Design paradigms for simple microscopic machines

Living systems are composed of many biomolecule-based machines that execute advanced functions, such as kinesin “walkers” that transport loads within a cell. Tremendous recent progress has been made towards understanding the principles that govern the structure of such biomolecular machines. However, the function of many molecular machines is tied also to dynamic conformational changes. We currently lack design paradigms for predicting and designing the dynamics of a microscopic machine, as well as the principles by which it can perform useful work. We demonstrate an experimental platform where the interaction between information-bearing subunits can be precisely controlled, explicitly calculated, and experimentally tested with high throughput. The system consists of lithographically patterned microscopic magnetic particles connected by flexible elastic hinges. These magnetic particles have fully programmable magnetic interactions, such that a linear chain of particles encodes a sequence of magnetic directions. We show that the energy landscape of this structure is controlled by the device parameters, and predicted by bifurcation theory. Leveraging these results, we demonstrate that the competition between the elastic and magnetic degrees of freedom could be structured in order to create functional finite state machines.