Stretchable temperature-sensing circuits with strain suppression based on carbon nanotube transistors

Abstract

For the next generation of wearable health monitors, it is essential to develop stretchable and conformable sensors with robust electrical performance. These sensors should, in particular, provide a stable electrical output without being affected by external variables such as induced strain. Here, we report circuit design strategies that can improve the accuracy and robustness of a temperature sensor based on stretchable carbon nanotube transistors. Using static and dynamic differential readout approaches, our circuits suppress strain-dependent errors and achieve a measured inaccuracy of only ±1 oC within a uniaxial strain range of 0–60%. We address device variability by using a one-time, single-point calibration approach. In contrast with previous approaches, which infer temperature change through a normalized measurement at two temperatures, our prototype devices provide an absolute output without temperature cycling. This is essential for practical deployment because heating and cooling the sensor is prohibitively slow and costly during real-time operation and production testing. Using carbon nanotube transistors, stretchable temperature sensor circuits can be designed that suppress strain-dependent errors and achieve a measured inaccuracy of only ±1 °C within a uniaxial strain range of 0–60%