Force sensing of carbon nanotube artificial muscles based on electrochemical double layer

Abstract

Carbon nanotube (CNT) artificial muscles driven by an electrochemical double layer demonstrate high performance owing to their coiled structure, which is formed by inserting a high twist density into CNT yarns. Although these coiled structures enable large strokes by twist transference from the yarn to the coil, they are susceptible to external loads, which deform their structure and affect their performance. Hence, the ability to sense external loads is essential for their optimal functionality. Artificial muscles with integrated perception and actuation enable efficient operation based on sensing. Herein, we demonstrate coiled CNT artificial muscles with integrated perception and actuation that exhibit varying electrochemical capacitance with external load. Higher external loads increase the yarn density, thereby decreasing their electrochemical surface area, and the elongated muscle is restored in response to external load changes by regulating the input voltage through electrochemical capacitive sensing.