Structural optimization of the micro-membrane for a novel surface stress-based capacitive biosensor

Thin membrane transducer can be used for detecting the surface stress induced by the bio-molecular reactions. Designing research of the capacitive thin membrane transducer is proposed in the paper. The relationship between the sensitivity of the surface stress-based biosensors and the geometrical parameters of membrane was analyzed using the finite element method. The thermal strain mismatch resulting from the CTE difference of the two-layers of the membrane was also studied. The structure characteristics were analyzed systematically, including shape, size, gold coverage, which are normally considered in the design of the biosensors. Furthermore, a novel bi-membrane structure, which has high signal-to-noise ratio and can minimize the influence of the environment, is proposed.

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► We optimized a surface stress-based membrane transducer systematically.
► The sensitivity of circular membrane improved 20% than square membrane.
► The maximum sensitivity was achieved when the gold coverage was 0.9.
► A novel bi-membrane structure was proposed.