Method for driving electrowetting device

Abstract

A method for driving an electrowetting device according to the present invention is such that, during a first frame period in which actuation electrodes arranged in m rows and n columns are sequentially scanned, a first operation is performed in which a selection signal is applied from the selection signal line of the first row to the selection signal line of the m-th row, a control signal is applied from the control signal line of the first column to the control signal line of the n-th column in synchronization with the driving of the selection signal line, and the control signal is applied to the actuation electrodes via a thin film transistor so as to charge a holding capacitive element, and during a second frame period, a second operation is performed in which a second selection signal is applied from the selection signal line of the first row to the selection signal line of the n-th row, a first reset signal having a lower potential than the control signal is applied from the control signal line of the first column to the control signal line of the m-th column in synchronization with the driving of the selection signal line, and the charge accumulated in the holding capacitive element is discharged to the control signal lines via the thin film transistor.

Description

Method for driving an electrowetting device

[0001] One embodiment of the present invention relates to a method for operating a device for controlling electrowetting to manipulate a flowable analyte.

[0002] In recent years, development of electrowetting devices utilizing the electrowetting effect has been progressing. The electrowetting effect is a phenomenon in which, when a voltage is applied between a liquid and an electrode, the energy at the solid-liquid interface between the electrode surface and the liquid changes, resulting in a change in the surface shape of the liquid. By utilizing this phenomenon, it is possible to construct a liquid delivery device capable of transporting microdroplets (see Patent Documents 1 to 6).

[0003] Japanese Patent Application Publication No. 2018-51685 Japanese Patent Application Publication No. 2012-163956 U.S. Patent No. 6,565,727 U.S. Patent No. 6,911,132 U.S. Patent Application Publication No. 2023 / 0110598 Japanese Patent Application Publication No. 2006-125900

[0004] Electrowetting devices manipulate fluid analytes by driving electrodes arranged on an array substrate with thin-film transistors. To ensure smooth analyte flow, the voltage applied to the electrodes must be appropriately controlled. However, because thin-film transistors have defect levels in their channel regions that trap carriers, switching the thin-film transistors from on to off makes it difficult for carriers to escape from the channel region, hindering smooth analyte manipulation.

[0005] A method for driving an electrowetting device according to one embodiment of the present invention includes the following steps: during a first frame period in which working electrodes arranged in m rows and n columns are sequentially scanned, a first selection signal is sequentially applied to the selection signal line in the first row to the selection signal line in the mth row; control signals are applied to the control signal line in the first column to the control signal line in the nth column in synchronization with the driving of the selection signal lines; a first operation is performed in which the control signal is applied to the working electrode via a thin film transistor that has been turned on by the first selection signal, thereby charging a storage capacitance element; and during a second frame period following the first frame period, a second selection signal is sequentially applied to the selection signal line in the first row to the selection signal line in the nth row; a first reset signal having a lower potential than the control signal is applied to the control signal line in the first column to the control signal line in synchronization with the driving of the selection signal lines; and a second operation is performed in which the charge accumulated in the storage capacitance element is released to the control signal line via the thin film transistor that has been turned on by the second selection signal. Here, the electrowetting device comprises an array substrate having working electrodes arranged in m rows and n columns (m and n are natural numbers greater than 4), thin film transistors connected to each of the working electrodes, storage capacitance elements connected to each of the working electrodes, selection signal lines and control signal lines arranged in correspondence with the arrangement of the working electrodes, and a counter substrate having a counter electrode, the array substrate and the counter substrate being arranged opposite and spaced apart, and having the function of controlling the flow of a sample in the space sandwiched between the working electrodes and the counter electrode.

[0006] 1A shows a plan view of an electrowetting device according to an embodiment of the present invention; FIG. 1B shows a cross-sectional structure corresponding to A1-A2 shown in FIG. 1A shows an arrangement of working electrodes of an electrowetting device according to an embodiment of the present invention; FIG. 1C shows the configuration of a drive circuit of an electrowetting device according to an embodiment of the present invention; FIG. 1D shows the configuration of a drive circuit of an electrowetting device according to an embodiment of the present invention; FIG. 1E shows a schematic cross-sectional structure of a cell of an electrowetting device according to an embodiment of the present invention; FIG. 1F shows a schematic cross-sectional structure of a cell of an electrowetting device according to an embodiment of the present invention; FIG. 1G shows a schematic cross-sectional structure of a cell of an electrowetting device according to an embodiment of the present invention; FIG. 1H shows an operation mechanism of an electrowetting device according to an embodiment of the present invention; FIG. 1I shows an equivalent circuit of a cell of an electrowetting device according to an embodiment of the present invention; FIG. 1I shows a voltage application state and its operation to a cell of an electrowetting device according to an embodiment of the present invention; FIG. 1I shows a voltage application state and its operation to a cell of an electrowetting device according to an embodiment of the present invention; FIG. 1I shows a timing chart of an electrowetting device according to an embodiment of the present invention; FIG. 1I shows a timing chart of an electrowetting device according to an embodiment of the present invention; 1 shows the operation of an electrowetting device according to an embodiment of the present invention; 2 shows the operation of an electrowetting device according to an embodiment of the present invention; 3 shows the operation of an electrowetting device according to an embodiment of the present invention; 4 shows the operation of an electrowetting device according to an embodiment of the present invention; 5 shows the operation of an electrowetting device according to an embodiment of the present invention;

[0007] Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the present invention can be implemented in many different forms, and should not be construed as being limited to the description of the following exemplary embodiments. For clarity of explanation, the drawings may show schematic representations of the width, thickness, shape, etc. of each part compared to the actual form. However, these are merely examples and are not intended to limit the interpretation of the present invention. Furthermore, in this specification and each drawing, elements similar to those previously described with reference to the preceding drawings are designated by the same reference numerals (or reference numerals with A, B, etc. suffixed thereto), and detailed descriptions may be omitted as appropriate. Furthermore, the letters "first" and "second" attached to each element are convenient labels used to distinguish each element and have no further meaning unless otherwise specified.

[0008] In this specification, when a component or region is referred to as being "on (or under)" another component or region, unless otherwise specified, this includes not only the case where it is directly above (or directly under) the other component or region, but also the case where it is above (or under) the other component or region, i.e., the case where another component is included between the component or region and above (or under) the other component or region.

[0009] 1A and 1B show the configuration of an electrowetting device 100 according to one embodiment of the present invention. FIG. 1A shows a plan view of the electrowetting device 100, and FIG. 1B shows a cross-sectional view corresponding to the line A1-A2 shown in the plan view. The electrowetting device 100 is a device that manipulates a fluid sample by the action of an electric field. The electrowetting device 100 is also called a microchannel chip or a lab-on-a-chip. The electrowetting device 100 can be used to analyze minute amounts of liquid samples, perform chemical reactions, and the like.

[0010] In this embodiment, the "analyte" refers to a substance having fluidity that causes electrowetting, specifically a liquid. In other words, the contact angle of the analyte on the surface it comes into contact with changes as a result of the operation of the electrowetting device 100, and the spread of the analyte on the contact surface also changes. Because the analyte is dropped into the injection port of the electrowetting device 100, it can also be read as a "droplet" in this embodiment.

[0011] Examples of specimens include liquids containing antibiotic-resistant pathogens such as methicillin-resistant Staphylococcus aureus (MESA), globular proteins such as human serum albumin (HSA), vegetative bacteria such as Escherichia coli, bacterial algae such as Bacillus atrophaeus (BG), and viruses such as bacteriophage viruses. Note that these examples are merely examples, and the electrowetting device 100 according to this embodiment can handle a variety of specimens that have fluidity.

