Smart Biomimetic Microswimmers with Adaptive, Environmentally Responsive Motion.

Abstract

Microswimmers have been designed to convert various forms of energy to mechanical motion. Their development has been driven by the desire to mimic the motion of biological systems as well as their many potential applications in sensing, drug delivery and environmental remediation. Chemically propelled swimmers show particular promise as microenvironmental sensors. While most current systems utilize metallic structures and hydrogen peroxide fuel, more biomimetic systems would employ organic fuels and possess soft, flexible bodies. Here, we report the development of autonomous soft microgel swimmers powered by the Belousov-Zhabotinsky (BZ) reaction, a nonlinear oscillatory reaction reminiscent of those utilized in biological systems, which consumes organic fuel and actuates motion via chemical waves. We demonstrate that these swimmers exhibit size-dependent and environmentally responsive motion, in which chemical wave patterns and propulsion characteristics systematically vary with chemical environment and microgel diameter. These smart swimmers adapt to variations in chemical inputs in either the reductant or oxidant concentrations, process them via the progress of the chemical reaction, and display multiple outputs, including variations in wave patterns, wave propagation speed, oscillation period, wavelength, and overall swimmer speed. This work establishes a versatile platform for soft, responsive microswimmers capable of complex, environment-responsive behaviors with relevance to adaptive soft robotics and to the future development of motility based chemical sensors.