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.
Highlights
Www.nature.com/scientificreports occupancy and ventilation rates; CO2 concentration can still be regarded as a proxy standard to measure ventilation per person[4]
We have described the functionality and utility of a developed low-power microelectronic research prototype integrated with an Room temperature ionic liquids (RTIL)-based electrochemical sensing platform for the detection of CO2 in exhaled breath as a measure of room occupancy
An empirical approach towards utilization of a unique sensing element – RTIL is evaluated towards development of a low-power CO2 gas
Summary
Www.nature.com/scientificreports occupancy and ventilation rates; CO2 concentration can still be regarded as a proxy standard to measure ventilation per person[4]. Integration of low- power microelectronics with sensing platforms offer a solution for room occupancy monitoring by providing real-time gas analysis of indoor CO2 with minimal user interference. Such a device needs to be portable, handheld, low-cost, low-power, small-size, sensitive to CO2, and highly selective to CO2 over other environmental gases and volatile organic compounds (VOC). We have described the functionality and utility of a developed low-power microelectronic research prototype integrated with an RTIL-based electrochemical sensing platform for the detection of CO2 in exhaled breath as a measure of room occupancy. We have leveraged the electrochemical double layer formation of the RTIL moieties to capture the interfacial modulations occurring as a result of RTIL-CO2 interactions at the RTIL- electrode interface through electrochemical impedance spectroscopy and chronoamperometric techniques
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