# US 2014/0190830 A1 · Microfluidic feedback using impedance detection

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- Number: US 2014/0190830 A1
- Document ID: US20140190830A1
- Status: Published application
- Kind: A1
- Application number: 14/116,553
- Filed: 2012-05-08
- Published: 2014-07-10
- Earliest claimed: 2011-05-09
- Assignees: Advanced Liquid Logic, Inc.
- Inventors: Ryan Sturmer; Vijay Srinivasan; Arjun Sudarsan
- Web page: https://patentgrep.com/patent/US20140190830A1

## CPC

- B01L 3/50273: {characterised by the means or forces applied to move the fluids}
- B01L 3/502792: {for moving individual droplets on a plate, e.g. by locally altering surface tension}
- G01N 27/048: {for determining moisture content of the material}
- B01L 2200/0621: Control of the sequence of chambers filled or emptied
- B01L 2200/10: Integrating sample preparation and analysis in single entity, e.g. lab-on-a-chip concept
- B01L 2200/14: Process control and prevention of errors
- B01L 2200/16: Reagents, handling or storing thereof
- B01L 2300/0645: Electrodes
- B01L 2300/0816: Cards, e.g. flat sample carriers usually with flow in two horizontal directions
- B01L 2300/0829: Multi-well plates; Microtitration plates
- B01L 2300/087: Multiple sequential chambers
- B01L 2300/089: Virtual walls for guiding liquids
- B01L 2400/0427: Electrowetting
- G01R 27/16: Measuring impedance of element or network through which a current is passing from another source, e.g. cable, power line
- B01L: CHEMICAL OR PHYSICAL LABORATORY APPARATUS FOR GENERAL USE
- G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q)
- G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12)

## Abstract

Methods comprising measuring the impedance of the electrode produced by the excitation signal, wherein the impedance indicates presence of liquid at the electrode are disclosed. Computer readable mediums storing processor executable instructions for performing the method, and systems are also disclosed. The systems comprise a processor, memory and code stored in the memory that when executed cause the processor at least to: receive an output voltage signal, superimpose an excitation signal onto the output voltage signal to produce a superimposed signal, connect the superimposed signal to an electrode in a droplet actuator, suppress the output voltage signal, when detecting an impedance of the electrode, and measure the impedance of the electrode produced by the excitation signal, wherein the impedance indicates presence of liquid at the electrode.

## Claims

### Claim 1

A method, comprising:
(a) receiving an output voltage signal produced by a power supply;
(b) superimposing an excitation signal onto the output voltage signal to produce a superimposed signal;
(c) connecting the superimposed signal to an electrode in a droplet actuator;
(d) suppressing the output voltage signal when detecting an impedance of the electrode; and
(e) measuring the impedance of the electrode produced by the excitation signal, wherein the impedance indicates presence of liquid at the electrode.

### Claim 2 (depends on 1)

The method of claim 1, wherein superimposing the excitation signal comprises adding the excitation signal to the output voltage signal.

### Claim 3 (depends on 1)

The method of claim 1, wherein suppressing the output voltage signal comprises stopping the output voltage signal.

### Claim 4 (depends on 1)

The method of claim 1, wherein suppressing the output voltage signal comprises disabling a switching action of the power supply.

### Claim 5 (depends on 1)

The method of claim 1, wherein suppressing the output voltage signal comprises disabling the power supply.

### Claim 6 (depends on 1)

The method of claim 1, further comprising receiving a suppression signal to suppress the output voltage signal from the power supply.

### Claim 7 (depends on 1)

The method of claim 1, further comprising determining a saturation of the impedance.

### Claim 8 (depends on 1)

The method of claim 1, further comprising:
(a) injecting the liquid into the droplet actuator; and
(b) stopping injection when the impedance indicates the liquid has flowed to the electrode.

### Claim 9 (depends on 1)

The method of claim 1, further comprising:
(a) injecting the liquid into a gap in the droplet actuator; and
(b) stopping injection when the impedance indicates the liquid has flowed to the electrode.

### Claim 10 (depends on 1)

The method of claim 1, further comprising:
(a) injecting the liquid into a reservoir in the droplet actuator; and
(b) stopping injection when the impedance indicates the liquid has flowed to the electrode.

### Claim 11 (depends on 1)

The method of claim 1, further comprising:
(a) injecting the liquid to fill a reservoir in the droplet actuator; and
(b) stopping injection when the impedance indicates the liquid has flowed from the reservoir to the electrode.

