WO2014063169A1 - Détecteur d'ammoniac faisant appel à un capteur à film mince à base de polyaniline - Google Patents

Détecteur d'ammoniac faisant appel à un capteur à film mince à base de polyaniline Download PDF

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Publication number
WO2014063169A1
WO2014063169A1 PCT/US2013/069204 US2013069204W WO2014063169A1 WO 2014063169 A1 WO2014063169 A1 WO 2014063169A1 US 2013069204 W US2013069204 W US 2013069204W WO 2014063169 A1 WO2014063169 A1 WO 2014063169A1
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Prior art keywords
analyzer
breath
ammonia
sensor
resistivity
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PCT/US2013/069204
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English (en)
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Anastasia Rigas
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Anastasia Rigas
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Publication date
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Publication of WO2014063169A1 publication Critical patent/WO2014063169A1/fr

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    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/08—Detecting, measuring or recording devices for evaluating the respiratory organs
    • A61B5/097—Devices for facilitating collection of breath or for directing breath into or through measuring devices
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/08—Detecting, measuring or recording devices for evaluating the respiratory organs
    • A61B5/082—Evaluation by breath analysis, e.g. determination of the chemical composition of exhaled breath

Definitions

  • the present invention relates to an ammonia (NH3) gas sensor using a thin film sensing element.
  • Breath analyzers have been used to detect various gases in human breath. The presence of ammonia in breath can be used to diagnose, indicate various diseases and conditions.
  • the invention provides a breath analyzer which can be used to detect ammonia in breath.
  • One objective of the present invention is to provide a breath analyzer which uses a polyaniline (PANI) sensor.
  • PANI polyaniline
  • Such sensor can be used to measure ammonia in human breath in order to detect the presence or absence of H. Pylori in humans.
  • PANI which was first reported in 1862, is one of the most investigated and widely used conducting polymer due to its facile synthesis in acidic aqueous solutions, environmental stability, inexpensive monomer, good processability and solubility in common organic solvents which allows it to be blended with other polymers.
  • PANI exhibits three different oxidation states: leucoemeraldine (LEB, fully reduced), emeraldine (EB, half-oxidized) and pemigiline (PNB, fully oxidized).
  • LEB leucoemeraldine
  • EB emeraldine
  • PNB pemigiline
  • emeraldine salt the protonated form of EB, is the only conducting form and is usually obtained by protonation of the basic amine and imine sites in EB with strong acids. This process is reversible thus imparting pH sensitivity to PANI.
  • the pH and ionic sensitivity can be tuned by doping PANI with mobile or immobile counter ions.
  • Figure 1 shows the acid - base transition of polyaniline which renders polyaniline pH sensitive. This is an important characteristic of PANI, which can be used for ammonia detection, as it deprotonates the amine groups in the emeraldine salt converting it to the emeraldine base form with a corresponding drop in conductivity of several orders of magnitude.
  • the reaction that allows this change in conductivity is given by the reaction:
  • the invention uses polyaniline as a sensor element in a breath analyzer to detect ammonia in breath.
  • the sensor may or may not be doped.
  • the invention provides a breath analyzer for detecting ammonia in breath, comprising a polyaniline sensor for detecting the presence of ammonia in breath, said sensor changing in resistivity in response to the presence of ammonia, and a circuit for detecting the change in resistivity in the sensor, to thereby indicate the presence and concentration of ammonia.
  • the invention provides a breath analyzer for detecting ammonia in breath, comprising a polyaniline sensor which is doped to increase stability and sensitivity.
  • the sensor may be doped with HC1 and further doped with camphor sulfonic acid for detecting the presence of ammonia in breath.
