A DEVICE, A SURFACE, AND A BIOSENSOR

Abstract

A device for manipulating a droplet comprising water is provided, the device including: (i) a surface configured to support the droplet, the surface including a hydrophobic region; and (ii) an ultrasound transducer array, the ultrasound transducer array being arranged above the surface and separated from the surface; wherein the ultrasound transducer array is configured to emit ultrasound for actuating a motion of the droplet along the surface by subjecting the droplet to an acoustic radiation force by the emitted ultrasound.

Claims

1. A device for manipulating a droplet comprising water, the device comprising: a surface configured to support the droplet, the surface comprising a hydrophobic region; and an ultrasound transducer array, the ultrasound transducer array being arranged above the surface, and separated from the surface; wherein the ultrasound transducer array is configured to emit ultrasound for actuating a motion of the droplet along the surface by subjecting the droplet to an acoustic radiation force by the emitted ultrasound.

2. The device of claim 1, wherein the surface of the device further comprises at least one guiding region, wherein the at least one guiding region has a lower hydrophobicity than the hydrophobic region, such that the droplet has a greater affinity to the at least one guiding region than to the hydrophobic region, whereby the hydrophobic region and the at least one guiding region form a guiding pattern of the surface, wherein the surface is configured to guide motion of the droplet along the surface by the guiding pattern.

3. The device of claim 2, wherein the guiding pattern comprises a track, the track having a width and a length, the length being larger than the width, the track being one of the at least one guiding regions of the surface, wherein the hydrophobic region of the surface borders the track on both sides of the track, along the length of the track, whereby the guiding pattern is configured to guide the motion of the droplet by favoring movement of the droplet along the track.

4. The device of claim 3, wherein the track is formed by a periodical repetition of a first part of the track and a second part of the track along the length of the track, wherein, in a direction along the length of the track, the width of the track narrows, in the first part of the track, from a maximum width to a minimum width, after which the width of the track widens, in the second part of the track, from the minimum width to the maximum width, and wherein, in the periodical repetition, the second parts of the track are shorter than the first parts of the track.

5. The device of claim 2, wherein the guiding pattern comprises a first separate patch and a second separate patch, the first and second separate patches being guiding regions of the least one guiding region of the surface, the first and second separate patches being separated from each other by the hydrophobic region, and wherein the ultrasound transducer array is configured to actuate the motion of the droplet from the first separate patch, via the hydrophobic region, to the second separate patch, whereby the guiding pattern is configured to guide the droplet in motion by favoring movement of the droplet towards a location centrally over the second separate patch.

6. The device of claim 5, wherein the guiding pattern comprises a matrix of patches, the matrix of patches being guiding regions of the least one guiding regions of the surface, each patch of the matrix of patches being separated from other patches by the hydrophobic region, and wherein the matrix of patches comprises the first and second separate patches.

7. The device of claim 1, wherein the hydrophobic region is super-hydrophobic.

8. The device of claim 2, wherein at least one guiding region of the at least one guiding region is hydrophobic.

9. The device of claim 2, wherein at least one guiding region of the at least one guiding region is hydrophilic.

10. The device of claim 2, wherein the hydrophobic region and the at least one guiding region comprise pillars of sub millimeter size.

11. The device of claim 1, wherein the device is configured to actuate the motion of the droplet by applying an acoustic radiation force to the droplet by focusing an ultrasound field from the ultrasound transducer array on the droplet.

12. The device of claim 1, wherein the device is configured to actuate the motion of the droplet by applying an acoustic radiation force to the droplet by trapping the droplet in an acoustic trapping potential that is generated by the ultrasound transducer array, and moving the acoustic trapping potential.

13. The device of claim 2, wherein the guiding pattern of the surface comprises a plurality of alternative paths for the droplet to move along on the surface of the device, the device further comprising a path selector, the path selector being configured to receive an input signal indicating a chosen path of the plurality of alternative paths, and wherein the device is configured to modify, over time, the acoustic radiation force applied to the droplet by the ultrasound transducer array to transport the droplet along the chosen path of the plurality of alternative paths.

14. A surface configured to be arranged under and separate from an ultrasound transducer array, the surface being configured to support a droplet comprising water, the surface comprising a hydrophobic region and at least one guiding region, wherein the at least one guiding region has a lower hydrophobicity than the hydrophobic region, such that the droplet has a greater affinity to the at least one guiding region than to the hydrophobic region, whereby the hydrophobic region and the at least one guiding region form a guiding pattern of the surface, and wherein the surface is configured to guide motion of the droplet along the surface by the guiding pattern, the motion of the droplet being motion actuated by ultrasound emitted from the ultrasound transducer array.

