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GB2067764A - Transcutaneous gas sensor - Google Patents

Transcutaneous gas sensor Download PDF

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Publication number
GB2067764A
GB2067764A GB8100105A GB8100105A GB2067764A GB 2067764 A GB2067764 A GB 2067764A GB 8100105 A GB8100105 A GB 8100105A GB 8100105 A GB8100105 A GB 8100105A GB 2067764 A GB2067764 A GB 2067764A
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United Kingdom
Prior art keywords
electrode
gas
lead
sensor according
film
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Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
GB8100105A
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GB2067764B (en
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NAT RES DEV
National Research Development Corp of India
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NAT RES DEV
National Research Development Corp of India
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Publication date
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Priority to GB8100105A priority Critical patent/GB2067764B/en
Publication of GB2067764A publication Critical patent/GB2067764A/en
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Publication of GB2067764B publication Critical patent/GB2067764B/en
Expired legal-status Critical Current

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    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61BDIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00Measuring for diagnostic purposes; Identification of persons
    • A61B5/145Measuring characteristics of blood in vivo, e.g. gas concentration or pH-value ; Measuring characteristics of body fluids or tissues, e.g. interstitial fluid or cerebral tissue
    • A61B5/14542Measuring characteristics of blood in vivo, e.g. gas concentration or pH-value ; Measuring characteristics of body fluids or tissues, e.g. interstitial fluid or cerebral tissue for measuring blood gases
    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61BDIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00Measuring for diagnostic purposes; Identification of persons
    • A61B5/145Measuring characteristics of blood in vivo, e.g. gas concentration or pH-value ; Measuring characteristics of body fluids or tissues, e.g. interstitial fluid or cerebral tissue
    • A61B5/1468Measuring characteristics of blood in vivo, e.g. gas concentration or pH-value ; Measuring characteristics of body fluids or tissues, e.g. interstitial fluid or cerebral tissue using chemical or electrochemical methods, e.g. by polarographic means
    • A61B5/1477Measuring characteristics of blood in vivo, e.g. gas concentration or pH-value ; Measuring characteristics of body fluids or tissues, e.g. interstitial fluid or cerebral tissue using chemical or electrochemical methods, e.g. by polarographic means non-invasive
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/26Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
    • G01N27/403Cells and electrode assemblies
    • G01N27/404Cells with anode, cathode and cell electrolyte on the same side of a permeable membrane which separates them from the sample fluid, e.g. Clark-type oxygen sensors

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  • Life Sciences & Earth Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Physics & Mathematics (AREA)
  • Pathology (AREA)
  • General Health & Medical Sciences (AREA)
  • Molecular Biology (AREA)
  • Chemical & Material Sciences (AREA)
  • Biophysics (AREA)
  • Animal Behavior & Ethology (AREA)
  • Veterinary Medicine (AREA)
  • Public Health (AREA)
  • Surgery (AREA)
  • Medical Informatics (AREA)
  • Optics & Photonics (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Engineering & Computer Science (AREA)
  • Biomedical Technology (AREA)
  • Heart & Thoracic Surgery (AREA)
  • Electrochemistry (AREA)
  • Immunology (AREA)
  • Biochemistry (AREA)
  • General Physics & Mathematics (AREA)
  • Analytical Chemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Measurement Of The Respiration, Hearing Ability, Form, And Blood Characteristics Of Living Organisms (AREA)

Abstract

A transcutaneous gas sensor intended for use in measuring the gas permeability of human skin consists of a series of flat flexible components, the components being a first non- porous polymeric film (10) which has a gas-permeable area (21), a working electrode (16), a first porous insulating layer (18), a reference electrode (20), a second porous insulating layer (22), a counter electrode (24) and a second non- porous polymeric film (26), the first and second films (10) (26) being sealed along their edges to retain the other components and an electrolyte. In a modification (Fig. 4) the aperture in the first film (10) is attached to the membrane layer of a metallised membrane electrode constituting the working electrode. <IMAGE>

