Design and development of MEMS biosensors

This thesis is focused on design and development of two types of MEMS bio/chemical sensors and the deposition of a thin Au film for functionalization of the sensors with thiol-SAMs. The effect of Au deposition rate on the morphology and crystallinity of the deposited Au film by thermal evaporation at room temperature on silicon was investigated. Formation of homogenous thiol-SAMs has been shown on the manufactured Au coated samples. A micro-paddle resonator as a potential mass sensor in a gas environment has been proposed. FIB machining was used to fabricate the prototype device on 500 nm thick LPCVD silicon nitride. The dynamic response of the sensor was investigated over a range of pressure and compared with the simulation results. The sensitivity of the sensor was determined experimentally to be 1.61 fg/Hz. The application of the sensor for detection of Au nanoparticles was shown. A novel type of hybrid static-dynamic micro sensor for detection in an aqueous medium was studied. This sensor is comprised of a thin membrane and a double-ended-tuning-fork (DETF) structure. The sensitivity of the sensor was numerically determined to be 91 Hz/(mJ/m2). FIB is used to make a high resolution Al2O¬3 mask for fabrication of the DETF structure