CLIP: Carbon Dioxide testing suitable for Low power microelectronics and IOT interfaces using Room temperature Ionic Liquid Platform

Ashlesha Bhide; Badrinath Jagannath; Ambalika Tanak; Richard Willis; Shalini Prasad

doi:10.1038/s41598-020-59525-y

CLIP: Carbon Dioxide testing suitable for Low power microelectronics and IOT interfaces using Room temperature Ionic Liquid Platform

Sci Rep. 2020 Feb 13;10(1):2557. doi: 10.1038/s41598-020-59525-y.

Authors

Ashlesha Bhide¹, Badrinath Jagannath¹, Ambalika Tanak¹, Richard Willis², Shalini Prasad³

Affiliations

¹ Department of Biomedical Engineering, University of Texas at Dallas, 800W Campbell Rd., Richardson, TX, 75080, USA.
² Department of Electrical and Computer Engineering, University of Texas at Dallas, 800W Campbell Rd., Richardson, TX, 75080, USA.
³ Department of Biomedical Engineering, University of Texas at Dallas, 800W Campbell Rd., Richardson, TX, 75080, USA. Shalini.Prasad@utdallas.edu.

Abstract

Health and safety considerations of room occupants in enclosed spaces is crucial for building management which entails control and stringent monitoring of CO₂ levels to maintain acceptable air quality standards and improve energy efficiency. Smart building management systems equipped with portable, low-power, non-invasive CO₂ sensing techniques can predict room occupancy detection based on CO₂ levels exhaled by humans. In this work, we have demonstrated the development and proof-of-feasibility working of an electrochemical RTIL- based sensor prototype for CO₂ detection in exhaled human breath. The portability, small form factor, embedded RTIL sensing element, integrability with low-power microelectronic and IOT interfaces makes this CO₂ sensor prototype a potential application for passive room occupancy monitoring. This prototype exhibits a wide dynamic range of 400-8000 ppm, a short response time of ~10 secs, and a reset time of ~6 secs in comparison to commercial standards. The calibration response of the prototype exhibits an R² of 0.956. With RTIL as the sensing element, we have achieved a sensitivity of 29 pF/ppm towards CO₂ at ambient environmental conditions and a three times greater selectivity towards CO₂ in the presence of N₂ and O₂. CO₂ detection is accomplished by quantifying the capacitance modulations arising within the electrical double layer from the RTIL- CO₂ interactions through AC- based electrochemical impedance spectroscopy and DC- based chronoamperometry.