Description

SPECIFICATION Transcutaneous gas sensor When a measurement is required of the concentration of a gas in a body tissue, it is preferable if the method of measurement is noninvasive. When the concentration of a gas is low, it may be difficult to make a reliable measurement by such a method.
One example of a non-invasive measurement is that in which oxygen in arterial blood is measured transcutaneously by placing a gas sensor housed in a rigid container on a patient's body over an artery. A disadvantage of the method is that the skin must be heated to about 400C to increase its permeability to oxygen, with the attendant risk of burning unless the sensor is frequently moved to different locations. Consequently the sensor cannot be left in position for long periods fqr use in a gas monitoring mode. Moreover, adequate sealing between the sensor and the skin is not ensured.
According to the invention, a transcutaneous gas sensor comprises a series of essentially flat, flexible components, the components being in order: a first non-porous film of high polymeric material, at least an area of which is permeable to the gas to be sensed; a working electrode; a first porous insulating layer; a reference electrode; a second porous insulating layer; a counter electrode; and a second non-porous film of high polymeric material; the three electrodes and the two insulating layers being of approximately the same area, the first and second films being of larger area than the other components and being sealed together at their edges in a liquid-tight manner so as to retain an electrolyte, and there being also provided a connection to each electrode which extends outside the first and second films through a liquid tight seal.
The working electrode may be a platinum electrode, either in the form of a gauze, or in the form of a metallised membrane of high polymeric material, the membrane then constituting the gas permeable area of the first non-porous film.
The reference electrode may be a gauze of silver, having an anodization coating of silver chloride.
The counter electrode may be a lead/lead dioxide electrode, formed electrochemically in situ by providing a sheet or gauze of lead, and causing the conditions in the sensor to be such that lead is oxidised in the electrolyte.
The gas permeable area of the the first film may comprise a piece of relatively thin film sealed at its edges to cover an aperture in a relatively thick, gas-permeable film, which in turn is sealed to the second non-porous film. The relatively thin film may be the membrane layer of a metallised membrane electrode.
The invention will now be described by way of example with reference to the accompanying drawings in which:~ Figure 1 illustrates in exploded form the layers in a first embodiment of a transcutaneous gas sensor; Figure 2 is a section through the sensor in its operating form; Figure 3 is a view of the sensor; and Figure 4 illustrates in exploded form the layers in a second embodiment of a transcutaneous gas sensor.
In Figure 1, a first sheet 10 of polyethylene 0.5 to 1.0 millimetres thick has a circular aperture which is closed by a sheet 12 of 6 to 12 microns thick polyethylene film; the sheets are heat sealed together around the aperture, as indicated at reference 14. Below the polypropylene film 12 is a platinum gauze 16, a filter paper 18, a silver/silver chloride gauze 20, a filter paper 22, a lead/lead oxide sheet or gauze 24 and a second sheet 26 of polyethylene 0.5 to 1.0 millimetres thick. The polyethylene sheets are of larger areas than the metal and filter paper layers, and are heat sealed together at their outer edges to give a sandwich construction of sensor as illustrated in Figure 2.
Just before the final length of heat seal is made, the sensor is filled with an electrolyte, then fully sealed. Wire contacts 28, 30, 32 to respectively the working, reference and counter electrodes extend through the heat seal and are connected to a potentiostatic electrical circuit 34.
A suitable electrolyte is a conductive gel, such as "Neptic" (Registered Trade Mark) electrode gel, which contains sodium chloride and glycerol, and is used for electrocardiograph or electroencephalograph electrodes. Alternatively, a gel made up with sodium sulphate may be used.
