Determination of gas concentrations and isotopologue ratios are a critical tool in plant, microbial and ecosystem ecology, hydrology, biogeochemistry studies, and interrogation of environmental remediation. In particular, real-time, high bandwidth, high sensitivity measurements of gases such as methane, nitrous oxide and carbon dioxide concentrations in air, soil, and water interfaces to ppm concentrations at a number of points within a given spatial-region would be extremely valuable for a variety of applications and models. This is especially true for the complex coastal environment. Isotopic labeling of these gases would also improve the usefulness of this information. In this SBIR program, Amethyst will design, construct, and deploy a prototype low cost, high sampling rate and high resolution autonomous gas measurement system. The system will be composed of multiple inexpensive single gas measurement sensors that can be designed to rapidly measure CH4, N2O and the carbon isotopes of CO2 at trace levels. Multiple single gas sensors can be placed at various locations and run by a base station. These low power automated gas measurements systems can be networked together with each system utilizing multiple senor heads that can be placed at multiple above and below ground locations as well as water interfaces. These sensor systems can be wirelessly connected to the main control system that can record the gas concentrations and CO2 isotopologue ratio at various sites in real time. The networked system will be able to operate unattended and upload data to the cloud so these gases can be monitored 24/7. Measurement speeds can be in the hertz range. During Phase I program Amethyst will build and test a demonstration resonant cavity photodetector-based gas sensor capable of detecting methane. Amethyst will also design the networked multi-gas sensor system and investigate an overall system design to optimize detection speed and sensitivity for a number of gases (CH4, 12CO2, 13CO2, and N2O). The Phase II program will construct the multi-point, multi gas networked sensor system then test and validate the sensor system in a field environment. The development of an inexpensive portable autonomous highly-sensitive multi-point and multi-gas sensor system capable of measurement of gases for monitoring microbial bio gases in soils, the air-water interface and in the air will be of very high value to the environmental, agricultural and biochemistry community. Development of gas sensors based on resonant cavity enhanced photodetectors will replace the expensive MWIR laser with a simple, inexpensive light emitting diode (LED), which will provide high sensitivity detection capabilities at a fraction of the cost of existing systems. After demonstration of high sensitivity CO2 N2O and CH4 detectors, the design can be extended to monitor other above and below ground gases with great utility in many industries where environmental monitoring is required.