[0012] The electrowetting device 100 has an array substrate 150 and a counter substrate 152. The array substrate 150 and the counter substrate 152 are disposed opposite each other and fixed together using a sealant 154. When the array substrate 150 and the counter substrate 152 are disposed opposite each other, a gap is provided to separate the opposing surfaces. A plurality of working electrodes 102, drive circuits (a first drive circuit 106A, a second drive circuit 106B), a power supply terminal 107, a signal terminal 108, etc. are provided on the surface of the array substrate 150 facing the counter substrate 152. A counter electrode 112 is provided on the counter substrate 152.

[0013] The array substrate 150 and the counter substrate 152 provide physical strength to the electrowetting device 100, as well as surfaces for forming a flow path for the analyte and controlling its flow. The materials for forming the array substrate 150 and the counter substrate 152 are not limited, and insulating substrates such as glass substrates, quartz substrates, plastic substrates containing polymers such as polyimide and polycarbonate, and metal substrates such as aluminum and stainless steel may be used. One or both of the array substrate 150 and the counter substrate 152 may be flexible. It is preferable that one or both of the array substrate 150 and the counter substrate 152 be configured to transmit light in at least a portion of the visible light spectrum. The transparency of one or both of the array substrate 150 and the counter substrate 152 allows the flow of the analyte to be visually observed, and the state of the analyte can be observed and analyzed using an optical microscope or various spectroscopes.

[0014] The sizes of the array substrate 150 and the counter substrate 152 can be determined arbitrarily. The length of one side of the array substrate 150 and the counter substrate 152 can be, for example, 10 mm or more and 200 mm or less. A part of the array substrate 150 is exposed from the counter substrate 152, and the power terminals 107, signal terminals 108, etc. are provided on the exposed part.

[0015] There is no limitation on the configuration of the sealant 154 that bonds the array substrate 150 and the counter substrate 152. FIG. 1A illustrates a shape in which the sealant 154 is provided continuously along the contour of the counter substrate 152. The sealant 154 is not limited to the shape shown in the figure, and may be provided discontinuously. Since it is not necessary to always hold a sample in the gaps of the electrowetting device 100, the sealant 154 may have a discontinuous structure (e.g., a dotted or dotted line shape). On the other hand, when hydrophobic oil or the like is filled in the gaps of the electrowetting device 100, it is preferable that the sealant 154 have a closed shape that forms a continuous contour.

[0016] At least two openings are provided in the opposing substrate 152. Figures 1A and 1B show a structure in which a first opening 114A and a second opening 114B are provided in the opposing substrate 152. In this embodiment, the first opening 114A is used as an inlet for injecting a sample, and the second opening 114B is used as an outlet for discharging the sample. A dropper, pipette, micropipette, syringe, or the like may be used to supply the sample to the first opening 114A and collect the sample from the second opening 114B.

[0017] The first opening 114A and the second opening 114B are formed by through holes provided in the counter substrate 152, but may be replaced with cutout portions. The cutout portion is a portion formed by cutting out a part of the counter substrate 152 from the outer periphery, and its outline forms part of the outer periphery of the counter substrate 152.

[0018] The first drive circuit 106A and the second drive circuit 106B are provided on the array substrate 150 and are electrically connected to the power supply terminal 107 and the signal terminal 108 by wiring (not shown). The power supply terminal 107 and the signal terminal 108 are electrically connected to an external control circuit board via a flexible printed circuit (FPC) (not shown). A control signal output from the external control circuit board is input to the signal terminal 108, and power for driving the electrowetting device 100 is input to the power supply terminal 107.

[0019] 1B , thin film transistors 118 are provided on the array substrate 150. Working voltages are applied to the working electrodes 102 individually by the thin film transistors 118. The first drive circuit 106A is a circuit that outputs signals (selection signals) that control the on / off of the thin film transistors 118, and the second drive circuit 106B may be a circuit that outputs working voltages to the individual working electrodes 102 via the thin film transistors 118. The structures and operations of the working electrodes 102 and the thin film transistors 118 will be described in detail below.

[0020] In this embodiment, a thin film transistor is used as the thin film transistor 118. More preferably, an n-channel thin film transistor having a lower midgap defect density (deep defect level density) than a p-channel thin film transistor is used.

[0021] As shown in FIG. 1B , in this embodiment, an area where one working electrode 102 and one counter electrode 104 form a pair, as shown in FIG. 4 , is a basic unit for exhibiting the functions of the electrowetting device 100. Therefore, in this embodiment, an area where one working electrode 102 and one counter electrode 104 form a pair is called a "cell 110." This concept also applies to the relationship between the working electrodes 102A_1, 102A_2 and the counter electrode 104, which can also be called a cell 110. Furthermore, when the working electrodes 102 are arranged in m rows and n columns, a specific cell is referred to as cell 110(m, n).

[0022] 1A shows an example in which the first drive circuit 106A is arranged on one side of the active region 101 in which the working electrodes 102 are arranged, but the first drive circuit 106A may be arranged on both sides of the active region 101. The first drive circuit 106A and the second drive circuit 106B may be formed by thin film transistors on the array substrate 150, or may be formed by a semiconductor integrated circuit chip (IC chip) mounted on the array substrate 150. Although omitted in FIGS. 1A and 1B, a selection signal line is connected to the first drive circuit 106A, and a control signal line is connected to the second drive circuit 106B.

[0023] The working region 101 is a region where the working electrodes 102 are arranged and which faces the counter electrode 104, and which operates the analyte.

[0024] The working electrodes 102 provided on the array substrate 150 are arranged in a matrix. A counter electrode 104 is arranged on the counter substrate 152. The counter electrode 104 is arranged so as to overlap the entire area in which the working electrodes 102 are arranged, excluding the areas of the first opening 114A and the second opening 114B. The working electrodes 102 and counter electrodes 104 arranged in a matrix form an working region 101 that controls the flow of the sample.

[0025] Selection signal lines, control signal lines, and common signal lines (not shown) are arranged in the active area 101. The selection signal lines are wires extending from the first drive circuit 106A, and the control signal lines are wires extending from the second drive circuit 106B. The common signal lines are wires connected to any signal terminal 108.

[0026] A first insulating layer 116A is provided on the array substrate 150 to cover the working electrode 102, and a second insulating layer 116B is provided on the counter substrate 152 to cover the counter electrode 104. The counter electrode 104 is provided to extend to (or close to) the opening edges of the first opening 114A and the second opening 114B, and preferably is covered with the second insulating layer 116B in this area to prevent the side edges of the counter electrode 104 from being exposed. This structure prevents corrosion of the counter electrode 104, which may occur depending on the type of analyte or reagent. Note that FIG. 1B shows a structure in which the second insulating layer 116B extends to the inner walls of the first opening 114A and the second opening 114B (the inner wall surfaces of the counter substrate 152). However, the illustrated structure is merely an example, and any structure in which the second insulating layer 116B covers the side edges of the counter electrode 104 may be used; the structure shown in FIG. 1B is not limited to this. The surfaces of the first insulating layer 116A and the second insulating layer 116B are water-repellent. The first insulating layer 116A and the second insulating layer 116B may be formed of a material that is water-repellent itself, or the surfaces may be subjected to a water-repellent treatment.