### Claim 12 (depends on 1)

The method of claim 1, further comprising:
(a) establishing a fluid path in the droplet actuator from an input port to a reservoir to the electrode;
(b) injecting the liquid through the input port to fill the reservoir; and
(c) stopping injection when the impedance indicates the liquid has flowed to the electrode.

### Claim 13 (depends on 1)

The method of claim 1, further comprising:
(a) arranging an input port outside a boundary of a reservoir in the droplet actuator;
(b) forming a fluid path from the input port to the reservoir to the electrode;
(c) injecting the liquid through the input port to fill the reservoir; and
(d) stopping injection when the impedance indicates the liquid has flowed to the electrode.

### Claim 14

A method, comprising:
(a) generating an output voltage by a power supply;
(b) storing charge produced by the output voltage;
(c) superimposing an excitation signal onto the output voltage to produce a superimposed signal;
(d) connecting the superimposed signal to an electrode in a droplet actuator;
(e) suppressing the output voltage from the power supply when detecting an impedance at the electrode;
(f) supplying the charge to the droplet actuator to activate the electrode during the impedance; and
(g) measuring the impedance produced by the excitation signal while the output voltage is suppressed, wherein the impedance indicates presence of liquid at the electrode.

### Claim 15 (depends on 14)

The method of claim 14, wherein superimposing the excitation signal comprises adding the excitation signal to the output voltage.

### Claim 16 (depends on 14)

The method of claim 14, wherein suppressing the output voltage comprises at least one of stopping the output voltage generated by the power supply, disabling a switching action of the power supply, and disabling the power supply during the impedance measurement.

### Claim 17 (depends on 14)

The method of claim 14, further comprising activating a suppression signal to suppress the output voltage generated by the power supply.

### Claim 18 (depends on 17)

The method of claim 17, further comprising deactivating the suppression signal to resume the output voltage generated by the power supply.

### Claim 19 (depends on 14)

The method of claim 14, further comprising charging a capacitor to store the charge.

### Claim 20 (depends on 14)

The method of claim 14, further comprising determining the impedance is saturated.

### Claim 21 (depends on 14)

The method of claim 14, further comprising:
(a) injecting the liquid into the droplet actuator; and
(b) stopping injection when the impedance indicates the liquid has flowed to the electrode.

### Claim 22 (depends on 14)

The method of claim 14, further comprising:
(a) injecting the liquid into a gap in the droplet actuator; and
(b) stopping injection into the gap when the impedance indicates the liquid has flowed to the electrode.

### Claim 23 (depends on 14)

The method of claim 14, further comprising:
(a) injecting the liquid into a reservoir in the droplet actuator; and
(b) stopping injection into the reservoir when the impedance indicates the liquid has flowed to the electrode.

### Claim 24 (depends on 14)

The method of claim 14, further comprising:
(a) establishing a fluid path in the droplet actuator from an input port to a reservoir to the electrode;
(b) injecting the liquid through the input port to fill the reservoir; and
(c) stopping injection when the impedance indicates the liquid has flowed to the electrode.

### Claim 25 (depends on 1)

The method of claim 1, further comprising:
(a) arranging an input port outside a boundary of a reservoir in the droplet actuator;
(b) forming a fluid path from the input port to the reservoir to the electrode;
(c) injecting the liquid through the input port to fill the reservoir; and
(d) stopping injection when the impedance indicates the liquid has flowed to the electrode.

### Claim 26

A system, comprising:
(a) a processor;
(b) memory; and
(c) code stored in the memory that when executed cause the processor at least to:
(i) receive an output voltage signal;
(ii) superimpose an excitation signal onto the output voltage signal to produce a superimposed signal;
(iii) connect the superimposed signal to an electrode in a droplet actuator;
(d) suppress the output voltage signal when detecting an impedance of the electrode; and
(e) measure the impedance of the electrode produced by the excitation signal, wherein the impedance indicates presence of liquid at the electrode.

### Claim 27 (depends on 26)

The system of claim 26, wherein the code further causes the processor to at least one of add the excitation signal to the output voltage signal, stop the output voltage signal, disable a switching action of the power supply, and disable the power supply.

### Claim 28 (depends on 26)

The system of claim 26, wherein the code further causes the processor to determine a saturation of the impedance.

