A Capacitive Readout Strategy for Ammonia Detection: Design Flow, Modeling and Simulation

In this article, the information reported is of a genetical metabolic disorder named Phenylketonuria PKU and the necessity for the development of a biosensor with a complete Point-of-Care system. The choice of the biosensor is a low-cost rapid prototyping sensor fabricated by Inkjet Printed (IJP) Interdigitated Capacitive Transducer (IDT) on a PET substrate. The work curtailed a detailed explanation on the chosen methodology indirect phenylalanine quantification by making use the dielectric permittivity variation caused by the chemical reaction between the functional layer with the residual Ammonia (NH3) generated by an enzymatic reaction involving phenylalanine. This work includes a clear elaboration of the sensor design flow and the modelling of the capacitive sensor with multiple layers on top of the electrodes (Functional layer and Material Under Test). Simulation results are shown which allow for the choice of optimal design parameters for the Capacitive sensor.