Lab-on-cloth integrated with a photoelectrochemical cell and ion imprinting for point-of-care testing of Hg(Ⅱ)

Abstract

In this work, we successfully developed a cloth-based device integrated with a photoelectrochemical (PEC) cell and ion imprinting for point-of-care testing (POCT) of divalent mercury ions (Hg(Ⅱ)). PEC cells have increasingly emerged as promising power supply units in recent years. The CdS/ZnS core-shell quantum dots (QDs) are used in the PEC cell, because they improve the spatial separation and transfer of charge and broaden the absorption of visible light. Ion imprinting can identify a specific metal ion selectively in the presence of other interfering ions. To achieve noninterference identification, the QDs-based PEC cell region is isolated from the ion imprinting-based detection area. In addition, wax screen-printing can be used in conjunction with carbon ink screen-printing for economical and facile fabrication of cloth-based devices. Under optimized conditions, Hg(Ⅱ) can be determined over the range of 0.0005–5 mg/L, with a detection limit of 0.090 µg/L (i.e., 0.45 nM). The proposed cloth-based devices are also applied successfully for the detection of Hg(Ⅱ) in sweat, complex water and food samples, with recoveries of 98.2–116.1% and relative standard deviations (RSDs) of 1.2–13.9%. Additionally, cloth-based devices have acceptable storage stability and selectivity. Therefore, the presented method offers a sensitive, low-cost, portable POCT device and has the potential to be applied for human body, environmental and food monitoring in remote areas and developing or industrialized countries.