SUBJECT: Ph.D. Dissertation Defense
BY: Alexander Ambrose
TIME: Wednesday, June 12, 2024, 11:00 a.m.
PLACE: Love Building, 295
TITLE: A Smart Prosthesis Socket Liner to Address Factors That Lead to Prosthesis Abandonment
COMMITTEE: Dr. Frank Hammond, Co-Chair (ME/BME)
Dr. Gregory Sawicki, Co-Chair (ME/BioSci)
Dr. Ellen Yi Chen Mazumdar (ME/AE)
Dr. Kinsey Herrin (ME)
Dr. Lewis Wheaton (BioSci)
Dr. Maegan Tucker (ME/ECE)


More than one in four upper-extremity prosthesis users choose not to wear their prosthesis regularly. Some notorious factors leading to prosthesis abandonment are discomfort, heat, medical complications, and inconvenience. These issues stem from the prosthesis socket rather than the terminal device. Yet, there is a lack of robotics research focused on improving the human-socket interface. The research presented here focused on developing the smart prosthesis socket liner, a soft-robotic system intended to mitigate the four aforementioned factors leading to prosthesis abandonment. The smart prosthesis socket liner had subsystems fabricated from flexible thermoplastic-polyurethane-coated textiles. The primary subsystem of this novel socket liner was a closed-loop pneumatic control system, which regulated the fit of the human-socket interface while autonomously accommodating residual-limb volume fluctuations that may occur throughout the day due to hydration and activity. Real-time classification algorithms were trained and implemented to prescribe the desired fit of the pneumatic control system depending on user activity. The classifiers employed signals from inertial measurement units and the state of the pneumatic control system. A flexible fabric-based heat-dissipation subsystem was implemented into the liner system to remove heat from the human-socket interface. The heat-dissipation subsystem used a closed-loop water cycle to extract the heat produced by the residual limb and dissipate it outside of the human-socket interface. These subsystems simultaneously perform their respective goals in the single integrated soft-robotic system. Furthermore, models were developed to estimate the contact pressure of the soft-pneumatic actuators and the mechanical compliance and attenuation of the interface between the user and the smart prosthesis socket liner. Lastly, users' responses to varying the mechanical impedance of this interface were investigated with a separate impedance-controlled wearable device. It is hoped that this research will advance other research efforts in developing new socket technologies to improve the comfort and functionality of prostheses.