### Claim 29 (depends on 26)

The system of claim 26, wherein the code further causes the processor to:
(a) cause injection of the liquid into the droplet actuator; and
(b) stop the injection when the impedance indicates the liquid has flowed to the electrode.

### Claim 30 (depends on 26)

The system of claim 26, wherein the code further causes the processor to:
(a) cause injection of the liquid into a gap in the droplet actuator; and
(b) stop the injection when the impedance indicates the liquid has flowed to the electrode.

### Claim 31 (depends on 26)

The system of claim 26, wherein the code further causes the processor to:
(a) cause injection of the liquid into a reservoir in the droplet actuator; and
(b) stop the injection when the impedance indicates the liquid has flowed to the electrode.

### Claim 32 (depends on 26)

The system of claim 26, wherein the code further causes the processor to:
(a) cause the injection of the liquid to fill a reservoir in the droplet actuator; and
(b) stop the injection when the impedance indicates the liquid has flowed from the reservoir to the electrode.

### Claim 33 (depends on 26)

The system of claim 26, wherein the code further causes the processor to:
(a) cause injection of the liquid into an input port of a reservoir in the droplet actuator; and
(b) stop the injection when the impedance indicates the liquid has flowed along a fluid path from the reservoir to the electrode.

### Claim 34

A computer readable medium storing processor executable instructions for performing a method, the method comprising:
(a) generating an output voltage by a power supply;
(b) storing charge produced by the output voltage;
(c) superimposing an excitation signal onto the output voltage to produce a superimposed signal;
(d) connecting the superimposed signal to an electrode in a droplet actuator;
(e) suppressing the output voltage from the power supply when detecting an impedance at the electrode;
(f) supplying the charge to the droplet actuator to activate the electrode during the impedance; and
(g) measuring the impedance produced by the excitation signal while the output voltage is suppressed, wherein the impedance indicates presence of liquid at the electrode.

### Claim 35 (depends on 34)

The computer readable medium of claim 34, further comprising instructions for at least one of adding the excitation signal to the output voltage, stopping the output voltage generated by the power supply, disabling a switching action of the power supply, and disabling the power supply during the impedance measurement.

### Claim 36 (depends on 34)

The computer readable medium of claim 34, further comprising instructions for activating a suppression signal to suppress the output voltage generated by the power supply.

### Claim 37 (depends on 36)

The computer readable medium of claim 36, further comprising instructions for deactivating the suppression signal to resume the output voltage generated by the power supply.

### Claim 38 (depends on 34)

The computer readable medium of claim 34, further comprising instructions for charging a capacitor to store the charge.

### Claim 39 (depends on 34)

The computer readable medium of claim 34, further comprising instructions for determining the impedance is saturated.

### Claim 40 (depends on 34)

The computer readable medium of claim 34, further comprising instructions for:
(a) injecting the liquid into the droplet actuator; and
(b) stopping injection when the impedance indicates the liquid has flowed to the electrode.

### Claim 41 (depends on 34)

The computer readable medium of claim 34, further comprising instructions for:
(a) injecting the liquid into a gap in the droplet actuator; and
(b) stopping injection into the gap when the impedance indicates the liquid has flowed to the electrode.

### Claim 42 (depends on 34)

The computer readable medium of claim 34, further comprising instructions for:
(a) injecting the liquid into a reservoir in the droplet actuator; and
(b) stopping injection into the reservoir when the impedance indicates the liquid has flowed to the electrode.

### Claim 43 (depends on 34)

The computer readable medium of claim 34, further comprising instructions for:
(a) injecting the liquid through an input port to fill a reservoir in the droplet actuator;
(b) stopping injection when the impedance indicates the liquid has flowed to the electrode.

### Claim 44 (depends on 34)

The computer readable medium of claim 34, further comprising instructions for:
(a) injecting the liquid into an input port of a reservoir in the droplet actuator; and
(b) stopping injection when the impedance indicates the liquid has flowed along a fluid path from the reservoir to the electrode.
(c) A method, comprisingreceiving an output voltage signal produced by a power supply;
(d) superimposing an excitation signal onto the output voltage signal to produce a superimposed signal;
(e) connecting the superimposed signal to an electrode in a droplet actuator;
(f) suppressing the output voltage signal when detecting an impedance of the electrode; and
(g) measuring the impedance of the electrode produced by the excitation signal, wherein the impedance indicates presence of liquid at the electrode.