Systems and methods for optical actuation of microfluidics based on opto-electrowetting
First Claim
1. A microfluidic circuit adapted to manipulate a droplet in response to light, the microfluidic circuit comprising:
- a first wall with at least a conductive layer adapted to be coupled to a first terminal of an alternating current (AC) voltage source;
a second wall adapted to be coupled to a second terminal of the AC voltage source such that an electric field is generated between the first wall and the second wall, where the second wall is responsive to light such that a portion of the second wall that is illuminated by a localized spot of light has a higher electric field intensity than a portion of the second wall that is not illuminated by the localized spot of light, wherein at least one of the first wall or the second wall is further adapted to allow light to pass through;
a cavity defined between the first wall and the second wall, where the cavity is adapted to hold the droplet for manipulation, wherein manipulation includes at least one of transporting, joining, cutting, or creating the droplet during operation; and
wherein the first wall further comprises a hydrophobic inner liner facing the cavity, and wherein the conductive layer of the first wall comprises indium-tin-oxide (ITO) glass and the hydrophobic inner liner comprises polytetrafluoroethytene (PTFE).
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Abstract
The invention is related to methods and apparatus that manipulate droplets in a microfluidic environment. Advantageously, embodiments of the invention manipulate droplets by controlling the electro-wetting characteristics of a surface with light, thereby inducing a gradient in the surface tension of a droplet. The gradient in the surface tension propels the droplet by capillary force. A variety of operations, such as transporting, joining, cutting, and creating can be performed. Advantageously, embodiments of the invention obviate the need to create a relatively large and complex control electrode array. A plurality of photoconductive cells or a layer of a photoconductive material selectively couples an electrode carrying an electrical bias to otherwise floating conductive cells in response to a beam of light. The electrical bias applied to the conductive cell generates a localized electric field, which can change the contact angle of the droplet, thereby permitting the droplet to be propelled.
170 Citations
20 Claims
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1. A microfluidic circuit adapted to manipulate a droplet in response to light, the microfluidic circuit comprising:
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a first wall with at least a conductive layer adapted to be coupled to a first terminal of an alternating current (AC) voltage source;
a second wall adapted to be coupled to a second terminal of the AC voltage source such that an electric field is generated between the first wall and the second wall, where the second wall is responsive to light such that a portion of the second wall that is illuminated by a localized spot of light has a higher electric field intensity than a portion of the second wall that is not illuminated by the localized spot of light, wherein at least one of the first wall or the second wall is further adapted to allow light to pass through;
a cavity defined between the first wall and the second wall, where the cavity is adapted to hold the droplet for manipulation, wherein manipulation includes at least one of transporting, joining, cutting, or creating the droplet during operation; and
wherein the first wall further comprises a hydrophobic inner liner facing the cavity, and wherein the conductive layer of the first wall comprises indium-tin-oxide (ITO) glass and the hydrophobic inner liner comprises polytetrafluoroethytene (PTFE).
