Mediated Enzymatic Bioelectrocatalysis on Polypyrrole-Based Trilayer Actuators - Toward Untethered Operation

Conducting polymer-based actuators are biocompatible, flexible, and require low power, making them interesting candidates to drive soft robots. Traditionally, these actuators rely on external electrical power sources. Enzymatic biofuel cells offer an untethered alternative capable of powering small implantable or wearable devices. The power generated by the biocatalysis of some enzymes, such as glucose oxidase (GOx) and laccase (Lac) in the presence of glucose and oxygen, respectively, in aqueous media, has been proven to be sufficient to drive these artificial muscles. Here, we investigate the mechanical design of PPy-based bending actuators and the electrochemistry of mediated glucose and oxygen bioelectrocatalysis in solution and at the electrode surface, followed by the evaluation of glucose-driven actuation for different enzyme immobilisation methods. GOx and Lac are employed as the bioanode and biocathode enzymes, respectively, using tetrathiafulvalene-tetracyanoquinodimethane (TTF-TCNQ) and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) as electron-transfer mediators. We demonstrate bioelectrocatalysis in solution and present a preliminary evaluation of glucose-driven actuation using different enzyme immobilisation strategies. These results demonstrate the potential for next-generation implantable or wearable biomedical devices without the need of external power lines.