[0027] Although there is no limitation on the distance (gap) separating the array substrate 150 and the counter substrate 152, it is preferably set to, for example, a range of 10 μm to 30 μm inclusive to allow the sample to flow smoothly. A spacer (not shown) may be provided to maintain a constant distance (gap) between the array substrate 150 and the counter substrate 152. More precisely, when the array substrate 150 and the counter substrate 152 are spaced apart and arranged facing each other, the distance (gap) is the distance from the surface of the first insulating layer 116A to the surface of the second insulating layer 116B. However, the thicknesses of the first insulating layer 116A, the second insulating layer 116B, the working electrode 102, the counter electrode 104, and other components are 1 μm or less, which is extremely thin compared to the distance (gap) and can therefore be ignored.

[0028] 2 shows working electrodes 102 arranged in m rows and n columns (m and n are natural numbers equal to or greater than 4). The working electrodes 102 include working electrodes 102A_1 and 102A_2 arranged in an area overlapping with the first opening 114A and the second opening 114B, and working electrode 102B arranged in an area sandwiched between the first opening 114A and the second opening 114B. The arrangement of these working electrodes 102 forms a working region 101 for manipulating an analyte.

[0029] The working electrodes 102A_1 and 102A_2 and the working electrode 102B have different sizes (areas) in a plan view. Specifically, the size (area) of the working electrodes 102A_1 and 102A_2 arranged in the first and mth rows is larger than the size (area) of the working electrodes 102B arranged in the second to m-1th rows. Therefore, even if the working electrode 102A_1 arranged in the first row overlaps with the first opening 114A and the working electrode 102A_2 arranged in the mth row overlaps with the second opening 114B, and thus has an area partially exposed from the counter electrode 104 (see FIGS. 1A and 1B ), other areas can be made to overlap with the counter electrode 104. With such an electrode shape and electrode arrangement, a sample can be injected through the first opening 114A (inlet), and the injected sample can be reliably introduced into the region facing the working electrode 102B and the counter electrode 104 at a distance by utilizing capillary action.

[0030] By individually controlling the voltages applied to the working electrodes 102B arranged in the second to (m-1)th rows, the flow of the analyte can be controlled in the working region 101 sandwiched between the working electrodes 102B and the counter electrode 104. The flowed analyte can then be moved to the second opening 114B (discharge port), where it can be collected and discharged using a pipette, syringe, or the like. A spacer 156 may be provided in the region where the working electrodes 102A and 102B are arranged to maintain a constant distance between the array substrate 150 and the counter substrate 152. The arrangement and number of spacers 156 are arbitrary, but it is preferable that they be disposed in the region between the electrodes so as not to impede the flow of the analyte.

[0031] 2, the areas of the working electrodes 102A_1 and 102A_2 arranged in the first and m-th rows are larger than the areas of the working electrodes 102B arranged in the second to (m-1)-th rows. Therefore, in order to more significantly change the contact angle of the analyte on the working electrode 102A_1 arranged in the first row and more efficiently transfer the analyte to the working electrode 102B in the second row or smoothly transfer the analyte from the working electrode 102B in the (m-1)-th row to the working electrode 102A_2 in the m-th row, it is necessary to drive the working electrodes 102A_1 and 102A_2 arranged in the first and m-th rows so that the rise rate when a working voltage is applied to them is the same as the rise rate when a working voltage is applied to the working electrodes 102B in the second to (m-1)-th rows.

[0032] To this end, the first drive circuit 106A may be configured so that the voltage of the selection signal applied to the working electrodes 102A_1 and 102A_2 arranged in the first and m-th rows is greater than the voltage of the selection signal applied to the working electrodes 102B arranged in the second to (n-1)-th rows.

[0033] 3A, the first drive circuit 106A that outputs the selection signal is provided with shift registers SR1 to SRm and output buffers BF1 to BFm corresponding to the selection signal lines 120_1 to 120_m. Furthermore, in the first and m-th rows, output buffer level shifters LS1 and LSm are provided between the shift registers SR1 and SRm and the output buffers BF1 and BFm.

[0034] With this circuit configuration, the voltage level of the selection signal output to the selection signal line 120_1 in the first row and the selection signal line 120_m in the m-th row can be made higher than the voltage level of the selection signals output to the selection signal lines 120_2 to 120_m-1 in the second to (m-1)th rows. By configuring the first drive circuit 106A in this way, it is possible to suppress delays when driving the working electrodes 102A_1 and 102A_2 arranged in the first and m-th rows, and to facilitate injection and discharge of the analyte.

[0035] Note that, due to the provision of the level shifters LS1 and LSm, the selection signals output to the selection signal lines 120_1 and 120_m may be delayed from the selection signals output to the selection signal lines 120_2 to 120_m-1. Therefore, as shown in FIG. 3B , delay buffer circuits DBF2 to DBFm-1 may be provided on the selection signal lines 120_2 to 120_m-1 in order to match the timing of the selection signals output to the selection signal lines 120_1 and 120_m and the selection signal lines 120_2 to 120_n-1.

[0036] FIG. 4 is a schematic cross-sectional view of a cell 110 of the electrowetting device 100, showing the cross-sectional structure of a region where the working electrode 102B is provided. As shown in FIG. 4 , a thin-film transistor 118B is provided on the array substrate 150 directly or via an optional underlying insulating layer 130. The structure of the thin-film transistor 118B is not limited, and various structures such as a top-gate type, a bottom-gate type, and a dual-gate type can be applied. The example shown in FIG. 4 shows an example where a top-gate type structure is adopted for the thin-film transistor 118B. Specifically, the thin-film transistor 118B includes a semiconductor layer 1182, a gate insulating layer 1184 covering the semiconductor layer 1182, and a gate electrode 1186 overlapping the semiconductor layer 1182 via the gate insulating layer 1184.

[0037] A gate electrode 1186 of the thin film transistor 118B is connected to the selection signal line 120 (see FIG. 8 ). The thin film transistor 118B is connected to a first input / output electrode 136 and a second input / output electrode 138. The first input / output electrode 136 is connected to one of a source region and a drain region formed in the semiconductor layer 1182, and the second input / output electrode 138 is connected to the other of the source region and the drain region. The first input / output electrode 136 may essentially also serve as the control signal line 122 (see FIG. 8 ). The first input / output electrode 136 and the second input / output electrode 138 are provided via an interlayer insulating layer 132 that covers the gate electrode 1186.

[0038] A planarization layer 134 is provided on the upper layer side of the thin film transistor 118B. By providing the planarization layer 134, structures such as the thin film transistor 118B can be embedded to form a flat surface. The working electrode 102B is provided on the planarization layer 134. The working electrode 102B has a flat surface except for the region of a contact hole that forms a connection with the second input / output electrode 138.

[0039] A first insulating layer 116A is provided on the array substrate 150 so as to cover the working electrode 102B. The first insulating layer 116A has a water-repellent surface. The first insulating layer 116A is formed of, for example, a silicon nitride film. Alternatively, the first insulating layer 116A may have a water-repellent surface formed by coating the surface of an insulating film (for example, an inorganic insulating film such as a silicon oxide film or a silicon nitride film, or an organic resin film such as a polyimide or an acrylic resin) with a thin fluorine film by fluorine plasma treatment.

[0040] A counter electrode 104 is provided on the counter substrate 152. The counter electrode 104 is connected to a common wiring provided on the array substrate 150 by a conductive member (not shown). A second insulating layer 116B is provided on the counter substrate 152 so as to cover the counter electrode 104. The second insulating layer 116B has a water-repellent surface similar to the first insulating layer 116A.

