Simulation and experiment of PDMS based thermopnuematic microvalve in microfluidic chip

A thermopneumatic microvalve for switching fluid in a microchannel of PDMS based microfluidic chip was designed and fabricated from multi-stack PDMS structure on a glass substrate. Microvalve structure consists of inlet and outlet, microchannel, a thermopneumatic actuation chamber, and a thin film heater. In microchannel, fluid is blocked or passed by the motion of actuation diaphragm. Actuation diaphragm is bent up and down by exploiting air expansion that is induced by increasing heater temperature. The microvalve was designed and simulated by ABQUS program, mechanical commercial finite element simulation software, to predict its characteristics and optimize the design. The microvalve created for simulation model has a diameter of 2.5 mm and a total height of 450 mum. The microvalve was then fabricated on glass substrate by low cost processes including PDMS spinning, oxygen plasma bonding, electroplated micromasking, and thermal evaporation. The microvalve characteristics were measured as a function of applied voltage and inlet pressure. From the experiment, a maximum inlet pressure of 10 kPa can be applied with 7-17 V applied voltage to the microvalve heater. The leak rate and maximum inlet pressure results obtained from ABQUS program agree well with the experimental data.