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The Washington Research Foundation Fellowship

Aaron Bestick, Electrical Engineering, 2010-11 WRFF

Aaron Bestick photoI have long been interested in tinkering with and building electronics and computers, so getting involved in research seemed like an obvious step after arriving at the UW. I first started in Alex Mamishev's Sensors, Energy and Automation Lab (SEAL) in winter of my sophomore year. Since then, I have worked on a variety of projects, but my current work is on a collaborative project with the Veterans Administration to develop a new shear- and pressure-force sensor for use in prosthetics research.

My research work has given me a host of amazing opportunities that I never would have had otherwise. I have been able to work closely with faculty and other researchers to develop technologies that are quite literally the state of the art in my field, travel to an international conference in Ottawa, Ontario, to present our work, and to collaborate on projects that have helped inspire me to pursue a graduate degree in Electrical Engineering after I finish my undergraduate work. My eventual career goal is to work on the development of sensors or other biomedical devices.

In short, my involvement with research has been one of the most valuable experiences of my time at the UW. It is an honor to receive a Washington Research Foundation Fellowship to continue my work through my senior year.

Mentor: Alexander Mamishev, Electrical Engineering

Project Title: Capactive Shear Force Sensors

Abstract: Skin ulcers and irritation at the interface between a prosthetic device and a patient's residual limb are common problems for amputees. At present, few quantitative methods exist for the measurement and adjustment of the forces exerted at this interface. A need exists for sensing technology which can be used to measure these forces and make precise adjustments to prosthetic geometry to increase wearer comfort. Our research objective is to produce a flexible, stretchable, capacitance-based shear and pressure force sensing array, which could then be integrated into a prosthetic socket liner, attached inside the prosthetic socket, and used to monitor and reduce factors which result in sores and discomfort.

Individual sensor array cells were composed of a top and bottom electrode plate separated by silicone rubber. Attached, microprocessor-based electronics were used to monitor the change in capacitance of each cell as it was deformed under load, and an algorithm was developed to derive the force applied to the cell based on its capacitance change. Finite element modeling was used extensively to optimize both the mechanical and electrical properties of the sensor cells to achieve the necessary sensitivity, dynamic range, and signal-to-noise ratio.

Subsequent research will focus on connecting multiple cells together using stretchable conductors to form a flexible, stretchable sensing array capable of measuring the interfacial force distribution inside a prosthetic socket. Other tasks will include integrating the array and associated electronics into a prosthetic liner, developing improved software to acquire sensor data, and testing and documenting the finished system. The end result of the project will be a complete, integrated sensor system that is ready for preliminary testing by biomedical researchers.