GB2559216A

GB2559216A - Droplet manipulation

Info

Publication number: GB2559216A
Application number: GB1711420.8A
Authority: GB
Inventors: Ma Hanbin; Nathan Arokia
Original assignee: Acxel Tech Ltd
Current assignee: Acxel Tech Ltd
Priority date: 2017-07-17
Filing date: 2017-07-17
Publication date: 2018-08-01
Anticipated expiration: 2037-07-17
Also published as: GB2560679B; GB2560679A; WO2019016506A1; CN109475871A; GB201711420D0; CN109475871B; KR102224545B1; KR20200018704A; GB201810375D0; GB2559216B

Abstract

An electrowetting-on-dielectric droplet (EWOD) manipulation device comprising a tessellated array of electrodes which includes at least some non-rectangular polygonal electrodes, an array of control devices, each control device comprising at least one switching element configured to control bias applied to a respective electrode in the tessellated array of electrodes and an array of control lines comprising a set of first control lines and a set of second control lines configured such that each control device is individually addressable by a given first control line 20 and a given second control line 21. Preferably the switching element comprises a transistor, more preferably a thin-film transistor. Ideally each control device comprises a capacitor. Preferably at least some of the non-rectangular polygonal electrode comprise first electrodes of a first shape, ideally the first shape has 3 or 6 sides. Further claimed is a method of controlling a tessellated array of electrodes comprising retrieving a set of route defining parameters and applying control signals. Further claimed is a method of controlling a tessellated array of electrodes comprising activating a first electrode, activating second and third electrodes and then de-activating the first electrode. The device can be used to control droplets in microfluidic applications.

Description

(54) Title of the Invention: Droplet manipulation

Abstract Title: An electrowetting on dielectric droplet manipulation device (57) An electrowetting-on-dielectric droplet (EWOD) manipulation device comprising a tessellated array of electrodes which includes at least some non-rectangular polygonal electrodes, an array of control devices, each control device comprising at least one switching element configured to control bias applied to a respective electrode in the tessellated array of electrodes and an array of control lines comprising a set of first control lines and a set of second control lines configured such that each control device is individually addressable by a given first control line 20 and a given second control line 21. Preferably the switching element comprises a transistor, more preferably a thin-film transistor. Ideally each control device comprises a capacitor. Preferably at least some of the nonrectangular polygonal electrode comprise first electrodes of a first shape, ideally the first shape has 3 or 6 sides. Further claimed is a method of controlling a tessellated array of electrodes comprising retrieving a set of route defining parameters and applying control signals. Further claimed is a method of controlling a tessellated array of electrodes comprising activating a first electrode, activating second and third electrodes and then de-activating the first electrode. The device can be used to control droplets in microfluidic applications.

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Droplet manipulation

Field of the Invention

The present invention relates to electrowetting-on-dielectric droplet manipulation.

Background

Electrowetting-on-dielectric droplet manipulation can be used to control droplets in microfluidic applications.

An introduction to electrowetting is given in F. Mugele and J. C. Baret:

“Electrowetting: from basics to applications”, Journal of Physics: Condensed Matter, volume 17, page R705 (2005) and an overview of electrowetting-on-dielectric devices is given in W. Nelson & C-J Kim: “Droplet Actuation by Electrowetting-on-Dielectric (EWOD): A Review”, Journal of Adhesion Science and Technology, volume 26, pages

1747-1771 (2012), which are incorporated herein by reference.

Reference is also made to US 2015/158028 Al and US 2017/113224 Al, which are incorporated herein by reference.

US 2015/158028 Ai ibid, describes an active matrix electrowetting-on-dielectric device which includes a plurality of array elements configured to manipulate one or more droplets of fluid on an array.

US 2017/113224 Ai ibid, describes a liquid droplet manipulation instrument.

