New Capacitive Thermal Age Tag for Predicting Remaining Thermal Life of Multiple Products

Abstract

This paper proposes use of a new capacitive thermal age sensor that inherently integrates time and temperature without batteries or electronic memory to predict the remaining thermal life of a wide range of monitored products. The sensor is a tiny capacitor comprising a polymeric dielectric between two conductive plates. Capacitance of the sensor increases during thermal aging due to shrinkage of the polymer. Additives such as catalysts adjust the activation energy (Ea) of capacitance change with thermal age.
A thermal age tag, incorporating two capacitive sensors of different activation energy, can be used to determine the effective temperature (Teff) of a complex thermal environment at wide range of product degradation activation energies. Correlation of the thermal age of the tag at the monitored product’s degradation activation energy to product thermal aging data provides estimated remaining thermal life of the product. The thermal age tag requires no batteries or electronic memory required in data-logging approaches resulting in reduced size, weight and cost. These passive tags are potentially maintenance free for the life of the product.
This paper describes the development of a universal thermal age (UTA) tag incorporating capacitive thermal age sensors and preliminary co-aging trials with a variety of selected polymeric products to demonstrate feasibility of this approach.