Element14®and Digikey®. As it will be evident in this review, using the appropriate “evaluation board,” in conjunction with a computing/microcontroller/FPGA platform can lead to great results at a very low cost. Such demo/evaluation boards are designed by large semiconductor manufacturers and very professionally and good high-frequency design practices are followed. In addition, such boards have professional soldering for difficult to solder surface mount components such as ball grid arrays. Most of the times, manufacturers also provide printed circuit board designs for these demo boards freely. In our review, we have found numerous examples of researchers utilizing these demo boards for open electronics hardware platforms. Typically these boards are helpful for (1) low noise designs, (2) difficult to solder integrated circuits, (3) saving prototyping time as there is no need to design, order, and assemble printed circuit boards. To summarize, we have studied a wide range of medical devices which have been prototyped using open electronics platforms. Progress made by both academic research groups as well as the hobbyist community has been reported. In Section 2, we have reviewed the developments in open/open-source medical ultrasound and found that both FPGAs as well as high-frequency microcontrollers have proven quite effective in generating ultrasonic images. Additionally, a number of development boards have been used effectively by open-source developers. Compared to open/open-source ultrasound, developments in field of X-Ray CT scanners have been very few. Historically, even though a hobbyist X-Ray scanner has been described as early as 1974 [35], developments have been fewer yet encouraging. As described in Section 4, numerous variants of ECG/EKG, EEG, and other neurological monitoring devices have been very widely prototyped using open-source electronic hardware. Open electronics can be potentially used for seizure prediction, as reported in some recent research, for example [36]. Developments in open and open-source electronics have now matured to cover measurements which require multi-channel high frequency data-acquisition as well as ultra-low noise amplifications. Such an example is electric impedance tomography covered in Section 5. Infusions pumps are perhaps one of the most widely open-source medical devices with some very popular projects such as [37]. These open electronics infusion pump projects and their potential economic impact is described in Section 6. Various open/open-source wearables, motion sensing, and posture detection/correction devices have been described in Section 7. Quite a wide range of hardware (accelerometers, gyroscopes, piezo-resistive sensors, ultrasonic sensors, cameras) has been used in such open electronic devices. Section 8 lists some unique advantages of using open electronic hardware, other than the obvious cost advantage. In short, open electronics devices have great potential to create large data sets to effectively leverage advances in machine learning and artificial intelligence. In addition, open electronics hardware enables medical innovation, modular design, and easy repairs. This review will be very relevant to engineers,.

(4) Electronics FOR PEER REVIEW Electronics2019, 2019,8,8,x1256. 3 of 3 of2525. innovation, modular design, and easy repairs. This review will be very relevant to engineers, researchers,and andother otherdevelopers developersofofopen openelectronics electronicsmedical medicalplatforms platformsasaswell wellasasphysicians physiciansand and researchers, other healthcare practitioners looking for novel approaches to medical device design. other healthcare practitioners looking for novel approaches to medical device design. OpenElectronics ElectronicsininMedical MedicalUltrasound UltrasoundImaging Imaging 2.2.Open typicalultrasonic ultrasonicdiagnostic diagnosticsystem systemworks worksby byexciting excitingan anultrasonic ultrasonictransducer transducerininaa1–100MHz 1–100MHz AAtypical range (2–10 MHz typical) with a peak-peak voltage of 50–200 volts. The system also requires low noise range (2–10 MHz typical) with a peak-peak voltage of 50–200 volts. The system also requires low amplifiers of very low signal to noise ratio. The sampling frequency often falls in range of 50–100 MHz noise amplifiers of very low signal to noise ratio. The sampling frequency often falls in range of 50– forMHz such systems. The sampling frequencyfrequency is beyondiswhat any what hobbyist can handlecan and 100 for such systems. The sampling beyond anymicrocontroller hobbyist microcontroller until aand fewuntil yearsaback, an open ultrasound would have been have inconceivable because of because the specialized handle few years back, an open ultrasound would been inconceivable of the engineering design involved in the process. A few selected universities have developed their own specialized engineering design involved in the process. A few selected universities have developed ultrasound platforms. A review of some of the leading research ultrasound platforms is provided their own ultrasound platforms. A review of some of the leading research ultrasound platforms is in [38]. Some example are SARUS RASMUS developeddeveloped by Danishby Technical [39], UARP provided in [38]. Some example areand SARUS and RASMUS Danish University Technical University developed by Leeds University [40], and ULA-OP 256 [41] by University of Florence. However these [39], UARP developed by Leeds University [40], and ULA-OP 256 [41] by University of Florence. ultrasound platforms have been developed at a very high cost and it is not possible for small research However these ultrasound platforms have been developed at a very high cost and it is not possible for groups to reproduce such platforms. of theseTwo platforms shown are in Figure small research groups to reproduce suchTwo platforms. of theseare platforms shown1.in Figure 1.. (a). (b). Figure 1. Ultrasound platforms: (a) RASMUS and (b) SARUS [39] by DTU. Figures used with permission. Figure 1. Ultrasound platforms: (a) RASMUS and (b) SARUS [39] by DTU. Figures used with permission.. These ultrasound platforms mainly consist of custom-designed printed circuit boards. A typical simplified architecture is shown in Figure 2. As shown in Figure 2, printed circuit boards consist of These ultrasound platforms mainly consist of custom-designed printed circuit boards. A typical specialized field programmable gate arrays (FPGAs) and other high-frequency components. Most of simplified architecture is shown in Figure 2. As shown in Figure 2, printed circuit boards consist of these components (especially high voltage pulser (HVP), low noise amplifier (LNA), ADC, and FPGA) specialized field programmable gate arrays (FPGAs) and other high-frequency components. Most of have difficult to solder packaging such as QFP, QFN, or BGA. If developed using FPGA development these components (especially high voltage pulser (HVP), low noise amplifier (LNA), ADC, and board or module (Figure 2), the ultrasound platforms are easier to assemble. However, if the FPGA) have difficult to solder packaging such as QFP, QFN, or BGA. If developed using FPGA FPGA-integrated circuit is used individually, the design is still more complicated as FPGAs often development board or module (Figure 2), the ultrasound platforms are easier to assemble. However, require a lot of peripheral components such as resistors, capacitors, well-regulated power supplies, if the FPGA-integrated circuit is used individually, the design is still more complicated as FPGAs and clock sources. often require a lot of peripheral components such as resistors, capacitors, well-regulated power supplies, and clock sources..

