Instant Sensitive Measurement of Hg Concentration Using Lab-on-a-Phone Colorimetry

Mercury is one of the most toxic heavy metals in the environment that can seriously damage the human health. Therefore, the identification of mercury in water sources such as rivers, lakes, and bays is very crucial. Many traditional methods are used for the detection of mercury (II) ions (Hg²⁺), but they suffer from dependence on expensive and complicated instruments and need time consuming operating process. Herein, a fast, low cost, and accurate lab-on-a-phone device has been introduced for on-site monitoring of Hg²⁺ in ppb level. It detects Hg²⁺ based on localized surface plasmon resonance property of gold nanoparticles. The apparatus consists of lightweight opto-mechanical attachment, wirelessly connected to a smart phone. This method presents a sensitive detection of Hg²⁺ in water with a detection limit of 3 nM (≈0.8 ppb). Detection limit of the proposed sensor is well below the maximum allowed containment level of Hg²⁺ for drinking water (6 ppb) by the World Health Organization.