Silicon photonic wire biosensors: Sensing, instrumentation, and applications

Photonic wire evanescent field (PWEF) sensor chips have been developed for multiplexed label free molecular detection. The sensors are made using 260 nm $\times {\bf 450}$ nm cross-section silicon waveguides folded into spirals less than 200 $\mu {\bf m}$ in diameter, but with an overall sensor length of more than a millimeter. The long propagation length gives a response to molecular binding much better than currently available tools for label-free molecular sensing. These sensors can be arrayed at densities up to ten or more per square millimeter. This talk reviews our ongoing work on the photonic wire sensor chip design and layout, on-chip integrated fluidics, optical coupling, and chip interrogation using arrays of grating couplers formed using sub-wavelength patterned structures. The goal is to develop a commercially viable sensor platform by addressing cost-of-instrumentation, cost per measurement, ease-of-use, and by increasing the number of sensors that can be simultaneously monitored.