Detection and Measurement of Heavy Metal Ions in Aqueous Solutions Using Resonant MEMS

8.aIn 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).




  1. 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.
  2. 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.