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SUMMARY:EESS talk on "Electrochemical Probes for Aquatic Analysis"
DTSTART:20230321T121500
DTEND:20230321T131500
DTSTAMP:20260929T171652Z
UID:7e4c387f87067cd4b73265ee919426166ba63d106153ba680d22749f
CATEGORIES:Conferences - Seminars
DESCRIPTION:Prof. Eric Bakker\, Chemical Sensors Research\, University of 
 Geneva\nAbstract:\nOur group aims to realize highly stable all-solid-conta
 ct potentiometric probes and their integration into submersible probes for
  aquatic analysis. This talk will show how three separate challenges can b
 e 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-t
 erm stability. This requires the design of an adapted reference element th
 at results in a so-called zero point in the middle of the calibration curv
 e. 2) Such probes are known to respond to ion activities and have uncertai
 nties originating from the liquid junction potential at the reference elem
 ent\, but a matrix-matched reference solution allows one to output ion con
 centration directly\, which is highly desired for environmental analysis. 
 3) An intermittent calibration step is introduced while maintaining a dire
 ct contact between the sensor and the aquatic sample\, allowing for operat
 ion at very low power. These advances are developed and explained separate
 ly and subsequently integrated into the design of a submersible probe\, wh
 ich is deployed in freshwater rivers and lakes\, including the Léxplore P
 latform on Lake Geneva.\nThe second part of the talk will focus on dramati
 cally improving the sensitivity of such probes by allowing for a small tra
 nsient current to pass through the cell. This so-called constant potential
  coulometric approach gives small current spikes that are easily observabl
 e and can be background subtracted to give unprecedented precision. An imp
 ortant application of this approach is the ultra-precise detection of pH\,
  including seawater pH\, which is important in view of quantifying ocean a
 cidification. The principle of the technique will be explained as well as 
 most recent advances achieved in our laboratory to make the approach matur
 e and field deployable. Other examples on using transient responses with s
 uch probes will also be shown including the development of self-powered se
 nsing principles where the probe turns on a display without the need for a
  traditional power supply or battery.\n\nShort biography:\nDr. Eric Bakker
  is professor of Analytical Chemistry at the University of Geneva. He rece
 ived his Ph.D. from ETH Zurich and spent 14 years in the U.S. as faculty m
 ember at Auburn University and Purdue University as well as three years in
  Australia at Curtin University before moving to Geneva in 2010. His inter
 ests 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 (Ameri
 can Chemical Society).\n 
LOCATION:GC B1 10 https://plan.epfl.ch/?room==GC%20B1%2010 https://epfl.zo
 om.us/j/69011077410
STATUS:CONFIRMED
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