Ultra-Sensitive, Rapid, Point-of-Use (POU) Mercury Sensor Enabled by Light-Pinpointed Enrichment

Ultra-Sensitive, Rapid, Point-of-Use Mercury Sensor Enabled by Light-Pinpointed Enrichment Freshwater from lakes and rivers has sustained human societies for millions of years. However, most natural water sources fail to meet modern safety standards due to dangerous metal contaminants and disease-causing pathogens. Modern cities with complex infrastructures provide purified water, essential for sustaining large populations. Yet, industrial spills, natural disasters, and unforeseen accidents can quickly compromise the quality of municipal water, severely endangering people’s safety and health, especially children and the elderly. For instance, alone in the 2021 Texas winter disaster, approximately 14.9 million people experienced disrupted or contaminated municipal water supplies. This underscores the urgency of strengthening societal resilience to counter unforeseen disasters' impacts. A critical need is to develop water-sensing technologies that empower individuals and households to assess water safety, particularly in detecting toxic metal contaminants like mercury, which can cause irreversible brain damage. Although various mercury sensors have been made, detecting low mercury concentrations in water with both high sensitivity and speed remains challenging, an intrinsic limitation in nanosensing technology. The overall aim of this project is to develop a portable, accurate, high-speed mercury sensor using environment friendly materials. Integrated with water drawing, dispersion, and a mobile app interface, the user-friendly device will greatly enhance the capability of individuals and households in assessing water safety, bolstering citizens’ resilience during natural disasters. The proposed innovation will leverage the PI-Prof. Fan’s two patented/disclosed techniques (PCT/078553, 2023, and UT Tech ID 8518 FAN), to overcome the grand challenges in nanosensing. Specifically, the proposed device will leverage the unique optoconductive property of semiconductor Silicon, which, can precisely concentrate biochemicals, ranging from small adenine molecules to large DNAs, just at the light-pointed Si nanorod sensors in an electric field, while the same laser simultaneously detects the enriched analytes via Raman spectroscopy. Preliminary results support the proposed research, which have demonstrated robust, five order-of-magnitude improvement of the limit of detection (LOD) from 0.1 nM to 1 fM, reaching a sensitivity of 0.6 fM of probing molecules. In this phase-I period, the PI will validate the proposed device concept, fabrication approach, and evaluate its performance in detecting trace mercury levels across diverse water conditions, including tap water, river water, and wastewater. The efforts will cement the overarching goal in inventing a POU, ultrasensitive, rapid Mercury sensor for the use by citizens and households.