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

Abstract

Health and safety considerations of room occupants in enclosed spaces is crucial for building management which entails control and stringent monitoring of CO ₂ levels to maintain acceptable air quality standards and improve energy efficiency. Smart building management systems equipped with portable, low-power, non-invasive CO ₂ sensing techniques can predict room occupancy detection based on CO ₂ 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 CO ₂ detection in exhaled human breath. The portability, small form factor, embedded RTIL sensing element, integrability with low-power microelectronic and IOT interfaces makes this CO ₂ 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 R ² of 0.956. With RTIL as the sensing element, we have achieved a sensitivity of 29 pF/ppm towards CO ₂ at ambient environmental conditions and a three times greater selectivity towards CO ₂ in the presence of N ₂ and O ₂. CO ₂ detection is accomplished by quantifying the capacitance modulations arising within the electrical double layer from the RTIL- CO ₂ interactions through AC- based electrochemical impedance spectroscopy and DC- based chronoamperometry.