Electrically actuated sampling and metering system for on-line microfluidic sensing platforms


In the last decade many microfluidic devices have been developed for a plurality of applications, ranging from biochemical analysis such as DNA and protein detection, biomedical diagnostics,  to environmental monitoring. Most of these devices are suitable for a single shot measurements where the heart of the system (microfluidic chip) is replaced after each measurement. One reason is that samples are usually still applied in a manual way.  However, few devices are available to perform multiple measurements over a prolonged period of time which is a must for on-line application in industrial environments. Even then, automated sampling usually is applied with off-chip discrete components (valves).

This project aims to develop on-chip valving and metering components based on electrowetting of a (normally) hydrophobic channel segment, allowing automatic sample intake and manipulation. Figure 1 shows a schematic of such an electrically operated valve. When a small voltage is applied to the embedded control electrode the surface becomes hydrophilic and water will flow through the valve. When the electrode is deactivated the water will evacuate the valve area due to the capillary pressure and the flow will stop. The hydrophobic air-vent channel allows air to flow in and out during switching. A series of such valve segments can be used to accurately separate a well-defined volume of fluid and transport it to the desired location on the chip for further processing (e.g. analysis or mixing)


Figure 1: Schematic of the microvalve.

The project comprises:

  • Identification and testing of proper materials for the hydrophobic electrodes
  • Design and simulation of valves and metering sections
  • Design of the microfluidic device and the fabrication process flow.



Andre Bossche