Monolithically integrated frequency-resolved Mach-Zehnder Interferometers for highly-sensitive multiplexed label-free bio/chemical sensing

The proven capability of optical biosensors for highly-sensitive biochemical determinations has not been proven so far adequate to render them into commercial, portable devices. Their advancement has mainly stumbled upon two challenges: the inherent inability of most sensors to integrate the optical source onto the same chip, and the need to specifically design the optical transducer per application. In this work, a radical approach for label-free multiplexed sensing is presented. It incorporates two significant novelties: (1) an all-silicon array of monolithically integrated optical transducers, all having their own excitation source but sharing a common detector, and (2) the Frequency-resolved Mach-Zehnder Interferometry (FR-MZI) principle of operation. Monolithically integrated FR-MZI devices showed a limit of detection of Δn=4×10^-6. The proposed device can be used interchangeably for a plethora of bio/chemical determinations becoming thus an unsurpassable versatile analytical tool.