Assembly Testing

Tests were performed to verify the amount of time it takes to construct the Pins Lab Model system in comparison to the amount of time it takes to construct the ML Model system. The Pins Lab Model system is constructed in three phases: construction of 6 PDMS rings, construction of the Thermanox® stage, and placement of fibrin microthreads onto PDMS rings. The ML Model system is constructed in four phases: removal of PDMS frames from mold, cutting of the fibrin microthread fixturing slits, placement of Thermanox® stage onto PDMS frame, and placement of fibrin microthreads into fixturing slits. To perform the assembly tests, four inexperienced users were timed when assembling each stage of the set up for the Pins Lab Model and the ML Model. These times were then compared to verify that the ML Model reduces

the assembly time. Assembly testing validates the ML Model is user friendly, standardized, and efficient.

5.2.1.1 Pins Lab Model Assembly Test

The three phases to construct the Pins Lab Model are construction of 6 PDMS rings, construction of the Thermanox® stage, and placement of fibrin microthreads onto PDMS rings. Each user followed a standard testing protocol (Appendix G) and was timed to determine how long it took to assemble each phase of the model. To create the 6 PDMS rings, cured PDMS was removed from a 11.7 cm by 7.5 cm plate and the edges of the PDMS rectangle were removed using a razor blade (Figure 29A). A ¾ inch diameter leather hole punch tool was used to make the inner diameter of 6 PDMS rings (Figure 29B). Then, a razor blade was used to cut out squares enclosing the punched-out hole in the center (Figure 29C). Once the 6 squares were created, the corners of the squares were removed using a razor blade to create an octagon shape and the sides were cut to ensure they are similar in width (Figure 29D).

Figure 29. Steps taken to construct the 6 PDMS rings for the Pins Lab Model.

To create the Thermanox® stages, first, a syringe was filled with silicone glue. A leather hole punch tool with a 5/32-inch diameter was then used to punch 12 posts out of PDMS (Figure 30A). Thermanox®coverslips were cut into six 3mm by 13mm rectangles, ensuring that the cell treated side of the plastic was not touching the benchtop (Figure 30B-C). The user used the syringe filled with silicone glue to make two dots of glue in the center of the 6-wells (Figure 30D). Then the PDMS posts were placed on the dots of glue using forceps (Figure 30E). Dots of silicone glue were put on the top of the PDMS posts and forceps were used to lay the

Figure 30. Steps taken to construct the Thermanox® stage for the Pins Lab Model.

In order to place the fibrin microthreads, a razor blade was used to create six parallel slits in the PDMS rings, three on each side of the ring (Figure 31A-B). Next a fibrin microthread was removed from the cardboard box, placed on the benchtop, and cut into three equal pieces using a razor blade (Figure 31C). A cut piece of the fibrin microthread is picked up using forceps. To place the fibrin microthread into the slit, the user pulls open the slit with one hand and places the fibrin microthread into the slit using forceps (Figure 31D). Each fibrin microthread was pulled taught on each side (Figure 31E).

Figure 31. Steps taken to construct place fibrin microthreads for the Pins Lab Model.

5.2.1.2 ML Model Assembly Test

The four phases to construct the ML Model include removal of PDMS frames from the mold, cutting of the fibrin microthread fixturing slits, placement of the Thermanox® coverslips onto the PDMS frames, and placement of fibrin microthreads into the fixturing slits. Each user followed the standard testing protocol (Appendix H) and was timed to determine how long it took to assemble each phase of the model.

To remove the PDMS frames from the mold, a microspatula (scoopula) was used to trace the edges of the PDMS frame and lift it out of the mold (Appendix H, Part 3.2) (Figure 32A-C). This was completed for all six frames in the mold (Figure 32D). Each user was timed as they completed Part 1 of the assembly procedure.

Figure 32. Steps taken to construct PDMS Frames for ML Model

The cutting guide and cutting tool were used to create the fibrin microthread fixturing slits in each PDMS frame. Three PDMS frames were aligned in the cutting guide (Figure 33A). Then, the cutting tool was aligned with the marks created on the cutting guide and pressed into the PDMS frames to create the fibrin microthreads fixturing slits (Figure 33B). This procedure was repeated for all six frames and each user timed themselves completing Part 2 of the ML Model assembly process (Appendix H, Part 3.3).

Figure 33. Steps taken to construct fibrin microthread fixation slits using cutting guide and tool

The mold to create the PDMS frames creates a groove in the PDMS frames to hold the Thermanox® coverslips in place. Thermanox® coverslips are cut into 3 x 24.5 mm rectangles using a ruler and scissors, ensuring that the cell treated side of the plastic was not in contact with the benchtop (Figure 34A-B). To place the Thermanox® coverslip into the groove, the user first puts a drop of silicone glue in each groove to hold the Thermanox® coverslip in place (Figure 34C). Then, the user used forceps to place the Thermanox® coverslip into the groove (Figure 34D). This process is repeated for all six frames, and each user was timed to complete Part 3 of the ML Model assembly procedure (Appendix H, Part 3.4).

Figure 34. Steps taken to place Thermanox® stage

In order to place the fibrin microthreads, a fibrin microthread was removed from the cardboard box, placed on the benchtop, and cut into three equal pieces using a razor blade. A cut piece of the fibrin microthread was picked up using forceps. To place the fibrin microthread into the slit, the user pulls open the slit with one hand and places the fibrin microthread into the slit using forceps (Figure 35A). This was completed 3 times for each of the six frames. The fibrin microthreads were pulled taught on each side after placement (Figure 35B-C). Each user was timed to complete Part 4 of the ML Model assembly procedure (Appendix H, Part 3.5).

Figure 35. Steps taken to place fibrin microthreads