Wireless Networked Sensors in Water for Heavy Metal Detection

Heavy metals such as lead, arsenic, chromium, mercury, and cadmium have attracted significant worldwide attention for their impact on human health. To allow the efficient monitoring of such RCRA 8 heavy metal levels in water in steam electric power plants and other facilities, a precise, mobile and highly sensitive measuring instrument is required. Traditional laboratory based water analysis systems are usually costly and bulky, so not suitable for wide scale field deployment. Statement of how this problem or situation is being addressed NanoSonic’s NanoCS® chemFET heavy metal sensors offer significantly improved chemical sensitivity and selectivity, and wireless communication of contaminant concentration data to fix or mobile receivers. Multiple sensor elements can be configured into a small, lightweight, low cost probe to measure all RCRA 8 heavy metal targets simultaneously, and can be configured for permanent installation or mobile testing. What was done in Phase I? During Phase I, NanoSonic proved the technical feasibility of our initial scientific hypothesis. NanoSonic demonstrated that 1) silicon nanomembranes may be used as single chemFET sensor transducers, and as individual elements in multielement chemical sensor arrays, 2) a minimum detection level of 0.01ppm of target material can be achieved, 3) high selectivity to specific heavy metals, such as arsenic, barium, cadmium, chromium, lead, mercury, selenium and silver can be realized using different, chemically self-assembled interfaces between the sensor elements and the water being analyzed. What is planned for Phase II? During the Phase II program, NanoSonic would transition these semiconductor nanomembrane chemFET RCRA 8 sensors and probes from their current concept and prototype stage to fielded instrumentation products. Prototype sensor probes capable of measuring all RCRA 8 heavy metal concentrations would be field tested by subcontractors in multiple steam electric power plants, other manufacturing facilities, and wastewater systems. This will require a complete understanding of sensor properties and the transduction mechanism, optimization of sensor design and production processes, completion of data acquisition and signal processing hardware and software, and the development of effective approaches to calibrate manufactured sensors and compensate for cross sensitivity effects. Commercial Applications and Other Benefits Multiple small, low cost sensor probes could be distributed over an area to allow the spatial mapping of heavy metal targets and the tracking of heavy metal concentrations as they change over time. The proposed NanoCS RCRA 8 heavy metal analysis tool would be a viable commercial product for NanoSonic. Key Words: Heavy Metal; RCRA 8s; chemFET; Nanomembrane; Sensor network; Wireless; Steam electric power plant