Photonic Crystals for Biosensing & Imaging

Photonic Crystals are the culmination of many fascinating developments in Physics, such as Bragg mirrors, Bloch modes, and bandstructures, and their ability to control the flow of light has given rise to many applications, ranging from light emission to optical switching and quantum communications. Here, we discuss the combination of biosensing with imaging, based on localised guided mode resonances, where each resonance can be considered the pixel of an image. This combination adds an exciting new imaging modality to the biophotonics toolkit, which allows us to image both cells and the biomarkers they secret in real time. Thinking of each resonance as an imaging pixel also provides a very simple readout mechanism, where we have now demonstrated nanomolar sensitivities with a device that, in principle, can be made for £10. Furthermore, we note that silicon photonic biosensors do not tend to exploit silicon’s obvious ability to conduct electricity, and we demonstrate the first hybrid silicon photonic - electrochemical biosensor.