Supercoiled Polymer Sensors From Twisting and Coiling Silver-Plated Nylon Threads

Abstract

Supercoiled polymer (SCP) artificial muscles have shown great potential for achieving simultaneous flexible sensing and actuating. However, the lack of clarity regarding the sensing mechanism, coupled with a manufacturing procedure primarily optimized for actuation, has posed challenges. This article introduces a novel flexible SCP sensor, denoted as SCPS, with a streamlined manufacturing process aimed at significantly enhancing sensing capabilities. The SCPS’ sensing mechanism is revealed by analyzing its mechanics and electrical reactions under tension, which is attributed to resistance change resulting from increased current along the helical fiber direction. The microstructure of the proposed SCPS is analyzed using scanning electron microscopy (SEM). A comprehensive set of experiments is undertaken to evaluate the sensor’s performance, revealing a remarkably fast response time (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\lt {100}~\text {ms}$ </tex-math></inline-formula>) and high linearity (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${R}^{{2}}={0}.{96}$ </tex-math></inline-formula>) within a strain range of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$ {25}\% $ </tex-math></inline-formula>. Furthermore, the experiments demonstrate the SCPS’ low hysteresis (5.3%) and exceptional repeatability (5.9%). A gesture recognition data glove is developed using four SCPSs and a recognition accuracy of 95% is achieved for eight distinct gestures.