Responsive biomimetic hydrogel valve for microfluidics

A biomimetic hydrogel valve capable of directional flow control in response to the local fluid environment in microfluidic channels is described. The valve consists of a pair of photopolymerized hydrogel bistrips with differe nt pH sensitivities, and becomes activated or deactivated reversibly based on local pH as a result of volume and shape changes. When activated at pH 8 , the valve mimics anatomic venous valves both functionally and structurall y, allowing fluid flow in one direction under forward pressure while restri cting flow in the opposite direction. At an applied pressure of 0.71 psi, t he forward flow rate was 140 muL/min, compared to a backward leakage rate o f 2.3 muL/min. (C) 2001 American Institute of Physics.