# US 2014/0194303 A1 · Active chemically-sensitive sensors with reset switch

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- Number: US 2014/0194303 A1
- Document ID: US20140194303A1
- Status: Published application
- Kind: A1
- Application number: 14/206,473
- Filed: 2014-03-12
- Published: 2014-07-10
- Earliest claimed: 2009-05-29
- Assignees: Life Technologies Corporation
- Applicants: Life Technologies Corporation
- Inventors: Mark J. MILGREW
- Web page: https://patentgrep.com/patent/US20140194303A1

## CPC

- G01N 27/4145: {specially adapted for biomolecules, e.g. gate electrode with immobilised receptors}
- C12Q 1/6869: Methods for sequencing
- C12Q 1/6874: involving nucleic acid arrays, e.g. sequencing by hybridisation
- G01N 27/27: Association of two or more measuring systems or cells, each measuring a different parameter, where the measurement results may be either used independently, the systems or cells being physically associated, or combined to produce a value for a further parameter
- G01N 27/414: Ion-sensitive or chemical field-effect transistors, i.e. ISFETS or CHEMFETS
- G01N 27/4148: {Integrated circuits therefor, e.g. fabricated by CMOS processing}
- G01N 33/54373: {involving physiochemical end-point determination, e.g. wave-guides, FETS, gratings}
- Y10T 29/49002: Electrical device making
- 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)
- C12Q: MEASURING OR TESTING PROCESSES INVOLVING ENZYMES, NUCLEIC ACIDS OR MICROORGANISMS (immunoassay G01N33/53); COMPOSITIONS OR TEST PAPERS THEREFOR; PROCESSES OF PREPARING SUCH COMPOSITIONS; CONDITION-RESPONSIVE CONTROL IN MICROBIOLOGICAL OR ENZYMOLOGICAL PROCESSES
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

Methods and apparatus relating to FET arrays for monitoring chemical and/or biological reactions such as nucleic acid sequencing-by-synthesis reactions. Some methods provided herein relate to improving signal (and also signal to noise ratio) from released hydrogen ions during nucleic acid sequencing reactions.

## Claims

### Claim 1

A method of operating an apparatus comprising an array of chemically sensitive sensors comprising chemically-sensitive field effect transistors (chemFETs) and amplifiers arranged in rows and columns, the method comprising:
inducing a flow of current in the chemFETs in a plurality of the sensors;
sequentially connecting each of the sensors in the plurality to an amplifier node;
amplifying a voltage on a conduction terminal of a chemFET in a particular sensor in the plurality coupled to the amplifier node using an amplifier;
coupling the amplified voltage to an output conductor in response to a select signal; and
resetting the amplifier node between the amplifying of the voltage for each of the sensors in the plurality.

### Claim 2 (depends on 1)

The method of claim 1, wherein the resetting includes using a pull up transistor coupled to the amplifier node, and responsive to a reset signal.

### Claim 3 (depends on 1)

The method of claim 1, wherein the inducing includes using respective transistors coupled to the chemFET in the sensors biased in a current limiting mode.

### Claim 4 (depends on 3)

The method of claim 3, wherein the inducing includes applying a sub-threshold voltage to the respective transistors in the sensor.

### Claim 5 (depends on 3)

The method of claim 3, wherein the inducing includes biasing the respective transistors in a reverse-bias diode mode.

### Claim 6 (depends on 3)

The method of claim 3, wherein the amplifying includes connecting the amplifier node to a gate of a first transistor in the amplifier, and turning on a second transistor coupled between a conduction terminal of the first transistor and the output conductor, in response to a row select signal.

### Claim 7 (depends on 1)

The method of claim 1, wherein the connecting each of the sensors includes coupling a conduction terminal of the chemFET via a switch transistor to the amplifier node, and the resetting includes using a pull up transistor coupled to the amplifier node, and responsive to a reset signal.

### Claim 8 (depends on 1)

The method of claim 1, including applying a chemical sample to chemical sample wells coupled to the plurality of sensors.

### Claim 9 (depends on 1)

The method of claim 1, wherein the chemFET includes a floating gate and a passivation layer, and a sensor surface on the passivation layer over the floating gate.

### Claim 10 (depends on 9)

The method of claim 9, wherein a voltage on the output indicates an ion-concentration of an analyte solution coupled to the floating gate via the passivation layer.

### Claim 11 (depends on 1)

The method of claim 1, the sensors in the array including chemical sample wells, and including applying an analyte solution to the chemical sample wells, and coupling a reference electrode to the analyte solution.