A microcantilever based photoacoustic sensor is generally provided. In one embodiment, the microcantilever includes: a substrate; a GaN layer on the substrate, wherein the GaN layer defines a cantilever extending beyond an edge of the substrate, with a base area of the cantilever defined by the area spanning the edge of the substrate; a heterojunction field effect transistor (HFET) deflection transducer positioned on the cantilever; a pair of electrical contacts, each electrically connected to the HFET deflection transducer; and a microfluidic channel in fluid communication with an analyte reservoir, wherein the analyte reservoir is positioned at the base of the cantilever. A sensing system is also generally provided.