15. A biosensor configured to identify a biological component, the biosensor comprising: a reagent configured to react with the biological component; and a device configured to manipulate a droplet comprising water, the device comprising: a surface configured to support the droplet, the surface comprising a hydrophobic region; and an ultrasound transducer array, the ultrasound transducer array being arranged above the surface, and separated from the surface; wherein the ultrasound transducer array is configured to emit ultrasound for actuating a motion of the droplet along the surface by subjecting the droplet to an acoustic radiation force by the emitted ultrasound, wherein the device is configured to at least one of: (i) manipulate the droplet to a location of the reagent when the droplet contains the biological component, or (ii) manipulate the droplet to a location of the biological component when the droplet contains the reagent, whereby the biological component and the reagent and the biological component is identified.

16. The biosensor of claim 15, wherein the surface of the device further comprises at least one guiding region, wherein the at least one guiding region has a lower hydrophobicity than the hydrophobic region, such that the droplet has a greater affinity to the at least one guiding region than to the hydrophobic region, whereby the hydrophobic region and the at least one guiding region form a guiding pattern of the surface, wherein the surface is configured to guide motion of the droplet along the surface by the guiding pattern.

17. The biosensor of claim 16, wherein the guiding pattern comprises a track, the track having a width and a length, the length being larger than the width, the track being one of the at least one guiding regions of the surface, wherein the hydrophobic region of the surface borders the track on both sides of the track, along the length of the track, whereby the guiding pattern is configured to guide the motion of the droplet by favoring movement of the droplet along the track.

18. The biosensor of claim 17, wherein the track is formed by a periodical repetition of a first part of the track and a second part of the track along the length of the track, wherein, in a direction along the length of the track, the width of the track narrows, in the first part of the track, from a maximum width to a minimum width, after which the width of the track widens, in the second part of the track, from the minimum width to the maximum width, and wherein, in the periodical repetition, the second parts of the track are shorter than the first parts of the track.

19. The biosensor of claim 16, wherein the guiding pattern comprises a first separate patch and a second separate patch, the first and second separate patches being guiding regions of the least one guiding region of the surface, the first and second separate patches being separated from each other by the hydrophobic region, and wherein the ultrasound transducer array is configured to actuate the motion of the droplet from the first separate patch, via the hydrophobic region, to the second separate patch, whereby the guiding pattern is configured to guide the droplet in motion by favoring movement of the droplet towards a location centrally over the second separate patch.

20. The biosensor of claim 19, wherein the guiding pattern comprises a matrix of patches, the matrix of patches being guiding regions of the least one guiding regions of the surface, each patch of the matrix of patches being separated from other patches by the hydrophobic region, and wherein the matrix of patches comprises the first and second separate patches.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0054] The above, as well as additional objects, features and advantages of the present inventive concept, will be better understood through the following illustrative and non-limiting detailed description, with reference to the appended drawings. In the drawings like reference numerals will be used for like elements unless stated otherwise.

[0055] FIG. 1 illustrates a device in the form of a biosensor.

[0056] FIG. 2 illustrates a track.

[0057] FIG. 3 illustrates a track.

[0058] FIG. 4 illustrates a track.

[0059] FIG. 5 illustrates a matrix of patches.

[0060] FIG. 6 illustrates a cross-section of a surface.

[0061] FIG. 7 illustrates a focused ultrasound field on a droplet.

[0062] FIG. 8 illustrates a focused ultrasound field on a droplet.

[0063] FIG. 9 illustrates a droplet in a trapping potential.

DETAILED DESCRIPTION

[0064] In cooperation with attached drawings, the technical contents and detailed description of the present invention are described hereinafter according to a preferable embodiment, being not used to limit the claimed scope. This invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided for thoroughness and completeness, and fully convey the scope of the invention to the skilled person.

[0065] FIG. 1 illustrates a device 1 for manipulating a droplet 2 comprising water. The device 1 comprises a surface 10 configured to support the droplet 2 and an ultrasound transducer array 20. The ultrasound transducer array 20 comprises ultrasound transducers 21, e.g. micromachined ultrasound transducers 21 such as e.g. piezoelectric micromachined ultrasound transducers 21 or capacitive micromachined ultrasound transducers 21. The ultrasound transducer array 20 is arranged above the surface and separated from the surface. Thus, there may be a free space between at least some of the ultrasound transducers 21 and the surface 10. The ultrasound transducer array 20 may of course be connected to a side wall, which in turn is connected to the surface 10. The side wall may herein be arranged such that it does not obstruct a free line of sight between the ultrasound transducer array 20 and the surface 10.

