Research On Thermal-actuated Microvalve Based On PDMS Film

Microvalve is one of the most important components of microcontroller and plays an important role in both the switch of microchannel and storage of chemical reagent. With the advancement in the development of MEMS technology, various types of microvalve are designed and fabricated. Among them, the thermal-actuated microvalve with its compatible with the biochip fabrication process and simple working principle has become one of the hot subjects in recent years. Using PDMS film, a new thermal-actuated microvalve was designed, which would be used in multi-channel flow control of biochip (such as PCR chip) or microfluidic chip.The thermal analysis of microheater and the thermal-structural coupled analysis of elastic thin film were carried by means of ANSYS10.0finite element analysis software, focusing on different structural parameters of heater, cavity and thickness of the PDMS film. The fabrication of microvalve included the design and printing of mask, sputtering of microheater, wet etching of microchannel chip and cavity chip and spin coating of PDMS film. Both the single-channel and multi-channel microvalves were packaged. To detect the performance of the microvalve, this paper designed a microvalve drive and control circuit, including the signal processing, A/D conversion, key control, heating control, FPGA and the display control.This paper conducted the analysis and calculation of the heat characteristics of microheater and temperature sensor and made comparison of the tensile properties of PDMS film before and after the modification treatment. The performance of single-channel microvalve with different structural dimensions, such as shape, width and depth of microchannel, the diameter and depth of cavity and the thickness of PDMS film, was estimated by threshold driving voltage in order to obtain the optimization process parameters. Besides, the back pressure, switching time and repeatability were also discussed to restrict the working conditions of microvalve. According to the experiment results, the thermal-actuated microvalve system achieved to switch the flow directions in the application of multi-channel.