A Flexible, Microfabricated Impedimetric Fluid Temperature Sensor

Abstract

A novel impedimetric temperature sensor which utilizes the electrochemical impedance between two electrodes exposed to an aqueous solution to transduce temperature is presented. The solution resistance between electrodes is highly temperature dependent since ionic mobility increases with temperature. High-frequency electrochemical impedance can be used to accurately measure solution resistance, and therefore transduce fluid temperature. A temperature sensor composed of two platinum electrodes on a thin film Parylene C substrate exposed to fluid was designed, fabricated, and tested. Fluid temperature was transduced with high sensitivity (-59.33 Ω/°C) by measuring the impedance magnitude between electrodes at an appropriate frequency where phase was minimized. Compared to conventional platinum resistance temperature detectors (RTDs), our sensor achieved over 4× higher sensitivity and resolution (±0.02°C). Furthermore, the sensor is specifically designed for use in liquids, and features flexible, biocompatible construction for biomedical or microfluidic applications.