Analysis of Stretch-Dependent Capacitance and Its Effects on Energy Conversion of a Donut-Shaped Dielectric Elastomer Generator

Abstract

Dielectric elastomer generator (DEG) comprises of soft and stretchable capacitive transducer. The DEG experiences a change in capacitance and provides a voltage gain ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$G$ </tex-math></inline-formula> ) with an applied mechanical excitation. This article interprets DEG as a machine that involves a cyclic change of finite-state transducer capacitances to transmit or modify energy. In this study, a relative analysis of capacitances associated with the DEG transducer is introduced and analyzed to improve the DEG performance. This article focuses on defining a relationship between the material stretch ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\lambda$ </tex-math></inline-formula> ) and finite-state capacitances associated with the DEG transducer. The estimation of stretch-imposed DEG capacitance under mechanical excitation is well investigated. Eventually, the analysis is experimentally validated with the developed mechanical prototype. For distinct transducer deformation, the associated capacitances are estimated with the capacitive extensometer method and the stretch ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\lambda$ </tex-math></inline-formula> ) is calculated. Moreover, for effective energy conversion, the finite state capacitance variation is maintained large enough to provide a relatively high voltage gain. Experimental results show that for 70% increase in capacitance difference at the DEG makes the specific energy increase from 3.5 to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$11.5~\mu \text{J}$ </tex-math></inline-formula> /g. This study could lead the DEG as an alternative power source for low-power electronic gadgets.