Towards a complete Lab-On-Chip system using integrated Mach-Zehnder interferometers

This article deals with our last steps towards the implementation of a Lab-On-Chip (LOC) platform which could be used as a portable testing device for diagnostics. As sensing elements we employ integrated Mach-Zehnder Interferometers (MZI) realized with Si/SiO2/Si3N4 waveguides of micro/nano dimensions, based on Total Internal Reflection (TIR) propagation. MZI sensors, that have already shown their high sensitivity for biosensing applications, are currently being implemented in a multiplexed configuration. We present here the first results of the design and simulation of a multiplexed MZI platform with 4 channels for the simultaneous detection of different analytes. Moreover, we describe a novel phase modulation technique which solves some of the problems inherent to standard MZI sensor. This modulation technique does not require additional fabrication process and will directly provide a linear phase response. Concerning the light coupling into the waveguides, it is achieved by the use of diffraction grating couplers, favoring the passage from bulky laboratory equipment to delocalized applications. We also describe an optimized process for surface biofunctionalization to bind the bioreceptors for target recognition and its validation with an immunoassay.