MEMS Biosensor Array for Biochemical and Clinical Diagnostics

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Calorimetry is a very versatile and effective investigative tool for analyzing biochemical reactions and is capable of providing continuous quantitative assays of biochemical reactions with exceptional operational stability. The ability to follow the progress of a biochemical reaction continuously as a function of time or reactant concentration has many research and clinical applications with far reaching consequences. However, calorimetric bioanalysis has been mostly hampered by the high cost, slow response times and cumbersome nature of the equipment. To address these limitations, a novel calorimetric biosensor is proposed by integrating a polymer based micro-reaction chamber on a MEMS thin film freestanding microthermopile sensor. The thermopile will be fabricated on a freestanding micromechanical structure such as a cantilever with the cold junctions placed on the bulk of the silicon chip (the rim) and the hot junctions on the freestanding structure. A polymer-based reaction chamber will be integrated right above the hot junctions of the thermopile. The large thermal mass and good thermal conductivity of the rim keeps the cold junctions at room temperature whereas the unconstrained cantilever tip will rise in temperature due to the heat of reaction. Coating the hot junctions with specific immobilized enzymes will provide selectivity by catalyzing only the reaction of the corresponding analyte. The sensor will also be used for the accurate measurement of the specific heat and thermal diffusivity of the reactants. Real-time monitoring of these thermal properties will provide with an independent tool for analyzing the progress of the biochemical reaction.