Current challenges in the domain on selective and highly sensitive sensors include design, development and characterization of low detection limit sensors, development of low-noise readout methods, positive identification of analytes and, identification and reduction of the effect of various noise sources - both intrinsic and extrinsic to the sensor. The design, fabrication, characterization and testing of a piezoresistive microcantilever array (PµCA) is presented. A novel aspect of the sensors developed is the use of n-type doping which increases the sensitivity of the device by one order of magnitude over existing cantilever sensors. Further, a method of low-noise measurement of cantilever resistance has been developed based on phase-sensitive detection techniques. Two novel techniques of chemical sensing: double- sided sensing and thermal array-based sensing have been investigated. These methods present means of extending the applicability and functionality of piezoresistive microcantilever sensors for chemical sensing. The use of cantilever sensors as platforms for investigation of microscale thermal phenomena is also presented.