Lateral Porous Silicon Interferometric Transducer for Sensing Applications

In this work, we demonstrate the transducing ability of lateral porous silicon membranes (LPSi) using optical interferometry. To this aim, we carry out Fourier-transform infrared spectroscopy measurements using a microscope equipped with an appropriate objective in order to overcome the difficulty to obtain interference signal from LPSi membranes with small dimensions. Reflectance spectra are recorded while filling the membrane with various solvents and their analysis provide estimations of the effective optical thicknesses and the resulting index of refraction of the fillers in the NIR range. The results show that the various solvents can appropriately be identified and discriminated through the derived refractive indices, thus providing a proof-of-concept of the LPSi interferometric transducer.