Acoustophoretic droplet handling in bulk acoustic wave devices

Patent metadata

Field	Value
Publication number	US-2016332159-A1
Application number	US-201515111854-A
Country	US
Kind code	A1
Filing date	Jan 12, 2015
Priority date	Jan 15, 2014
Publication date	Nov 17, 2016
Grant date	—

Abstract

An acoustofluidic system comprises a substrate ( 10 ) having an essentially rectangular recess with side walls ( 33 ), wherein the recess provides a microfluidic channel ( 30 ) containing a fluid with droplets ( 31 ), and at least one electromechanical transducer ( 20 ) attached at the substrate ( 10 ) adapted to excite an acoustic field in said channel ( 30 ). The side walls ( 33 ) are hard acoustic walls having a high specific acoustic impedance mismatch to said fluid in the channel ( 30 ) and the transducer ( 20 ) is configured to excite bulk acoustic waves (BAW) as standing waves ( 32 ) of a predetermined harmonic resonance mode between said hard acoustic side walls ( 33 ), which couple into the fluid in the channel ( 30 ) exerting acoustic pressure on droplets ( 31 ) suspended in said fluid towards the pressure nodal line, pressure antinode line or centerline of the standing wave ( 32 ).

First claim

1 .- 13 . (canceled)

14 . An acoustofluidic system, comprising
a substrate; at least one electromechanical transducer attached at the substrate; an essentially rectangular recess within the substrate; a fluid provided within the rectangular recess; at least a droplet provided within the fluid;
wherein the rectangular recess comprises two opposite side walls, wherein the recess provides a microfluidic channel containing the fluid with said droplets, wherein the at least one electromechanical transducer is configured to excite an acoustic field in said microfluidic channel, wherein the transducer is configured to excite bulk acoustic waves as standing waves of a predetermined harmonic resonance mode between said side walls, which couple into the fluid in the channel exerting acoustic radiation forces on said droplets suspended in said fluid towards the pressure nodal line of the standing wave or towards the pressure antinode line of the standing wave, depending on the fluid and droplet properties.

15 . The acoustofluidic system according to claim 14 , wherein the side walls of the channel are acoustically hard walls having a high specific acoustic impedance mismatch to said fluid in the channel.

16 . The acoustofluidic system according to claim 14 , wherein the electromechanical transducers for droplet handling are bulk piezoelectric transducers.

17 . The acoustofluidic system according to claim 14 , wherein the microfluidic channel in the substrate is covered by a glass plate.

18 . The acoustofluidic system according to claim 14 , wherein the height of the channel compared to its width is between 1:3 and 1:10.

19 . The acoustofluidic system according to claim 18 , wherein the height of the channel compared to its width is between 1:4 and 1:6.

20 . The acoustofluidic system according to claim 14 , further comprising two or more inlet nozzles adapted to deliver a fluid and/or a fluid comprising droplets.

21 . The acoustofluidic system according to claim 19 , wherein the inlet nozzle comprises a droplet generating T-junction adapted to deliver in conjunction with the fluid provided with a predetermined flow rate a droplet generating amount of a further liquid generating at the end wall of the channel a droplet having a diameter essentially similar to the height of the channel.

22 . The acoustofluidic system according to claim 19 , employed for acoustophoretic droplet merging/fusion, wherein the flow rate of the fluid delivered by the inlet nozzles is a predetermined different rate, so that each slower droplet is recovered by one of the faster droplets creating a merged droplet on the center nodal line.

23 . The acoustofluidic system according to claim 22 , wherein the fluid rate and size of the slower and faster droplets is predetermined so that the merged droplet is able to move on far away from the merging point in the channel before the next merger takes place.

24 . The acoustofluidic system according to claim 14 , employed for acoustophoretic droplet handling tasks such as droplet sorting, wherein the end area of the channel outlet comprises two outlets with an intermediate separating wall.

25 . The acoustofluidic system according to claim 24 , wherein the intermediate separating wall is a rounded nose.

26 . The acoustofluidic system according to claim 24 , wherein the separating wall is provided outside the middle axis of the channel, dividing the cross-section into a smaller outlet on the side of the intermediate separating wall and a broader outlet on the other side, so that when droplets are introduced into the channel on the side where the separating wall is provided, the droplet is evacuated in the smaller outlet when the transducer is not excited or when the transducer is excited in a λmode, and that the droplet is evacuated in the broader outlet when the transducer is excited in a λ/2 mode, since the acoustic pressure pushes the droplet towards the central nodal line.

27 . The acoustofluidic system according to claim 14 , employed for the exchange of the continuous fluid in which the droplets are suspended, wherein at least two inlet nozzles provide different first and second fluids and wherein any droplet provided in the first fluid is pushed out of this first fluid into the stream of the second fluid through the standing waves having a nodal centerline in the second fluid.

28 . The acoustofluidic system according to claim 14 , wherein the droplets are generated to be entered into the microfluidic channel having a diameter of 10-250 μm.

29 . The acoustofluidic system according to claim 28 , wherein the height of the channel is in the range between 100 and 200 μm.

30 . The acoustofluidic system according to claim 14 , wherein at least one of said droplets contains at least one cell or at least one virus.

Assignees

• Eth Zuerich

Inventors

• Dual Jurg
• Leibacher Ivo
• Reichert Peter

Classifications

• B01L3/502784 Primary

  specially adapted for droplet or plug flow, e.g. digital microfluidics · CPC title

• B01L3/50273 Primary

  characterised by the means or forces applied to move the fluids · CPC title

• B01L3/502715

  characterised by interfacing components, e.g. fluidic, electrical, optical or mechanical interfaces · CPC title

• B01L2200/0673

  Handling of plugs of fluid surrounded by immiscible fluid · CPC title

• B01L2300/0816

  Cards, e.g. flat sample carriers usually with flow in two horizontal directions · CPC title