Optimizing Fabrication Method and Surface Modification of Polyvinyl Acetate-Benzophenone Emission Filters for Complementary Metal-Oxide-Semiconductor Imager Chips towards Biosensing Applications

Several techniques are available to determine an analyte, but the most preferred technique is fluorescence-based sensing owing to its sensitivity and selectivity. One of the main components of fluorescent-based sensors is a filter that allows a specific range of wavelengths to pass through and reach the sensing element. Existing filters still lack certain aspects such as durability, interference, cost, integration with a sensing element, biocompatibility, etc. This research aims to design and develop a polyvinyl acetate (PVAc)-benzophenone-based emission filter by spin coating and integrating it with a complementary metal-oxide semiconductor imaging sensor for use as a portable biochemical sensing device. In addition, the fabricated filter is intended to allow the conjugation of recognition elements necessary for biosensing using plasma oxidation. In this study, PVAc and benzophenone concentrations were optimized to fabricate an emission filter (EF) with precise thickness and uniformity. Subsequently, the fabricated EF underwent analysis using a single-beam UV-Vis spectrophotometer. Additionally, plasma treatment was administered to the EF, enabling further examination using fluorescein isothiocyanate dye under a fluorescent microscope. These examinations collectively suggest that the prepared filter possesses dual properties, i.e., it not only serves as an emission filter but also facilitates surface modification through plasma oxidation for the conjugation of chemical groups that can selectively bind to target analytes for biosensing purposes.