Spectroscopic Detection of Water Contaminants Using Glow Discharges from Liquid Microelectrodes
Inventors: Yogesh Gianchandani, Chester Wilson
The Wisconsin Alumni Research Foundation (WARF) is seeking commercial partners interested in developing a system for on-site, real-time analysis of trace contaminants in liquids and gases.
Threats to drinking water supplies from industrial and biochemical pollutants have created the need for rapid, on-site tools that detect and analyze trace contaminants in water. Current protocols for assessing water quality typically require transport of water samples to a laboratory for analysis with a plasma spectrometer. In plasma spectroscopy, a water sample is sprayed into a high-frequency, RF inductively-coupled plasma. Vaporized water droplets are then spectrally analyzed to determine the composition and quantity of impurities, such as heavy metals.
UW-Madison researchers have developed a micro-fabricated, on-chip spectroscopic system for on-site, real-time analysis of trace contaminants in liquids and gases. The system works as follows: Two microfluidic channels transport sampled water from two large reservoirs into two smaller pools, or liquid electrodes. A micro-glow discharge generated between the liquid electrodes sputters water molecules and impurity atoms into the discharge region. The resulting discharge emits discrete wavelengths of light that correspond to specific atomic transitions. By analyzing a spectrum of these wavelengths, the chemical composition of the water can be determined.
- Water impurity analysis
- Gas detection for military applications
- Localized detection of automobile emissions
- Wastewater analysis for compliance with environmental regulations
- Small and portable, allowing real-time, on-site analysis of trace contaminants in water
- Very inexpensive to manufacture compared to current large-scale plasma spectroscopy systems
- Allows maintenance of a continuous glow discharge in air at atmospheric pressure, eliminating the need for a vacuum system
- Electrodes are replenished by liquid flow, eliminating concern for electrode wear.
Stage of Development
Device was shown to detect sodium impurities at concentrations of 10 ppm, and lead at concentrations of 5 ppm.