- 2 Summary

According to a first aspect of the present invention there is provided an electrowettingon-dielectric droplet actuation device. The device comprises a tessellated array of electrodes which includes at least some non-rectangular polygonal electrodes, an array of control devices, each control device comprising at least one switching element, including a switching element, configured to control bias applied to a respective electrode in the tessellated array of electrodes, and an array of control lines comprising a set of first control lines and set of second control lines configured such that each control device is individually addressable by a given first control line and a given second control line.

Each control device may comprise a switching element, i.e. one switching element. The droplet may comprise an aqueous or non-aqueous liquid. The droplet may comprise a polar or a covalent liquid.

The switching element may comprise a transistor, for example, a thin-film transistor. The thin-film transistor may be formed from an inorganic semiconductor material, such as silicon or metal oxide, or an organic semiconductor material. A channel of the transistor may be interposed between the respective electrode and a gate of the transistor. A gate of the transistor may be interposed between the respective electrode and a channel of the transistor. Each control device may comprise a capacitor. The control device may take the form of a one transistor, one capacitor cell (or “1T1C” cell). The switching element may be disposed substantially in a centre of a respective electrode in the tessellated array of electrodes. The control device may comprise a second switching element. The second switching element may comprise a transistor, for example, a thin-film transistor. The control device may take the form of a one transistor, one capacitor cell (or “2T1C” cell).

The device may further comprise an array of sensors, each sensor arranged to sense a respective electrode in the tessellated array of electrodes. The sensor may sense, for example, impedance.

The array of control lines may further comprise a set of third control lines.

The at least some non-rectangular polygonal electrodes may comprise first electrodes of a first shape. The first shape may have 3, 5, 6 or 8 sides. The first shape may be a

-3regular polygon. The tessellated array of electrodes may comprise hexagonal electrodes. The tessellated array of electrodes may consist mainly of hexagonal electrodes. The tessellated array of electrodes may comprise second electrodes of a second, different shape. The second shape may be rectangular. The second shape may be square.

The tessellated array of electrodes may comprise at least 1,000 electrodes or at least 10,000 electrodes.

The device may comprise first and second substrates which are facing and having first and second surfaces respectively which are facing, wherein the tessellated array of electrodes are supported by the first surface of the first substrate, a channel interposed between the first and second substrates in which droplet(s) are actuated, a dielectric layer interposed between the tessellated array of electrodes and the channel, a hydrophobic layer interposed between the dielectric layer and the channel. The device may include a grounding electrode supported by the second substrate and a hydrophobic layer interposed between the grounding electrode and the channel.

The dielectric layer may comprise an inorganic dielectric material, for example silicon dioxide, silicon nitride, aluminium oxide or a high-k dielectric material such as hafnium oxide, zirconium oxide or lantalum oxide. The dielectric layer may comprise an organic dielectric material. The thickness of the dielectric layer is sufficiently thick to avoid breakdown and may be, for example, between 20 nm to 5 pm. The hydrophobic layer may comprise a suitable material, such as polytetrafluoroethylene (PTFE) or Cytop (RTM) and the like.

According to a second aspect of the present invention there is provided a module comprising the device of first aspect of the present invention, and a first driver arranged for driving the set of first control lines.

The module may further comprise or may be provided with a separate module comprising a second driver arranged for driving the set of second control.

According to a third aspect of the present invention there is provided a system comprising the module according of the second aspect of the present invention and a controller arranged to control the first and second drivers.

-4According to a fourth aspect of the present invention there is provided a method of controlling a tessellated array of electrodes which includes at least some nonrectangular polygonal electrodes. The method comprises retrieving a set of routedefining parameters stored a computer-readable data structure for defining a set of electrodes in the tessellated array of electrodes that are to be active in a given time window (or “frame”) and causing first and second address control units to apply control signals to corresponding pairs of lines in the first and second address lines so as to activate the set of electrodes in a given time window.

An electrode may be made active by applying a voltage of suitable magnitude, for example, in a range between ι V to 200 V, with suitable polarity for a given liquid.

