Sensors and Systems for Wearable Environmental Monitoring Toward IoT-Enabled Applications: A Review

Environmental pollution is a major issue for public health and safety. Measurement of fine-grain spatiotemporal distribution of pollution for a micro-environment is necessary to explore the correlations among environment, health, and behavior. The continuous advancement of miniature environmental sensing devices, microelectronics, and communication technologies propelled the development of wearable devices for environmental monitoring applications. This type of devices are able to acquire high-resolution objective geo-tagged data. The aim of this review is to summarize the contemporary research and developments on wearable devices intended for environmental Internet of Things (IoT) applications. This paper provides comprehensive descriptions of the state-of-the-art wearable environmental monitoring systems (WEMS) and compares them in terms of sensing and communication technologies. The reviewed WEMS are mainly classified into two groups based on whether they used commercial off-the-shelf (COTS) sensors or self-developed sensors. The first group is further categorized based on their wearability. In line with this, a consolidated description is provided by presenting the main features of the available wearable environmental monitoring devices from the industry. In addition, several issues are identified for WEMS and future research directions are provided. Thus, this review paper examines the current research on WEMS and can serve as a reference for the researchers and developers to provide perspectives toward future research improvements.