System and method for droplet formation and manipulation using ferrofluids

Patent metadata

Field	Value
Publication number	US-2018296992-A1
Application number	US-201615767979-A
Country	US
Kind code	A1
Filing date	Oct 7, 2016
Priority date	Oct 15, 2015
Publication date	Oct 18, 2018
Grant date	—

Abstract

A microfluidic device for forming droplets includes at least one ferrofluid reservoir disposed in the microfluidic device and containing a ferrofluid therein. The microfluidic device includes a continuous-phase reservoir disposed in the microfluidic device and containing an oil phase therein and one or more microfluidic channels connecting between the at least one ferrofluid reservoir and the continuous-phase reservoir, the continuous-phase reservoir comprising a step region having an increased height as compared to a height of the one or more microfluidic channels. To form droplets an externally applied magnetic field is applied to the device to pull the ferrofluid into the continuous-phase reservoir, whereby droplets are formed at step region.

First claim

1 . A method of forming droplets in a microfluidic device using a ferrofluid comprising:
providing a microfluidic device having one or more ferrofluid reservoirs containing a ferrofluid therein and a continuous-phase reservoir containing an oil therein, wherein the one or more ferrofluid reservoirs are coupled to the continuous-phase reservoir via one or more microfluidic channels, the continuous-phase reservoir comprising a step region having an increased height as compared to a height of the one or more microfluidic channels; and applying an external magnetic field to the microfluidic device, wherein the external magnetic field moves the ferrofluid solution along the one or more microfluidic channels and generates droplets in the continuous-phase reservoir.

2 . The method of claim 1 , wherein the one or more microfluidic channels interface with the step region at a terraced region, the terraced region having a height equivalent to the height of the one or more microfluidic channels.

3 . The method of claim 1 , wherein a plurality of microfluidic channels connect between a single ferrofluid reservoir and the continuous-phase reservoir.

4 . The method of claim 1 , wherein the ferrofluid comprises an aqueous solution containing magnetic nanoparticles suspended therein.

5 . The method of claim 4 , wherein the magnetic nanoparticles have a diameter that is less than 100 nm.

6 . The method of claim 1 , wherein the ferrofluid solution comprises a mixture of a sample solution and an aqueous ferrofluid solution.

7 . The method of claim 6 , wherein the sample solution comprises one or more reagents.

8 . The method of claim 6 , wherein the sample solution comprises one or more cells.

9 . The method of claim 1 , further comprising imaging the droplets.

10 . The method of claim 1 , further comprising passing at least some of the droplets through a porous membrane located in the continuous-phase reservoir by applying an external magnetic field to the droplets.

11 . (canceled)

12 . The method of claim 1 , wherein the microfluidic device has a plurality of ferrofluid reservoirs, each containing a different reagent and a ferrofluid.

13 . The method of claim 12 , wherein the plurality of ferrofluid reservoirs contain differing concentrations of magnetic nanoparticles.

14 . A method of forming droplets in a microfluidic device using a ferrofluid comprising:
providing a microfluidic device having one or more ferrofluid reservoirs containing an organic ferrofluid therein and a continuous-phase reservoir containing an aqueous solution therein, wherein the one or more ferrofluid reservoirs are coupled to the continuous-phase reservoir via one or more microfluidic channels, the continuous-phase reservoir comprising a step region having an increased height as compared to a height of the one or more microfluidic channels; and applying an external magnetic field to the microfluidic device, wherein the external magnetic field moves the organic ferrofluid solution along the one or more microfluidic channels and generates organic droplets in the continuous-phase reservoir.

15 . The method of claim 14 , further comprising passing at least some of the droplets through a porous membrane located in the continuous-phase reservoir by applying an external magnetic field to the droplets.

16 . (canceled)

17 . A microfluidic device for forming droplets comprising:
at least one ferrofluid reservoir disposed in the microfluidic device and containing a ferrofluid therein; a continuous-phase reservoir disposed in the microfluidic device and containing an oil phase therein; one or more microfluidic channels connecting between the at least one ferrofluid reservoir and the continuous-phase reservoir, the continuous-phase reservoir comprising a step region having an increased height as compared to a height of the one or more microfluidic channels; and a moveable external magnet located adjacent to the microfluidic device.

18 . The microfluidic device of claim 17 , wherein the one or more microfluidic channels interface with the step region at a terraced region, the terraced region having a height equivalent to the height of the one or more microfluidic channels.

19 . The microfluidic device of claim 17 , wherein a plurality of microfluidic channels connect between one of the at least one ferrofluid reservoir and the continuous-phase reservoir.

20 . The microfluidic device of claim 17 , further comprising a track or stage for moving the external magnet.

21 . The microfluidic device of claim 17 , wherein the continuous-phase reservoir comprises a porous membrane disposed therein, and further a secondary liquid phase disposed on a side of the porous membrane opposite a side contained in the continuous-phase reservoir .

22 . (canceled)

23 . The microfluidic device of claim 21 , further comprising a collection chamber disposed on a side of the porous membrane opposite a side contained in the continuous-phase reservoir.

24 - 25 . (canceled)

Assignees

• Univ California

Inventors

• Di Carlo Dino
• Kahkeshani Soroush

Classifications

• B01F3/0815 Primary

  Operations & Transport · mapped topic

• A61K9/0097

  Medicinal compositions released by microdevices, e.g. microelectromechanical systems [MEMS], microdevices comprising chips or microdevices on silicon · CPC title

• B01F13/0077

  Operations & Transport · mapped topic

• B01F33/30

  Micromixers · CPC title

• B01F23/411 Primary

  using electrical or magnetic fields, heat or vibrations · CPC title