The set of route-defining parameters may be a first set of route-defining parameters, the set of electrodes may be a first set of electrodes and the given time window may be a first time window. The method may further comprise retrieving a second set of routedefining parameters stored the computer-readable data structure for defining a second set of electrodes in the tessellated array of electrodes that are to be active in a second, following time window and causing first and second address control units to apply control signals to corresponding pairs of lines in the first and second address lines so as to activate the second set of electrodes in a second time window

According to a fifth aspect of the present invention there is provided a method of controlling a tessellated array of electrodes which includes at least some nonrectangular polygonal electrodes. The method comprises activating a first electrode in the tessellated array of electrodes, activating second and third electrodes which are adjacent to each other and which are adjacent to the first electrode, and, after activating second and third electrodes, de-activating the first electrodes.

The method may comprise causing first and second address control units to control manipulate droplets in different regions of the tessellated array of electrodes independently. Thus, same tessellated array of electrodes can have different regions in which operate separately.

The method may comprise causing first and second address control units and a third address control unit to activate a first electrode at a first active level (e.g. Vi) and a

-5second, different electrode at a second, different activate level (e.g. V2, where | V21 >

I Vi I. This can allow a droplet to be split into two droplets of different sizes by applying different voltages to adjacent electrodes.

According to a sixth aspect of the present invention there is provided a computer program which, when executed by at least one processor, causes the processor to perform the method of the fifth or sixth aspect of the invention.

According to a seventh aspect of the present invention there is provided a computer program product comprising a computer-readable medium (which maybe nontransitory) which stores the computer program according to the sixth aspect of the present invention.

According to an eighth aspect of the present invention there is provided a computer15 readable data structure comprising a sequence of sets of route-defining parameters, each set of route-defining parameters defining a set of electrodes in a tessellated array of electrodes that are to be active in a given time window.

-6Brief Description of the Drawings

Certain embodiments of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which:

Figure l is schematic block diagram of a microfluidic system which includes an electrowetting-on-dielectric droplet manipulation device;

Figure 2 is a cross-sectional view of a pixel comprising a bottom-gate thin-film transistor used in the droplet manipulation device shown in Figure l;

Figure 3 is a cross-sectional view of a pixel comprising a top-gate thin-film transistor; Figure 4 schematically illustrates an array of control lines for addressing electrodes; Figure 5 schematically illustrates circuit cells for controlling electrodes;

Figure 6 is a plan view of layout of a circuit cell;

Figure 7 illustrates droplet splitting in a droplet actuation device;

Figure 8A to 8C illustrates droplet creation in a droplet actuation device;

Figure 9 illustrates a tessellated array of electrodes using irregular pentagonal electrodes; and

Figure 10 illustrates a tessellated array of electrodes using triangular electrodes and square electrodes.

Detailed Description of Certain Embodiments

Microfluidic system 1

Referring to Figure 1, a microfluidic system 1 is shown.

Referring also to Figures 2, 3, 4 and 5, the microfluidic system 1 includes an electrowetting-on-dielectric (EWOD) droplet manipulation device 2 in or on which droplets 3 can be freely manipulated in two-dimensions across a surface 4 using a tessellated array of electrodes 5. As will be explained in more detail later, the surface 4 is provided by a hydrophobic layer 6 supported on a dielectric layer 7 which is used to help isolate droplets 3 from underlying electrodes 5. The device can be used a variety of different liquids such as, for example, a saline buffer, biosamples (such as DNA or proteins) or bodily fluids (such as blood or urine). Droplet size can vary from, for example, 10 pi to, for example, 1 ml.

Droplet manipulation 3 can take different forms.

A droplet 3 can be moved (or “actuated”) along a routable path, in other words, along a path whose course can be selectably set and changed. As will be explained in more

-Ίdetail later, a route can be defined as sequence of coordinates, such as Cartesian coordinates (x, y) or three-axis coordinates (a, b, c), vectors, or other route-defining parameters stored in a table, script or other suitable computer-readable data structure. Manipulation of droplets 3 can also take the form of two or more droplets 3 being fused into a single droplet 3 or, conversely, a single droplet 3 being split into two or more droplets 3. A sequence of droplet manipulations can be performed.