[0066] In the device of FIG. 1, the surface 10 comprises a hydrophobic region 12 and several guiding regions 14 of lower hydrophobicity. The illustrated guiding regions 14 form a guiding pattern 30 comprising a first 40′ and second 40″ track and a matrix 50 of patches 51. In the figure the surface 10 further comprises several reservoir regions 60. The droplet 2 may thus be moved between reservoir regions 60 via the guiding regions 14. The guiding pattern 30 herein comprises a plurality of alternative paths for the droplet 2 to move along on the surface 10 of the device 1. The droplet may e.g. move from a first reservoir region 60′ along the first track 40′. At the crossing between the first 40′ and second 40″ track the droplet may continue on the first track 40′ or turn into the second track 40″. A path selector 80 may receive an input signal in the form of instructions of how the droplet should be moved at the crossing and control the ultrasound transducer array 20 such that it forces the droplet 2 to be moved accordingly. The path selector 80 may be e.g. a processor or an application-specific integrated circuit.

[0067] In the device 1 of FIG. 1 a droplet 2 may be moved from a first reservoir region 60′ to a second 60″ or third 60′″ reservoir region. In the device of FIG. 1, the second 60″ and third 60′″ reservoir region comprises a reagent 110 each, the reagents 110 being different from each other. The reagents 110 may herein be antibodies attached to the surface 10 in the second 60″ and third 60′″ reservoir region. When a droplet 2 comprising water and a biological component, e.g. a cell or a protein, is transported to the second 60″ or third 60′″ reservoir region, the biological component may react with the reagent and the biological component may be detected. For example, the droplet 2 may carry biological cells marked with fluorescent markers. If the cells become immobilized as the droplet is manipulated over a region coated with antibodies the cells may be identified as cells of a type corresponding to said antibody.

[0068] A device 1 comprising a reagent 110 for identifying a biological component may be considered to be a biosensor 100. It should be understood that in a biosensor 100 the reagent 110 does not need to be attached to the surface 10 of a reservoir region 60 like the antibodies in the above example. The reagent 110 may alternatively be attached to the surface of a guiding region 14 or not attached to the surface 10 at all. The reagent 110 may be comprised in a liquid droplet, e.g. in a droplet 2 comprising water. As an alternative to manipulating a droplet 2 comprising water and the biological component to a location of the reagent 110, a droplet 2 comprising water and the reagent 110 may be manipulated to a location of the biological component.

[0069] It should be understood that a device 1 according to the inventive concept does not necessarily need to be a biosensor 100, it may e.g. be a chemical sensor which manipulates droplets 2 comprising water and a chemical component, whereby the chemical component may be identified. The device does not need to be a sensor at all, it may be configured to transport and/or mix droplets 2 comprising water. The device 1 does not necessarily need to comprise reservoir regions 60. The device 1 does not necessarily need to comprise a reagent 110.

[0070] FIG. 2 illustrates a track 40 wherein the droplet 2 may move equally easily forward and backwards along the track 40. A current position of the droplet 2 is illustrated with a solid line while future possible positions are illustrated with dashed lines. The illustrated track 40 has a uniform width, in this case smaller than the diameter of the droplet 2. The track 40 has a lower hydrophobicity than the surrounding hydrophobic region 12. The track 40 may e.g. be super-hydrophobic with a contact angle to water of 150 degrees, or more. The hydrophobic region 12 may e.g. be super-hydrophobic with a contact angle to water of at least 1 degree more, or at least 5 degrees more, than the contact angle for the track 40. Alternatively, the track 40 may be hydrophobic with a contact angle to water below 150 degrees, e.g. 100 degrees, while the hydrophobic region 12 may be super-hydrophobic.

[0071] FIGS. 3 and 4 illustrate tracks 40 which are configured to favor movement of the droplet 2 in one direction 45 along the length of the track 40. A current position of the droplet 2 is illustrated with a solid line while future possible positions are illustrated with dashed lines. Thus, the droplets 2 in FIGS. 3 and 4 preferentially move to the right. In FIG. 3, the track 40 narrows slowly from a maximum width 43 to a minimum width 44 in the first part 41 of the track 40, and then widens abruptly from the minimum width 44 to the maximum width 43 in the second part 42 in the direction 45 along the length of the track 40. Thus, the droplet 2 may preferentially move in said direction 45. It should be understood that the second part 42 of the track 40 may be infinitesimally small, as exemplified in FIG. 4. A track 40 configured to favor movement of the droplet 2 in one direction 45 has a lower hydrophobicity than the surrounding hydrophobic region 12. The track 40 may e.g. be super-hydrophobic with a contact angle to water of 150 degrees, or more. The hydrophobic region 12 may e.g. be super-hydrophobic with a contact angle to water of at least 1 degree more, or at least 5 degrees more, than the contact angle for the track 40. Alternatively, the track 40 may be hydrophobic with a contact angle to water below 150 degrees, e.g. 100 degrees, while the hydrophobic region 12 may be super-hydrophobic.

