Study And Design Of Micro Fabrication And Test Platform Of PGMS Micromembrane Capacitive Biosensor Based On Surface Stress

Micro-electromechanical system (MEMS) is an interdisciplinary frontiertechnology based on semiconductor manufacturing, it has characteristics ofminiaturization, integration and suitable for mass production. After nearly50years of rapid development, MEMS has attracted great attention and become oneof the major areas of science and technology with huge application value anddevelopment potential. MEMS has many branches, among which BioMEMS is arepresentative that can be applied in biology and medicine.A typical BioMEMS usually includes the front biosensor and the matchingtest platform. This thesis focuses on the PDMS micromembrane capacitivebiosensor based on surface stress, designs the micro fabrication of biosensor,and solves the difficult problems of preparing and handling the macromoleculeorganic silicon compound like PDMS. The1μm thick PDMS micromembranewith properties of uniformity, smooth surface and excellent performance wasachieved when the mixture proportion is PDMS base: curing agent: n-hexane=10:1:50and hold150s at the spin coating speed of8500rpm. The PDMSmicromembrane was etched and corroded by the method of combing dry etching and wet etching, realizing the intact release of the biosensor cavity. Furthermore,the array type differential detection method was used to improve the signal tonoise ratio and anti-jamming ability of biosensor effectively. This fabricationtechnology has characteristics of less steps, good repeatability, high success rateand low cost, which lays the technical foundation for mass production ofbiosensors.A test platform made up of the hardware circuit and the Serial Toolboxsoftware was designed. In the measuring part of the hardware circuit, theconversion of capacitance to digital signal is completed by adopting AD7746. Inthe transmission part of the hardware circuit, the wireless informationinterchange between the measurement circuit and PC is realized with ZigBeetechnology. The hardware circuit is simple in structure, small in size, short indevelopment cycle, highly integrated and low cost, which provides the technicalsupport for high integration detection of high sensitive biological signal. TheSerial Toolbox software not only has strong data processing and graphicalfunctions, but also has a friendly, simple and clear interface and good userexperience.In this thesis, the circuit performance test, the characteristic evaluation ofbiosensor, the functionalization of biosensor and the test of Hemoglobin werecompleted based on the BioMEMS made of the PDMS micromembranecapacitive biosensor based on surface stress and the test platform. The testresults show that the circuit resolution is0.1fF when the conversion time of AD7746is set to109.6ms. The biosensor has high sensitivity and good stability.The functionalization of biosensor using the16-MHA solution performs well.The preliminary test results of Hemoglobin are consistent with the theoreticalanalysis and the measurement results of semiconductor properties analyzer. Thissystem provides a new train of thought and solution for the testing and analyzingof Hemoglobin, which has a great potential application.