The tessellated array of electrodes 5 takes the form of an array of hexagonal electrodes 5. A hexagonal shape is closer to the shape of a liquid droplet than a square shape.

Also, for a given pitch, a hexagonal array can allow a tighter packing of electrodes, than square electrodes. A hexagonal array can make it easier to split a droplet. Furthermore, a hexagonal array can provide a better inlet design.

The droplet manipulation device 2 comprises a first, main portion 9 (or “base”) which provides the surface 4 on which droplets 3 are manipulated and an optional second, overlying portion (or “cover”) 10.

The base 9 comprises a first substrate 11, for example a generally planar substrate, having first and second opposite faces 12,13 (herein referred to as lower and upper faces or surfaces) and which supports the electrodes 5 either directly or indirectly on the upper face 13.

The substrate 11 supports an array of control devices 17 for controlling a bias applied to each electrode 5, each of which, in this case, comprise a thin-film transistor 18 having a channel C, a source S, a drain D and a gate G, and a capacitor 19. The substrate 11 also supports respective sets of first and second control lines 20, 21 (herein referred to as “rows” and “columns” respectively) which are arranged in such a way that each control device 17 is individually addressable by a given pair of first and second transverse (or “crossing”) control lines 20, 21. A set of third control lines 22 may be optionally provided. A set of third control lines 22 can be used to provide multilevel voltages, which can be used define more than one active voltage for additional functionality with respect to droplet manipulation. The substrate 11 also supports dielectric layers 23, 24.

The thin-film transistor 18 can take the form of a bottom-gate thin-film transistor, for example, as shown in Figure 2, a top-gate thin-film transistor, for example, as shown in

-8Figure 3. The electrode 5 and corresponding control device 18 is herein also referred to a “pixel”.

The cover 10 includes a second substrate 25 having first and second opposite faces 26, 27 (herein referred to as lower and upper faces or surfaces). The lower face 26 may support (in order going away from the second substrate 25) an electrode 28, a dielectric layer (not shown) and a hydrophobic layer 30 which provides a base-facing surface 31 (or “lower cover face”). The base 9 and cover 10 define a shallow space 32 between the upper base surface 4 and the lower cover face 31, through which droplets 3 may move.

Referring in particular to Figure 1, the droplet manipulation device 2 may include reservoir electrodes 33 (which are generally larger than the tessellated electrodes 5) which can be used to supply droplets 3 into (or receive droplets 3 from) the tessellated array of electrodes 5.

The droplet manipulation device 2 may include wells 34 to hold respective charges 35 of liquid and which are arranged to supply liquid to (or receive liquid from) the reservoir electrodes 33. Supply of liquid to or from the wells 34 may be assisted by gravity. Supply of liquid may, however, be controlled electrostatically.

The system 1 may include a fluid handling system 36, e.g. comprising tubes (not shown), valves (not shown) and pumps (not shown), for controlling supply and removal of liquid from the droplet manipulation device 2. The fluid handling system 36 maybe provided with an interface 37 to other instruments, such as, for example, flow cytometry instrument, a next-generation sequencing machine, a mass spectrometer, an electrochemical workstation or the like.

Referring also to Figure 2, the system 1 includes first and second address control units 38, 39 (herein also referred to as “control line drivers”) for applying control signals to respective sets of first and second orthogonal control lines 20, 21. The system 1 may optionally include a third address control unit 40 for applying control signals to the set of third control lines 22.

The system 1 includes a controller 41 for example in the form of a microcontroller or single-board computer for controlling the fluid handling system 36 and the address control units, 38, 39, 40. The controller 41 may be provided with a display 44.

