Arbitrary flow control in microfluidic systems using networks of bio-inspired soft valves

For decades, semiconductor fabrication methods and mechanically actuated pumps and valves have been used to facilitate flow-control in microfluidic systems. However, these systems require energy input to regulate flow, and the cost increases accordingly. In this work, we propose a novel flow control system where a network of soft bio-inspired passive valves enables nearly arbitrary flow control. The valve action is facilitated by soft elements inside a microfluidic channel, which are deformed by the applied pressure. This leads to a highly nonlinear relation between applied pressure and flow rate. By building networks of these soft valves, we demonstrate a constant-current system - where flow is independent of applied pressure – as well as devices with nearly arbitrary pressure-drop / flow rate relations. Applications to flow control in chemical reactors, cell culturing systems, and drug delivery are discussed.