Here’s a literature review I did several years ago on opto-electrowetting (or opto-EWOD). I think this would make a great collaborative open-hardware project. This technique is particularly interesting because it solves many of the problems with other types of DMF (e.g., EWOD). I made this post a wiki, so edits/contributions are welcome and encouraged!
These are the reasons why opto-EWOD is interesting:
- You get millions of addressable fluxels from a projector that fits in your pocket and costs <$200 (and getting cheaper every year).
- You only need 2 electrical connections (GND and HV). Connectors are one of the biggest challenges and biggest expenses for traditional DMF platforms.
- Fabrication of the devices is 1D vs 3D. For DMF, you need a to fabricate an electrode pattern at <100um resolution (2D), then you need to build up the z-layer stack (dielectric, hydrophobic layers) with a surface roughness of 0.1-1um. It’s possible, but it pushes the limits of all of the technologies involved. For opto-EWOD, fabrication is as easy as it gets; you can choose from a selection of simple printing and lamination processes. The only trick is materials science, but there seem to be practical materials available right now; it’s just that the processes and tricks are not as widely known in the community.
- I’m not 100% sure about the patent landscape, but the first patent I am aware of is from 2004, which means that it is due to expire in the very near future.
- Chiou, P. Y., Moon, H., Toshiyoshi, H., Kim, C.-J. & Wu, M. C. Light actuation of liquid by optoelectrowetting. Sens. Actuators Phys. 104, 222–228 (2003). [cited by 226]
- P. Y. Chiou, Z. Chang, and M. C. Wu, “Droplet Manipulation With Light on Optoelectrowetting Device,” J. Microelectromechanical Syst., vol. 17, no. 1, pp. 133–138, Feb. 2008. [cited by 58]
- P. Y. Chiou, S.-Y. Park, and M. C. Wu, “Continuous optoelectrowetting for picoliter droplet manipulation,” Appl. Phys*. Lett.*, Dec. 2008. [cited by 46]
- Pei, S. N. et al. Light-actuated digital microfluidics for large-scale, parallel manipulation of arbitrarily sized droplets. in 2010 IEEE 23rd International Conference on Micro Electro Mechanical Systems (MEMS) 252–255 (2010). doi:10.1109/MEMSYS.2010.5442519 [cited by 25]
- J. K. Valley, S. NingPei, A. Jamshidi, H.-Y. Hsu, and M. C. Wu, “A unified platform for optoelectrowetting and optoelectronic tweezers,” Lab. Chip, vol. 11, no. 7, pp. 1292–1297, Apr. 2011. [cited by 32]
1. S. N. Pei, “Optofluidic Devices for Droplet and Cell Manipulation,” 2015.
- This is an excellent thesis and provides a lot of optimization information on light power, color, photoconductor thickness, etc.
- Optimizes OEW process so that it can be controlled via a DLP projector instead of a laser
1. P. Y. Chiou, “Systems and methods for optical actuation of microfluidics based on opto-electrowetting,” WO2004012848 A2, 12-Feb-2004.
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