-9The system l includes a computer system 45 which can be used to control the controller 41. As will be explained in more detail later the computer system 42 includes at least one processor 46 and memory 47 which stores control program 48 and droplet manipulation instructions 49 which may take the form of a script or a series of tables, one table for each frame, each storing a list of active electrodes. In some cases, the controller 41 may store the control program 48 and droplet manipulation instructions 49. Thus, the computer system 42 may, therefore, be omitted, at least during operation.

Referring to Figure 6, the thin-film transistor 18 is disposed at the centre of the electrode 5.

The arrangement can help to provide symmetric droplet movement in all directions.

Programmable control

The address control units 38, 39, under the control the controller 41, activate and deactivate electrodes 5 in a series of frames (herein referred to as “time windows”) t_x, t₂,

..., ti,...tN. As explained earlier, a computer-readable data structure such a table or script store a sequence of sets of route-defining parameters, each set of route-defining parameters specifying which electrodes in a given frame are active. The table or script can be seen as a video or movie of active (and inactive) pixels. By changing the routedefining parameters, different routes can be selected. Thus, using the same droplet manipulation device 2, different microfluidic operations can be performed.

Droplet splitting

Referring to Figure 7, splitting of a single droplet 31 into two droplets 3₃, 3₃ will now be described.

The address control units 38, 39activate a first electrode 51 (for example, by causing the control device 17 to apply a positive bias to the electrode 51) which causes the droplet 31 to be held at a first position 5I1 (step S7.1).

The address control units 38, 39 then additionally activate a first neighbouring pair of adjacent electrodes 52,5₃ and a second neighbouring pair of adjacent electrodes 54, 5₅which lie on opposite sides of (or “at opposite ends of’) the first electrode 51 (step S7.2).

- 10 The first neighbouring pair of adjacent electrodes 52,5₃ comprises second and third electrodes 52,5₃ which are adjacent to the first electrode 51 (i.e. they are neighbouring) and to each other (i.e. they are an adjacent pair). Likewise, the second neighbouring pair of adjacent electrodes comprise fourth and fifth electrodes 54,5₅ which are adjacent to the first electrode 51 and to each other. Activating opposite, neighbouring pairs of adjacent electrodes 52,5₃,5₄,5₅ causes the droplet 31 to be stretched not only in opposite directions, but also to be spread out in a direction which is generally orthogonal to the direction of splitting thereby giving the droplet 31 a “bone-shaped”- or “bow-tie”-like appearance.

The address control units 38, 39 then de-activate the first electrode 51 (step S7.3). This results in first and second elliptical droplets 32, 3₃ which are spread over the first pair of adjacent electrodes 52,5₃ and the second pair of adjacent electrodes 52,5₃ respectively.

The address control units 38, 39 then de-activate one electrode in each electrode pair 52,5₃,5₄, 5₅ which causes the droplet 31 to be held at a second and third position 512, 5i₃(step S7.4).

Using neighbouring, adjacent pixels, especially using hexagonally-shaped pixels, can help to split a droplet more evenly compared with square electrodes.

Droplet creation

Referring to Figures 8A to 8C, creation of droplets 3i will now be described.

A well 34 holds a charge 35 of liquid (step S8A.1).

The address control units 38, 39 activate a reservoir electrode 33 and a neighbouring pair of adjacent bridging electrodes 5a, 5b which draws a pool 52 of liquid which sits on the reservoir electrode 33 and the first adjacent electrodes 5a, 5b (step S8A.2). The neighbouring pair of first adjacent electrodes 5a, 5b lie between reservoir electrode 33 and a bridging electrode 5c. The bridging electrodes 5a, 5b, 5c form a bridge (or “connection”) between the reservoir electrode 33 and the rest of the tessellated array of electrodes 5. Thus, to reach the tessellated array of electrodes 5, liquid flows through one or both of the first and second bridging electrodes 5a, 5b and through the third bridging electrode 5c.

- 11 The address control units 38,39) then de-activate the reservoir electrode 33 (step S8A.3). This results in an elliptical droplet 3a which is spread over the first and second bridging electrodes 5a, 5b.

Droplets of different sizes can be injected into the array.

