Activating a CMOS Pixelated Capacitive Sensor Platform by Inkjet Printer

Abstract

The Epson ET-8500 inkjet printer was modified to deposit precise quantities of ink on CMOS chips, enabling the fabrication of capacitive sensors. This project explores the potential of using affordable, consumer-grade printing technology for advanced sensor development, typically requiring expensive equipment. The research focused on understanding the interaction between printed ink and environmental variables such as humidity, light, and temperature. Three measurement setups were developed to detect capacitance changes under varying conditions. The setups for light and humidity successfully generated usable data, while the temperature setup needs redesigning for consistency. Key findings include the exponential relationship between humidity and capacitance in water-based inks. Light exposure generally decreased capacitance, except for white, zinc oxide and tin oxide under UV light. A machine learning model, using a neural network with a cross-entropy loss function, effectively identified inked electrodes but requires more variance in the datasets.