Monolithic silicon optical microchips for broad-band Mach-Zehnder interferometry and highly sensitive label free immunosensing

The increasing demand of enhanced sensitivity in the detection of various biochemical analytes paves the way for the development of a new generation of biosensors. Label free multianalyte immunosensing methods utilizing photonic probing have proven to result in better sensitivity and reliability than other types of biosensing methods. Here we described a monolithic silicon optoelectronic transducer capable of label-free and multianalyte determinations. The transducer includes ten Mach-Zehnder interferometers each of which is coupled to its own broad band light emitting device. The adlayers on the sensing arm cause spectral shifts detected at the output of the interferometers by coupling a portable spectrometer through an external fiber. Fourier transform techniques are employed to determine with a high degree of accuracy the shifts of the sinusoidal spectral outputs. The microphotonic chip was integrated with a microfluidic module and a model binding assay (mouse-antimouse) was run to demonstrate the operation.