Referring in particular to Figure 8B, creation of a smaller droplet, which covers an area roughly that of an electrode 5, will first be described.

The address control units 38,39 activate (in addition to the already-activated first and second bridging electrodes 5a, 5b), the third bridging electrodes 5c and a neighbouring pair of adjacent electrodes 5d, 5e which lie next to the third bridging electrode 5c (step S8B.1). This causes the droplet 3a to be pull and stretched into a “bone-shaped” droplet.

The address control units 38, 39 (under the control the controller 41) then de-activate the third bridging electrode 5c (step S8B.2). This results in first and second elliptical droplets 3b, 3c which are spread over the first and second bridging electrodes 5a, 5b and the neighbouring pair of adjacent electrodes 5d, 5e respectively.

The address control units 38, 39 (under the control the controller 41) then activate a sixth electrode 5f which is adjacent to both the neighbouring pair of electrodes 5d, 5e and then deactivate the neighbouring pair of electrodes 5d, 5e (step S8B.3). This results in a droplet 3c sitting over the sixth electrode 5f. In some cases, the neighbouring pair of electrodes 5d, 5e may be de-activated at the same as the sixth electrode 5f is activated.

Referring to Figure 8C, creation of a larger droplet, which covers an area roughly double the area of an electrode 5, will now be described.

The address control units 38, 39 (under the control the controller 41) activate (in addition to the already-activated first and second bridging electrodes 5a, 5b) a third, bridging electrode 5c which is adjacent to both the first and second bridging electrodes 5a, 5c and then deactivate the first and second bridging electrodes 5a, 5b (step S8C.31). This results in a droplet 3d sitting over the third electrode 5c.

- 12 The address control units 38, 39 (under the control the controller 41) activate (in addition to the already-activated third bridging electrode 5c) a neighbouring pair of adjacent electrodes 5d, 5e which lie next to the third bridging electrode 5c (step S8C.2). This results in an elliptical droplet 3e spread over the neighbouring pair of adjacent electrodes 5d, 5eThe address control units 38, 39 (under the control the controller 41) then activate a sixth electrode 5f which is adjacent to both the neighbouring pair of electrodes 5d, 5e and then deactivate the neighbouring pair of electrodes 5d, 5e (step S8C.3). This results in a droplet 3f sitting over the sixth electrode 5f. In some cases, the neighbouring pair of electrodes 5d, 5e may be de-activated at the same as the sixth electrode 5f is activated

Other shapes of electrodes and other arrangements of tiled arrays

As explained earlier, the tessellated array of electrodes 5 can be provided by hexagonally-shaped electrodes. The array of electrodes, however, can be provided by electrodes of other shapes.

Referring to Figure 9, the array of electrodes can be provided by monohedral tiling of irregular pentagonal electrodes 5. Shapes with greater number of sides, such as irregular octagonal electrodes may be used.

Monohedral tiling, however, need not be used.

Referring to Figure 10, the array of electrodes can be provided by tiling of electrodes of two (or more) shapes, such as regular (i.e. equilateral) triangular- and square-shaped electrodes 5. 5₂. Other shapes can be used, such as regular octagons.

Addressing of the electrodes can be carried out in the same way as that described earlier. If necessary, however, there may be redundancy, in other words, there is no control device at certain pairings of row and columns.

Modifications

It will be appreciated that various modifications may be made to the embodiments hereinbefore described. Such modifications may involve equivalent and other features which are already known in the design, manufacture and use of electrowetting-ondielectric droplet actuation devices and microfluidic systems and component parts

-13thereof and which may be used instead of or in addition to features already described herein. Features of one embodiment may be replaced or supplemented by features of another embodiment.

Although claims have been formulated in this application to particular combinations of features, it should be understood that the scope of the disclosure of the present invention also includes any novel features or any novel combination of features disclosed herein either explicitly or implicitly or any generalization thereof, whether or not it relates to the same invention as presently claimed in any claim and whether or not it mitigates any or all of the same technical problems as does the present invention. The applicants hereby give notice that new claims may be formulated to such features and/or combinations of such features during the prosecution of the present application or of any further application derived therefrom.