In use, the potentiostatic circuit 34 applies a voltage (which may be variable) to the lead/lead oxide counter electrode 24 such that the platinum working electrode 16 is held at a fixed potential with respect to the silver/silver chloride reference electrode 20 which is constant and at which any hydrogen gas permeating through the permeable membrane 12 is oxidised. There is a corresponding reduction reaction at the counter electrode and the current generated by the electrochemical reaction is measured as the potential drop across a current measuring resistor in series with the counter electrode.The electrochemical cell is operated in the diffusion limited mode i.e. the rate of reaction is limited by the diffusion or mass transport of the reacting gas passing through the polyethylene film 12; the current generated is proportional to the concentration (partial pressure) of reactive gas in the gas sample. The current is measured by the circuit 34.
When the cell is constructed, a sheet or gauze of freshly scraped lead is placed at the counter electrode position, and is oxidised in situ when the sensor is complete and filled with electrolyte. The membrane 12 is exposed to an oxygen-containing gas, such as air, and the connections 28,32 of the working electrode and counter electrode to the circuit 34 are reversed. The circuit is arranged to apply to the working electrode a potential (about -400 to -600 millivolts) with respect to the reference electrode 20 such that the lead sheet or gauze is oxidised. A layer of lead dioxide forms on the surface of the lead to give a lead/lead dioxide electrode.For use as a hydrogen sensor, the two connections are then reversed to their original positions and a potential of +200 to +300 millivolts with respect to the reference electrode is applied.
The layer of lead dioxide formed in this way is ordered, with regular close packing, and adheres to the lead very strongly; the electrode is therefore insensitive to vibration. Further, only one allotrope of three possible oxides is formed giving further stability in contrast with a mixed allotrope lead dioxide which has varying electrical properties.
The thickness of the lead dioxide layer increases with time in accordance with Faraday's and Coulomb's laws and since lead dioxide is reduced in the sensing mode of the cell, the life of the counter electrode can be predicted. It is a great advantage that the counter electrode can be regenerated after use by reversal of the two electrode connections as before. As an example, if the hydrogen sensor is to measure very low concentrations of hydrogen, such as a few parts per million, then a lead/lead dioxide counter electrode having a life of 12 months can be prepared by running the cell in the reverse mode for 8 hours.
The fully-prepared sensor is moderately flexible, and even when flexed the components retain essentially the same geometric relationship. As a consequence the electromechanical kinetic equilibria are undisturbed by minor flexing. The flexibility allows the sensor to be applied to a curved surface, such as a human limb, and an airtight seal between the skin and the gas permeable film can be made. The sensor is very sensitive and the skin does not need to be heated to allow measurement of hydrogen concentration to be made, even if it is as low as 1 or 2 parts per million. The sensor can be left in place to allow continuous gas monitoring over extended periods.
An external construction suitable for application to a human limb is illustrated in Figure 3. Two edges of the square sensor are attached to strips 36 of "Velcro" (Registered Trade Mark). The sensor is placed in position with membrane 12 on the skin over a vein or artery in a limb, and the strips 36 are wrapped round to overlap and hold the sensor securely in position without discomfort.
In a modification (not illustrated) a rubber washer is placed between the human limb and the outer part of the area of the device which contacts it. Use of such a washer minimises noise generation due to movement of the patient.
A modified construction is shown in Figure 4.
Items identical to those in Figure 1 are given the same reference numerals. The aperture in the first sheet 10 is attached by a heat seal 38 to the membrane layer 40 of a metallised membrane electrode, which comprises a 6 to 25 micron sheet of polycarbonate or polyethylene on to which a layer 42 of platinum has been deposited. The metal layer 42 is in contact with a platinum ring 44 to which the working electrode connection 28 is attached. The other parts of the cell are identical to those in Figure 1. It is an advantage of the use of a metallized membrane electrode that the response time of the cell is reduced in comparison with a cell having a gas-permeable layer and a separate platinum gauze working electrode.
By choice of suitable materials for the permeable film, the electrodes and the electrolyte, gases other than hydrogen can be sensed.
However, it is an advantage of the use of a dilute sodium chloride as in the example above that if the membrane punctures when in contact with a patient, the released liquid is not harmful.

