Electrostatic Steering of Charged Droplets in Microfluidic Devices

Summary The invention consists of means of charging droplets and then using that charge to choose which channel a droplet will enter at a bifurcation.

There is a need to have fast, accurate means of precisely sorting and directing materials in an automated way on a microfluidic device. Examples of materials that one would want to sort are mixtures of living and dead cells, or male and female embryos. Other situations where there is a need to steer droplets are for combinatorial chemistry mixing and analysis in lab-on-a-chip devices and for concentrating materials.

Streams of immiscible fluids, fluid A and fluid B, are brought together in microfluidic channels where droplets of fluid B, the dispersed phase, are formed in fluid A, the continuous phase. An electric field is applied during drop break-off so that electric charge is deposited on the surface of the droplet. The droplets can then be directed to enter a specific channel at a bifurcation in the channels through the application of a second electric field at the bifurcation. This technique is extremely robust and allows for fast sorting due to the high speeds at which fields can be switched and the large electrostatic forces that can be generated.

Applications Uses:
(1) Precise placement of droplets Combinatorial chemistry: The composition of fluid A can be systematically varied to generate droplets of various given compositions. This invention can then be used to put those droplets into a specific channel based on their composition for analysis or continued processing in lab-on-a-chip applications.
(2) Cell sorting Mixtures of cells, for example living and dead cells or male and female embryos, can be carried in an aqueous stream at low concentration. This invention would be used to make charged droplets containing zero or one cell. Analysis of the droplet would be made as it flows down the channel as in traditional cell cytometry. For Further Information Please Contact the Director of Business Development Daniel Behr Email: daniel_behr@harvard.edu Telephone: (617) 495-3067

Inventor(s): Link, Darren R.

Type of Offer: Licensing

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