Piezotronic strain sensor with uniform and switchable sensitivity by conductivity transformation

Piezotronic strain sensors that convert mechanical deformation into electrical signals are becoming increasingly important in artificial intelligence, human-machine interfaces, and robotic technologies. These applications require piezotronic sensor with the integration of high-sensitivity, high-stability, and versatile-functionality, which are limited by the single conductivity mechanism. In this study, we propose a piezotronic strain sensor with uniform and switchable sensitivity in a short channel field-effect junction. The strain-induced piezo-potential can be used to switch the conductivity between Schottky and Ohmic regime, leading to an exponential (linear) piezotronic modulation in Schottky (Ohmic) conductivity elucidated by Fermi occupation theory. Local gauge factor reaches a high value of 1330 in Schottky conductivity and a low value of 320 in Ohmic regime, yielding a higher ratio of 4.2. The stable conductivity makes these high and low sensitivity uniform over a wide strain range. This study gives a deep insight into the correlation of strain-sensing performance and conductive mechanism in piezotronic sensors, and offers a new avenue to develop multifunctional and high-sensitivity sensors.