Design and analysis of capacitance based Bio-MEMS cantilever sensor for tuberculosis detection

Recently, Micro Electro-Mechanical systems (MEMS) have been vital in molecular diagnosis. In this paper, micro-cantilever beam based bio-sensing system is designed and analyzed for the detection of bio-molecules. Modal and static analysis is performed to study the vibration frequencies and deflection of cantilever respectively. The surface of the cantilever is coated with the anti-bodies of the suspected antigen in a patient's blood. The anti-bodies are specific for specific antigens. Hence, the presence of mycobacterium tuberculosis in a suspected patient's blood is identified through the deflection of cantilever beam. The deflection of the beam is detected using capacitance method. 3D finite element analysis is performed to study the stability, sensitivity and modal frequencies of the cantilever beam(s). The modal frequencies are very important in vibration to voltage conversion of a capacitor for deflection detection. Fixed beam and stepped beam are also considered for comparison. The model is found to be cost effective as well as simple when compared to the conventional techniques like ELISA and PCR.