CHAPTER 7: Coupling Mechanics to Chemical Reactions to Create “Materials that Compute”

Polymer gels undergoing the Belousov-Zhabotinsky (BZ) reaction display chemo-mechanical transduction, converting the chemical energy from the internal reaction into the oscillatory mechanical motion of the sample, and hence, the gels pulsate autonomously. These BZ gels also display mechano-chemical transduction, converting an applied force into chemical energy. The ability to interconvert different modes of energy is vital to materials systems that perform bioinspired functions such as sensing, actuation, communication and computation. To design such multi-functional materials, we first develop models to capture the response of an oscillating BZ gel to an applied periodic force and analyze the entrainment of the gel to the applied deformation. The ability to entrain the gels in this manner opens routes to creating actuators that can sense and be regulated by an external periodic load. Building on these findings, we designed material systems that undergo effective communication by coupling the self-oscillating BZ gels to a piezoelectric (PZ) micro-electro-mechanical system (MEMS). The individual BZ-PZ units are interconnected by electrical wires and the transduction between chemo-mechanical and electrical energy induces signals that propagate rapidly over long distances. This permits remote, non-diffusively coupled oscillators to communicate and synchronize. The synchronization between the coupled oscillators allows the system to perform computational tasks such as pattern recognition. Using our theoretical models, we predict the synchronization behavior that can be used for these computational tasks, and thereby enable the creation of ″materials that compute″.