Time-resolved measurements of DNA interactions in an electrowetting-on-dielectric system using confocal microscopy

© Fraunhofer FIT
Sequence of a drop movement from a reservoir via an electrode array to the detection point and back. The drop volume is about 150 nl.
© Fraunhofer FIT
Schematic representation of the functioning of EWOD-BioPro.
© Fraunhofer FIT
Bracket with EWOD chip and connections for the control.

The EWOD-BioPro Electrowetting-On-Dielectric System allows the transport and manipulation of the smallest liquid volumes (approx. 150 nl). Standard microfluidic operations can be performed on individual drops. This includes

  • the drop transport,
  • the symmetrical split of a drop into two small drops,
  • bringing togehter and merging two drops into a drop,
  • and separating a drop from a larger liquid reservoir.

With these basic operations drops can be specifically manipulated. Together with existing techniques for single-molecule detection (Toposcan platform), time-resolved measurements of molecular interactions on single-molecule molecules are possible.

The EWOD BioPro Electrowetting-On-Dielectric System can help to improve the understanding of biological mechanisms and interactions considerably. The identification of new drug candidates and the development of new therapeutics are facilitated with the system.

Application areas

  • Point-of-care diagnostics
    • Examination of blood samples, urine samples etc. by means of enzymatic assays
    • Applications in DNA examinations, biological probes, biomarkers
  • Parallelization and miniaturization of laboratory analyzes
    • Reduction of chemicals and sample consumption
    • Acceleration of investigations
  • Basic research
    • Understanding of biological interactions (drug-target-structure interactions)

The above-mentioned systems are essentially dependent on a combination of the electrowetting with suitable detection methods (eg. Toposcan platform, IMIKRID).

© Fraunhofer FIT
Fluorescence signal of a colored DNA solution, which was moved to the detection spot several times by means of EWOD-BioPro.

The proof-of-concept i.e. the combination of an EWOD device with a confocal microscope was displayed by the merging of two droplets and the measuring of fluorescence increase due to molecule diffusion from one droplet to another. In addition, a small droplet of DNA solution was moved in and out of the detection spot of the microscope. The measured intensity signals are reproducible without any signal loss from peak to peak. This indicates the good suitability of the combined system for further molecule interaction measurements.

Further experiments are planned to investigate the interaction of biomolecules. 

Further details on the system can be found in the linked publication below.