Surface Stress-based MEMS Biosensor

With new applications in the areas of genetics, diagnostics, drug discovery, the need for high-throughput label-free multiplexed sensors for chemical and biological sensing has in creased tremendously. MEMS-based biosensor combined micro-sensors, micro-actuators, microfluidics system, light system and micro mechanical components to a body just satisfying the requirement, which has has been widely used in medicine, food engineering, and biomedical engineering, etc.Surface stress-based biosensor is a new type of biosensor, using the free energy of chemical bonding between molecular, which can provide a common platform for the ciochemical test. Nowadays it is one of the international research hotspot for its higher sensitivity.In this paper, we make a detailed analysis of theoretical basis of the surface stress, make a minute exposition of the the principle of surface stress biosensor and two kind of testing method for surface stress (micro-cantilever based method and micro-membrane based method). Two novel conceptual models were designed.ANSYS (finite element analysis software) is used to establish the finite element model of the two kinds of structure and the structures are optimized systematically. The static deflection and resonant modes of cantilever beam are simulated and verified their sensing properties. The static deflection and capacitance sensing characteristic of micro-membrane are simulated. Two typical geometry (circular and square) were contrastively analyzed under the same conditions. The structure characteristics can be acquired systematically through the stimulation, including shape, size, gold coverage and the thickness, which can provide fundamental principles for the sensor’s design and fabrication.Based on the simulation, more reasonable technological process is designed which conqer the difficulty of process compatibility. Eventually the fabrication of the micro-membrane capacitive biosensor is successful, which build a solid foundation for the final application and testing of this kind of biosensor.