(5) Electronics 2019, 8, 1256. 4 of 25. Electronics 2019, 8, 1256 Electronics 2019, 8, 1256. 4 of 25 4 of 25. Figure 2. Simplified architecture of a typical research ultrasound platform. Typical packaging is. 2. Simplified architectureof of a a typical research ultrasound platform.platform. Typical packaging is shown Figure 2.Figure Simplified architecture typical research ultrasound Typical packaging is shown each component. critical component. for eachfor critical shown for each critical component.. investment involved in such a design project, a low-cost open Considering the thetime timeand andfinancial financial investment involved in such a design project, a low-cost ultrasound seems unviable. However a recent study by K. Divya Krishna and co-workers [42] has open ultrasound seems unviable. However a recent study by K. Divya Krishna and co-workers [42] Considering the time and financial investment involved in such a design project, a low-cost open developed a multiple element ultrasound using off-the-shelf development kits. The platform is has developed a multiple element ultrasound using off-the-shelf development kits. The platform ultrasound seems unviable. However a recent study by K. Divya Krishna and co-workers [42] has shown in in Figure Xilinx® is shown Figure3. 3.The Theplatform platformdeveloped developedby byK. K.Divya Divya Krishna Krishna and and co-workers co-workers uses Xilinx® developed a multiple element ultrasound using off-the-shelf development kits. The platform is Kintex® development board in conjunction with a Raspberry Pi. Although not described explicitly Kintex® development board conjunction shown in Figure 3. The platform developedTexas by Instruments K. Divya Krishna co-workers uses Xilinx® Instruments evaluationand AFE5808 in the publication, the research has utilized Texas evaluation module [43] for AFE5808 Kintex® analog development board innow conjunction withInstruments a Raspberry Pi. Although not described explicitly obsolete Texas TX-SDK-V1/NOPB-Evaluation Module. front end as well as TX-SDK-V1/NOPB-Evaluation Module. AFE is a critical part of any ultrasound system as ultrasonic signals have very high attenuation and AFE is a critical of any ultrasound system as ultrasonic signals evaluation have very high attenuation in the publication, thepart research has utilized Texas Instruments module [43]and forsoAFE5808 so a very low noise amplifier is required to resolve the reflected echoes. An advanced AFE chip such a very low noise amplifier is required to resolve the reflected echoes. An advanced AFE chip such asModule. analog front end as well as now obsolete Texas Instruments TX-SDK-V1/NOPB-Evaluation as AFE5808 used in the study ball-grid array pattern and hence it is very difficult to prototype in AFE5808 used in the study has has ball-grid array pattern and hence it is very difficult to prototype in a low AFE is a critical part of any ultrasound system as ultrasonic signals have very high attenuation and a low budget laboratory. However, there are multiple evaluation boards AFE 4) (Figure which budget laboratory. However, there are multiple evaluation boards for AFEfor (Figure which4)have an so a veryappropriate low an noise amplifier is required to resolve the reflected echoes. advanced AFE chip such have appropriate coaxial connection for easy Such low noise An AFE evaluation boards coaxial connection for easy usage. Such usage. low noise AFE evaluation boards (example-AFE as AFE5808 used in the study has ball-grid array patternfrom andmanufacturers hence it is very difficult prototype in (example-AFE 5808, AD8331, and AD8310) aresemiconductor available semiconductor manufacturers such as 5808, AD8331, and AD8310) are available from such as Analog to Devices Analog Devices and However, Texas Instruments. Hence evaluation modules very effective way of and Texas Instruments. Hence evaluation modules provide a veryprovide effective of assembling a4) which a low budget laboratory. there are multiple evaluation boardsa way for AFE (Figure assembling a functional system at a very low budget. AD8310 is especially useful for ultrasonic functional system at a very low budget. AD8310 is especially useful for ultrasonic applications as it is have an appropriate coaxial connection for easy usage. Such low noise AFE evaluation boards it is a logarithmic amplifier the andincreasing compensates the increasing (withattenuation propagation aapplications logarithmicas and compensates (withfor propagation distance) of (example-AFE 5808,amplifier AD8331, and AD8310)for are available from semiconductor manufacturers such as distance) attenuation of ultrasonic waves. ultrasonic waves.. Analog Devices and Texas Instruments. Hence evaluation modules provide a very effective way of assembling a functional system at a very low budget. AD8310 is especially useful for ultrasonic applications as it is a logarithmic amplifier and compensates for the increasing (with propagation distance) attenuation of ultrasonic waves.. Figure shelf components [42] (Creative Commons CC CC BY Figure 3. 3. Ultrasound Ultrasound imaging imagingplatform platformusing usingoff offthe the shelf components [42] (Creative Commons 4.0 license). BY 4.0 license).. Figure 3. Ultrasound imaging platform using off the shelf components [42] (Creative Commons CC.

(6) Electronics 2019, 8, 1256. Electronics 2019, 8, 1256 Electronics 2019, 8, 1256. 5 of 25. 5 of 25 5 of 25. Figure 4. Some examples of ultrasound analog front-end evaluation boards.. Other than various research articles published by K. Divya Krishna and co-workers [42,44,45], 4. Someand examples of ultrasound analog front-end evaluation boards. another study byFigure Techavipoo co-workers [46] has explicitly used off-the-shelf evaluation boards Figure 4. Some examples of ultrasound analog front-end evaluation boards. to design an ultrasonic system from scratch as well as to minimize the design of printed circuit Other than various research articles published by K. Divya Krishna and co-workers [42,44,45], boards.Other than various research articles published by K. Divya Krishna and co-workers [42,44,45], another study by Techavipoo and co-workers [46] has explicitly used off-the-shelf evaluation boards to Sobhani et by al.Techavipoo [47] have developed an ultrasonic system based on raspberry pi and PIC32 another and co-workers hasminimize explicitly used off-the-shelf evaluation boards design anstudy ultrasonic system from scratch as well[46] as to the design of printed circuit boards. microcontroller. The setupsystem is shown in Figure 5. as Thewell research isminimize based onthe an annular array ultrasonic to design an ultrasonic from scratch as to design of printed circuit Sobhani et al. [47] have developed an ultrasonic system based on raspberry pi and PIC32 transducer, which is very promising for both medical as well as non-destructive testing applications. boards. microcontroller. The setup is shown in Figure 5. The research is based on an annular array ultrasonic Such annular array transducer research has until nowsystem been conducted by using pi commercial Sobhani et al. [47] have developed ultrasonic based on raspberry and PIC32 transducer, which is very promising for bothanmedical as well as non-destructive testing applications. ultrasonic platforms, which cost at-least $50,000. For further research on annular array ultrasonics, microcontroller. setup is shown Figure Thebeen research is based an annular arrayultrasonic ultrasonic Such annular arrayThe transducer researchinhas until5.now conducted byon using commercial the reader canwhich refer is tovery [48–52]. Annular arrays with small number of elements (4–12) andapplications. a variable transducer, promising for both medical as well as non-destructive testing platforms, which cost at-least $50,000. For further research on annular array ultrasonics, the reader can focus unique for development ofnow low-cost yet high-resolution ultrasound. Suchtooffer annular arrayopportunity transducer has until been by focus usingoffer commercial refer [48–52]. Annular arrays withresearch small number of elements (4–12)conducted and a variable unique However, despite using specialized and micromachined annular array transducers and inertial ultrasonic platforms, which cost at-least $50,000. For further research on annular array ultrasonics, opportunity for development of low-cost yet high-resolution ultrasound. However, despite using tracking system, the ultrasonic images presented in Sobhani et. al. [47] are not very(4–12) conclusive. In this the reader can micromachined refer to [48–52]. Annular arrays with smalland number elements andultrasonic a variable specialized and annular array transducers inertialoftracking system, the direction, a significant improvementforover [47] is Jonveaux [53]. Jonveaux has describedultrasound. a highly focus offer unique opportunity development low-cost yet high-resolution images presented in Sobhani et. al. [47] are not veryofconclusive. In this direction, a significant modular ultrasound imaging platform based on microcontrollers and not using FPGAs altogether. However, despite using specialized micromachined annular transducers andimaging inertial improvement over [47] is Jonveaux [53]. and Jonveaux has described a highlyarray modular ultrasound Hence it might be very promising topresented combine in theSobhani work et. of al. Jonveaux [53]very withconclusive. annular array tracking system, the ultrasonic images [47] are not In this platform based on microcontrollers and not using FPGAs altogether. Hence it might be very promising transducers for high-resolution imaging. Further, the work of Jonveaux [53] provides a very significant improvement over annular [47] is Jonveaux [53]. Jonveaux has describedimaging. a highly todirection, combine athe work of Jonveaux [53] with array transducers for high-resolution comprehensive reference for researchers interested in low-cost microcontroller-based systems and modular imaging[53] platform based on comprehensive microcontrollers and notfor using FPGAs interested altogether. Further, theultrasound work of Jonveaux provides a very reference researchers avoiding complexities with using FPGAs. itthe might be veryassociated promising to and combine thethe work of Jonveaux [53] with annular array inHence low-cost microcontroller-based systems avoiding complexities associated with using FPGAs. transducers for high-resolution imaging. Further, the work of Jonveaux [53] provides a very comprehensive reference for researchers interested in low-cost microcontroller-based systems and avoiding the complexities associated with using FPGAs.. Figure 5. Microcontroller-based ultrasound platform with sample images [53]. (Creative Commons CC Figure 5. Microcontroller-based ultrasound platform with sample images [53]. (Creative Commons BY 4.0 license). CC BY 4.0 license).. Other than academic research groups, there have been some important efforts by the hobbyist Other than academic research groups, there have been some important efforts by the hobbyist Figureto 5. Microcontroller-based ultrasound platform with sample images [53]. (Creative community design open ultrasound. The open-source project echOpen [54] isCommons developing community to design open ultrasound. CC TheBYopen-source project echOpen [54] is developing 4.0 license). “echostethoscopy” (ultrasonic imaging tool). The project uses MAX-4940 pulser module, as shown “echostethoscopy” (ultrasonic imaging tool). The project uses MAX-4940 pulser module, as shown in in Figure 6, to produce high frequency (several MHz) and high voltage (−97v) ultrasonic pulses. Other than academic research groups, there have been some important efforts by the hobbyist community to design open ultrasound. The open-source project echOpen [54] is developing “echostethoscopy” (ultrasonic imaging tool). The project uses MAX-4940 pulser module, as shown in.

