Recent developments on aerial lab-on-a-drone platforms for remote environmental monitoring: A review.

Background: Distinct classes of environmental contaminants - such as microplastics, volatile organic compounds, inorganic gases, hormones, pesticides/herbicides, and heavy metals - have been continuously released into the environment from different sources. Anthropogenic activities with unprecedented consequences have impacted soil, surface waters, and the atmosphere. In this scenario, developing sensing materials and analytical platforms for monitoring water and air quality is essential to supporting worldwide environmental control agencies. Moreover, the distribution of such chemicals in the environment is not uniform, which requires the development of mobile and versatile analytical platforms to characterize the spatial and temporal profile of the pollutant's dispersion.

Results: Drones are excellent alternatives for in-field and remote monitoring with onboard analytical platforms. This review presents and discusses critical aspects related to drone-based platforms - i.e. lab-on-a-drone - for sampling and/or quantifying analytes dedicated to environmental (i.e. water and air) applications. A practice guide including the price range, max payload, flying time, and commercially available models is also introduced to support researchers selecting drones. As analytical procedures, colorimetric and electrochemical devices are described as powerful analytical tools to be attached in drones and to perform different environmental analyses. Lastly, examples of applications involving direct and indirect analysis of distinct pollutants, including toxic gases, particulate matter, and organic and inorganic ones, are highlighted. To date, no other review addresses the critical aspects of recent developments over the past five years in sampling and detection systems embedded in drones for environmental applications.

Significance And Novelty: This review provides a comprehensive overview of technological innovations and compares the features of leading drone models, highlighting critical aspects for implementing portable analytical systems for air and water sampling and chemical analysis. We hope this work offers a clear perspective on current trends and provides valuable practical guidance for researchers and professionals interested in conducting remote environmental analyses.