In this project we use silicon micro-mechanical resonators as ultra-sensitive mass sensors for the detection of trace amounts of copper ions in water samples. The approach is based on the reduction of aqueous metal ions by the silicon in a resonant structure and consequently deposition of a very thin metal layer on the resonator surface changing its resonant frequency. We have successfully detected sub-ppm concentrations of copper (II) ions in water using capacitive silicon-based resonant structures. Relatively large frequency shifts (hundreds of ppm) have been measured for resonators exposed to copper concentrations as low as 4μM (0.26 ppm).
- A. Rahafrooz, S. Pourkamali, “Resonant MEMS sensors for detection of aqueous heavy metal ions with sub-ppm resolution,” Proceedings, IEEE Electron Devices and Solid-State Circuits Conference, 2008.
- A. Rahafrooz, and S. Pourkamali, “Detection of sub-ppm traces of aqueous heavy-metal ions using micro-electro-mechanical beam resonators,” Journal of Micromechanics and Microengineering, vol. 19, no. 11, 115003, September 2009.