This course involves an group project where users create an assistive technology device that addresses the needs of a client. This requires reading scientific literature, engineering skills, and technical writing. It culminates in a May Assistive Technology fair where students present in front of parents.
Problem Statement
Over 2 million people in the United States live with limb loss (Zhu et al., 2022). This paper will refer to individuals with limb differences as ILDs. Amputation can be very traumatic for a patient, as it often limits their ability to perform activities of daily life (ADLs). Most qualifying amputees will choose to use a prosthetic device to offset the issues caused by the loss of a limb, allowing them some sense of normalcy with the ability to integrate into society without the need for constant assistance. The component of the prosthetic limb that directly contacts the residual limb to form a connection between the body and the prosthetic is the socket. When properly fitted, a comfortable socket can be extremely influential in maximizing the prosthetic’s utility in daily use, as otherwise the discomfort, or in some cases pain, will lead the amputee to abandon their prosthetic (Klute et al., 2001). Under the socket, ILDs must wear a silicone liner below the socket to improve comfort and safety (Zepeda, 2023). The silicone acts as a protective layer between the residual stump and the carbon fiber socket, providing equal pressure distribution and padding for the user’s comfort. On top of this liner, they wear many layers of socks to ensure that the prosthetic device fits snugly.
Despite the benefits of using prosthetics and silicone layers, any amputees notice that after wearing their prosthesis for a few hours, especially if they were physically active in that period, their silicone liners can get very hot, and this often leads to discomfort in the form of irritation, infection, and an excessive buildup of perspiration, all of which may have a highly detrimental effect on quality of life (Ghoseiri & Safari, 2014). Many amputees with lowered quality of life will notice effects such as anxiety, depression, lower social output, and much more (Manz et al,. 2022), as well as a ceasing use of their prosthetics (Williams, 2020). In fact, over 53% of prosthetic users who discontinue use cite discomfort as a primary reason, suggesting that a cooling solution could mitigate non-use by overcoming these side-effects (Webster et al., 2023).
Design Approach
A decision matrix informed our design approach and allowed us to come up with a final design.
We wanted our design to be lightweight and user-friendly, while still cooling the user's residual limb.
Final Prototype
Our final design consists of an Arduino Nano that is connected to a motor controller, which then connects to a Peltier module and a motorized water pump. The Arduino is also connected to a 24V fan through a step-up converter. We use a 12V 2000mA power supply that connects to a wall outlet, and we use a breadboard to connect our power supply to our device. Connected to the water pump is a long stretch of tubing, with a thin 1mm OD tubing lining the inside of the prosthetic. A heat sink is connected to the Peltier module, and the fan is attached on top of the heat sink, adding with it a plastic shell around this part of the device. A resin-printed reservoir is attached between the tubing, serving as an easy way to load water into the system or to deposit water out of the system.
This was the poster we presented at the fair:
Citations
Ghoseiri, K., & Safari, M. R. (2014). Prevalence of heat and perspiration discomfort inside prostheses: literature review. Journal of rehabilitation research and development, 51(6), 855–868. https://doi.org/10.1682/JRRD.2013.06.0133
Klute, G. K., Kallfelz, C. F., & Czerniecki, J. M. (2001). Mechanical properties of prosthetic limbs: adapting to the patient. Journal of rehabilitation research and development, 38(3), 299–307.
Manz, S., Valette, R., Damonte, F., Avanci Gaudio, L., Gonzalez-Vargas, J., Sartori, M., Dosen, S., & Rietman, J. (2022). A review of user needs to drive the development of lower limb prostheses. Journal of neuroengineering and rehabilitation, 19(1), 119. https://doi.org/10.1186/s12984-022-01097-1
Webster, J., Borgia, M., & Resnik, L. (2023). Prosthesis nonuse and discontinuation in United States veterans with major limb amputation: Results of a national survey. Prosthetics and orthotics international, 47(6), 575–585. https://doi.org/10.1097/PXR.0000000000000248
Williams, R. J. (2020). Exploring thermal discomfort amongst lower-limb prosthesis wearers [Doctoral dissertation, University College London]. ProQuest Dissertations & Theses Global. https://discovery.ucl.ac.uk/id/eprint/10095050/
Zepeda, E. (2023, June 29). Prosthetic Liner Guide: Types, Benefits & More. PrimeCare Orthotics and Prosthetics. https://primecareprosthetics.com/blog/prosthetic-liner-guide-types-benefits-more
Zhu, Z., Li, J., Boyd, W. J., Martinez-Luna, C., Dai, C., Wang, H., Wang, H., Huang, X., Farrell, T. R., & Clancy, E. A. (2022). Myoelectric Control Performance of Two Degree of Freedom Hand-Wrist Prosthesis by Able-Bodied and Limb-Absent Subjects. IEEE Transactions on Neural Systems and Rehabilitation Engineering, 30, 893–904. https://doi.org/10.1109/tnsre.2022.3163149