Paper-Based Electrical Sensors for Aqueous Heavy Metal Ion Detections

Trace levels of heavy metals such as lead, cadmium, mercury, and arsenic can have harmful effects on human health, causing damage to organs and the nervous system. As a result, it is essential to monitor heavy metal concentrations continuously and in real-time, with detection limits of less than nanomolar to reduce their impact on the environment and human health. The development of paper-based microfluidics in recent years has made it a promising platform for lab-on-a-chip devices capable of detecting heavy metals on a large scale and on-site for environmental purposes. This review article will introduce commonly used paper-based electrical sensing (including electrochemical, FETs, and chemiresistive sensors), existing fabrication and analysis techniques, and various application areas for these heavy metal ion sensors. Additionally, the challenges that must be addressed for paper-based sensors to realize their full potential and future outlooks will be discussed.