The broader impact/commercial potential of this Small Business Technology Transfer (STTR) Phase I project is to address the need for accurate devices capable of operating in extreme environments exceeding 250 °C. Many sensors have key components made of quartz, known for its high sensitivity, accuracy, and stability; but it cannot operate at temperatures exceeding 250 °C. The applications requiring sensitive components operating at these high temperatures include interplanetary spacecraft, nuclear reactors, deep drilling, enhanced geothermal systems, and hypersonic aircrafts and missiles. The proposed project will develop new sensors using advanced material technologies. This Small Business Technology Transfer (STTR) Phase I project aims to develop a novel resonator on piezoelectric materials optimized for performance at high temperature and pressure. The proposed dual-mode resonators are expected to exhibit much higher stability and accuracy. They are also expected to have significantly less need for systemic recalibration. The three main objectives in this project are to optimize the cut angles of the piezoelectric material; develop wafer-level fabrication processes, for size and cost reduction; and to develop a wafer bonding process for eventual wafer-level packaging of the resonators. The effort address translation challenges in device structure, synthesis, modeling and optimization, wafer level fabrication and packaging, to make highly sensitive, accurate, small footprint, low-cost resonators.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.