Claims

Claims

1. An electrowetting-on-dielectric droplet actuation device comprising:

a tessellated array of electrodes which includes at least some non-rectangular polygonal electrodes;

an array of control devices, each control device comprising at least one switching element, including a switching element, configured to control bias applied to a respective electrode in the tessellated array of electrodes; and an array of control lines comprising a set of first control lines and a set of second control lines configured such that each control device is individually addressable by a given first control line and a given second control line.
2. The device of claim l, wherein the switching element comprises a transistor.
3. The device of claim l or 2, wherein the transistor is a thin-film transistor.
4. The device of claim 2 or 3, wherein a channel of the transistor is interposed between the respective electrode and a gate of the transistor.
5. The device of claim 2 or 3, wherein a gate of the transistor is interposed between the respective electrode and a channel of the transistor.
6. The device of any one of claims 1 to 5, wherein each control device comprises a capacitor.
7. The device of any one of claims 1 to 6, wherein the switching element is disposed substantially in a centre of a respective electrode in the tessellated array of electrodes.
8. The device of any one of claims 1 to 7, wherein each control device comprises a second switching element.
9. The device of any one or claims 1 to 8, further comprising:

an array of sensors, each sensor arranged to sense a respective electrode in the tessellated array of electrodes

-1510. The device of any one of claims l to 9, wherein the array of control lines further comprises a set of third control lines.

11. The device of any one of claims 1 to 10, wherein the at least some non-rectangular polygonal electrodes comprise first electrodes of a first shape.

12. The device of claim 11, wherein the first shape has 3 or 6 sides.

13. The device of claim 11 or 12, wherein the first shape is a regular polygon.

14. The device of any one of claims 1 to 13, wherein the tessellated array of electrodes comprises hexagonal electrodes.

15. The device of claim 15, wherein the tessellated array of electrodes consists mainly of hexagonal electrodes.

16. The device of any one of claims 11 to 13, wherein the tessellated array of electrodes comprises second electrodes of a second, different shape.

17. The device of claim 16, wherein the second shape is rectangular.

18. The device of claim 17, wherein the second shape is square.

19. The device of any one of claims 1 to 18, wherein the tessellated array of electrodes comprises at least 1,000 electrodes or at least 10,000 electrodes.

20. The device according to any one of claims 1 to 19, comprising:

first and second substrates which are facing and having first and second surfaces respectively which are facing, wherein the tessellated array of electrodes are supported by the first surface of the first substrate;

a channel interposed between the first and second substrates in which droplet(s) are actuated;

a dielectric layer interposed between the tessellated array of electrodes and the channel;

a hydrophobic layer interposed between the dielectric layer and the channel.

-1621. A module comprising:

the device of any one of claims l to 20; and a first driver arranged for driving the set of first control lines.

22. A module of claim 21, further comprising:

a second driver arranged for driving the set of second control.

23. A system comprising:

the module according of claim 20 or 21; and a controller arranged to control the first and second drivers.

24. A method of controlling a tessellated array of electrodes which includes at least some non-rectangular polygonal electrodes, the method comprising:

retrieving a set of route-defining parameters stored a computer-readable data structure for defining a set of electrodes in the tessellated array of electrodes that are to be active in a given time window; and causing first and second address control units to apply control signals to corresponding pairs of lines in the first and second orthogonal address lines so as to activate the set of electrodes in a given time window.