[0041] The electrowetting device 100 is a device that manipulates the flow of an analyte by applying an electric field generated between a working electrode 102B and a counter electrode 104 to the analyte. The working electrodes 102B are arranged in a matrix in the working region 101, and a working voltage is applied to each working electrode 102B individually via a thin-film transistor 118B. The analyte flows through the region sandwiched between the working electrode 102B and the counter electrode 104, and the flow is controlled by the voltage of the working electrode 102B. Therefore, the structure shown in FIG. 4 , in which one working electrode 102B and counter electrode 104 form a pair, can be considered as a basic unit of the working region 101.

[0042] 4, the cell 110 includes a storage capacitor element connected in parallel to the working electrode 102B with respect to the thin film transistor 118. The storage capacitor element can be formed using the same layer as the semiconductor layer 1182, the gate insulating layer 1184, and the gate electrode 1186, and can also be formed using the same layer as the gate electrode 1186, the interlayer insulating layer 132, and the first input / output electrode 136. The storage capacitor element is provided to maintain the potential of the working electrode 102B.

[0043] The layers provided on the array substrate 150 and the counter substrate 152 are formed using the following materials. The semiconductor layer 1182 is formed of a silicon semiconductor such as amorphous silicon or polycrystalline silicon, or an oxide semiconductor including a metal oxide such as indium oxide, zinc oxide, or gallium oxide. The gate insulating layer 1184 and the interlayer insulating layer 132 are formed of an insulating material that can be formed into a thin film. For example, the gate insulating layer 1184 and the interlayer insulating layer 132 are formed using a silicon oxide film or a silicon nitride film, and are formed as a single layer of these films or a stacked structure of these films. The gate electrode 1186 (and the selection signal line 120) is formed using a conductive material, such as molybdenum (Mo), tungsten (W), or an alloy thereof. The first input / output electrode 136 and the second input / output electrode 138 (and the control signal line 122) are formed using a conductive material, such as a titanium (Ti) / aluminum (Al) / titanium (Ti) stacked structure or a molybdenum (Mo) / aluminum (Al) / molybdenum (Mo) stacked structure. The planarization layer 134 may be formed using any material that is flat and insulating after formation, such as an organic insulating material. Examples of organic insulating materials include acrylic resins, epoxy resins, and polyimide materials. The working electrode 102B and the counter electrode 104 are formed using a metal material or a conductive material (transparent conductive film material) that becomes transparent when formed into a thin film. Examples of metal materials include aluminum (Al). Examples of transparent conductive film materials include indium tin oxide (ITO), zinc oxide (ZnO), and indium zinc oxide (IZO).

[0044] When the counter electrode 104 is formed of a transparent conductive film, an auxiliary electrode 105 may be provided. FIG. 5 shows an example of the structure of the counter electrode 104 and the auxiliary electrode 105. The auxiliary electrode 105 is provided in contact with the counter electrode 104. The auxiliary electrode 105 may have a lattice (or mesh) pattern or a stripe pattern. The auxiliary electrode 105 is preferably formed of a metal such as aluminum (Al), molybdenum (Mo), or titanium (Ti), and may have a layered structure such as titanium (Ti) / aluminum (Al) / titanium (Ti) or molybdenum (Mo) / aluminum (Al) / molybdenum (Mo).

[0045] 5 shows a structure in which the auxiliary electrode 105 is provided between the counter electrode 104 and the second insulating layer 116B, but the arrangement of the auxiliary electrode 105 is not limited to the illustrated structure. For example, the auxiliary electrode 105 may be provided between the counter electrode 104 and the counter substrate 152. By providing the auxiliary electrode 105 in contact with the counter electrode 104, the surface resistance (sheet resistance) of the counter electrode 104 can be reduced. As a result, the resistance component of the counter electrode 104 is reduced, and the time constant determined by the capacitance (C) and resistance (R) can be made smaller. In other words, the response speed when a working voltage is applied to the working electrode 102B can be increased, allowing the analyte to move more smoothly.

[0046] 6 is a schematic cross-sectional view of the cell 110 of the electrowetting device 100, showing the cross-sectional structure of the working region 101 where the working electrode 102A_1 is provided. The working electrode 102A_1 is the same as the working electrode 102B shown in FIG. 4 except for the area in a plan view. Therefore, the thin-film transistor 118A-1 connected to the working electrode 102A_1 has the same configuration as the thin-film transistor B shown in FIG.

[0047] Meanwhile, a first opening 114A is provided in the counter substrate 152 in a region overlapping with the working electrode 102A_1. The working electrode 102A_1 is disposed so as to partially overlap with the first opening 114A. In other words, a portion of the working electrode 102A_1 is exposed to the outside through the first opening 114A. The region of the working electrode 102A_1 that does not overlap with the first opening 114A overlaps with the counter electrode 104. Note that FIG. 6 illustrates a structure in which the edge of the counter electrode 104 does not reach the opening edge of the first opening 114A. In other words, the opening edge of the counter electrode 104 is disposed outside the opening edge of the first opening 114A. In such a structure, the second insulating layer 116B can cover the upper surface and side end surfaces of the counter electrode 104 and further contact the upper surface of the counter substrate 152. The second insulating layer 116B can be structured to be in close contact with the opposing substrate 152 in the region adjacent to the opening end of the first opening 114A, thereby preventing peeling and more reliably preventing deterioration of the opposing electrode 104 due to corrosion, etc.

[0048] As shown in FIG. 6 , the analyte 200 can be placed on the working electrode 102A_1 by dropping the analyte 200 into the first opening 114A. The analyte 200 flows into the gap between the array substrate 150 and the counter substrate 152 by capillary action and comes into contact with the first insulating layer 116A and the second insulating layer 116B. Because the first insulating layer 116A and the second insulating layer 116B have water-repellent surfaces, the contact angle of the analyte 200 increases when no voltage is applied to the working electrode 102A_1. FIG. 6 shows this state of the analyte 200 using dotted lines. In this embodiment, this state is referred to as "State A."

[0049] On the other hand, when a predetermined voltage is applied to the working electrode 102A_1, a fringe electric field generated near the edge of the analyte 200 generates a force that presses the analyte 200 toward the working electrode 102A_1, and the contact angle becomes relatively smaller than in state A. Figure 6 shows, using solid lines, a state in which a fringe electric field acts on the analyte 200. In this embodiment, this state is called "state B."

[0050] Although not shown, the same applies to the second opening 114B and the overlapping working electrode 102A_2. Therefore, when the second opening 114B is used as an outlet for the specimen 200, the specimen can be dropped from the second opening 114B by utilizing gravity. Furthermore, the specimen 200 that has flowed into the second opening 114B can be sucked out using a dropper, pipette, syringe, or the like.

[0051] The contact angle of the analyte 200 with respect to the first insulating layer 116A changes reversibly depending on whether or not a voltage is applied to the working electrode 102A_1 (and the working electrode 102B). In other words, the change from state A to state B and the change from state B to state A can be controlled by the voltage applied to the working electrode 102A_1 (and the working electrode 102B).

[0052] 6 does not show the analyte 200 in state B spreading over the adjacent working electrodes 102B_1 to 102B_3 as shown in FIG. 7, but by controlling the potential difference between the counter electrode 104 and the working electrode 102A_1, the analyte 200 can be spread over the adjacent working electrodes, and the analyte 200 can be moved to the top of the adjacent working electrode. Furthermore, the spread of the analyte 200 in state B depends on the gap between the first insulating layer 116A and the second insulating layer 116B, so this gap is set to allow the analyte 200 to move.

[0053] 6 shows a state in which the analyte 200 in State B spreads only over the working electrode 102A_1, but in reality, the size relationship between the working electrode and the analyte 200 may be such that the analyte 200 spreads over multiple working electrodes 102B_1 to 102B_3, as shown in Fig. 7. Furthermore, the size by which the analyte 200 spreads in State B may be smaller than the length in the direction in which the analyte 200 moves (movement distance).