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2. A microfluidic circuit adapted to manipulate a droplet in response to light, the microfluidic circuit comprising:
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a first wall with at least a conductive layer adapted to be coupled to a first terminal of an alternating current (AC) voltage source;
a second wall adapted to be coupled to a second terminal of the AC voltage source such that an electric field is generated between the first wall and the second wall, where the second wall is responsive to light such that a portion of the second wall that is illuminated by a localized spot of light has a higher electric field intensity than a portion of the second wall that is not illuminated by the localized spot of light, wherein at least on of the first wall or the second wall is further adapted to allow light to pass through, wherein the second wall comprises;
a substrate made from an insulating material;
an insulating layer that faces the cavity;
a photoconductive layer disposed between the substrate and the insulating layer;
a first electrode disposed between the substrate and the photoconductive layer, where the first electrode is adapted to be coupled to the second terminal of the AC voltage source; and
a plurality of conductive cells disposed between the photoconductive layer and the insulating layer, wherein the conductive cells are electrically isolated such that the conductive cells are electrically floating; and
a cavity defined between the first wall and the second wall, where the cavity is adapted to hold the droplet for manipulation, wherein manipulation includes at least one of transporting, joining, cutting, or creating the droplet during operation. - View Dependent Claims (3, 4, 5, 6, 7, 8, 9)
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10. A microfluidic circuit adapted to manipulate a droplet in response to light, the microfluidic circuit comprising:
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a first wall with at least a conductive layer adapted to be coupled to a first terminal of an alternating current (AC) voltage source;
a second wall adapted to be coupled to a second terminal of the AC voltage source such that an electric field is generated between the first wall and the second wall, where the second wall is responsive to light such that a portion of the second wall that is illuminated by a localized spot of light has a higher electric field intensity than, portion of the second wall that is not illuminated by the localized spot of light, wherein at least one of the first wall or the second wall is further adapted to allow light to pass through wherein the second wall comprises;
a substrate made from a transparent insulating material;
an insulating layer that faces the cavity;
a plurality of conductive lines disposed between the substrate and the insulating layer, where the conductive lines are coupled to the second terminal of the AC voltage source;
a plurality of conductive cells disposed between the substrate, and the insulating layer, where the conductive cells are adjacent to the conductive lines; and
a plurality of photoconductive cells, where a photoconductive cell is configured to couple a conductive line to at least one conductive cell; and
a cavity defined between the first wall and the second wall, where the cavity is adapted to hold the droplet for manipulation, wherein manipulation includes at least one of transporting, joining, cuffing, or creating the droplet during operation. - View Dependent Claims (11, 12, 13)
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14. A microfluidic circuit adapted to manipulate a droplet in response to light, the microfluidic circuit comprising:
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a first optical electro-wetting structure adapted to be coupled to a first voltage reference, where the first optical electro-wetting structure includes a first insulating layer and at least a first region sensitive to light such that the first region couples the first voltage reference to at least part of the first insulating layer in response to light;
a second optical electro-wetting structure spaced apart from the first optical electro-wetting structure, where the second optical electro-wetting structure is adapted to be coupled to a second voltage reference, where the second optical electro-wetting structure includes a second insulating layer and a second region sensitive to light such that the second region couples the second voltage reference to at least part of the second insulating layer in response to light, and where the second optical electro-wetting structure is sufficiently transparent to allow light that impinges on a first area of one side of the second optical electro-wetting structure to pass through and expose a corresponding second area of the first optical electro-wetting structure; and
a cavity defined between the first optical electro-wetting structure and the second optical electro-wetting structure, where the cavity is adapted to hold the droplet. - View Dependent Claims (15, 16, 17)
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18. A microfluidic circuit adapted to manipulate a droplet in response to light, the microfluidic circuit comprising:
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a first wall with at least a conductive layer adapted to be coupled to a first terminal of an altemating current (AC) voltage source;
a second wall adapted to be coupled to a second terminal of the AC voltage source such that an electric field is generated between the first wall and the second wall, where the second wall is responsive to light such that a portion of the second wall that is illuminated by a localized spot of light has a higher electric field intensity than a portion of the second wall that is not illuminated by the localized spot of light, wherein at least one of the first wall or the second wall is further adapted to allow light to pass through wherein the second wall further comprises;
a photoconductive layer responsive to light, where the photoconductive layer is adapted to be coupled to the second terminal of the AC voltage source; and
an insulating layer that faces the cavity, where a portion of the insulating layer adjacent to an illuminated portion of the photoconductive layer has a higher electric field intensity than a portion of the insulating layer adjacent to a portion of the photoconductive layer that is not illuminated; and
a cavity defined between the first wall and the second wall, where the cavity is adapted to hold the droplet for manipulation, wherein manipulation includes at least one of transporting, joining, cutting, or creating the droplet during operation. - View Dependent Claims (19, 20)
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Specification