Ahlrrrcr -In this paper we present a mcrhod for microcantilever deflection measurement utilizing a stress-tunable photonic crystal (Photonic Bandgap, PBC) waveguide. The method uses the mechanochromic effect, i.e. the modulation of transmissive properties by applied force. A 2D photonic crystal-based channel waveguide with a 90' band is used as sensitive element. The stmctiire is monolithically integrated with the hasis of the inicrocantilever where deflection-induced stress is maximal. Applied stress simultaneously causes a shift of the photonic handgap cdge and photoelastic refractive index change and this is used for amplitude modulation of light signal. The approach may he used in deflection or stress sensing in various other MEMS SC11SOIS.