Portable Pumpless 3D-Printed Chip for On-Site Colorimetric Screening of Hg2+ in Lake Water

The early detection of mercury ions in water sources should be emphasized to prevent human exposure to mercury through drinking water or food consumption. Here, we used a three-dimensional (3D)-printed multiarray chip to achieve colorimetric detection of inorganic mercury ions in environmental matrices such as lake water. The chip designed for the multidetection of inorganic mercury did not require an electrical syringe pump or a complex analytical system, thereby making it suitable for on-site detection. The chip could detect inorganic mercury ions via rolling circle amplification, by selectively harnessing thymine-Hg 2+ -thymine coordination chemistry. Additionally, the activities of rolling circle amplification in simple and environmental matrices were compared. The limits of detection for inorganic mercury ions were 3.4 and 4.1 µg/L in the simple and environmental matrices, respectively. Further, the chip was successfully applied for the detection of mercury in actual lake water samples collected from locations nearby inland fish farms. The results were quantitatively comparable to those obtained using a conventional mercury analyzer.