  • the sensor may be formed of interdigitated fingers of conductive material formed on a substrate, and having polyanilene spun cast on top, and a circuit for detecting the change in resistivity in the sensor, to thereby indicate the presence and concentration of ammonia.
  • the detection of ammonia can be used to diagnose whether a person has H. Pylori.
  • Figure 1 shows acid - base (ES - EB) transition for polyaniline
  • Figure 2 shows interdigitated platinum finger electrodes with spun cast polyaniline on top
  • Figure 3 A shows the output of the sensor as change in resistance of the conducting polymer film, and Figure 3B shows corresponding change in the current;
  • Figure 4 shows analytical response of 2 (AR/Ri vs % nitrogen concentration) on the PANI- CSA sensor
  • Figure 5 A shows change in resistivity
  • Figure 5B shows change of current of the sensor on exposure to air
  • Figure 6A shows sensor response for C02 sensitivity conductivity change
  • Figure 6B shows change in the corresponding output current
  • Figure 7 shows a calibration plot for CC air mixture
  • Figure 8 shows the response of the PANI sensor to C02 and NH3 after using a NaOH filter
  • Figure 9 shows the response of the PANI sensor to NH3, with Figure 9A showing the effect on conductivity and Figure 9B showing corresponding change in the current. Calibration was performed using the Model 1010 gas diluter;
  • Figure 10 shows a calibration plot for NH3 sensitivity using the gas diluter
  • Figure 1 1 shows the response of the PANI sensor to NH3/air, with Figure 11A showing the change in the conductivity and Figure 1 IB showing the corresponding change in the current of the device;
  • Figure 12 shows a calibration plot for NH 3 for samples injected using a 20cc syringe;
  • Figure 13 shows overall sensitivities of the PANI-CSA ammonia sensor to different gases;
  • Figures 14-23 show the results of testing different clinical samples of exhausted breath;
  • Figure 24 shows an ammonia breath analyzer.
  • the invention provides a breath analyzer for detecting ammonia in breath, comprising a polyaniline sensor for detecting the presence of ammonia in breath, said sensor changing in resistivity in response to the presence of ammonia, and a circuit for detecting the change in resistivity in the sensor, to thereby indicate the presence and concentration of ammonia.
  • the polyaniline sensor may be doped.
  • the doping can be with HCl and further doped with camphor sulfonic acid.
  • the sensor may be formed of interdigitated fingers of conductive material formed on a substrate, and having polyanilene spun cast on top.
  • the conductive material may be platinum.
  • the fingers may be spaced about 100 ⁇ apart.
  • the analyzer may further include a filter to filter out C02 from the breath.
  • the filter may comprise a NaOH medium.
  • the filter may filter out moisture from the breath.
  • the invention provides a breath analyzer for detecting ammonia in breath, comprising a polyaniline sensor doped with HCl and further doped with camphor sulfonic acid for detecting the presence of ammonia in breath, said sensor being formed of interdigitated fingers of conductive material formed on a substrate, and having polyanilene spun cast on top, and a circuit for detecting the change in resistivity in the sensor, to thereby indicate the presence and concentration of ammonia.
  • aniline (Sigma > 99%) was freshly double distilled before use.
  • Hydrochloric acid HCl (ACS reagent), ammonium persulfate (APS), ammonium hydroxide (25 %), chloroform (> 99%) and camphor sulfonic acid (CSA) were purchased from Sigma and were used as received.
  • Thin film interdigitated platinum film electrodes (IDA) (line spacing ⁇ ) were purchased from the Electronic Design Center, Case Western University, precision gas diluter Model 1010 was purchased from Custom Sensor Solutions. A 25ppm ammonia/dry 2 was used as the calibration standard and was purchased from Prest-0 sales.
  • Polyaniline (PANI) doped with HCl was prepared by chemical oxidative polymerization of aniline in aqueous acidic medium (1M HCl) with APS as an oxidant. It has been reported earlier that higher polymerization yields were obtained by using oxidant to monomer ratio of 1 :2. 50 ml of 0.48 M APS in 1M HCl was added slowly to 50 ml, 0.4M aniline solution in a beaker. The mixture was left to polymerize overnight at room temperature. The PANI precipitate was collected on a filter paper and washed repeatedly with 0.1M HCl followed by repeated washes with acetone.