[0054] Next, the basic operation of the electrowetting device 100 will be described. FIG. 7 is a diagram illustrating the concept of operation of the electrowetting device 100, showing a state in which a specimen 200 is sandwiched between the working electrodes 102B_1 to 102B_3 and the counter electrode 104 (actually, between the first insulating layer 116A and the second insulating layer 116B). Working electrodes 102B_1 to 102B_3 are arranged on the array substrate 150, and each working electrode is connected to a respective thin-film transistor 118B_1 to 118B_3. The thin-film transistors 118B_1 to 118B_2 are connected to a power supply EV1, and when any of the thin-film transistors 118B_1 to 118B_3 is turned on, a predetermined working voltage is applied from the power supply EV1 to the working electrode 102B_1 to 102B_3 connected to it. On the other hand, the counter electrode 104 is connected to a switch SW1, and can be switched between a grounded state and a state connected to a power source EV2 by operating the switch SW1.

[0055] The electrowetting device 100 can manipulate the analyte 200 and move the position of the analyte 200 by temporally changing the potentials of the working electrodes 102B_1 to 102B_3 and the counter electrode 104. For example, with the counter electrode 104 grounded, the analyte 200 can be moved from the working electrode 102B_1 side to the working electrode 102B_3 side by turning on the thin-film transistor 118B_1 and turning off the thin-film transistors 118B_2 and 118B_3 as a first state, turning off the thin-film transistor 118B_1, turning on the thin-film transistor 118B_2, and turning off the thin-film transistor 118B_3 as a second state, and turning off the thin-film transistor 118B_1 and turning on the thin-film transistors 118B_2 and 118B_3 as a third state.

[0056] In the above case, when a positive voltage is applied from power supply EV1 to each of working electrodes 102B_1 to 102B_3, the negative charge of analyte 200 is attracted to working electrodes 102B_1 to 102B_3, thereby reducing the contact angle of analyte 200. When the switching of thin film transistors 118B_1 to 118B_3 is controlled to sequentially switch from the first state to the third state, analyte 200 spreads toward the working electrode to which the working voltage is applied, resulting in analyte 200 moving from the working electrode 102B_1 side to the working electrode 102B_3 side.

[0057] On the other hand, when the counter electrode 104 is connected to the power supply EV2 and the potential of the power supply EV1 is set lower than the potential of the power supply EV2, a phenomenon opposite to that described above occurs. That is, the positive charge of the analyte 200 is attracted to the working electrodes 102B_1 to 102B_3, the contact angle of the analyte 200 decreases, and the analyte 200 can be similarly moved. The state in which the counter electrode 104 is connected to the power supply EV2 is the opposite state to the state in which the counter electrode 104 is grounded, and therefore can also be called inversion driving. By alternately switching the potential of the counter electrode 104 between the ground potential and a potential based on the power supply EV2, or by intermittently switching it, it is also possible to invert the direction of the electric field acting on the analyte 200.

[0058] FIG. 8 shows an equivalent circuit of the cell 110 (working electrode 102, thin film transistor 118, counter electrode 104, and storage capacitor element 126) described with reference to FIG. 4. The equivalent circuit shown in FIG. 8 schematically shows that the working electrode 102 and the counter electrode 104 are arranged opposite each other. The working electrode 102 is connected to the thin film transistor 118. The thin film transistor 118 has a gate, a source, and a drain. The selection signal line 120 is a signal line extending from the first drive circuit 106A and connected to the gate of the thin film transistor 118. The control signal line 122 is a signal line extending from the second drive circuit 106B and connected to one of the source and drain of the thin film transistor 118. The other of the source and drain is connected to the working electrode 102. In other words, the control terminal (gate) of the thin film transistor 118 is connected to the selection signal line 120, one of the input / output terminals is connected to the control signal line 122, and the other of the input / output terminals is connected to the working electrode 102.

[0059] The counter electrode 104 is connected to a common signal line 124. A holding capacitance element 126 is connected in parallel to the working electrode 102. The holding capacitance element 126 is provided to hold the voltage applied to the working electrode 102 for a certain period of time.

[0060] The thin film transistor 118 is turned on when a selection signal is input from the selection signal line 120. When a control signal is applied from the control signal line 122 in synchronization with this, an operating voltage is applied to the working electrode 102 via 118. At the same time, the holding capacitance element 126 is charged with the operating voltage. Meanwhile, a predetermined voltage is applied to the counter electrode 104 from the common signal line 124. As described with reference to FIG. 2, the working electrodes 102 are arranged in a matrix. In other words, the cells 110 are arranged in a matrix in the working region 101. Each cell 110 has the circuit configuration shown in FIG. 8, and therefore the state of each cell 110 can be individually controlled by the first drive circuit 106A and the second drive circuit 106B. A method for driving the electrowetting device 100 having such a configuration will be described in detail later.

[0061] In this way, the electrowetting device 100 can manipulate the analyte and move it in the desired direction by sequentially changing the potential of the arranged working electrodes 102 using the thin film transistors 118 on the array substrate 150. To move the analyte smoothly, it is necessary to precisely control the timing of the voltage applied to each working electrode 102. To achieve this, it is desirable that there be no delay in the rise and fall times of the thin film transistors 118.

[0062] It is known that thin-film transistors have trap levels in their channel regions that capture carriers. It has been pointed out that the influence of these trap levels shifts the threshold voltage, affecting switching operation (see, for example, Japanese Patent Application Laid-Open No. 2008-028191). Specifically, when the gate of a thin-film transistor is turned on, electrons are trapped in the trap levels in the channel region, causing the threshold voltage to shift positively over time. On the other hand, when the gate is turned off, the trapped electrons are released, causing the threshold voltage to decrease over time. When comparing the switching operation of a thin-film transistor between an on-to-off transition and an off-to-on transition, a high initial threshold voltage results in a slower on-to-off transition. When the gate is turned off, the threshold voltage decreases as described above, but the electrons trapped in the trap levels are not instantly released, resulting in delays in switching when the thin-film transistor is frequently turned on and off.

[0063] The electrowetting device 100 uses a thin film transistor 118 to apply a voltage to the working electrode 102 at a predetermined timing to move the analyte, but if there is a delay in switching, the analyte cannot be moved smoothly. Therefore, the electrowetting device 100 according to this embodiment suppresses delays in response time caused by carriers remaining in the channel region by optimizing the timing of the voltage applied to the transistor 118 and the timing of the voltage applied to the counter electrode 104. The driving method will be described in detail below.

[0064] 9A to 9D show an equivalent circuit of the cell 110 and illustrate an example of the operation of the electrowetting device 100. FIG.

[0065] 9A shows the first operation. In this operation, a working voltage Vop is applied to the working electrode 102. In this operation, the thin-film transistor 118 is turned on by a selection signal (Vg1) applied from a selection signal line 120. The working voltage Vop is applied to the first input / output terminal (source or drain) of the thin-film transistor 118 from a control signal line 122. Since the thin-film transistor 118 is turned on, the working voltage Vop is applied to the working electrode 102, and at the same time, the holding capacitance element 126 is charged by the working voltage Vop. In this operation, a common voltage Vcom is applied to the counter electrode 104. The common voltage Vcom is, for example, 0 V, which is the ground potential. In this operation, the thin-film transistor 118 is turned on, which may trap electrons in the channel region and cause a positive shift in the threshold voltage.