(7) Electronics 2019, 2019, 8, 8, 1256 1256 Electronics. 66of of 25 25. Figure 6, to produce high frequency (several MHz) and high voltage (−97v) ultrasonic pulses. The The project also utilizes Arduino®controlled motors and 3-D printing for producing an ultrasonic project also utilizes Arduino® controlled motors and 3-D printing for producing an ultrasonic b-scan. b-scan. The project has successfully acquired b-scan images. The project has successfully acquired b-scan images.. Figure 6. Open-source Open-source project echOpen [54] (Creative Commons CC BY 4.0 license).. Another project [55,56] based on Lattice-FPGA and Raspberry Pi (Figure 7) is perhaps Another project“Echomod” “Echomod” [55,56] based on Lattice-FPGA and Raspberry Pi (Figure 7) is the most advanced among the hobbyist community, with very high resolution images and detailed perhaps the most advanced among the hobbyist community, with very high resolution images and layouts and software available available on its GitHub Anypage. hobbyists interested interested in developing a low cost detailed layouts and software on itspage. GitHub Any hobbyists in developing platform will find thewill project for beginning design. The project has aultrasound low cost ultrasound platform findand thelayouts projectuseful and layouts useful their for beginning their design. beenproject verified to been workverified with various used (or various refurbished) ultrasonic probes ultrasonic available off-shelf The has to work with usedmechanical (or refurbished) mechanical probes from websites such as eBay. The project is useful for both medical imaging as well as non-destructive available off-shelf from websites such as eBay. The project is useful for both medical imaging as well testing (NDT). as non-destructive testing (NDT).. Figure 7. Open-source motor driven ultrasound “Echomod” [55,56] (Creative Commons CC BY 4.0 Figure license).7. Open-source motor driven ultrasound “Echomod” [55,56] (Creative Commons CC BY 4.0 license).. While both researchers and hobbyists have made significant progress in developing open and While researchers and hobbyists made significant progress in miniaturized. developing open and open-sourceboth ultrasound devices, so far thehave prototypes are not compact and One of open-source ultrasound devices, so far the prototypes(2–20 are not compact and miniaturized. One of the the challenges is that typical ultrasound frequencies MHz) require specialized high-frequency challenges is that typical frequencies (2–20MHz) require “development specialized high-frequency design and researchers haveultrasound often tackled this challenge by incorporating boards.” Such design and researchers have often tackled this challenge by incorporating “development boards.” development boards are very common because of the large size of worldwide commercial ultrasound Such development boards are very common becauseboards of theoften largetakes size aoftoll worldwide commercial market. However, incorporating multiple development on the compactness of ultrasound market. However, incorporating multiple development boards often a toll as onwell the the prototype. A greater usage of integrated circuits having multiple channel pulser,takes receivers, compactness ofsame the prototype. greater usage ofopen-architecture integrated circuitsultrasound. having multiple channel pulser, as ADC on the chip, will A result in compact receivers, as well as ADC on the same chip, will result in compact open-architecture ultrasound..

