Ultrasensitive strain gauge with tunable temperature coefficient of resistivity

We demonstrate an ultrasensitive strain gauge based on a discontinuous metal film with a record detection limit as low as 8.3 × 10–6. Constructed by well-tunable crevices on the nanometer scale within the film, this gauge exhibits an ultrafast dynamic response to vibrations with a frequency range of 1 Hz to 10 kHz. More importantly, the temperature coefficient of resistivity (TCR) of the metal film is tunable owing to the cancellation effect caused by the possibility of tunneling across the nanoscale crevices (showing a negative temperature dependence) and the electron conduction within the metal islands (showing a positive temperature dependence). Consequently, a nullified TCR is achievable when the crevice size can be precisely controlled. Thus, a fabrication strategy to precisely control the nanoscale crevices was developed in this study through the real-time tracking of the electrical conductivity during thermal evaporation. The ultrasensitive strain gauge with a tunable thermal drift introduces numerous opportunities for precision devices and wearable electronics with superior reliability.