Ricerc@Sapienza

Here we present the design of an amorphous silicon photodetector integrated with an ion-exchanged waveguide on the same glass substrate in order to obtain an evanescent waveguide sensor for on-chip biomolecular recognition in Lab-on-Chip applications. We studied the behaviour of a monochromatic light in a channel waveguide and its coupling into the thin-film sensor, using COMSOL Multiphysics. Simulations show that the presence of the photodiode’s insulation layer and transparent electrode strongly affects the coupling efficiency between the waveguide and the sensor.

The detection of biomarkers of past or present life is a high priority task for the astrobiological exploration of the Solar System, currently pursued through in situ analyses by gas chromatography coupled with mass spectrometry. Lab-on-chip systems are under study as a very promising alternative approach, offering high specificity and detectability and minimizing employed resources as volume, mass, power consumption.