(8) Electronics 2019, 8, 1256 Electronics 2019, 8, 1256. 7 of 25 7 of 25. Toconclude, conclude,for fora ahigh-frequency high-frequency low noise healthcare project as ultrasound, a designer To low noise healthcare project suchsuch as ultrasound, a designer may may itfind verytouseful to aleverage a range of evaluation off-the-shelf evaluation boards for FPGA, find very ituseful leverage range of off-the-shelf boards for FPGA, microprocessor, microprocessor, analog to digital converter, ultrasonic pulser, front end etc. System on Chip,System analogontoChip, digital converter, ultrasonic pulser, analog front analog end etc. Although Although has been great for platforms, ultrasonic platforms, it is use high FPGA has FPGA been used with used great with success forsuccess ultrasonic it is possible topossible use hightofrequency frequency microcontrollers simpler designs [47,53]. microcontrollers for simplerfor designs [47,53]. 3. Computed Tomography Tomography Scanner Scanner Based Based on on Open Open Electronics Electronics X-ray Computed Computed Tomography Scanner Scanner (CT scanner) scanner) is is an an important important piece piece of of medical medical equipment equipment widely usedininthe thehealthcare healthcare industry. CT Scanning is for used for[57], brain [57], neck [58], lungs widely used industry. CT Scanning is used brain neck [58], lungs [59], liver [59], [60], liver [61], and numerous other diagnosis. typical CT-scan series of planar heart[60], [61],heart and numerous other diagnosis. A typicalACT-scan consists consists of seriesofof planar X-ray X-ray scans scans combined together. One the earliest X-ray apparatus for hobbyists described C.L.Tong combined together. One of theofearliest X-ray apparatus for hobbyists waswas described by by C.L.Tong in in Amateur Scientist in 1974. A large number of webpages describe X-ray scanners TheThe Amateur Scientist [35][35] in 1974. A large number of webpages describe X-ray scanners [62,63],[62,63], which which can be by hobbyists. main components an X-Ray scanner the(for X-Ray tube can be built bybuilt hobbyists. The mainThe components of an X-Rayofscanner are the X-Rayare tube example(for example-Coolidge tube, rotated anode tube, etc.) and a high voltage power supply, as shown Coolidge tube, rotated anode tube, etc.) and a high voltage power supply, as shown in Figure 8. in In Figure 8. In States, the United States, United Nuclear [64]aisnumber selling aofnumber of x-ray products-the x-ray the United United Nuclear [64] is selling x-ray products-the x-ray tube andtube the and thesupply. power As supply. Ascompany per the company website, the components do not require any Further, licensing. power per the website, the components do not require any licensing. a Further, a large of number x-ray are tubes are easily available on popular websites suchasaswww.ebay.com. www.ebay.com. large number x-rayoftubes easily available on popular websites such Additionally, Additionally,aa number number of of radioactive radioactive sources sources with with low low radiation (and hence not requiring licensing) are available from $80–$400 from a number of vendors are available from $80–$400 from a number of vendors(for (forexample example[65,66]). [65,66]).. (a). (b) Figure 8. Basic components of an X-ray tube: (a) Coolidge side window tube-A: anode, C: cathode, X: Figure 8. Basic components of an X-ray tube: (a) Coolidge side window tube-A: anode, C: cathode, X: X-rays, Ua and Uh : voltages, Win and Wout : water inlet and outlet (cooling device) (b) Rotating anode X-rays, Ua and Uh: voltages, Win and Wout: water inlet and outlet (cooling device) (b) Rotating anode tube: A: anode, C: cathode, T: anode target, W: X-ray window. Images from [67] ((a): public domain tube: A: anode, C: cathode, T: anode target, W: X-ray window. Images from [67] (8(a): public domain image from www.wikipedia.org and (b) reused under Creative Commons license CC BY-SA 3.0). image from www.wikipedia.org and (b) reused under Creative Commons license CC BY-SA 3.0).. Some typical X-ray tubes are shown in Figure 9. The supply voltage and short circuit current Some X-ray are25shown in1.5 Figure 9. The supply voltage short circuit current specified fortypical a typical tubetubes [64] are KV and mA respectively. Further, theand minimum input voltage specified for a typical tube [64] are 25 KV and 1.5 mA respectively. Further, the minimum input and current as per [64] are mentioned as 12 volts and 1.5 A DC respectively. Hence, we can anticipate voltage and current as per [64] are mentioned as 12 volts and 1.5 A DC respectively. Hence, we can that maximum power requirement for a hobbyist/open-source X-Ray to be around 18–20 voltages. anticipate that maximum power requirement for a hobbyist/open-source be around 18–20 Since the power requirement is quite low, in addition to using bench-topX-Ray powertosupplies (present voltages. Since the power requirement is quite low, in addition to using bench-top power supplies state-of-art), it is feasible to use various small form factor DC-DC power conversion modules. Another (present state-of-art), it is feasible to use various small form factor DC-DC power conversion modules..

(9) Since the major components of CT scanner, the X-ray tube, and high voltage power supply are already available online, some open-source CT scanner designs [68,69] are freely available. Additionally an optical scanner, shown in Figure 11 is described [70] which can form the basis of xray CT scanner, if properly coupled to an X-Ray tube and high voltage power source. One of the Electronics 2019, 8, x FOR PEER REVIEW 8 of 25 Electronics 2019, 8, 1256 (shown in Figures 10 and 11) has active open-source repositories. Ben 8Krasnow of 25 scanners from Jansen 223has described Another approach is to a “ZVS controlled flyback transformer” as described in scanner great detail the details of design an Arduino® do it yourself (DIY) CT [71]inin[63]. a video 224posted Designing a power supply can further reduce costs as well and result in a compact device. online.isKrasnow alsoflyback described an innovative use ofinvarious image processing software approach to design has a “ZVS transformer” as described great detail in [63]. Designing a 225to processSince the major components of CT scanner, the X-ray tube, and high voltage power supply are power CT-scans. supply can further reduce costs as well and result in a compact device.. 226 227 228 229 230 231 232. already available online, some open-source CT scanner designs [68,69] are freely available. Additionally an optical scanner, shown in Figure 11 is described [70] which can form the basis of xray CT scanner, if properly coupled to an X-Ray tube and high voltage power source. One of the scanners from Jansen (shown in Figures 10 and 11) has active open-source repositories. Ben Krasnow has described the details of an Arduino® controlled do it yourself (DIY) CT scanner [71] in a video posted online. Krasnow has also described an innovative use of various image processing software to process CT-scans.. 233 234 235. Figure 9. X-Ray tube and circuit for a typical power supply [63] (Creative Commons CC BY-NC-SA 4.0 license). 4.0 license). Since the major components of CT scanner, the X-ray tube, and high voltage power supply are already available online, some open-source CT scanner designs [68,69] are freely available. Additionally an optical scanner, shown in Figure 11 is described [70] which can form the basis of x-ray CT scanner, if properly coupled to an X-Ray tube and high voltage power source. One of the scanners from Jansen (shown in Figures 10 and 11) has active open-source repositories. Ben Krasnow has described the details 9. X-Ray tube and for a typical supply[71] [63]in(Creative CC BY-NC-SA of anFigure Arduino®controlled docircuit it yourself (DIY) power CT scanner a video Commons posted online. Krasnow has 4.0 license). also described an innovative use of various image processing software to process CT-scans.. Figure 9. X-Ray tube and circuit for a typical power supply [63] (Creative Commons CC BY-NC-SA. Figure 10. Arduino® based optical scanner as described in [70] (Creative Commons CC BY 4.0 license).. 236 237 238. Figure 10. Arduino®based optical scanner as described in [70] (Creative Commons CC BY 4.0 license). Figure 10. Arduino® based optical scanner as described in [70] (Creative Commons CC BY 4.0 license)..

