Development of Prototype Low-Cost QTSS™ Wearable Flexible More Enviro-Friendly Pressure, Shear, and Friction Sensors for Dynamic Prosthetic Fit Monitoring

Abstract

There is a current healthcare need for improved prosthetic socket fit provision for the masses using low-cost and simple to manufacture sensors that can measure pressure, shear, and friction. There is also a need to address society’s increasing concerns regarding the environmental impact of electronics and IoT devices. Prototype thin, low-cost, and low-weight pressure, shear, and loss of friction sensors have been developed and assembled for trans-femoral amputees. These flexible and conformable sensors are simple to manufacture and utilize more enviro-friendly novel magnetite-based QTSS™ (Quantum Technology Supersensor™) quantum materials. They have undergone some initial tests on flat and curved surfaces in a pilot amputee trial, which are presented in this paper. These initial findings indicate that the prototype pressure sensor strip is capable of measuring pressure both on flat and curved socket surfaces in a pilot amputee trial. They have also demonstrated that the prototype shear sensor can indicate increasing shear forces, the resultant direction of the shear forces, and loss of friction/slippage events. Further testing, amputee trials, and ongoing optimization is continuing as part of the SocketSense project to assist prosthetic comfort and fit.

A Scoping Review of Pressure Measurements in Prosthetic Sockets of Transfemoral Amputees during Ambulation: Key Considerations for Sensor Design

“…A method for the repeatable placement of sensors is particularly advantageous for inter-subject comparisons, but is also helpful for testing different sockets for the same subject [ 78 ]. This procedure is likely to be directly transferable between transtibial and transfemoral socket types.…”

“…To properly validate a sensor system, several different types of scenarios might have to be considered—a potentially costly requirement. As an example, a recently developed sensor system was validated in three scenarios: (1) a flat bench-top test, (2) in a prosthetic socket at a low curvature site, and (3) in a socket at a higher curvature site [ 78 ]. In fact, the same sensors were also tested under dynamic cyclic loading to simulate realistic use conditions.…”

“…For example, electromyography (EMG) [ 82 ] and temperature sensors [ 83 ] can provide insights to the relationship between muscle activities and intra-socket climate, respectively, with interface pressure. The integration of gait monitoring devices is undoubtedly useful to evaluate these sensor measurements as a function of the gait cycle, or with respect to level of activity [ 4 , 9 , 32 , 78 , 82 ]. This might seem trivial to accomplish, but there are several reasons why researchers are currently avoiding this approach.…”

Analyzing Dynamic Operational Conditions of Limb Prosthetic Sockets with a Mechatronics-Twin Framework

“…For the physical dynamic testing, our approach adopts the printed wearable soft sensor Quantum Technology Super Sensor (QTSS™) [26] as the base technology for the intra-socket dynamic pressure measurement. Such a choice is motivated by the facts that such sensors could be more robust against environmental disturbances (e.g., vibration, acceleration, or temperature fluctuation) and more transparent for the intra-socket deployment, compared to other pressure sensor technologies, such as resistive transducer, piezoelectric transducer, optical pressure transducer, and capacitive transducer [27].…”

Multilayered Composites with Modulus Gradient for Enhanced Pressure—Temperature Sensing Performance

“…Rapid advances in flexible pressure sensors are driving interest in electronic skin [ 1 , 2 , 3 , 4 ], electronic textiles [ 5 , 6 , 7 , 8 , 9 ], flexible touch displays [ 10 , 11 , 12 , 13 , 14 , 15 ], soft robotics [ 16 , 17 ], and energy harvesting [ 18 , 19 , 20 ]. Recently, flexible pressure sensors, which mimic various biostructures [ 1 , 16 , 21 ] and use a characteristic material [ 1 , 22 , 23 , 24 , 25 , 26 ], have attracted significant research interest.…”