An impedance spectrometer for the river: biofilm monitoring in Montana
For Montana State University we built a portable EIS datalogger and deployed it on the Clark Fork River in September 2024.
Electrochemical impedance spectroscopy detects biofilms by their effect on the interface between electrode and water: a small AC signal swept across a frequency range, and the impedance response reveals the state. In the lab this needs an impedance analyser, mains-powered, bulky, expensive. Prof. Stephan Warnat at Montana State University wanted to take the measurement into the river.
Over a year we developed a datalogger with an integrated spectrum analyser for exactly that: battery or solar powered, robust against temperature and humidity, autonomous for weeks, tolerating partial failures without losing the measurement record. Hardware, firmware and enclosure went through several iterations. Tabea Bökelmann carried much of the practical engineering.
On 4 September 2024 we installed the system on the Clark Fork River north of Butte, a river with a mining legacy and ongoing remediation, exactly the environment where sensitive biofilm monitoring is scientifically interesting.
Field-ready instrumentation is at the core of our DAQ work. How the project came about and what happened at the river is told in the field report on the blog.