Elastic instability-mediated actuation by a supra-molecular polymer

Abstract

The elastic energy built up during peptide self-assembly is exploited in the realization of a microactuator. The energy stored is released on millisecond timescales via a buckling instability controlled with droplet microfluidics. In nature, fast, high-power-density actuation can be achieved through the release of stored elastic energy by exploiting mechanical instabilities in systems including the closure of the Venus flytrap1 and the dispersal of plant or fungal spores2. Here, we use droplet microfluidics to tailor the geometry of a nanoscale self-assembling supra-molecular polymer to create a mechanical instability. We show that this strategy allows the build-up of elastic energy as a result of peptide self-assembly, and its release within milliseconds when the buckled geometry of the nanotube confined within microdroplets becomes unstable with respect to the straight form. These results overcome the inherent limitations of self-assembly for generating large-scale actuation on the sub-second timescale and illuminate the possibilities and performance limits of irreversible actuation by supra-molecular polymers.