  • Deprotonation of the resulting PANI salt was performed by stirring the powder in an aqueous 0.1M NH 4 OH solution for 24 hours at room temperature thus obtaining the emeraldine base (EB) which was then washed with water repeatedly until neutral pH and then dried under vacuum for 48 hours at 60°C.
  • EB emeraldine base
  • PANI was redoped with CSA with molar ratio of 1 :2.
  • a 0.5 wt% solution of the resulting PANI-CSA complex (37.5 mg PANI, 48mg CSA) in 5 ml chloroform was prepared and allowed to dissolve for 2 days with constant stirring. The solutions were filtered with a 0.2 ⁇ PTFE syringe filter to remove any particulate impurities.
  • An Agilent 4155C semiconductor analyzer was used for taking the measurements and customized test software was developed using the EasyDesktop software provided with the analyzer.
  • Tedlar bags (5L, prest-0 sales and 0.5L Zefon) were used to make the required dilution with the gas diluter.
  • a DropSens flow cell setup was employed to inject ammonia gas over the electrode. Teflon tubing was used to connect the gas to the flow setup to minimize any NH 3 absorption. Measurements were made by applying a fixed potential of IV to the sensor and measuring the resulting current which changed as a function of gas passed over the sensor surface.
  • the sensor films are prepared by spin coating the PANI-CSA solution on the IDA electrodes. Prior to spin coating, the electrodes were cleaned by rinsing in methanol followed by rinsing with deionized water and drying in a stream of dry nitrogen. PANI films were spun cast onto the IDA electrodes by adding 100 ⁇ solutions at 500 RPM. The electrode pads were cleaned with a Q-tip dipped in methanol to facilitate direct electrical contact with the analyzer.
  • Figure 2 shows interdigitated finger electrodes of platinum with spun cast polyanilene-CSA on top. The electrodes are connected to contact pads.
  • the calibration of the PANI-CSA sensors was performed by making serial dilutions of the 25 ppm NH 3 /N2 standard gas using the gas diluter. Dilutions were made for 12.5 ppm, 2.5 ppm, 250 ppb and 25 ppb in air. Calibrations were also performed to see the effect of N2 and CO2 on the PANI-CSA sensor by connecting a 5L Tedlar bag to the gas input of the diluter and turning the knob to the required dilution (10% - 100%). Before administering the sample, air was used to stabilize the sensor which effectively removes any moisture from the film. Also after injecting the sample gas, air was used to flush the sensor to return the signal to initial baseline.
  • Figure 3A shows the calculated change in the resistance on exposure to nitrogen dilution while Figure 3B shows the actual change in current which was used to calculate calculated change in resistance. It can be observed that nitrogen alone has an effect on the conductivity of polyaniline which can be associated with the removal of surface/bulk trapped water molecules in the polyaniline film. A maximum response of about 18% resistivity change was observed with 100% nitrogen.
  • the calibration for N3 ⁇ 4 was performed in two ways; first by directly using the diluter and changing the onboard dilution ratios and also by using a 20cc syringe.
  • Figure 10 shows the response of the PANI sensor to NH3, with Figure 10A showing the effect on conductivity and Figure 10B showing corresponding change in the current.
  • the calibration was performed by first making serial dilutions of the 25ppm ammonia to 2.5 ppm, 250 ppb and 25 ppb i.e. 10% dilutions each in tedlar bags. A 20 cc syringe was used to collect the sample from the tedlar bags and then injecting it directly over the sensors.
  • the calibration with the syringe showed lower percentage change in the resistivity at higher concentration (45% at 25ppm) due to the fact that less volume of the gas was available to force a change in the conductivity of the PANI sensor.
  • the percentage change at lower concentration (2.5 ppm) was still around 15% compared to 17% for that with the diluter indicating that 20 cc would be a good enough volume to test the breath samples.
  • the response observed for 250 ppb and 25 ppb was around 4.8% and 2.5% respectively which is high enough so that breath samples in the trace level ppb values can be analyzed reliably.
  • the signals could be much higher in those ranges but due to the fact that the components in the diluter could absorb some amount of ammonia limits the calibration of the samples in the ppb range.
