Integrated elastomeric components for autonomous regulation of sequential and oscillatory flow switching in microfluidic devices

A critical need for enhancing the usability and capabilities of microfluidic technologies is the development of standardized, scalable and versatile control systems(1,2). Electronically controlled valves and pumps typically used for dynamic flow regulation, although useful, can limit convenience, scalability and robustness(3-5). This shortcoming has motivated the development of device-embedded non-electrical flow-control systems. Existing approaches to regulate operation timing on-chip, however, still require external signals such as timed generation of fluid flow, bubbles, liquid plugs or droplets or an alteration of chemical compositions or temperature(6-16). Here, we describe a strategy to provide device-embedded flow switching and clocking functions. Physical gaps and cavities interconnected by holes are fabricated into a three-layer elastomer structure to form networks of fluidic gates that can spontaneously generate cascading and oscillatory flow output using only a constant flow of Newtonian fluids as the device input. The resulting microfluidic substrate architecture is simple, scalable and should be applicable to various materials. This flow-powered fluidic gating scheme brings the autonomous signal processing ability of microelectronic circuits to microfluidics where there is the added diversity in current information of having distinct chemical or particulate species and richness in current operation of having chemical reactions and physical interactions.