[0066] FIG. 9B shows the second operation. The second operation is an operation of extracting the charge stored in the capacitance element 126. In the second operation, the thin-film transistor 118 is turned on by a selection signal (Vg1) applied from the selection signal line. A first reset voltage Vrs1 is applied from the control signal line 122 to the first input / output terminal (source or drain) of the thin-film transistor 118. The first reset voltage Vrs1 is a voltage lower than the operating voltage Vop and may be a voltage of opposite polarity. Under these voltage application conditions, the charge stored in the capacitance element 126 flows into the control signal line 122, discharging the capacitance element 126 and releasing the accumulated charge. Furthermore, the charge stored in the parasitic capacitance between the working electrode 102 and the counter electrode 104 is also removed.

[0067] FIG. 9C shows a third operation. The third operation is an operation for resetting the thin-film transistor 118. In the third operation, a voltage (Vg2) lower than the normal off voltage is applied to the gate of the thin-film transistor 118 from the selection signal line 120. A second reset voltage Vrs2 is applied to the first input / output terminal (source or drain) of the thin-film transistor 118 from the control signal line 122. The second reset voltage Vrs2 is a voltage lower than the operating voltage Vop and may be a voltage of opposite polarity. The second reset voltage Vrs2 may also be a voltage higher than the first reset voltage Vrs1. By applying the second reset voltage Vrs2 to the thin-film transistor 118, carriers of opposite polarity to when the thin-film transistor 118 is on are collected in the channel region, canceling carriers (electrons) trapped in the trap level and enabling the carriers to be removed. The operation of FIG. 9C may be performed multiple times.

[0068] 9D shows a fourth operation. In the fourth operation, a voltage is applied to the thin film transistor 118 under the same conditions as in the first operation, but the common voltage Vcom applied to the counter electrode 104 is different. That is, a voltage higher than the working voltage Vop is applied to the counter electrode 104 as the common voltage Vcom. The working voltage Vop applied in the fourth operation may be a voltage lower than the working voltage Vop applied in the first operation. Under these voltage application conditions, the potentials of the working electrode 102 and the counter electrode 104 are inverted, enabling the inversion driving described with reference to FIG. 7 to be performed.

[0069] Next, an example of a method for driving the electrowetting device 100 will be described with reference to an equivalent circuit of the active region 101.

[0070] A first driving method of the electrowetting device 100 will be described with reference to Figures 10, 14A, and 14B. Figure 10 shows a timing chart relating to the first driving method, and Figures 14A and 14B show an equivalent circuit of an action region 101 in which cells 110 are arranged in m rows and n columns. It is assumed that selection signal lines 120_1 to 120_m extending from the first driving circuit 106A and control signal lines 122_1 to 122_n extending from the second driving circuit 106B are arranged in the action region 101. Here, a case in which a specimen is moved from cell 110(1,1) to cell 110(1,3) will be described.

[0071] 10, the first operation of applying the working voltage Vop to the working electrode 102 is performed as described with reference to FIG. 9A. As shown in FIG. 10, during the first frame period, a selection signal (Vg1) is applied from the selection signal lines 120_1 to 120_3 every horizontal period (1H), and working voltages (Vop1, Vop2, Vop3) are sequentially applied to the control signal line 122_1 in synchronization therewith. Here, the working voltages have the relationship Vop1<Vop2<Vop3.

[0072] More specifically, as shown in FIG. 14A , during the first horizontal period, cell 110(1,1) is selected by a selection signal (Vg1) from selection signal line 120_1, and an operating voltage (Vop1) is applied from control signal line 122_1 to the working electrode 102 and storage capacitor 126 of cell 110(1,1). In FIG. 14A , the flow of charge accompanying this operation is indicated by arrows. This causes the contact angle of the sample on cell 110(1,1) to increase.

[0073] In the second horizontal period following the first horizontal period, cell 110(2,1) is selected by the selection signal (Vg1) on selection signal line 120_2, and an operating voltage (Vop2) is applied from control signal line 122_1 to working electrode 102 and storage capacitor element 126. Here, because operating voltage (Vop2) is higher than operating voltage (Vop1), the contact angle of the analyte becomes even smaller. As a result, the operating voltage (Vop2) applied to cell 110(2,1) can spread the analyte to cell 110(2,1).

[0074] During the third horizontal period following the second horizontal period, cell 110(3,1) is selected by the selection signal (Vg1) on selection signal line 120_3, and an operating voltage (Vop3) is applied from control signal line 122_1 to working electrode 102 and storage capacitor 126. Here, operating voltage (Vop3) is higher than operating voltage (Vop2), further reducing the contact angle of the analyte. The operating voltage (Vop3) applied to cell 110(3,1) allows the analyte to spread to cell 110(3,1).

[0075] In this way, cell 110(1,1), cell 110(2,1), and cell 110(3,1) are selected in sequence, and an applied voltage is applied, thereby allowing the analyte to spread from cell 110(1,1) to cell 110(3,1).

[0076] In the second frame period following the first frame period, the second operation described with reference to Fig. 9B is performed, i.e., the first reset operation of extracting charges from the holding capacitance element 126. As shown in Fig. 10, in the second frame period, selection signals (Vg1) are sequentially applied to the thin film transistors 118 of the cells from the selection signal lines 120_1 to 120_3 for each horizontal period, and in synchronization therewith, a first reset signal (Vrs1) is applied to the control signal line 122_1.

[0077] 14B , during the first horizontal period of the second frame period, the cell 110(1,1) is selected by the selection signal (Vg1) of the selection signal line 120_1, and a first reset signal (Vrs1) is applied from the control signal line 122_1 to the working electrode 102 and the holding capacitor element 126 of the cell 110(1,1). During the second horizontal period following the first horizontal period, the cell 110(2,1) is selected by the selection signal (Vg1) of the selection signal line 120_2, and a first reset signal (Vrs1) is applied from the control signal line 122_1 to the working electrode 102 and the holding capacitor element 126 of the cell 110(2,1). In the third horizontal period following the second horizontal period, the cell 110(3,1) is selected by the selection signal (Vg1) of the selection signal line 120_3, and the first reset signal (Vrs1) is applied from the control signal line 122_1 to the working electrode 102 and the holding capacitance element 126 of the cell 110(3,1).

[0078] In this manner, cells 110(1,1), 110(2,1), and 110(3,1) are sequentially selected, and the first reset signal (Vrs1) is applied, causing the charge stored in the storage capacitor element 126 of each cell to be released to the control signal line 122_1. This phenomenon is schematically illustrated by arrows in FIG. 14B . As the voltage at the working electrode 102 of each cell decreases, the contact angle of the analyte increases. By sequentially resetting cells 110(1,1), 110(2,1), and 110(3,1) during the second frame period, the region in which the analyte spreads shifts from cell 110(1,1) to cell 110(3,1), effectively moving the analyte from cell 110(1,1) to cell 110(3,1).

[0079] Here, an action voltage is applied to move the sample from cell 110(1,1) to cell 110(3,1), and no action voltage is applied to other cells, but a first reset voltage (Vrs1) may also be applied to control signal lines 122_2 to 122_n to perform a reset operation on all cells 110.

[0080] Next, a second driving method of the electrowetting device 100 will be described with reference to Figures 11 and 14C. As shown in Figure 11, in the second driving method, the second frame period is divided into two sub-frame periods. In the first sub-frame period, an operation of removing carriers (electrons) trapped in the channel region of the thin-film transistor 118 (third operation described in Figure 9C) is performed, and in the second sub-frame period, an operation of drawing out the charge stored in the storage capacitance element 126 (second operation described in Figure 9B) is performed.

