Exploiting Nonlinear Dynamics for Programmable Behavior in Microfluidic Networks

The development of microfluidic systems that do not rely on abundant external hardware, yet retain controllable, complex behavior has been a primary research goal for the past decade. Microfluidic systems are composed of a network of flow channels and are generally considered to be linear systems; however, by creating nonlinearities in the network we are able to produce a diverse range of flow dynamics. Here, I present a simple microfluidic network that exhibits spontaneous oscillations in the flow rate. It is possible to switch between an oscillating and steady flow state by only changing the driving pressure. This functionality does not rely on external hardware and may even serve as an on-chip memory or timing mechanism. Further, I demonstrate the ability to control the direction of flow though intermediate channels not directly connected to the controlled terminal. I use analytic models and rigorous fluid dynamics simulations to show these results. We expect this work to advance built-in control mechanisms in microfluidic systems towards the goal of designing portable systems that are as controllable as microelectronic circuits.