Detection of heavy metal by paper-based microfluidics

• The detection of heavy metal ions based on microfluidic paper-based analytical devices has been reviewed.
• Selection of substrates, fabrication methods, and relevant theories of paper-based analytical devices were discussed.
• Various detection mechanisms for detection of heavy metal ions were compared and discussed.
• Despite challenges, there is bright future for using paper-based devices for comprehensive heavy metal detection.

Heavy metal pollution has shown great threat to the environment and public health worldwide. Current methods for the detection of heavy metals require expensive instrumentation and laborious operation, which can only be accomplished in centralized laboratories. Various microfluidic paper-based analytical devices have been developed recently as simple, cheap and disposable alternatives to conventional ones for on-site detection of heavy metals. In this review, we first summarize current development of paper-based analytical devices and discuss the selection of paper substrates, methods of device fabrication, and relevant theories in these devices. We then compare and categorize recent reports on detection of heavy metals using paper-based microfluidic devices on the basis of various detection mechanisms, such as colorimetric, fluorescent, and electrochemical methods. To finalize, the future development and trend in this field are discussed.