Photonic Crystal Resonators as Transduction Elements for Biosensing

A biosensor is a device that detects, records, and transmits information regarding a physiological change or process. Designing a high quality biosensor requires the design and optimization of the bio-recognition process, the transduction element and the electronics for signal analysis. The bio-recognition process is responsible for capturing a target analyte with sufficient specificity and in close proximity to the transduction element. The transducer detects all analytes captured by the biorecognition process, while the electronics allow the user to interpret the transduction signal. We present our work in the design and simulation of the transducer, based on photonic crystal (PC) resonators. Significant advantages of PC-resonators are narrow spectral resonances, simple interpretation of the output signal and most importantly, compatibility with the silicon-on-insulator (SOI) platform leading to cheap and mass-producible sensors. Furthermore, the small size of photonic crystal resonators pave way for a high sensor density on any given chip. We have designed and simulated a single-input/single-output silicon-on-insulator photonic biosensor capable of detecting multiple analytes. Individual sensing elements are designed with varying resonance frequencies allowing the use of a single input/output and simultaneously avoiding interference effects. Resonance is achieved using a tunable laser in the near-IR. Grating couplers are utilized to allow multiple sensors on the same chip. Biosensing is achieved by functionalization of individual sensors and subsequent measurement of the resonance shift after the introduction of the target analyte. The size of individual sensors are in the order of 10m2.