Design and simulation of a normally closed glucose sensitive hydrogel based microvalve

In drug delivery systems microvalves are the key components that have been developed for active control of drugs. In this research a normally closed microvalve with a glucose sensitive hydrogel actuating system is designed and simulated. Swelling of the hydrogel forces a silicone rubber membrane to deflect and causes the valve to be opened. The component of the valve that can be opened because of the hydrogel pressure is a silicon nitride cantilever beam which is sealed with a parylene layer. Simulations have been done by FEM analysis and the results show that membrane deflection is large enough to enable the valve to be opened and the fluid to flow through the microchannel. For both rectangular and trapezoidal microchannels with various hydraulic diameters, output flow rates less than 50 μl/min to several hundreds of μl/min can be achieved. Final design has been optimized for the opening point of microvalve at glucose concentration of 15 mM. Overall investigation has been done for a microvalve with specific dimensions and with 4 kPa input pressure the output flow rate of 100 μl/min has been generated which is in the desired range.