A low noise optical sensor and biocompatible microscale optical filters for integrated fluorescence sensors were developed and tested. The sensor was fabricated in a 0.5 mum CMOS process. The measured reset noise of the sensor is reduced by a factor of 10 compared to conventional active pixel sensors. The transmission ratio in the pass-band and suppression ratio in the stop-band of the optical filters are comparable to that of macroscopic commercial filters for fluorescence microscopy