Single material thermocouples from graphite traces: Fabricating extremely simple and low cost thermal sensors

Abstract

Thermocouples are a universal type of thermal sensors routinely used in different applications for the measurement and monitoring of temperature. Traditionally, they are constructed from two dissimilar conductors. In this work, single material thermocouples are fabricated using graphite pencil traces patterned on cellulose paper. The different magnitudes of the Seebeck coefficients in different grade pencils facilitate successful construction of a graphite‐only thermocouple sensor. These extremely simple, low-cost, and eco-friendly thermocouple sensors have shown stable and reliable sensitivity of 7.4 (±0.3) µVK−1, indicating a good temperature resolution of better than 0.2 K. With the advantage of simple and solvent-free fabrication process, such devices can be developed as cheap, environmentally friendly, and disposable thermal sensors.