(10) Electronics 2019, 8, 1256. 9 of 25. Electronics 2019, 8, 1256. 9 of 25. Figure Figure 11. 11. An An active active open-source open-source X-Ray X-Ray CT CT scanner scanner [68,69] [68,69] (Creative Commons CC BY 4.0 license).. strong potential to be developed developed for The open-source CT scanner developed by Jansen [68] has a strong This scanner scanner is is currently currently in the development stage with a small medical tomography and diagnosis. This build and scan volume suitable for scanning small objects (size of an apple). The CT scanners used medical industry industry have have aa large large scan scan volume volume as as they they employ employ aa sizeable sizeable x-ray x-ray source, source, detector, detector, by the medical and related optical setup, which which rotates rotates around around the the specimen specimen object object (adult (adult human). human). On Onthe thecontrary, contrary, [68] consists consists of a small stationary radioactive source, parallel the open-source CT scanner ver. 22 [68] detectors, and and optics optics but but instead instead has has aa rotating rotating gantry gantry to to rotate rotate the the specimen specimen object object for for imaging, imaging, detectors, volume. TheThe smaller size of theof source (limited(limited by power) detectors consequently limiting limitingthe thescan scan volume. smaller size the source by and power) and (limited by(limited lower resolution) limits the applicability this open-source CT open-source scanner. detectors by lower severely resolution) severely limits theofapplicability of this CT A CT scanner is a sophisticated device integrating complex electronics, mechanical assembly, scanner. and A software. For isthe open-source CT scanner to mature in functionality and applicability, the CT scanner a sophisticated device integrating complex electronics, mechanical assembly, electronics and For the related software development significant attention and development. Some and software. the open-source CT scanner needs to mature in functionality and applicability, the of the challenges involve high-resolution imaging by integrating smalldevelopment. x-ray tubes, which electronics and the relateddeveloping software development needs significant attention and Some will theinvolve source developing power, andhigh-resolution by increasing the number of parallel small detectors of of theimprove challenges imaging by integrating x-raycomprising tubes, which low-cost radiation sensors, theand detector array’s the resolution be improved. will improve the source power, by increasing number can of parallel detectors Furthermore, comprising of with lowadditional high-resolution detectors and complex optics, a more sophisticated 3D-slicer is cost radiation sensors, the detector array's resolution can be improved. Furthermore, withsoftware additional required for further improvement. The mechanical tomographic platform deployed in the open-source high-resolution detectors and complex optics, a more sophisticated 3D-slicer software is required for CT scanner is simple, compact, customizable, and modular. Additionally, for integrating x-ray sources, further improvement. The mechanical tomographic platform deployed in the open-source CT better shielding requiredcustomizable, as the currentand mechanical consistsfor of integrating a wooden assembly and scanner is simple,iscompact, modular. setup Additionally, x-ray sources, framework. Despite all the shortcomings, the mechanical developments in open-source scanningassembly are promising better shielding is required as the current setup consists ofCT a wooden and as a multitude of scansallperformed on organic the samples have been reported [68]. framework. Despite the shortcomings, developments in open-source CT scanning are promising as a multitude of scans performed on organic samples have been reported [68]. 4. Electrocardiograph (ECG/EKG), Electroencephalogram (EEG) and Neurological Monitoring. 4. Electrocardiograph (ECG/EKG), (EEG) Neurological Monitoring ECG is perhaps one of the mostElectroencephalogram widely prototyped [72–81] andand well-documented medical devices usingECG openis electronics. ECG is a most widely used for medical diagnosis andwell-documented monitoring. Most of the perhaps one of the widely prototyped [72–81] and medical open platform ECGelectronics. devices have theisadvantage of being readily connected to the Internet using devices using open ECG a widely used for medical diagnosis and monitoring. MostIoT of functionalities which are a regular part of open electronics boards such as Arduino®(Figure 12) and the open platform ECG devices have the advantage of being readily connected to the Internet using. IoT functionalities which are a regular part of open electronics boards such as Arduino® (Figure 12) and Raspberry Pi. ECG signals require a very high signal to noise ratio and very low noise amplification with high common-mode rejection ratio amplifier. Such an amplification system is very.

(11) 256 Electronics 2019, 8, 1256. 10 of 25. gn using discrete electronic components. However, most of the EC Raspberry Pi. ECG signals require a very high signal to noise ratio and very low noise amplification zed “analog front ends” such as AD8232 and ADAS1000 ECG mo with high common-mode rejection ratio amplifier. Such an amplification system is very difficult to design using discrete electronic components. However, most of the ECG projects have utilized latform for ECG appears to be Arduino® [73–76,79], some projects h specialized “analog front ends” such as AD8232 and ADAS1000 ECG modules. While the most popular platform for ECG appears to be Arduino® [73–76,79], some projects have also focused on ms such as Raspberry Pi and ESP32 [78,80,81]. other platforms such as Raspberry Pi and ESP32 [78,80,81].. Figure 12. Schematic and final breadboard ECG circuit using an Arduino® [75] (Creative Commons. chematic andCCfinal breadboard ECG circuit using an Arduino® [75] (Creativ BY 3.0 license). Open-BCI [82] offers EEG, ECG, and EMG for brain, muscle, and heart monitoring on a single cense). platform. The hardware platform is open-source and Arduino®-compatible (Figure 13). The platform has been very successful with the scientific community and has been utilized in many peer-reviewed research articles. Similar to OpenBCI, there are several other platforms offering multiple biosensor integration and the reader is directed to Niezen et al. [22] for further reading.. [82] offers EEG, ECG, and EMG for brain, muscle, and heart monito ardware platform is open-source and Arduino®-compatible (Figure 1 uccessful with the scientific community and has been utilized in man s. Similar to OpenBCI, there are several other platforms offering mu.

(12) Electronics 2019, 8, 1256 Electronics 2019, 8, 1256. 11 of 25 11 of 25. Figure 13. OpenBCI platform and headset [82] (Creative Commons CC BY CC 3.0 license). Figure 13. OpenBCI platform and headset [82] (Creative Commons BY 3.0 license).. Other than medical device, thanks to readily available IoT functionality, openthanbeing beinga alow-cost low-cost medical device, thanks to readily available IoT functionality, source ECG/EKG offers an unprecedented advantage in diagnosis of epilepsy, strokes etc. Various open-source ECG/EKG offers an unprecedented advantage in diagnosis of epilepsy, strokes etc. researchresearch papers [83–87] highlighted the role of abnormalabnormal neurological activity, Various papershave [83–87] have highlighted theECG rolein ofdetecting ECG in detecting neurological such as epileptic seizures.seizures. Hence, using a low-cost platform, it is possible not only activity, such as epileptic Hence, using a ECG low-cost ECG platform, it isto possible todiagnose not only abnormal neurological activity but perhaps forewarn an impending neurological condition. diagnose abnormal neurological activity buttoperhaps toabout forewarn about an impending neurological Open-source electronicselectronics are highlyare relevant such platforms being widely by patients all over condition. Open-source highlytorelevant to such platforms beingused widely used by patients the world a low at cost. Open electronics platformsplatforms also provide unique to integrate all over theatworld a low cost. Open electronics alsothe provide theopportunity unique opportunity to multiple sensors such as such accelerometers, temperature sensors, humidity sensors, galvanic skin integrate multiple sensors as accelerometers, temperature sensors, humidity sensors, galvanic response, brainbrain waves, andand others to monitor and perhaps predict skin response, waves, others to monitor and perhaps predictabnormal abnormalneurological neurologicalactivity. activity. An article by Sriram Ramgopal and co-workers [84] provides a highly relevant list of sensor platforms platforms manage seizures. seizures. Additionally, which can be used to manage Additionally, some open electronics platforms platforms [88–91] are available for forseizure seizure detection. However, research data are before needed before any drawing any detection. However, moremore research data are needed drawing conclusion conclusion about practical utility of such platforms. about practical utility of such platforms. Apart from reducing the cost of of neurological neurological monitoring, monitoring, open open electronics electronics offers offers the opportunity opportunity to collect data using common data interchange formats such as JSON. Such data can be collected and shared by multiple researchers around the world using machine learning. Open Open electronics electronics also offers offers practically unlimited modularity-multiple sensors that can be selectively used, resulting in more data for predicting electronics offers a unique opportunity to predicting abnormal abnormalneurological neurologicalactivity. activity.Hence Henceopen open electronics offers a unique opportunity treat and manage potentially life-threatening medical conditions. Recent works by Vergara andand coto treat and manage potentially life-threatening medical conditions. Recent works by Vergara workers [36][36] cancan be referred forfor such an an IoT-based seizure prediction. co-workers be referred such IoT-based seizure prediction. The various open/open-source BCI and neurological devices devices are significantly mature in their development, andthey theyare areemployed employed medical professionals researchers globally for EEG, development, and byby medical professionals andand researchers globally for EEG, ECG, ECG, and EMG measurement analysis. However, BCI technology doesnot notclassify classifyneural neural activity and EMG measurement and and analysis. However, BCI technology does accurately. It detects the smallest smallest of changes changes in the energy radiated radiated by the brain when it thinks in a certain way; BCI recognizes specific energy/frequency patterns in the brain. Additionally, the most limiting factor of BCI is interfacing. BCIs placed outside the skull have limited ability to read the brain.

