Researcher(s)
- Tyler Roesel, Mechanical Engineering, University of Delaware
Faculty Mentor(s)
- Jill Higginson, Mechancial Engineering, University of Delaware
Abstract
Introduction
The Smart Sleeve is a carbon nanocomposite sensor integrated into a compressive fabric knee sleeve to measure knee flexion angle since sensor resistance changes as it elongates. The goal is to evaluate the accuracy of the Smart Sleeve during static knee angle holds.
Methods
Participants (n=2, 2M) wore the Smart Sleeve on their right legs. A HUMAC Norm dynamometer was used to position their legs at exact angles for 10-second holds. For all participants, two trials started at full flexion (120 degrees), and two started at full extension (0 degrees). All holds changed by 15-degree increments to the opposite position and back. Sensor resistance (ohms) was measured during each static hold.
MATLAB and Excel were used to plot each static hold, fit the data with linear and 2nd-order polynomial regression, report R^2 results, and analyze resistance decay.
Results
The R^2 values for linear and polynomial regression for all static holds were 0.60±0.19 and 0.65±0.18, respectively, and the resistance drop at holds from initial to final data points was 177.53±85.41 ohms. For R^2 values during flexion, linear was 0.64±0.17, polynomial was 0.71±0.15, and the resistance drop was 222.54±79.53 ohms. For R^2 values during extension, linear was 0.53±0.20, polynomial was 0.58±0.20, and the resistance drop was 132.52±65.36 ohms.
Discussion
The Smart Sleeve, on average, showed that the linear correlation coefficient was lower than the polynomial, which is surprising, as it was expected there would be a constant resistance as the sensor was held at a constant angle. The sleeve also had a higher R^2 correlation coefficient during flexion than extension. There was a much larger resistance drop during flexion than extension, which will lead us to investigate hysteresis effects in future work.