  • the gas diluter was not validated to be used for ammonia detection and so there is no reliable data as to what dilution ranges it could be used. However, it still is the only existing device in the market that could make accurate dilutions.
  • the calibration results for the PANI-CSA sensor indicate that it can be used for ammonia detection in the trace ppb level.
  • NaOH filter can possibly absorb carbon dioxide and moisture.
  • Figures 14-23 show the results of testing different clinical samples of exhausted breath which were obtained as blind samples numbered appropriately in a 0.5L Tedlar bag.
  • the testing of the samples was performed by injecting the sample directly over the PANI-CSA coated platinum interdigitated electrode through the flow cell. A 20 cc syringe was used to inject all the samples except Sample FA and Sample II, which were injected with a lOcc syringe. The sample was injected over the electrode by hand typically for 20 seconds. Air from the gas diluter was then used to recover the signal.
  • a potential of IV was applied to the IDA electrode and the resulting current was measured using the Agilent 4155c semiconductor parametric analyzer. Change in the resistivity as a function of ammonia concentration in the injected breath sample was then plotted. Overall percentage change in the resistivity was calculated as AR/Ri, where AR (Rf-Ri) is the change in resistance of the PANI film on exposure to breath sample. For calculating the percentage change in the resistivity, the minimum resistance of the representative sample was considered for uniformity of the calculated resistivity change. Typically three sets of sample injections were performed for all the samples (see Figures 16-23), except the samples for the subject of Figures 14 and 15, and the average value for the percentage change was used for plotting the bar plots.
  • Figures 14-23 show that two samples were obtained from each of a number of different subjects.
  • the two breath samples were collected from subjects for the purpose of identifying the presence of NH3 in their breath.
  • the first sample is collected while the subject is fasting and it is characterized as baseline sample, and the second is collected after the subject has ingested urea containing meal and the sample is characterized as post urea ingestion sample.
  • the purpose of this type of collection is to demonstrate the increase in NH3 in breath of the subject in the event H. Pylori is present in the subject's digestive tract. The difference in the ammonia detected in the two samples will indicate the presence of H.Pylori.
  • the device can be supplied with a computation unit for computing the concentration of ammonia in ppb (parts per billion) based on the resistivity of the sensor, and then storing the value detected.
  • a memory can also be supplied for storing the plural values obtained.
  • the computation unit can then be used to calculate the average value from the plural values detected.
  • the computation unit and memory can also be used to store the baseline fasting values and post fasting values to calculate the difference which can be used to diagnose the presence of H. Pylori.
  • Figure 24 shows an ammonia breath analyzer comprising a breath sample injector tube made of a non-reactive material such as polytetrafluoroethylene (PTFE), commercially available from duPont under the trademark Teflon, so as not to interfere with ammonia absorption.
  • PTFE polytetrafluoroethylene
  • the sensor is a PANI-CSA sensor which, during breath analysis, is placed in the center of the device, and is sealed by closing the top of the device. The breath is injected through the breath sample injector. Data for signal analysis are transferred to a computer via the port.
  • a memory device and computation device can be incorporated into the analyzer to store values and to compute ammonia concentrations readings based on the results obtained, including averaging plural values, and computing the difference in ammonia detected between a baseline measurement obtained from a subject during fasting, and after a urea containing meal.
  • the memory can store the breath samples from each person separate from other persons in assigned memory locations, so that breath readings can be stored and retrieved for a number of persons.
  • the analyzer can also have a display for displaying the results of the sampling and computation, indicating the person. Thus the analyzer can provide a self- contained, hand-held device.

