Research & development - Eindhoven | About a week ago
Conductivity is one of the most often determined fluid parameters and is a measure for the total amount of dissolved ions. To determine conductivity, the resistance of a fluid sample located in the area between at least two electrodes is determined by impedance spectroscopy. The conductivity is then given by multiplying the measured conductance with the so-called cell constant of the sensor (Kcell).
The conductivity range that can be determined with a sensor depends on the chosen Kcell. This implies that a correct conductivity sensor must be chosen, fitting with the expected concentration range in the targeted application.
Commercially available conductivity sensors utilize two parallel planar electrodes (with a certain area and distance that define the Kcell). Such a geometry is difficult to miniaturize. However, Timmer et al  describe how planar interdigitated 2-electrode sensors on chip can be designed and how the Kcell value can be derived. A disadvantage of the 2-electrode conductivity sensor is the large electrode-electrolyte interface resistance which limits its application for a wide range of conductivity solutions. To minimize this, a 4-electrode sensor can be used, in which one pair of electrodes are injecting the current, while the other pair are sensing the voltage. We have extended this concept to microfabricated 4-electrodes conductivity sensor .
sensor to be embedded in concrete, so far 4 electrode measuring principle has
not been tested. The use of four-electrode technique will open new
possibilities for concrete application. Moreover, the same investigation in
agricultural substrate, like rock wool, will give new insight of the sensor
 B. Timmer, W. Sparreboom, W. Olthuis, P. Bergveld and A. van den Berg, “Optimization of an electrolyte conductivity detector for measuring low ion concentrations,” Lab Chip, vol. 2, pp 121-124, 2002
 Brom-Verheijden, Greja JAM, Martijn H. Goedbloed, and Marcel AG Zevenbergen. "A Microfabricated 4-Electrode Conductivity Sensor with Enhanced Range." Multidisciplinary Digital Publishing Institute Proceedings. Vol. 2. No. 13. 2018.
Click on ‘apply’ to submit your application. You will then be redirected to e-recruiting.
Please be advised that non-EU/EEA country students that are studying outside of the Netherlands, need to have a work-permit to be able to do an internship in the Netherlands.