Functionalised porous silicon as a biosensor: emphasis on monitoring cells in vivo and in vitro.

Porous silicon photonics is the ideal platform for high sensitivity, high selectivity monitoring of biological molecules in a complex fluidic environment. The potential of this technology was identified almost 15 years ago, however, it has taken considerable advances in porous silicon surface chemistry, photonics, and micro-fabrication to create truly effective devices that can provide new insights into the behaviour of biological systems. In this review we provide a critical assessment of the development of porous silicon optical biosensors from the early demonstrations of affinity based sensing to the current trends in monitoring single cell activity and perspectives in the use of photonic microparticles for biomedical applications.