(13) signals because of high attenuation by the skull. However, with advancements in low noise amplifiers, we can expect more robust open-source BCIs. For more advanced research, a headset with 32–128 electrodes is required, which is much beyond 2019, the capacity of any OpenBCI boards and headsets. The Cyton board offered by OpenBCI, Electronics 8, 1256 12 of 25 which is a 16-channel board suitable for most applications, but for more complex arrangements of electrodes, a daisy chain or a parallel arrangement setup may be required, thus escalating the cost of certain way; BCI recognizes specific the brain. Additionally, the most hardware. Hence a moderately higherenergy/frequency cost of OpenBCI patterns devices isinanother disadvantage compared to limiting factor of BCI is interfacing. BCIs placed outside the skull have limited ability to read the brain some of the commercial BCI devices with limited functionality such as NeuroSky MindWave signals because of high attenuation by the skull. However, with advancements in low noise amplifiers, headsets. we can expect more robust open-source BCIs. For more advanced research, a headset with 32–128 electrodes is required, which is much beyond 5. Electric Impedance Tomography the capacity of any OpenBCI boards and headsets. The Cyton board offered by OpenBCI, which is a Electrical impedance tomography (EIT) is noninvasive medical imaging to monitor 16-channel board suitable for most applications, but for more complex arrangements of electrodes, physiological functions on the basis of the conductivity or permittivity of body-tissue. The technique a daisy chain or a parallel arrangement setup may be required, thus escalating the cost of hardware. involves taking electrical measurements at the surface of the body by employing conducting Hence a moderately higher cost of OpenBCI devices is another disadvantage compared to some of the electrodes that are attached to the skin and applying small (mA) alternating currents. The resulting commercial BCI devices with limited functionality such as NeuroSky MindWave headsets. electrical potentials are measured to infer the electrical conductivity, impedance, and permittivity of a part of the body to form a tomographic image of that part. 5. Electric Impedance Tomography In recent years, numerous open-source EIT devices based on Arduino® platforms have been Electrical impedance tomography (EIT) such is noninvasive medical imaging to monitor reported for a host of diagnosis applications as stroke [93], pulmonary diseases [94], physiological epilepsy [95], functions on the basis of the conductivity or permittivity of body-tissue. The technique involves taking neurology [92], and generic systems [96]. The EIT system developed by Avery et al. [92], known as electrical measurements at the surface of the body by conducting electrodes (as shown in ScouseTom for brain imaging application (Figure 14)employing is one of the most versatile and reproducible Figure that arebe attached to the and applyingapplications. small (mA) alternating currents. The resulting devices14) that can modified for skin other diagnostic The versatile applicability of the electrical potentials are measured to infer the electrical conductivity, impedance, and permittivity a ScouseTom system can be estimated from work reported by Goren et al. [93], which used of the part of the body to form a tomographic image of that part. ScouseTom system for stroke patients.. Figure 14. Overview of the ScouseTom system [92] (Creative Commons CC BY 4.0 license). Figure 14. Overview of the ScouseTom system [92] (Creative Commons CC BY 4.0 license).. A conventional system open-source constitutes a EIT current source, switching circuitry to address multiple In recent years, EIT numerous devices based on Arduino®platforms have been electrodes, a voltage measurement unit, and a controller to automate the measurement process. In a reported for a host of diagnosis applications such as stroke [93], pulmonary diseases [94], epilepsy [95], typical EIT system, an alternating current of a defined amplitude and frequency in a range of 10 neurology [92], and generic systems [96]. The EIT system developed by Avery et al. [92], knownHz as to 1 MHz is injected through a pair of electrodes, with electric potential measured at all electrodes ScouseTom for brain imaging application (Figure 14) is one of the most versatile and reproducible devices (generally to 256). for Theother measurement employs low noise amplifiers capable measuring that can beup modified diagnosticcircuitry applications. The versatile applicability of theofScouseTom ~100 nV, typically characterized by SNR > 75 dB. These et voltage measurements canScouseTom be obtainedsystem either system can be estimated from work reported by Goren al. [93], which used the for stroke patients. A conventional EIT system constitutes a current source, switching circuitry to address multiple electrodes, a voltage measurement unit, and a controller to automate the measurement process. In a typical EIT system, an alternating current of a defined amplitude and frequency in a range of 10 Hz.

(14) Electronics 2019, 8, 1256. 13 of 25. to 1 MHz is injected through a pair of electrodes, with electric potential measured at all electrodes 13 of 25 (generally up to 256). The measurement circuitry employs low noise amplifiers capable of measuring ~100 nV, typically characterized by SNR > 75 dB. These voltage measurements can be obtained either serially or in parallel on all electrodes. The open-source ScouseTom EIT systems (details shown in serially or in parallel on all electrodes. The open-source ScouseTom EIT systems (details shown in Figure 15) are compatible with these standards and finding numerous applications in neurological Figure 15) are compatible with these standards and finding numerous applications in neurological imaging, stroke diagnosis, epilepsy, and other related fields. For more details about the ScouseTom imaging, stroke diagnosis, epilepsy, and other related fields. For more details about the ScouseTom system, the reader cancan refer toto[92]. havereported reportedanan Arduino® based generic system, the reader refer [92].Dimas Dimaset etal. al. [96] [96] have Arduino®based generic EIT EIT system thatthat employs upup to to 6464electrodes be employed employedfor fora host a host of applications system employs electrodes and and can can be of applications suchsuch as as pulmonary, throat, cervix, and Arduino® based system developed pulmonary, throat, cervix, andbreast breastdiagnosis. diagnosis. Another Another Arduino®based EITEIT system developed by by Chitturi et al.et [94] hashas been extensively pulmonarydisease disease and modeling. a simple Chitturi al. [94] been extensivelyused used for pulmonary and modeling. ThisThis is a is simple design to reproduce and and getting as itas integrates off-shelfoff-shelf components and open-source design to reproduce gettingstarted started it integrates components and software, open-source EIDORS, for image reconstruction. software, EIDORS, for image reconstruction. Electronics 2019, 8, 1256. Figure 15. Arduino®-based electrical impedance tomography (EIT) system (Creative Figure 15. Schematic Schematicofof Arduino®-based electrical impedance tomography (EIT)[92] system [92] Commons CC BY 4.0 license). (Creative Commons CC BY 4.0 license).. The open-source EIT devices such as ScouseTom are technologically mature for both research. Thecommercial open-source EIT devices as ScouseTom are as technologically mature forand both research and deployment for such a variety of applications, the front-end electronics control and system commercial deployment a variety of applications, as the front-end electronics and control involved in this havefor already been developed and matured more than a decade ago. However, system this have already been developed matured more and thandevelopment a decade ago. However, for involved fast neuralinactivity measurements and imaging, and significant research work is required. of themeasurements major problems and withimaging, most EIT significant systems is the inabilityand to process continuous for fast neuralOne activity research development work is impedance signals with other additional signals such as EEG, both of which are necessary for EIT required. One of the major problems with most EIT systems is the inability to process continuous of fast-neural FPGA-based data acquisition and processing be necessary implemented impedance signalsactivity. with other additional signals such as EEG, both of need whichtoare for as EIT of Arduino®based systems cannot handle the massive influx of data that drastically increases the fast-neural activity. FPGA-based data acquisition and processing need to be implemented as complexity and processing as the number of electrodes and scanning frequency increases. Further, Arduino® based systems cannot handle the massive influx of data that drastically increases the performing the signal processing on Arduino®based hardware severely limits the ability to adjust complexity and processing as the number of electrodes and scanning frequency increases. Further, parameters such as carrier frequency, scanning and measurement speed, and filter bandwidth to meet performing theapplication signal processing on Arduino® based popularity hardwareof severely the ability to adjust the diverse requirements. With the recent various limits FPGA-based low noise parameters as carrier frequency, scanning and measurement and filter bandwidth and highsuch frequency open-source projects for ultrasound (Section 2), we speed, can expect open-source EIT to to meetfollow the diverse application requirements. With the recent popularity of various FPGA-based low the same trend of using off-the-shelf FPGA modules. noise and high frequency open-source projects for ultrasound (section 2), we can expect open-source 6. follow Infusion Pumps EIT to the same trend of using off-the-shelf FPGA modules. Infusion pumps or syringe pumps are one of the most widely used medical devices. Infusion. 6. Infusion Pumps pumps are used to deliver nutrients and medications to patients. Some reports have suggested that the global market for infusion pumps are in tens of billions of US$ [97,98]. A 2010 white paper [99] by Infusion pumps or syringe pumps are one of the most widely used medical devices. Infusion the United States Food and Drug Administration (FDA) cites a market research estimation of over 2. pumps are used to deliver nutrients and medications to patients. Some reports have suggested that the global market for infusion pumps are in tens of billions of US$ [97,98]. A 2010 white paper [99] by the United States Food and Drug Administration (FDA) cites a market research estimation of over 2 million external infusion pumps in the United States in the year 2006. Hence, infusion pump devices are a very high impact and still a growing class of medical devices..