[0081] 11, in the first sub-frame period (first sub-frame period) of the second frame period, for each horizontal period, a voltage (Vg2) lower than the normal off voltage is applied from the selection signal lines 120_1 to 120_3 to the thin-film transistor 118. A second reset voltage Vrs2 is applied to the control signal line 122_1.

[0082] 14C , during the first horizontal period within the first subframe period, cell 110(1,1) is selected by the selection signal (Vg2) of selection signal line 120_1, and a first reset signal (Vrs1) is applied to cell 110(1,1) from control signal line 122_1. During the second horizontal period following the first horizontal period, cell 110(2,1) is selected by the selection signal (Vg2) of selection signal line 120_2, and a second reset signal (Vrs2) is applied to cell 110(2,1) from control signal line 122_1. During the third horizontal period following the second horizontal period, cell 110(3,1) is selected by the selection signal (Vg2) of selection signal line 120_3, and a second reset signal (Vrs2) is applied to cell 110(3,1) from control signal line 122_1.

[0083] 9C is performed during the first subframe period. That is, carriers (electrons) trapped in the channel region of the thin-film transistor 118 of the cell 110 are canceled, and the thin-film transistor 118 is returned to its initial state (a state in which no charge is trapped in the channel region). In this operation, the second reset signal (Vrs2) may also be applied to the control signal lines 122_2 to 122_n to reset the thin-film transistor of each cell.

[0084] In a second sub-frame period following the first sub-frame period, a second operation of extracting the charge stored in the storage capacitor element is performed, similar to the first driving method. Note that the operation of extracting the charge performed in the second sub-frame may be performed multiple times.

[0085] In this manner, by extracting carriers (electrons) trapped in the channel region of the thin film transistor 118, a shift in the threshold voltage of the thin film transistor 118 can be suppressed, thereby suppressing a decrease in response speed. As a result, the analyte can be moved smoothly within the active region 101. Note that FIG. 11 illustrates an example in which the operation of removing carriers (electrons) trapped in the channel region of the thin film transistor 118 and the operation of extracting the charge stored in the capacitance element 126 are performed in subframe periods. However, each operation may be performed in one frame period. That is, the operation of applying the working voltage Vop to the working electrode 102 may be performed in the first frame period, the operation of removing carriers (electrons) trapped in the channel region of the thin film transistor 118 may be performed in the second frame period following the first frame period, and the operation of extracting the charge stored in the capacitance element 126 may be performed in the third frame period following the second frame period.

[0086] A third driving method of the electrowetting device 100 will be described with reference to Fig. 12. Fig. 12 shows a timing chart for the third driving method. The third driving method differs from the first driving method in that the common voltage applied to the counter electrode 104 changes every horizontal period.

[0087] During the first frame period, the first operation described with reference to Fig. 9A and the fourth operation described with reference to Fig. 9D are performed. As shown in Fig. 12, during the first horizontal period of the first frame period, a selection signal (Vg1) is applied to the selection signal line 120_1, and an operating voltage Vop1 is applied to the cell 110(1,1) and the control signal line 122_1. At this time, the common voltage Vcom of the counter electrode 104 is set to the ground potential.

[0088] In the next horizontal period, a selection signal (Vg1) is applied to the selection signal line 120_2 to select the cell 110(2,1), and an operating voltage Vop2 is applied to the control signal line 122_1. At this time, the voltage of the counter electrode 104 changes to a common voltage Vcom_h. The common voltage Vcom_h is higher than the voltage of the operating electrode Vop2 (Vcom_h>Vop2).

[0089] Furthermore, in the next horizontal period, a selection signal (Vg1) is applied to the selection signal line 120_3 to select the cell 110(3,1), and an operating voltage Vop3 is applied to the control signal line 122_1. At this time, the common voltage Vcom of the counter electrode 104 is set to the ground potential. In this way, in the third driving method, the voltage level of the counter electrode 104 changes every horizontal period within one frame period. In this way, in the third driving method, the potential of the counter electrode 104 when an odd-numbered selection signal line is selected is different from the potential of the counter electrode 104 when an even-numbered selection signal line is selected.

[0090] The third driving method also allows the analyte to move from cell 110(1,1) to cell 110(3,1), as described with reference to Fig. 14A. Note that the state of the analyte changes as the common voltage of the counter electrode 104 fluctuates, as described with reference to Fig. 9D. In the second frame period following the first frame period, the second operation is performed, similar to the first driving method.

[0091] According to the third driving method, the common voltage of the counter electrode 104 is changed every horizontal period, thereby reversing the direction of the electric field acting on the specimen.

[0092] A fourth driving method of the electrowetting device 100 will be described with reference to Fig. 13. Fig. 13 shows a timing chart of the third driving method. The fourth driving method differs from the first driving method in that the common voltage applied to the counter electrode 104 changes every frame period.

[0093] 13, during the first frame period, the operating voltages Vop1 to Vop3 are sequentially selected for the cells 110(1,1), 110(2,1), and 110(3,1) by the selection signals on the selection signal lines 120_1 to 120_3. At this time, the common voltage Vcom of the counter electrode 104 is at ground potential. Therefore, the operation during the first frame period is the same as that of the first driving method.

[0094] During the second frame period following the first frame period, a second operation is performed to extract the charge stored in the storage capacitor element 126. During the second frame period, the cells 110(1,1), 110(2,1), and 110(3,1) are sequentially selected by the selection signals on the selection signal lines 120_1 to 120_3, and a first reset signal (Vrs1) is applied to each of the cells 110(1,1) to 110(3,1). During the second frame period, the potential of the counter electrode 104 changes to Vcom_h. The common voltage Vcom_h has a higher potential than the working voltages Vop1, Vop2, and Vop3 applied to the working electrodes.

[0095] When the first reset signal (Vrs1) is applied, the potential of the working electrode 102 decreases, but the potential of the counter electrode 104 changes to Vcom_h, thereby maintaining the potential difference between the working electrode 102 and the counter electrode 104.

[0096] According to the fourth driving method, the common voltage of the counter electrode 104 is changed every frame period, thereby reversing the direction of the electric field acting on the specimen.

[0097] 15 and 16, an example of the operation of the electrowetting device 100 based on the first to fourth driving methods described above will be shown.

[0098] 15, the first opening 114A is divided into multiple parts, which are used as a first inlet 114A_1, a second inlet 114A_2, and a third inlet 114A_3. The first inlet 114A_1 can be used as an inlet for injecting, for example, a specimen 200, the second inlet 114A_2 can be used as an inlet for injecting a reagent 202A, and the third inlet 114A_3 can be used as an inlet for injecting a reagent 202B.

[0099] As disclosed in this embodiment, the electrowetting device 100 is capable of moving the specimen 200 and the reagent 202 in the X direction, Y direction, and a direction intermediate between the X and Y directions shown in FIG. 15 by controlling the voltage of the working electrodes 102 (102A_1, 102A_2, 102B) arranged in the working area 101.

[0100] For example, the specimen 200 can be supplied to the first inlet 114A_1, the reagent 202A can be supplied to the second inlet 114A_2, the specimen 200 and the reagent 202A can be mixed and reacted in the cell S1 region via routes A1 and A2, and the reaction can be detected, observed, and measured.Alternatively, the specimen 200 can be supplied to the first inlet 114A_1, the reagent 202B can be supplied to the third inlet 114A_3, the specimen 200 and the reagent 202B can be mixed and reacted in the cell S2 region via routes B1 and B2, and the reaction can be detected, observed, and measured. Furthermore, by supplying the specimen 200 to the first inlet 114A_1, the reagent 202A to the second inlet 114A_2, and the reagent 202B to the third inlet 114A_3, the reaction when the specimen 200 and the reagent 202A and the reagent 202B are mixed in the cell S3 area can be detected, observed, and measured by route C1, route C2, and route C3.

