# US 2014/0151232 A1 · Active matrix electrowetting-on-dielectric device

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- Number: US 2014/0151232 A1
- Document ID: US20140151232A1
- Status: Published application
- Kind: A1
- Application number: 13/693,250
- Filed: 2012-12-04
- Published: 2014-06-05
- Earliest claimed: 2012-12-04
- Assignees: Sharp Kabushiki Kaisha
- Applicants: Sharp Kabushiki Kaisha
- Inventors: Benjamin James Hadwen
- Web page: https://patentgrep.com/patent/US20140151232A1

## CPC

- C25B 9/65: Means for supplying current; Electrode connections; Electric inter-cell connections
- B01L 3/502792: {for moving individual droplets on a plate, e.g. by locally altering surface tension}
- G02B 26/005: {based on electrowetting}
- G09G 3/348: {based on the deformation of a fluid drop, e.g. electrowetting}
- B01L 2300/0816: Cards, e.g. flat sample carriers usually with flow in two horizontal directions
- B01L 2300/0887: Laminated structure
- B01L 2400/0427: Electrowetting
- C25B: ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR (anodic or cathodic protection C23F13/00; single-crystal growth C30B)
- B01L: CHEMICAL OR PHYSICAL LABORATORY APPARATUS FOR GENERAL USE
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G09G: ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION (arrangements for transferring data between digital computers and displays G06F3/14; static indicating arrangements comprising an association of a number of separate sources or light control cells G09F9/00; static indicating arrangements comprising integral associations of a number of light sources H01J, H01K, H10H, H05B33/12; scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission, details thereof H04N1/00)

## Abstract

An active matrix electrowetting on dielectric (AM-EWOD) device includes a plurality of array elements configured to manipulate one or more droplets of fluid on an array, each of the array elements including a corresponding array element circuit. Each array element circuit includes write circuitry configured to write data to the corresponding array element for controlling the manipulation of the droplets of fluid, and sensor circuitry configured to sense an impedance present at the corresponding array element. The sensor circuitry is configured to operate in one of a normal mode of sensitivity for detection of a droplet, or a high mode of sensitivity to detect an electric property of an array element hydrophobic surface. The sensor circuitry includes an active element, such as an active capacitor or active transistor, and a capacitance across the active element is different in the normal sensitivity mode as compared to the high sensitivity mode.

## Claims

### Claim 1

An active matrix electrowetting on dielectric (AM-EWOD) device, comprising:
a plurality of array elements configured to manipulate one or more droplets of fluid on an array, each of the array elements including a corresponding array element circuit,
wherein each array element circuit includes:
write circuitry configured to write data to the corresponding array element for controlling the manipulation of the one or more droplets of fluid; and
sensor circuitry configured to sense an impedance present at the corresponding array element, and the sensor circuitry is configured to operate in one of at least a first mode or a second mode, the different modes each having different sensitivity ranges.

### Claim 2 (depends on 1)

The AM-EWOD device of claim 1, wherein the sensor circuitry includes an active element, and a capacitance across the active element is different in the first mode of sensitivity as compared to the second mode of sensitivity.

### Claim 3 (depends on 2)

The AM-EWOD device of claim 2, further comprising a row select line that inputs a voltage to the active element, wherein the mode of the sensor circuitry is set based on a voltage level of the row select line.

### Claim 4 (depends on 3)

The AM-EWOD device of claim 3, wherein the capacitance across the active element is switched as between the first mode and the second mode by switching the voltage level of the row select line.

### Claim 5 (depends on 4)

The AM-EWOD device of claim 4, wherein the capacitance across the active element is determined based on a voltage difference between the voltage level of the row select line and a voltage level of an electro-wetting drive electrode of the array element.

### Claim 6 (depends on 2)

The AM-EWOD device of claim 2, wherein:
the active element is an active capacitor;
in the first mode of sensitivity the active capacitor has a first capacitance and in the second mode of sensitivity the active capacitor has a second capacitance; and
the first capacitance is greater than the second capacitance.

### Claim 7 (depends on 6)

The AM-EWOD device of claim 6, wherein the second capacitance is ten percent of the first capacitance or less.

### Claim 8 (depends on 2)

The AM-EWOD device of claim 2, wherein:
the active element is a transistor;
in the first mode of sensitivity the transistor has a first capacitance between gate and at least one of source and drain terminals, and in the second mode of sensitivity the transistor has a second capacitance between the gate and at least one of source and drain terminals; and
the first capacitance is greater than the second capacitance.

### Claim 9 (depends on 1)

The AM-EWOD device of claim 1, wherein the first mode of sensitivity corresponds to a low range of sensitivity, and the second mode of sensitivity corresponds to a high range of sensitivity relative to the first mode of sensitivity.

### Claim 10 (depends on 9)

The AM-EWOD device of claim 9, wherein the at least first mode and second mode further comprises a third mode, wherein the third mode corresponds to a mode of sensitivity intermediate between the first and second modes of sensitivity.

### Claim 11 (depends on 1)

The AM-EWOD device of claim 1, further comprising a hydrophobic surface.

### Claim 12 (depends on 11)

The AM-EWOD device of claim 11, wherein in the first mode of sensitivity, the sensor circuitry is configured to sense a liquid droplet on the hydrophobic surface.

### Claim 13 (depends on 11)

The AM-EWOD device of claim 11, wherein in the second mode of sensitivity, the sensor circuitry is configured to detect a change in an electrical property of the hydrophobic surface.

### Claim 14 (depends on 12)

The AM-EWOD device of claim 12, further comprising a receptor for, in the second mode of sensitivity, binding molecules detected on the hydrophobic surface.

### Claim 15 (depends on 1)

The AM-EWOD device of claim 1, further comprising a first substrate containing the plurality of array elements.

### Claim 16 (depends on 1)

The AM-EWOD device of claim 1, wherein the plurality of array elements are arranged in an array of a plurality of rows and columns.

### Claim 17

A method of operating an active matrix electrowetting on dielectric (AM-EWOD) device, wherein the AM-EWOD device includes a plurality of array elements configured to manipulate one or more droplets of fluid on an array, the method comprising the steps of:
applying a first voltage to a row select line of an array element;
setting sensor circuitry of the array element to operate in a first mode of sensitivity based on the first voltage;
applying a second voltage to the row select line; and
setting the sensor circuitry of the array element to operate in a second mode of sensitivity based on the second voltage;
wherein the first and second modes of sensitivity have differing sensitivity ranges.

### Claim 18 (depends on 17)

The method of operating an AM-EWOD device of claim 17, wherein the first mode of sensitivity has a low sensitivity range and the second mode of sensitivity has a high sensitivity range relative to the first mode of sensitivity.

### Claim 19 (depends on 17)

The method of operating an AM-EWOD device of claim 17, further comprising:
in the first mode of sensitivity, detecting with the sensor circuitry a liquid droplet on a hydrophobic surface of an array element from among the plurality of array elements; and
in the second mode of sensitivity, detecting with the sensor circuitry a change in an electrical property of the hydrophobic surface of the array element.

### Claim 20 (depends on 19)

The method of operating an AM-EWOD device of claim 19, further comprising performing a manipulation operation based on the detections, wherein the manipulation operation comprises at least one of moving a droplet containing a cleaning fluid over the array element, binding detected molecules to receptors on the hydrophobic surface, coalesce a plurality of droplets on the array element to initiate a reaction, and analyze biological or chemical species adsorbed on the hydrophobic surface of the array element.