(15) worldwide suffer from diabetes. However, despite such a high global demand, the cost of a typic nsulin pump is between $7000–$10,000. AlthoughElectronics small2019, volume drug delivery pumps such as insulin pumps require a high degree 8, 1256 14 of 25 recision and reliability, open electronic platforms have shown tremendous promise in reducing th ost and at themillion sameexternal time infusion a promise and reliability. Niezen and co-worke pumpsof in maintaining the United States precision in the year 2006. Hence, infusion pump devices are a veryof high impacthardware and still a growing class of medical devices. 22], in their review open medical devices have provided an excellent compilation Advanced small volume infusion pumps (an example shown in Figure 16) require precise control uch medical pumps. The authors have also reviewed glucose monitors such as Diabeto, Nightscou of fluid dispensation mechanism and cost anywhere between a few hundred dollars to few thousand nd X-Drip [102–104] are critical tocrucial designing opendrug hardware-based insulin pumps. A recen US dollars.which Such smaller pumps are for controlled delivery, such as insulin. In 2016, the Time magazine voted a new “smart” insulin pump [37] as onecommercially of the top 20 inventions of the year. pen-source project [100,101] has used components from available syringe pump Millions of people worldwide suffer from diabetes. However, despite such a high global demand, hown in Figure 16)ofin combination with open$7000–$10,000. hardware and software. the cost a typical insulin pump is between. Figure 16. A raspberry pi controlled insulin infusion pump [100,101] (Creative Commons CC BY 4.0 Figure 16. A raspberry pi controlled insulin infusion pump [100,101] (Creative Commons CC BY 4.0 license from www.raspberrypi.org). license from www.raspberrypi.org).. Although small volume drug delivery pumps such as insulin pumps require a high degree of precision and reliability, open electronic platforms have shown tremendous promise in reducing the While thecost development of open hardware insulin mentioned the previous projects and at the same time a promise of maintaining precisionpumps and reliability. Niezen andin co-workers [22], their review open hardware medical components devices have provided an excellent compilation of such pumps. Suc ncouraging, instill, theseofprojects require from commercial insulin medical pumps. The authors have also reviewed glucose monitors such as Diabeto, Nightscout, omponents cost a few hundred to several thousand US dollars. Commercial insulin pumps a and X-Drip [102–104] which are critical to designing open hardware-based insulin pumps. A recent microfluidics devices although it is outside thefrom scope of this available study to calculate open-sourceand project [100,101] has used components commercially syringe pumps the precisio (shown in Figure 16) initcombination open hardware and software. equired for actuating them, is likelywith that the actuation precision is comparable to that of 3While the development of open hardware insulin pumps mentioned in the previous projects rinters. Sinceis encouraging, most of the printers now routinely open insulin electronic such a still, 3-D these projects require components fromuse commercial pumps. hardware Such cost a few hundred several thousand US dollars. Commercial insulin pumps are rduino®, it iscomponents highly likely that in thetofuture, there will be fully open low volume medical pump microfluidics devices and although it is outside the scope of this study to calculate the precision ncouraging developments in this direction are numerous recent studies on open electroni required for actuating them, it is likely that the actuation precision is comparable to that of 3-D printers. microfluidics [105–109]. White and now co-workers have developed Arduino®-based kit (a Since most of the 3-D printers routinely use[110] open electronic hardware suchan as Arduino®, it is highly likely that in the future, there will be fully open low volume medical pumps. Encouraging xample shown in Figure 17) for microfluidics control. developments in this direction are numerous recent studies on open electronics microfluidics [105–109]..

