Here we investigate the feasibility of detecting the photo-reversible inter-conversion between the two thermo-dynamically stable states of the photochromic molecule spiropyran, using silicon microcantilever sensors. The merging of microcantilever technology and spiropyran photochromic brushes for the first time, offers a good route for the pairing of a sensitive transducer with a sensing surface which can be optically controlled. Photo-induced switching between the spiropyran isomers has been tracked through changes in surface stress of the cantilever that can be detected by monitoring the cantilever deflection.