# US 9,435,788 B2 · System and method for analysing and measuring ammonia levels in a sample

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- Number: US 9,435,788 B2
- Document ID: US9435788B2
- Status: Granted
- Kind: B2
- Application number: 14/434,257
- Filed: 2013-10-09
- Published: 2015-09-17
- Granted: 2016-09-06
- Earliest claimed: 2012-10-09
- Assignees: Dublin City University
- Applicants: Dublin City University
- Inventors: Anthony Killard; Troy Hibbard; Karl Crowley
- Web page: https://patentgrep.com/patent/US9435788B2

## CPC

- G01N 33/497: of gaseous biological material, e.g. breath
- A61B 5/082: {Evaluation by breath analysis, e.g. determination of the chemical composition of exhaled breath (A61B5/083, A61B5/091 take precedence)}
- A61B 5/097: Devices for facilitating collection of breath or for directing breath into or through measuring devices
- G01N 27/021: {before and after chemical transformation of the material}
- G01N 33/4975: {other than oxygen, carbon dioxide or alcohol, e.g. organic vapours}
- Y10T 436/175383: Ammonia
- Y10T 436/255: including use of a solid sorbent, semipermeable membrane, or liquid extraction
- Y10T 436/25875: Gaseous sample or with change of physical state
- 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)
- A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D)
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

A system for sensing and measuring ammonia in a breath sample is described. The system includes a sampling means for capturing and directing a breath sample from a subject to an ammonia sensor, the ammonia sensor including a conducting polymer polyaniline sensor. The sampling means includes a breath sample capture chamber, the chamber having an inlet and outlet, the inlet having a first valve through which a breath is exhaled into the sample capture chamber, the outlet having a second valve through which breath surplus to the volume of the chamber is expelled, to provide capture of a breath sample of predefined volume.

## Claims

### Claim 1

A system for sensing and measuring ammonia in a breath sample, comprising:
an ammonia sensor, and
a sampling means for capturing and directing a breath sample from a subject to the ammonia sensor,
wherein:
the ammonia sensor comprises a conducting polymer polyaniline sensor, and
the sampling means comprises a capture chamber, the capture chamber having an inlet and outlet and a capture chamber volume defined by the dimensions of the capture chamber, wherein the capture chamber provides a breath sample of predefined volume from the capture chamber across the ammonia sensor,
the inlet having a first valve through which a breath is exhaled into the capture chamber, and
the outlet having a second valve through which breath surplus to the volume of the capture chamber is expelled.

### Claim 2 (depends on 1)

The system of claim 1, wherein the sampling means comprises directing means for directing the breath sample of predefined volume from the capture chamber across the ammonia sensor.

### Claim 3 (depends on 2)

The system of claim 2, wherein the directing means is operable to direct the breath sample of predefined volume across the sensor at a predefined volume flow rate.

### Claim 4 (depends on 1)

The system of claim 1, wherein the sensor has a response to the breath sample, and wherein the response from the sensor is proportional to a concentration of ammonia in the breath sample.

### Claim 5 (depends on 1)

The system of claim 1, comprising measuring means for measuring change in conductivity or impedance of the sensor on exposure to ammonia in the breath sample, the change in conductivity or impedance being indicative of ammonia concentration in the breath sample.

### Claim 6 (depends on 1)

The system of claim 1, the sensor comprising one of:
a polyaniline nanoparticle based material;
a polyaniline composite;
a PANI-silver composite; or
a PANI-carbon nanotube composite.

### Claim 7 (depends on 1)

The system of claim 1, wherein the sensor is integrated with a heater configured in operation to control response of the sensor to ammonia.

### Claim 8 (depends on 1)

The system of claim 1, the sensor comprising a membrane layer applied to the sensor for protecting the sensor from humidity in the breath sample while allowing detection of ammonia.

### Claim 9 (depends on 8)

The system of claim 8, wherein the membrane layer is in the form of a pre-fabricated membrane.

### Claim 10 (depends on 8)

The system of claim 8, wherein the membrane layer is a printable membrane layer.

### Claim 11 (depends on 8)

The system of claim 8, wherein the membrane layer is of a membrane material impermeable to water molecules.

### Claim 12 (depends on 8)

The system of claim 8, wherein the membrane layer is of polytetrafluoroethene, or other polymer material permeable to ammonia gas and having water repellent properties.

### Claim 13 (depends on 8)

The system of claim 8, wherein the membrane layer comprises a solubilised polymer or a suspension of micro- or nanoparticles.

### Claim 14 (depends on 13)

The system of claim 13, wherein the particles are dispersible in aqueous solvents and annealeable to form a continuous film upon application of heat, and/or light energy and/or chemical treatment.

### Claim 15 (depends on 1)

The system of claim 1, the sensor comprising a membrane layer applied to the sensor for controlling a response of the sensor to humidity in the breath sample.

### Claim 16 (depends on 1)

The system of claim 1, wherein the volume of the capture chamber is of the order 0.25 to 0.5 of an average human non-forced exhalation of breath.

### Claim 17 (depends on 1)

The system of claim 1, the sampling means comprising displacement means configured to provide displacement of any air or other sample present in the capture chamber prior to capture of a breath sample.

### Claim 18 (depends on 1)

The system of claim 1, the sampling means including a sampling interface for interfacing with the subject whose breath is to be sampled, the sampling interface comprising a mask or spirette.

### Claim 19 (depends on 18)

The system of claim 18, wherein a bacterial or viral filter is provided located between the interface and sample capture chamber.

### Claim 20 (depends on 1)

A point of care testing device comprising a system for sensing and measuring ammonia in a breath sample as claimed in claim 1, wherein the device is configured to provide a real time measurement of the concentration of ammonia in a breath sample.

### Claim 21 (depends on 1)

A point of care testing device comprising a system for sensing and measuring ammonia in a breath sample as claimed in claim 1, wherein the device is configured to provide a continuous monitoring of ammonia in a breath sample over a period of time.

### Claim 22

A method of sensing ammonia in a breath sample comprising:
capturing a breath sample of predefined volume in a capture chamber having an inlet and an outlet, wherein dimensions of the capture chamber define the predefined volume, the inlet includes a first valve through which a breath is exhaled into the capture chamber, and the outlet includes a second valve through which breath surplus to the volume of the capture chamber is expelled;
directing the breath sample of predefined volume across an ammonia sensor comprising a conducting polymer polyaniline sensor; and
measuring a response of the sensor to ammonia in the breath sample.

### Claim 23 (depends on 22)

A method as claimed in claim 22 wherein measuring the response of the sensor comprises measuring a change in conductivity or impedance of the sensor on exposure to ammonia in the breath sample, the change in conductivity or impedance being proportional to an ammonia concentration in the breath sample.

### Claim 24 (depends on 22)

A method as claimed in claim 22 wherein the directing the breath sample across the sensor comprises: directing the breath sample across the sensor at a defined and/or at a measurable volume flow rate.

### Claim 25

A system for sensing and measuring ammonia in a breath sample, the system comprising:
an ammonia sensor comprising a conducting polymer polyaniline sensor and a membrane layer applied to the sensor and configured to protect the sensor from humidity in breath sample while allowing detection of ammonia; and
a sampling means for capturing and directing a breath sample from a subject to the ammonia sensor, the sampling means comprising a capture chamber having an inlet and an outlet, wherein dimensions of the capture chamber define a predefined volume, the inlet includes a first valve through which a breath is exhaled into the capture chamber, and the outlet includes a second valve through which breath surplus to the volume of the capture chamber is expelled.