(16) Electronics 2019, 8, 1256. 15 of 25. White and co-workers [110] have developed an Arduino®-based kit (an example shown in Figure 17) for microfluidics control. Electronics 2019,8,8,1256 1256 Electronics 2019, 1515ofof2525. Figure 17. AAmicrofluidics microfluidics syringe pump described by Lake and co-workers [106] (Creative Commons Figure17. 17.A microfluidicssyringe syringepump pumpdescribed describedby byLake Lakeand andco-workers co-workers[106] [106](Creative (CreativeCommons Commons Figure CC BY 3.0 license). CCBY BY3.0 3.0license). license). CC. While small volume infusion pumps such asasinsulin present challenge, many larger volume Whilesmall smallvolume volumeinfusion infusionpumps pumpssuch suchas insulinpresent presentaaachallenge, challenge,many manylarger largervolume volume While insulin peristaltic pumps based on Arduino®, Raspberry pi etc., can be found from popular vendors such asas peristalticpumps pumpsbased basedon onArduino®, Arduino®,Raspberry Raspberrypipietc., etc.,can canbebefound foundfrom frompopular popularvendors vendorssuch suchas peristaltic Sparkfun [111], Adafruit [112], etc. Although the hobbyist community has mostly used these pumps Sparkfun[111], [111],Adafruit Adafruit[112], [112],etc. etc.Although Althoughthe thehobbyist hobbyistcommunity communityhas hasmostly mostlyused usedthese thesepumps pumps Sparkfun for non-medical applications, it is possible that they can be used in medical application after proper fornon-medical non-medicalapplications, applications,ititisispossible possiblethat thatthey theycan canbebeused usedininmedical medicalapplication applicationafter afterproper proper for scientific and medical studies. Kassis etetal. al. [113] have developed biocompatible Raspberry pi-based scientificand andmedical medicalstudies. studies.Kassis Kassiset al.[113] [113]have havedeveloped developedaaabiocompatible biocompatibleRaspberry Raspberrypi-based pi-based scientific piezoelectric pump driver (Figure 18). Such pump driver can be very crucial tototruly truly open-source piezoelectricpump pumpdriver driver(Figure (Figure18). 18).Such Suchaaapump pumpdriver drivercan canbe bevery verycrucial crucialto trulyopen-source open-source piezoelectric small infusion pumps. smallinfusion infusionpumps. pumps. small. Figure18. 18.Pi-flow Pi-flowfrom fromKassis Kassiset [113](Creative (CreativeCommons CommonsCC CCBY BY4.0 4.0license). license). Figure 18. Figure Pi-flow from Kassis etetal al.al[113] [113] (Creative Commons CC BY 4.0 license).. Whileinfusion infusionpumps pumpshave been very widely prototyped using open electronic platforms, key While widely prototyped using open electronic platforms, a akey While infusion pumps havebeen beenvery very widely prototyped using open electronic platforms, a challenge that forsmall small volume pumps (such insulin), these open-source projects still rely on challenge isisthat for volume pumps (such asasinsulin), these open-source projects still rely on key challenge is that for small volume pumps (such as insulin), these open-source projects still rely components from commercial devices. Therefore, the challenge infabricating fabricatingbiocompatible biocompatible components from commercial devices. Therefore, the on components from commercial devices. Therefore, thechallenge challengelies liesin in fabricating small-volumeliquid liquiddispensing dispensingsystems. systems.While Whilethe thehobbyist hobbyistcommunity communityhas hasmade madesignificant significant small-volume small-volume liquid While the hobbyist community has made contributions, this is an area of research which would involve significant effort from well-established contributions, this is an an area area of of research research which which would would involve involve significant significant effort effort from from well-established well-established scientificresearch researchgroups groupsin inthe thefield fieldofof ofmicrofluidics andnanofluidics. nanofluidics. With rapid developments scientific With rapid developments inin scientific research groups in the field microfluidicsand nanofluidics. With rapid developments field microfluidics and their associate open electronics-based drivers/controllers suchas asthose those the field ofofmicrofluidics and their associate open electronics-based drivers/controllers such inthe the field of microfluidics and their associate open electronics-based drivers/controllers such as described in [113], we can expect more open-source small volume infusion pumps. For larger volume described in [113], canwe expect more open-source small volume infusioninfusion pumps. pumps. For larger volume those described inwe [113], can expect more open-source small volume For larger infusioninfusion pumps,the theopen-source/open open-source/open electronics projectsseem seem have already reached significant infusion pumps, electronics projects totohave already reached a asignificant volume pumps, the open-source/open electronics projects seem to have already reached a levelofofmaturity. maturity. However,However, thereisisstill still significant roomfor forroom improvement largevolume pumps level there a asignificant room improvement ininlarge pumps significant level ofHowever, maturity. there is still a significant for improvement involume large volume byutilizing utilizing fullpotential potential openelectronics. electronics. Forexample-integration example-integration withvarious various other biomedical by full ofofopen For with other biomedical pumps by utilizing full potential of open electronics. For example-integration with various other sensors,bubble bubbledetection, detection,IoT IoTconnectivity, connectivity,incorporating incorporatingAI AIand anddeep deeplearning learningfor foroptimal optimaldosage. dosage. sensors, greaterinteraction interactionbetween betweenphysicians/healthcare physicians/healthcareworkers workersand andthe theopen-source open-sourceprototyping prototyping AAgreater communityisisrequired requiredfor forfully fullyutilizing utilizingthe thepotential potentialoffered offeredby bymaking makinglarge largevolume volumeinfusion infusion community pumpsopen opensource. source. pumps.

(17) Electronics 2019, 8, 1256. 16 of 25. biomedical sensors, bubble detection, IoT connectivity, incorporating AI and deep learning for optimal dosage. A greater interaction between physicians/healthcare workers and the open-source prototyping community is required for fully utilizing the potential offered by making large volume infusion pumps open source. Electronics 2019, 8, 1256 16 of 25 7. Miscellaneous Medical Medical Devices: Devices: Wearables, Wearables, Posture Posture Detection, Detection, and 7. Miscellaneous and Sensor Sensor Networks Networks Other devices such such as as ultrasound, X-ray CT, CT, ECG, Other than than the the highly highly specialized specialized medical medical devices ultrasound, X-ray ECG, and and infusion pumps discussed in previous sections, there is a wide range of miscellaneous medical devices infusion pumps discussed in previous sections, there is a wide range of miscellaneous medical that have utilized open electronics platforms. Primarily, such devices constitute wearables (fitness devices that have utilized open electronics platforms. Primarily, such devices constitute wearables monitoring) and simple sensor networks (accelerometer, temperature, pulse rate, blood pressure, etc.,). (fitness monitoring) and simple sensor networks (accelerometer, temperature, pulse rate, blood Haghi et al. [114] have reviewed a wide range of commercial wearable and motion tracking devices. pressure, etc.,). Haghi et al. [114] have reviewed a wide range of commercial wearable and motion Accelerometers, and gyroscopes, temperatureand sensors are the primary components ofcomponents majority of tracking devices.gyroscopes, Accelerometers, temperature sensors are the primary wearable motion tracking devices. For more advanced wearable devices described in [114], additional of majority of wearable motion tracking devices. For more advanced wearable devices described in sensors such as heart rate sensors are incorporated. Given the easy availability of all these sensors [114], additional sensors such as heart rate sensors are incorporated. Given the easy availability of all these for platforms such as Arduino®and Raspberry Pi, it is possible researchers to easily put together sensors for platforms such as Arduino® and Raspberry Pi, it is for possible for researchers to easily put atogether wireless wearable platform at a very low cost, for example: Mukherjee and co-workers [115] have a wireless wearable platform at a very low cost, for example: Mukherjee and co-workers [115] utilized Arduino®and for for a gesture control device; Rakay have utilized Arduino® accelerometers and accelerometers a gesture control device; Rakayand andco-workers co-workers[116] [116] have have implemented temperature, air flow and body position sensing on Arduino®(Figure 19); Kemis implemented temperature, air flow and body position sensing on Arduino® (Figure 19); Kemis andand coco-workers [117] have implemented Arduino®based heartrate ratemonitor; monitor;Mallick Mallickand and Patro Patro [118] [118] have workers [117] have implemented Arduino® based heart have designed designed an an optical optical heart heart rate rate sensor sensor from from scratch scratch and and utilized utilized ititwith withArduino®. Arduino®. Many Many other other wearable wearable sensors [119–124] based on open electronics are published in scientific literature. sensors [119–124] based on open electronics are published in scientific literature.. Figure19. 19.Temperature, Temperature,pulse pulse++ oxygen oxygen and body position Figure position sensors sensorsas asdescribed describedinin[116] [116](Creative (Creative Commons CC BY 4.0 license). Commons CC BY 4.0 license).. In the field of rehabilitation, there have been a number of studies [125–134] utilizing open electronics for posture detection, monitoring, and correction. Such posture detection mainly utilizes wearable “smart fabrics” [125,127–130,132], accelerometers [126], or ultrasonic sensors [133]. Rawal and Nagtilak [135] have used cameras for drowsiness detection. It is possible to use external cameras.

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