Electrodes-oxide-semiconductor device for biosensing: Renewed conformal analysis and multilayer algorithm

Abstract

Intelligence technologies aim at providing sense organs to machines such as artificial nose or tongue. Inspired by chemically-sensitive devices and antenna couplers, the Insulated Substrate Impedance Transducer (ISIT) reacts to neighboring electro-active targets by changes in its built-in properties, measured through interface electrodes. Exhaustive comprehension of their interactions with medium and substrate is key to ISIT operation and embodiments efficiency. Among simulation approaches, versatile numerical methods, handy conformal analyses and other partial capacitances yet require computational tuning while loosely ensuring previsions quality. The present work then revisits compact modeling of the ideal though essential 2D cases, planar interdigitated electrodes lengthy-fingers arrays on various materials stacks. Starting from a passive membrane with or without back contact, it tackles computability at thin-film and infinite-medium horizons given clear definitions. Optimally simplified formula are proven for membrane thickness down to zero and fingers' spacing around 10 % to 90 % of their periodicity. A straightforward algorithm going beyond “partial-images” is further proposed for multilayers. Sounded for engineers, it is generic, fast and accurate up to 4 arbitrary substrate layers. The method is verified against extensive Finite Elements and validated with measurements in a metallic biolabels sensing application.