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Epidermal sensors as personal chemical environmental monitoring tools

Periodic Reporting for period 1 - E-SCENT (Epidermal sensors as personal chemical environmental monitoring tools)

Reporting period: 2018-06-01 to 2020-05-31

The E-SCENT project focused on developing low-cost sensors for measurement of indoor air pollution. An estimated 4.3 million deaths occur each year from exposure to indoor air pollution. The average European spends 90% of their time indoors where exposure to air pollution can be substantially greater than exposures occurring outdoors.

Volatile organic compounds (VOCs) are a diverse group of chemical compounds present in indoor air that can frequently reach higher indoor concentrations compared to outdoors. Exposure to some VOCs can have serious health implications (e.g. asthma, nervous system impairment, cancer). Measurement of indoor air pollution is an integral part of exposure monitoring and human health risk assessment, but urgently requires development of appropriate tools to assist evidence-based public health and environmental measures due to the current dependence on outdoor air quality data.

Current air quality sensor technology is largely constrained to sensing physical parameters, and while chemical detection of some airborne pollutants in private households is possible (e.g. carbon monoxide alarms, radon test kits), measurement of chemically diverse analytes (e.g. VOCs) remains reliant on high-end instrumentation. The E-SCENT project aimed to progress beyond the current state of the art by developing colorimetric sensor arrays for measurement of chemically diverse analytes in indoor air. Colorimetric sensors undergo a colour change in the presence of an analyte. This approach takes advantage of strong chemical interactions between a sensor and analyte and offers a simple, cost-effective and easy-to-visualise method for the detection of VOCs.

The scientific objectives of this Marie Skłodowska Curie Action (MSCA) were to develop a colorimetric sensor array for measurement of VOCs in indoor air and to use this technology to monitor indoor air pollution with a focus on end-user activities. Another goal of the MSCA Individual Fellowship was to foster the development of the individual researcher.
Work was conducted via 6 work packages (WPs): (1) project management, (2) training and knowledge transfer, (3) development of sensors for measuring VOCs (4) integration of sensors in a prototype, (5) sensor application to indoor air quality monitoring, (6) communication and dissemination.

The project was managed under WP1. As part of WP2 (researcher training and transfer of knowledge), the Research Fellow attended 34 training workshops and multi-day conferences. She provided supervision and mentoring to early career researchers and educated over 300 undergraduate and postgraduate students through a series of guest lectures and demonstrations. During this MSCA Fellowship, she received the Irish Research Council Lindau Nobel Meeting Award, was elected to the Management Committee of COST Action CA17136 (Indoor Air Pollution Network) and as Leader of the Action’s Early Career Investigator Network. She was invited to speak at numerous events including a Gordon Research Conference and the IFSCC International Speaker Program. She also earned a professional certificate from the Institute of Leadership and Management.

WP3 involved developing and testing sensor materials for detection of VOCs. WP3 delivered a suite of 16 sensor formulations, a training data set, and an image analysis method to measure sensor colour changes. WP4 aimed to integrate the materials developed in WP3 into a prototype suitable for field deployment in WP5. WP4 delivered a protype sensor platform and a transfer printing method for rapid sensor fabrication. WP4 also delivered a packaging method for sensor preservation. Sensors were employed for differentiation of emissions from cooking activities and sensor performance was validated. WP5 involved sensor application to indoor air pollution monitoring. A training data set for different indoor environments was established and the environments were differentiated from each other based on their unique chemical fingerprints. WP5 culminated in a citizen science survey of household air pollution in 11 homes. In WP6 the Research Fellow delivered 14 public engagement activities to educate individuals on the importance of indoor air quality and communicate research findings.

Results of this MSCA are reported in (1) a forthcoming paper on monitoring VOC emissions from different cooking activities; (2) a forthcoming paper on monitoring household air pollution with colorimetric sensors; (3) a forthcoming paper on colorimetric sensing of VOC emissions from human skin. The datasets collected during this MSCA will continue to inform and enhance numerous publications in the coming years.
This MSCA has contributed to the advancement of indoor air pollution research in numerous ways. E-SCENT sensors go beyond state of the art by enabling measurement of chemically diverse species in indoor air. The sensor’s unique interaction with different VOCs produced characteristic colour changes enabling molecular recognition of a variety of chemicals. This represents a significant advance over existing low-cost sensor technologies which provide a limited measure of total VOCs and no information on chemical class. E-SCENT sensors target priority groups of chemicals (including carbonyl compounds which are of concern in relation to carcinogenicity) to provide more meaningful information on indoor air pollution which will allow human exposure and health impact assessments.

Advances in sensor printing and packaging enabled rapid production and transport of sensors for field testing in various indoor environments. Sensor deployments in different household environments revealed that activities like cooking, cleaning and burning scented candles were associated with increased VOC levels that could be monitored using this approach. The sensors provided important information on the levels of carbonyl compounds released from cooking activities and were capable of distinguishing between different cooking oils and foods based on VOC emissions.

Impacts anticipated from this action were achieved and several additional projects and outputs are under development. Communication activities increased the awareness of children and young students in science and technology, through workshops, demonstrations and lectures. A citizen science project provided citizens with opportunities to monitor household air quality and to become more informed about air pollution in their homes. The general public were reached through several publications in Irish media streams, including a timely article in the Irish Times on improving indoor air quality published during the COVID-19 lockdown.

Overall the technology developed in this Action offers excellent potential to enhance indoor air pollution monitoring by enabling low-cost, high-density deployment of sensors for the collection of representative exposure data in a variety of indoor settings. Potential impact areas include indoor air pollution research, monitoring in private and public buildings, evaluation of cooking associated air pollution in commercial and residential kitchens, personal exposure monitoring, citizen science initiatives and crowdsourcing of air pollution data. Further development of E-SCENT technology could enable high-resolution pollution mapping to promote action at local and European levels by informing policy development on indoor air quality and improving evidence-based public health measures.
Colorimetric sensor arrays for measurement of indoor air pollution