Differential spectrometric gas sensor with dual out-of-phase microplasma sources

This Letter presents a method for gas sensing based on differential microplasma emission spectroscopy. The method used two strip line split-ring resonator microplasma sources that were powered differentially by modulated power supplies. It was shown to reduce 1/f noise and improve the signal-to-noise ratio and exhibited good accuracy and linearity for sensing CO2 concentration over close to two orders of magnitude. The focus of the study was improved response time and stability, and the results show a 0.2 s response time dominated by advection through the integrated fluidics, and a more than six times stability improvement compared to previous studies. The latter was likely due to several parallel effects, including reduced heat loss in the microplasma sources, and the differential embodiment of the system that balanced temperature and pressure-dependent drift. In a preliminary evaluation, the system displayed a sensitivity of 19 mu V/% CO2, a linearity of 0.999, an accuracy of 580 ppm, a response time of 0.2 s, and a maximum averaging time of 620 s, along with ample opportunities for further optimization. Overall, the proposed sensing method shows promise for many kinds of gas sensing applications, particularly for stable and precise measurements in environments where drift is a concern. VC 2023 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).