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/Job opportunities/Student Project: Miniaturized embedded electrochemical sensor for environmental application

Student Project: Miniaturized embedded electrochemical sensor for environmental application

Research & development - Eindhoven | More than two weeks ago

Electrochemical conductivity sensors are well known to indirectly determine moisture and salt concentration in different environmental applications such as in concrete and agricultural substrates. This sensor will be a node in the broader IoT application for smart cities. Your assignment will be to find an optimized sensor design and its operational parameters which are suitable for embedding the sensor in concrete and agricultural substrates. This work also includes a literature review of the sensor application, sensor design, and experimental work in the lab.

Student Project: Miniaturized embedded electrochemical sensor for environmental application

What you will do

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 [1] 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 [2].

For 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 performance.

[1] 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

[2] 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.

Tasks:

  • Literature search (4-electrode impedance measurement, moisture detection sensors).
  • Experimental work to investigate optimized parameters for measurements in concrete and agricultural substrates.
  • Give advice and/or design a new 4-electrode conductivity sensor with a specified Kcell that fits the target applications.

Who you are

  • You are a Msc or Bsc student in Applied Physics, Biomedical Engineering, Chemical Engineering, Electrical Engineering, Mechanical Engineering or Mathematics.
  • You are available for a period of 6 months.
  • Affinity for experimental work in the lab.
  • Interest and knowledge of sensor specifications, especially electrochemical sensors.
  • Motivated student eager to work independently and expand knowledge in the field.
  • Good written and verbal English skills.
  • Entitled to do an internship in the Netherlands. 
For internship opportunities at imec in Holst Centre, please visit the holst centre website: https://www.holstcentre.com/careers/thesis-opportunities/

Interested

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.