Distributed Sensing for Prosthetic Sockets

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DESCRIPTION (provided by applicant): The shape and surface conditions of the residual limbs of amputees change throughout the day. Therefore, traditional static prosthetic devices cause discomfort after relatively short use. The long-term objective of this research direction is to create a new class of prosthetic and orthotic interfaces. These devices will dynamically conform to the human body while managing the environment variables at the interface, including pressure distribution, shear stress, moisture, temperature, degree of contamination, and skin condition. These devices will allow much longer periods of comfortable wear without formation of friction blisters and other forms of skin and tissue damage. The goal of the proposed project is to develop enabling sensing technology based on a flexible array and to build a prototype of a prosthetic liner with distributed sensing capability. The central idea behind the flexible array is to use unimodal field sensing, in this case, electric field, for measurement of properties of interest through selective surface functionalization. This approach offers advantages over multi-principle sensor fusion approaches because it allows reduction of complexity of electronic interface of the sensor array. Reduced complexity of electronics at the sensor cell level is critical for achieving the goal of thin, compact, high- resolution, and flexible sensor arrays that can measure multiple variables at the prosthetic liner/residual limb interface. The specific aims include a) the design of the flexible sensing array for measurement of moisture, temperature, pressure, and shear stress; b) integration of this array into a prosthetic liner/socket; and c) testing of device performance. These aims will be realized using cutting- edge developments in materials science and microprocessor control. Thin-film organic electronics will be combined with elastomeric conductors, metal electrode arrays, and multiplexed with a central microcontroller in order to achieve real-time measurement of temperature, moisture concentration, pressure, and shear stress. The final objective for the sensor prototype is to achieve measurement of all variables of interest with a sufficient accuracy, resolution, and repeatability. The project will set the stage for two future research directions: a) design of better prosthetic devices, and b) fundamental study of processes that take place at the liner-limb interface.