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  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Biomedical Technology (AREA)
  • Molecular Biology (AREA)
  • Pulmonology (AREA)
  • Biophysics (AREA)
  • Pathology (AREA)
  • Engineering & Computer Science (AREA)
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  • Heart & Thoracic Surgery (AREA)
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  • General Health & Medical Sciences (AREA)
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  • Veterinary Medicine (AREA)
  • Investigating Or Analyzing Materials By The Use Of Fluid Adsorption Or Reactions (AREA)
  • Investigating Or Analyzing Materials By The Use Of Electric Means (AREA)

Abstract

L'invention porte sur un analyseur d'haleine pour la détection de l'ammoniac (NH3) qui fait appel à un capteur à film mince à base de polyaniline (PANI) pour détecter le H. Pylori et d'autres maladies. Le capteur à film mince à base de polyaniline selon l'invention est dopé avec du HCl et de l'acide sulfonique de camphre.
PCT/US2013/069204 2012-10-19 2013-11-08 Détecteur d'ammoniac faisant appel à un capteur à film mince à base de polyaniline WO2014063169A1 (fr)

Applications Claiming Priority (4)

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US201261716267P 2012-10-19 2012-10-19
US61/716,267 2012-10-19
US201314058020A 2013-10-18 2013-10-18
US14/058,020 2013-10-18

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2015179751A1 (fr) * 2012-03-14 2015-11-26 Anastasia Rigas Analyseur d'haleine et procédés de test d'haleine
WO2015179755A1 (fr) * 2014-05-22 2015-11-26 Anastasia Rigas Analyseur d'haleine et procédé de test d'haleine
US9678058B2 (en) 2010-09-03 2017-06-13 Anastasia Rigas Diagnostic method and breath testing device
WO2020123565A1 (fr) 2018-12-10 2020-06-18 Anastasia Rigas Dispositifs analyseurs de gaz respiratoires et procédés de test de gaz respiratoires

Citations (7)

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US6723056B1 (en) * 1998-04-30 2004-04-20 Aerocrine Ab Device for the collection, storage and/or transport of gas samples
US7014612B2 (en) * 2001-11-13 2006-03-21 Photonic Biosystems, Inc. Method for diagnosis of helicobacter pylori infection
US20070256477A1 (en) * 2004-02-05 2007-11-08 Moor Timothy N Fluid Analyser Systems
US20090294303A1 (en) * 2004-10-12 2009-12-03 The Regents Of The University Of California method for identifying compounds that affect a transport of a protein through menbrane trafficking pathway
US20110056846A1 (en) * 2008-11-25 2011-03-10 Sureshraja Neethirajan Poly(aniline boronic acid) polymers and methods of use
WO2011104567A1 (fr) * 2010-02-25 2011-09-01 Bedfont Scientific Limited Appareil et procédé pour la détection d'ammoniac dans de l'air expiré
US20120237968A1 (en) * 2011-03-14 2012-09-20 Anastasia Rigas Detector and Method for Detection of H. Pylori

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6723056B1 (en) * 1998-04-30 2004-04-20 Aerocrine Ab Device for the collection, storage and/or transport of gas samples
US7014612B2 (en) * 2001-11-13 2006-03-21 Photonic Biosystems, Inc. Method for diagnosis of helicobacter pylori infection
US20070256477A1 (en) * 2004-02-05 2007-11-08 Moor Timothy N Fluid Analyser Systems
US20090294303A1 (en) * 2004-10-12 2009-12-03 The Regents Of The University Of California method for identifying compounds that affect a transport of a protein through menbrane trafficking pathway
US20110056846A1 (en) * 2008-11-25 2011-03-10 Sureshraja Neethirajan Poly(aniline boronic acid) polymers and methods of use
WO2011104567A1 (fr) * 2010-02-25 2011-09-01 Bedfont Scientific Limited Appareil et procédé pour la détection d'ammoniac dans de l'air expiré
US20120237968A1 (en) * 2011-03-14 2012-09-20 Anastasia Rigas Detector and Method for Detection of H. Pylori

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US9678058B2 (en) 2010-09-03 2017-06-13 Anastasia Rigas Diagnostic method and breath testing device
US10401318B2 (en) 2011-03-14 2019-09-03 Anastasia Rigas Breath analyzer and breath test methods
WO2015179751A1 (fr) * 2012-03-14 2015-11-26 Anastasia Rigas Analyseur d'haleine et procédés de test d'haleine
EP3145403A4 (fr) * 2012-03-14 2018-01-24 Anastasia Rigas Analyseur d'haleine et procédés de test d'haleine
WO2015179755A1 (fr) * 2014-05-22 2015-11-26 Anastasia Rigas Analyseur d'haleine et procédé de test d'haleine
US20170105656A1 (en) * 2014-05-22 2017-04-20 Anastasia Rigas Breath analyzer and breath test method
WO2020123565A1 (fr) 2018-12-10 2020-06-18 Anastasia Rigas Dispositifs analyseurs de gaz respiratoires et procédés de test de gaz respiratoires
EP3893736A4 (fr) * 2018-12-10 2022-08-10 Anastasia Rigas Dispositifs analyseurs de gaz respiratoires et procédés de test de gaz respiratoires

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