Ultratrace and Multiplex Visual/Smartphone Detection of Heavy Metal Ions by their Sulfidation on a Superhydrophobic Concentrator

Stanford researchers have developed a portable sensor device for rapid detection of heavy metal ions using a sulfidation process and concentrator for increased visual detection. The device achieves ultratrace and multiplex quantification of Pb²⁺, Ni²⁺, Cr³⁺, Cu²⁺ and Co²⁺ in 8 minutes with 90% accuracy and only requires 5 microliters of sample. The device contains four components: 1) a superhydrophobic concentrator (SPOT) sensor, 2) a miniature droplet heater, 2) a portable microscope, and 4) a smartphone image analyzer. In contrast to conventional optical sensors, this device's mobility allows for on-site testing of wastewater, groundwater, and soil etc. The unique SPOT concentrator continuously accumulates the heavy metal sulfides making visual detection easy down to a lower detection limit of 0.1 nanomolar, 3-6 orders of magnitude higher than WHO and EPA permissible levels. This device is applicable for field testing and other environmental monitoring purposes.

Stage of Research