Optoelectrowetting for actuation of nanoliter droplets, revisited
Final Report Abstract
With the transition of analytical chemistry to "lab on a chip 2.0" approaches relying on individual liquid droplets (digital microfluidics, DMF) instead of capillary fluid channels, droplet actuation/movement has become important. One possible approach is based on electrowetting on dielectric (EWOD) with electrical control of droplet movement on a suitably coated substrate. This procedure has the disadvantage that all the desired droplet positions have to be known before the chip is manufactured, as one of the electrode layers has to be structured accordingly. For optoelectrowetting (OEW), none of the electrode layers needs to be structured; however, the layer sequence is more complex due to an additional photoconductive layer. The drop is moved to where a light spot is moved, which changes the electrical parameters of the layer sequence locally. The project has provided design rules for optimizing the relevant parameters of the layer sequence, the droplet, and its illumination. Nevertheless, OEW application remains difficult in practice, as the effect depends on droplet size, conductivity, illuminated droplet fraction, illumination wavelength and intensity, which requires optimization in each individual case of application.
Publications
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Optimizing contact angle changes for droplet actuation by optoelectrowetting (OEW): A numerical multi-parameter analysis. Sensors and Actuators A: Physical, 365, 114835.
Oliveira, E.; Doering, C. & Fouckhardt, H.