[0101] Furthermore, by arranging routes C2 and C3 to merge midway along route C1 and observing the specimen 200 (and the mixed reagents 202A and 202B) flowing along route C1 on the spot, the reaction process between the specimen 200 and the reagents 202A and 202B can be evaluated.

[0102] The first opening 114A and the second opening 114B for injecting and discharging the specimen and the reagent can be disposed in any region of the action region 101. Fig. 16 shows an embodiment in which the positions of the second injection port 114A_2 and the third injection port 114A_3 are different from those of the configuration shown in Fig. 15. Specifically, the second injection port 114A_2 and the third injection port 114A_3 for supplying the reagents 202A and 202B may be disposed along different sides of the action region 101 relative to the first injection port 114A_1 for supplying the specimen 200.

[0103] 16 , the reaction between the sample 200 and the reagent 202A, the reaction between the sample 200 and the reagent 202B, and the reactions between the sample 200 and the reagents 202A and 202B can be simultaneously evaluated. That is, the sample 200 is supplied to the first inlet 114A_1, the reagent 202A is supplied to the second inlet 114A_2, and the sample 200 and the reagent 202A are mixed and reacted in the cell S1 region via routes A1 and A2, and the reaction can be detected, observed, and measured. Furthermore, the sample 200 is supplied to the first inlet 114A_1, the reagent 202B is supplied to the third inlet 114A_3, and the sample 200 and the reagent 202B are mixed and reacted in the cell S2 region via routes C1 and C2, and the reaction can be detected, observed, and measured. Furthermore, a specimen 200 is supplied to the first inlet 114A_1, a reagent 202A is supplied to the second inlet 114A_2, and a reagent 202B is supplied to the third inlet 114A_3, and the specimen 200 and the reagent 202A are mixed and reacted via routes B1 and B2, and further the reagent 202B is mixed and reacted via route B3, and the reactions when the respective reagents are mixed can be detected, observed, and measured.

[0104] 15 and 16 are merely examples, and there is no limit to the number of openings corresponding to first opening 114A and second opening 114B. By increasing the number of openings corresponding to first opening 114A and second opening 114B, it is possible to use more specimens and reagents and detect their reactions.

[0105] The various configurations of the electrowetting device exemplified as one embodiment of the present invention can be combined as appropriate as long as they are not mutually contradictory. Furthermore, electrowetting devices in which a person skilled in the art appropriately adds or deletes components or modifies the design, or adds or omits steps or modifies conditions, based on the electrowetting device disclosed in this specification and drawings, are also included in the scope of the present invention as long as they include the gist of the present invention.

[0106] Even if there are other effects and advantages different from those brought about by the aspects of the embodiments disclosed in this specification, those that are clear from the description in this specification or that can be easily predicted by a person skilled in the art are naturally understood to be brought about by the present invention.

[0107] 100: electrowetting device, 101: working area, 102: working electrode, 104: counter electrode, 105: auxiliary electrode, 106A: first driving circuit, 106B: second driving circuit, 107: power supply terminal, 108: signal terminal, 110: cell, 112: counter electrode, 114A: first opening, 114B: second opening, 116A: first insulating layer, 116B: second insulating layer, 118, 118A-1, 118A-2, 118B: thin film transistor, 1182: Semiconductor layer, 1184: gate insulating layer, 1186: gate electrode, 120: selection signal line, 122: control signal line, 124: common signal line, 126: storage capacitor element, 130: base insulating layer, 132: interlayer insulating layer, 134: planarization layer, 136: first input / output electrode, 138: second input / output electrode, 150: array substrate, 152: opposing substrate, 154: sealing material, 156: spacer, 200: specimen, 202: reagent, EV1: power supply, EV2: power supply, SW1: switch

Claims

1. A method for driving an electrowetting device, wherein the electrowetting device comprises an array substrate having working electrodes arranged in m rows and n columns (m and n are natural numbers greater than 4), thin film transistors connected to each of the working electrodes, storage capacitor elements connected to each of the working electrodes, selection signal lines and control signal lines arranged in correspondence with the arrangement of the working electrodes, and a counter substrate having counter electrodes, wherein the array substrate and the counter substrate are arranged opposite to each other and spaced apart, and the electrowetting device has a function of controlling the flow of a sample in a space sandwiched between the working electrodes and the counter electrode, and the driving method comprises the steps of: during a first frame period in which the working electrodes arranged in m rows and n columns are sequentially scanned, first selection signals are sequentially applied to the selection signal lines in the first row to the selection signal lines in the mth row, control signals are applied to the control signal lines in the first column to the control signal lines in the nth column in synchronization with the driving of the selection signal lines, and a first operation is performed in which the control signals are applied to the working electrodes via the thin film transistors turned on by the first selection signals to charge the storage capacitor elements, a second operation of discharging the charge stored in the capacitance element to the control signal line via a thin film transistor turned on by the second selection signal; 2. A method for driving an electrowetting device as described in claim 1, wherein the second frame period includes a first sub-frame period and a second sub-frame period, and during the first sub-frame period, during which the arranged working electrodes are sequentially scanned, a third selection signal having a potential lower than the potential at which the thin film transistor is turned off is sequentially applied to the selection signal line in the first row to the selection signal line in the mth row, a second reset signal having a potential lower than the control signal is applied to the control signal line in the first column to the control signal line in the nth column in synchronization with the driving of the selection signal line, and a third operation is performed to release charges trapped in the channel regions of the thin film transistors to the control signal lines, and during the second sub-frame period, the second operation is performed.

3. The method for driving an electrowetting device according to claim 2, wherein the third operation is repeated multiple times.

4. The method for driving an electrowetting device according to claim 1, wherein the potential of the counter electrode is maintained at a constant potential during the first operation and the second operation.

5. A method for driving an electrowetting device as described in claim 1, wherein in the first operation and the second operation, a first selection signal is applied sequentially to the selection signal line in the first row to the selection signal line in the mth row, and when an odd-numbered selection signal line is selected, the potential of the opposing electrode is set to a first potential, and when an even-numbered selection signal line is selected, the potential of the opposing electrode is set to a second potential, and the second potential is higher than the first potential.

6. A method for driving an electrowetting device according to claim 1, further comprising a third frame period following the second frame period and a fourth frame period following the third frame period, wherein the first operation is performed during the third frame period and the second operation is performed during the fourth frame period, the potential of the opposing electrode is set to a first potential during the first frame period and the second frame period, the potential of the opposing electrode is set to a second potential during the third frame period and the fourth frame period, and the second potential is made higher than the first potential.

7. A method for driving an electrowetting device as described in claim 1, wherein, in the first operation, when a first selection signal is sequentially applied to the selection signal line in the first row to the selection signal line in the mth row, the potential of the control signal is sequentially increased in response to the first selection signal being sequentially applied to the selection signal lines.

8. A method for driving an electrowetting device as described in claim 1, wherein the opposing substrate has a first opening through which the sample is supplied, the arranged working electrodes of the array substrate include a first working electrode that at least partially overlaps with the first opening and a second working electrode that overlaps with the opposing electrode, and in the first operation, the voltage level of the first selection signal applied to the first working electrode is higher than the voltage level of the first selection signal applied to the working electrodes other than the first working electrode.

9. The method for driving an electrowetting device according to claim 1, wherein the thin film transistor is an n-channel thin film transistor.

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