Torsion Sensing on a Cylinder Using a Flexible Piezoelectric Wrist Band

A wrist band undergoes torsional loads during twisting motions of the human forearm. In this article, we investigate sensing torsional loads on a silicone cylinder using a wrist band hosting a sensor. We utilize a flexible sensor based on polyvinylidene fluoride, which is a flexible piezoelectric material. The flexible piezoelectric sensor is inserted into a pocket of the wrist band and outputs an electrical response to the torsional loads on the cylinder. We model the sensing response from the wrist band during the torsional loads on the silicone cylinder through an electromechanical model for a piezoelectric beam. To validate the model, we compare theoretical predictions with experimental data at systematically varied torsional loading conditions. The experimental results demonstrate that the sensor outputs are linearly proportional to the rotation angle of the cylinder. Moreover, we conduct human tests using the flexible piezoelectric wrist band sensor, and its result shows the same linearity about twisting motion angles of the human forearm. This article shows the feasibility of sensing from the twisting motion of a human forearm using a wrist band with a piezoelectric sensor.