Printed Silicon Nanoribbon-Based Temperature Sensors on Flexible Substrates

Abstract

Sensor-laden electronic skins (e-skins) are needed for robots and wearable systems to feel external stimuli such as temperature and pressure. Temperature sensing is particularly of interest to allow timely action by robots against painful hot or very cold conditions. Herein, we present doped silicon nanoribbons (Si NRs) based miniaturized (≈315 μm<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup>) and highly sensitive temperature sensors printed onto flexible substrates. The arrays of temperature sensors based on p–i–n junctions formed along the length of the doped Si NRs are obtained on flexible substrates using custom-built direct roll printing method combined with a few conventional microfabrication process steps. In the constant current mode, the sensors exhibit a high thermal sensitivity of −1mV ± 0.3°C<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> (extracted from voltages at specific currents) over the tested temperature range of 5°C and 75°C, along with excellent repeatability with no hysteresis over multiple cycles. Furthermore, the printed temperature sensor demonstrates ∼9.4% increase in current per°C, highlighting its excellent response to temperature variations. These results show the promise of the presented temperature sensors hold for wider application of e-skin in areas such as health monitoring, robotics, digital agriculture etc.