[0072] FIG. 5 illustrates a matrix 50 of patches 51, wherein each patch 51 is a guiding region 14 surrounded by the hydrophobic region 12. Any two adjacent patches 51 may be seen as a first 51′ and second 51″ patch. The ultrasound transducer array 20 may be configured to actuate the motion of the droplet 2 from the first separate patch 51′, via the hydrophobic region 12, to the second separate patch 51″. The droplet 2 may thus be moved between different patches 51, as illustrated in the figure where a current position of the droplet 2 is illustrated with a solid line while future possible positions are illustrated with dashed lines. The patches 51 have a lower hydrophobicity than the surrounding hydrophobic region 12. The patches 51 may e.g. be super-hydrophobic with a contact angle to water of 150 degrees, or more. The hydrophobic region 12 may e.g. be super-hydrophobic with a contact angle to water of at least 1 degree more, or at least 5 degrees more, than the contact angle for the patches 51. Alternatively, the patches 51 may be hydrophobic with a contact angle to water below 150 degrees, e.g. 100 degrees, while the hydrophobic region 12 may be super-hydrophobic. Alternatively, the patches 51 may be hydrophilic while the hydrophobic region 12 may be super-hydrophobic.

[0073] The surface 10 in any of the above examples may be glass. The hydrophobicity of the surface in the hydrophobic region 12 and the guiding region 14 may be at least partially defined by the surface morphology. For example, the hydrophobic region 12 and the at least one guiding region 14 may comprise pillars 16 of sub millimeter size, formed on a substrate 18, as illustrated in a cross-section of the surface in FIG. 6. The figure illustrates a droplet 2 in a guiding region 14 comprising short, wide pillars 16, with a low pillar surface density. The illustrated guiding region 14 has one hydrophobic region 12 to the left and one to the right, wherein both hydrophobic regions 12 comprise long, thin pillars 16, with a high pillar surface density. Thus, the hydrophobicity of the surface may depend on the pillar size and pillar surface density. Thinner pillars 16 may result in a higher hydrophobicity. Longer pillars 16 may result in a higher hydrophobicity. A higher pillar surface density may result in a higher hydrophobicity. The hydrophobicity of the illustrated guiding region 14 may correspond to a contact angle to water of 150 degrees, or more. The hydrophobicity of the illustrated hydrophobic region 12 may correspond to a contact angle to water of at least 1 degree more, or at least 5 degrees more, than the contact angle to water of the guiding region 14. The hydrophobicity may alternatively or additionally depend on the chemical composition of the surface. The pillars 16 may be etched into a coating on the surface, wherein the coating has a hydrophobicity arising from the chemical composition. The coating may be formed from by a fluorinated surface treatment of a glass surface.

[0074] The ultrasound transducer array 20 may be an ultrasound transducer phased array, wherein the phases of at least a subset of the ultrasound transducers are adjustable. Thus, the ultrasound beam may be shaped and/or steered. The ultrasound transducer array 20 may actuate a motion of the droplet 2 along the surface 10 by focusing the ultrasound field 70. For example, as illustrated in FIG. 7, the ultrasound field 70 may be focused on one side of the droplet 2, whereby the droplet 2 may be subjected to an acoustic radiation force pushing the droplet 2 in the direction of the opposite side. As illustrated in FIG. 8 the ultrasound field 70 may be focused on the droplet 2 via a reflection on the surface 10, whereby the droplet is pushed from below.

[0075] The ultrasound transducer array 20 may actuate a motion of the droplet 2 along the surface 10 by applying an acoustic radiation force to the droplet through trapping the droplet 2 in an acoustic trapping potential 71, generated by the ultrasound transducer array 20, and moving the acoustic trapping potential 71. FIG. 9 illustrates a droplet 2 in a trapping potential 71. The illustrated trapping potential 71 is a ring-shaped potential wherein the ultrasound field has a maximum pressure region forming a ring around the droplet 2. Thus, a ring-shaped wall of increased potential may surround a lower potential inside the ring. When the wall moves the droplet 2 inside may be pushed along. The shape of the trapping potential 71 does not necessarily need to be ring-shaped, it may e.g. be a quadratic potential, or a gaussian potential. The acoustic trapping potential may be a minimum, e.g. local minimum, in an acoustic potential. The acoustic trapping potential 71 may be formed by the ultrasound transducer array 20 according to the principles of acoustic tweezers. The acoustic trapping potential 71 may be formed by a standing wave between the ultrasound transducer array 20 and the surface 10.

[0076] In the above the inventive concept has mainly been described with reference to a limited number of examples. However, as is readily appreciated by a person skilled in the art, other examples than the ones disclosed above are equally possible within the scope of the inventive concept, as defined by the appended claims.