25. The method of claim 24, wherein the set of route-defining parameters are a first set of route-defining parameters, the set of electrodes is a first set of electrodes and the given time window is a first time window, the method comprising:

retrieving a second set of route-defining parameters stored the computerreadable data structure for defining a second set of electrodes in the tessellated array of electrodes that are to be active in a second, following time window; and causing first and second address control units to apply control signals to corresponding pairs of lines in the first and second orthogonal address lines so as to activate the second set of electrodes in a second time window

26. A method of controlling a tessellated array of electrodes which includes at least some non-rectangular polygonal electrodes, the method comprising:

activating a first electrode in the tessellated array of electrodes;

activating second and third electrodes which are adjacent to each other and which are adjacent to the first electrode; and after activating second and third electrodes, de-activating the first electrode.

-1727- The method of any one of claims 24 to 26, comprising:

causing first and second address control units to independently control or manipulate droplets in different regions of the tessellated array of electrodes.

28. The method of any one of claims 24 to 27, comprising:

causing first and second address control units and a third address control unit to activate a first electrode at a first active level and a second, different electrode at a second, different activate level.

Amendments to the claims have been made as follows:

Claims

1. An electrowetting-on-dielectric droplet actuation device comprising:

a tessellated array of electrodes which includes at least some non-rectangular 5 polygonal electrodes;

an array of control devices, each control device comprising at least one switching element, including a first switching element, configured to control bias applied to a respective electrode in the tessellated array of electrodes; and an array of control lines comprising a set of first control lines and a set of second io control lines configured such that each control device is individually addressable by a given first control line and a given second control line.

2. The device of claim l, wherein the first switching element comprises a transistor.

15 3· The device of claim 2, wherein the transistor is a thin-film transistor.

4. The device of claim 2 or 3, wherein a channel of the transistor is interposed between the respective electrode and a gate of the transistor.

T” 20 5. The device of claim 2 or 3, wherein a gate of the transistor is interposed between the respective electrode and a channel of the transistor.

6. The device of any one of claims 1 to 5, wherein each control device comprises a capacitor.

7. The device of any one of claims 1 to 6, wherein the first switching element is disposed substantially in a centre of a respective electrode in the tessellated array of electrodes.

30 8. The device of any one of claims 1 to 7, wherein each control device comprises a second switching element.

9. The device of any one or claims 1 to 8, further comprising:

an array of sensors, each sensor arranged to sense a respective electrode in the

35 tessellated array of electrodes
10. The device of any one of claims l to 9, wherein the array of control lines further comprises a set of third control lines.
11. The device of any one of claims 1 to 10, wherein the at least some non-rectangular 5 polygonal electrodes comprise first electrodes of a first shape.
12. The device of claim 11, wherein the first shape has 3 or 6 sides.
13. The device of claim 11 or 12, wherein the first shape is a regular polygon.
14. The device of any one of claims 1 to 13, wherein the tessellated array of electrodes comprises hexagonal electrodes.
15. The device of claim 14, wherein the tessellated array of electrodes consists more

15 of hexagonal electrodes than non-hexagonal electrodes.
16. The device of any one of claims 11 to 13, wherein the tessellated array of electrodes comprises second electrodes of a second, different shape.

T” 20
17. The device of claim 16, wherein the second shape is rectangular.

CO
18. The device of claim 16, wherein the second shape is square.
19. The device of any one of claims 1 to 18, wherein the tessellated array of electrodes 25 comprises at least 1,000 electrodes or at least 10,000 electrodes.
20. The device according to any one of claims 1 to 19, comprising:

first and second substrates which are opposite facing and having first and second surfaces respectively which are opposite facing, wherein the tessellated array of

30 electrodes are supported by the first surface of the first substrate;

a channel interposed between the first and second substrates in which droplet(s) are actuated;

a dielectric layer interposed between the tessellated array of electrodes and the channel;

35 a hydrophobic layer interposed between the dielectric layer and the channel.
21. A module comprising:

the device of any one of claims l to 20; and a first driver arranged for driving the set of first control lines.

5
22. A module of claim 21, further comprising:

a second driver arranged for driving the set of second control.
23. A system comprising:

the module according of claim 21 or 22; and

10 a controller arranged to control the first and second drivers.

31 01 18

Intellectual

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Application No: GB1711420.8 Examiner: Mr Peter Davies