An Autonomous, On-Site Sampling / Analyzing System for Measuring Heavy Metal Ions in Ground Water

by MacKnight, Eric

The object of this thesis is to develop an autonomous on-site sampling system with electrochemical detection of heavy metals in ground water. The measuring system is comprised of three layers of components: an electrochemical control layer, a fluidic control layer, and a control interface layer. The electrochemical control layer consists of a commercial off-the-shelf (COTS) electrochemical potentiostat, disposable sensor chips, and the circuit board associated with them. The fluidic control layer consists of a pump, valves, polycarbonate microfluidic motherboard with the microfluidic channels etched in, and a circuit board for associated components. The control interface layer consists of a software program written in LabVIEW development environment, a data acquisition card (DAQ), and wireless components. The control interface layer works with both other layers to make the control strategy complete.

The autonomous system was developed in coordination with the development of new disposable Bismuth electrochemical sensors. Bismuth electrodes have the advantage of being more environmentally friendly than traditional Mercury drop electrodes, while maintaining similar sensitivity and other desirable characteristics. The system is approximately 8” W x 11” L (roughly the size of notebook paper) and about 3” deep. The small size and wireless computer interface gives the advantage of being portable for field use while not sacrificing portability for accuracy of measurement.

The developed sampling system was fully characterized for sampling and measuring functions in sequence for the analysis of heavy metals from both ground and surface water.