Temperature-insensitive silicon carbide resonant micro-extensometers

Abstract

This work presents thin-film polycrystalline silicon carbide resonant micro-extensometers fabricated on a singlecrystalline silicon substrate that are temperature-insensitive near room temperature. The slight difference in thermal expansion coefficient between the device layer and the substrate induces a slight tensile strain near room temperature, which counteracts material softening of the resonator. An analytical model that accounts for these thermal effects predicts that this system will exhibit a turnover temperature near room temperature. A temperature sensitivity of 0.7 Hz/°C (3.6 ppm/°C) from 17 to 65°C is measured experimentally, without compromising the strain-sensing capability of the resonator. This is nearly a 10-fold improvement over an equivalent epitaxial silicon resonant miro-extensometer (-30 ppm/°C) [1].

Silicon carbide resonant tuning fork for microsensing applications in high-temperature and high G-shock environments

“…Several different authors have proposed temperature compensation methods for tuning forks. This includes passive compensation by using materials of different CTE, [20][21][22] methods using pairs of resonators, 10,23 or measuring two quantities 9 or modes 24 of the same resonator. Example time-lapse photography of the G-shock testing is shown in Fig.…”