Ultimate strength and cyclic fatigue testing were performed on the telescoping poles of our second prototype iteration. Since the hinges were removed in this new iteration, the maximum load testing was repeated without the hinges as the limiting factor for strength. Both testing methods were measured using a INSTRON universal testing machine. For maximum load testing, a telescoping pole was secured in a vertical position on the bed of the INSTRON, and the load cell was lowered on to the pole at a rate of 5 mm/min to test the pole's maximum compressive load. The poles were able to withstand a compressive force of 5kN (1124 lbs.) without failure, reaching the maximum capacity of the load cell. The only sign of deformation was a slight compression of the pins that adjust the height of the telescoping poles. This component of the device far surpassed our intended weight maximum of 250 pounds, resulting in a safety factor of ~4.5.

Cyclic testing was performed on the other, identical set of telescoping poles at a rate of 30 cycles per minute with a load of 125 pounds. While the ideal amount of testing cycles was determined to be 500,000 based on estimated patient usage, the machine was only available to perform 7650 cycles. At the maximum machine rate, completing 500,000 cycles would've taken 11.5 days to complete, which was not feasible for the team or the lab which offered us the use of their machine. Only slight elongation of the pin was observed over the cycles performed, but the device was still functional and safe. Thank you to Dr. Arin Ellingson and the Minnesota Rehabilitation Biomechanics Lab for the use of their testing machine.

To test the device's functionality, each member donned the device and attempted to walk down a hallway with a tile floor at full weight bearing capacity. Every team member was able to lift and walk with the device without falling, indicating our prototype was both lightweight and stable.

In regards to comfort, every team member expressed dissatisfaction with the seat design. While the seat was made out of foam to provide a comfortable surface to sit on, the foam chosen was not dense enough to resist compression from the weight of each user, so users were in nearly direct contact with the metal bar embedded in the seat. To address this issue, the team constructed the final prototype's seat out of a denser foam to improve comfort.

Another issue is that the device can only be donned and doffed when the patient was standing up. Additionally, attempting to don and doff the device without placing load on the injured leg was very difficult for all team members and required assistance to be done effectively. In future device iterations, the seat mount and upper frame may need to be changed to allow donning and doffing while sitting down (preferred), or the method of attachment may need to be altered so patients can effectively and safely don and doff while standing up.