Porous silicon biosensors are by far used in optical monitoring of molecular interactions. These photonic devices could greatly benefit of integration with specific microfluidic circuits that allow small volume, and thus low consumption of reagents, fast time of incubation, and highly controlled reaction conditions. In this paper, we summarize the experience of our research group in fabrication and characterization of optical biochip, and also present new, original results on biosensing. In particular, a porous silicon based microarray of one-dimensional photonic crystals has been integrated with innovative microfluidic circuit for parallel feeding of chemical solutions. The device has been used for the label free optical monitoring of ssDNA–cDNA interaction.