Variable Interference Filter (VIF) for biological and Chemical sensors

A high-resolution and compact wavelength detector capable of resolving very small changes in the spectral information of the incident light is highly desirable for many applications such as Lab-on-Chip systems, biosensors, chip-sized detectors, on-chip fluorescence spectrometry, wavelength shift detectors, interrogations system, and more. In this work is present the project, simulations, fabrications and calibration of a variable interference filter (VIF) constituted by a wedgeshaped Fabry-Perot cavity placed between two stacks of thin films, forming dielectric reflectors. This device constitutes an optical filter that converts the spectral information in a position dependent signal that can be measured by a photo detector array (PDA). We have investigated the performance of the designed VIF depending on its optical properties in order to optimize its geometrical configuration. With the results obtained we fabricated a multi-channel spectral detector that can be used in environmental analysis. To demonstrate this viability, it is proposed a basic system composed of a VIF mounted on top of a matrix of sensors connected to a dedicated electronic module, to measure and store the intensity of the incident radiation data and the absorption spectra of molecules present in a detection chamber of a microfluidic system. This prototype is aimed to analyze biological fluids, human urine, and results will be compared with results obtained using standard commercial instruments.