The broader impact/commercial potential of this Small Business Innovation Research (SBIR) Phase II project is to improve personnel safety from flammable gas leaks in industrial, commercial, and residential facilities. Additionally, the technology contributes to combating climate change by tackling one of the leading sources of carbon emissions, methane emissions from oil and gas facilities. The technology enables the mitigation of methane and refrigerant leaks that constitutes a significant market opportunity in the oil, gas and HVACR (heating, ventilation, air conditioning and refrigeration) markets. The innovation may solve important technical bottlenecks that have prevented widespread adoption of pervasive gas sensing in Internet of Things (IoT) applications. As an enabling system, it may be utilized in a variety of other applications area such as the detection of explosives, narcotics, chemical weapons, indoor air quality monitoring, and diagnosis of disease via breath analysis.This Small Business Technology Transfer Phase II project seeks to develop a gas sensor with an unparalleled combination of size, power, and cost while offering high detection performance. The proposed architecture fabricates high-frequency bulk acoustic resonators directly on the backend of CMOS (Complementary Metal Oxide Semiconductor) integrated circuit chips which permits low-cost, mass-production and improved noise characteristics of the sensors. The direct co-integration also allows the fabrication of a receptor array to obtain responses from multiple target analytes that can be used to classify materials and for real-time calibration against environmental confounders. The objective of this project is the development of a single-chip gas sensor based on co-integrated piezoelectric materials. This effort will consist of the design, fabrication and characterization of integrated resonator arrays onto silicon circuits; integration of the chips with receptor materials, allowing selective adsorption of target gas molecules; and testing to assess the gas sensing performance.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.