EESS talk on "Electrochemical Probes for Aquatic Analysis"


Event details

Date 21.03.2023
Hour 12:1513:15
Speaker Prof. Eric Bakker, Chemical Sensors Research, University of Geneva
Location Online
Category Conferences - Seminars
Event Language English
Our group aims to realize highly stable all-solid-contact potentiometric probes and their integration into submersible probes for aquatic analysis. This talk will show how three separate challenges can be overcome to make these sensors as useful and robust as possible: 1) the concept of symmetry between the indicator and reference electrode must be restored to drastically reduce temperature fluctuations and enhance long-term stability. This requires the design of an adapted reference element that results in a so-called zero point in the middle of the calibration curve. 2) Such probes are known to respond to ion activities and have uncertainties originating from the liquid junction potential at the reference element, but a matrix-matched reference solution allows one to output ion concentration directly, which is highly desired for environmental analysis. 3) An intermittent calibration step is introduced while maintaining a direct contact between the sensor and the aquatic sample, allowing for operation at very low power. These advances are developed and explained separately and subsequently integrated into the design of a submersible probe, which is deployed in freshwater rivers and lakes, including the Léxplore Platform on Lake Geneva.
The second part of the talk will focus on dramatically improving the sensitivity of such probes by allowing for a small transient current to pass through the cell. This so-called constant potential coulometric approach gives small current spikes that are easily observable and can be background subtracted to give unprecedented precision. An important application of this approach is the ultra-precise detection of pH, including seawater pH, which is important in view of quantifying ocean acidification. The principle of the technique will be explained as well as most recent advances achieved in our laboratory to make the approach mature and field deployable. Other examples on using transient responses with such probes will also be shown including the development of self-powered sensing principles where the probe turns on a display without the need for a traditional power supply or battery.

Short biography:
Dr. Eric Bakker is professor of Analytical Chemistry at the University of Geneva. He received his Ph.D. from ETH Zurich and spent 14 years in the U.S. as faculty member at Auburn University and Purdue University as well as three years in Australia at Curtin University before moving to Geneva in 2010. His interests are in chemical sensors, with a particular emphasis on ion-selective membranes. He has published about 400 papers so far that have been cited nearly 30’000 times. He serves as Executive Editor of ACS Sensors (American Chemical Society).

Practical information

  • General public
  • Free
  • This event is internal


  • EESS - IIE


  • Prof. Urs von Gunten, LTQE


aquatic sensing environmental analysis potentiometric probes ocean acidification novel methodologies