Claims (8)

1. A transcutaneous gas sensor comprises a series of essentially flat, flexible components, the components being in order:~ a first non-porous film of high polymeric material, at least an area of which is permeable to the gas to be sensed; a working electrode; a first porous insulating layer; a reference electrode; a second porous insulating layer; a counter electrode; and a second non-porous film of high polymeric material; the three electrodes and the two insulating layers being of approximately the same area, the first and second films being of larger area than the other components and being sealed together at their edges in a liquid-tight manner so as to retain an electrolyte, and there being also provided a connection to each electrode which extends outside the first and second films through a liquidtight seal.
2. A sensor according to Claim 1 in which the working electrode is a platinum gauze.
3. A sensor according to Claim 1 in which the working electrode is a metallised membrane of high polymeric material, the membrane also constituting the gas-permeable area of the first non-porous film.
4. A sensor according to any preceding claim in which the reference electrode is a silver gauze having an anodisation coating of silver chloride.
5. A sensor according to any preceding claim in which the counter electrode is a lead/lead dioxide electrode formed electrochemically in situ by providing a sheet or gauze of lead, and causing the lead to be oxidised in the electrolyte.
6. A sensor according to any preceding claim in which the gas permeable area of the first film comprises an area of relatively thin film sealed at its edges to cover an aperture in a relatively thick, gas-impermeable film.
7. A sensor according to any preceding claim containing an electrolyte which is an electrically conductive gel.
8. A transcutaneous gas sensor substantially as hereinbefore described with reference either to Figure 1, 2 and 3 or to Figure 4 of the accompanying drawings.
GB8100105A 1980-01-09 1981-01-05 Transcutaneous gas sensor Expired GB2067764B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB8100105A GB2067764B (en) 1980-01-09 1981-01-05 Transcutaneous gas sensor

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB8000743 1980-01-09
GB8100105A GB2067764B (en) 1980-01-09 1981-01-05 Transcutaneous gas sensor

Publications (2)

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GB2067764A true GB2067764A (en) 1981-07-30
GB2067764B GB2067764B (en) 1984-01-25

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Cited By (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4664119A (en) * 1985-12-04 1987-05-12 University Of Southern California Transcutaneous galvanic electrode oxygen sensor
WO1998025138A1 (en) * 1996-12-07 1998-06-11 Central Research Laboratories Limited Electrochemical cell
WO1999024826A1 (en) * 1997-11-10 1999-05-20 Central Research Laboratories Limited A gas sensor
DE102004037312A1 (en) * 2004-07-31 2006-03-23 Dräger Safety AG & Co. KGaA Electrochemical gas sensor and method for its production
CN105759022A (en) * 2016-04-25 2016-07-13 盛密科技(上海)有限公司 Gas sensor and detection equipment for percutaneous gas analysis
CN111789575A (en) * 2020-07-14 2020-10-20 天津大学 Flexible epidermal electrochemical sensor based on polymer support
CN113827248A (en) * 2021-09-18 2021-12-24 宁波慈溪生物医学工程研究所 A multi-layer composite electrode system for non-contact ECG detection
US11867652B2 (en) 2014-10-23 2024-01-09 Abbott Diabetes Care Inc. Electrodes having at least one sensing structure and methods for making and using the same
US12239442B2 (en) 2020-12-23 2025-03-04 Abbott Diabetes Care Inc. Analyte sensors with reduced interferent signal and methods
US12239463B2 (en) 2020-08-31 2025-03-04 Abbott Diabetes Care Inc. Systems, devices, and methods for analyte sensor insertion
US12268496B2 (en) 2017-01-23 2025-04-08 Abbott Diabetes Care Inc. Systems, devices and methods for analyte sensor insertion
US12274548B2 (en) 2006-10-23 2025-04-15 Abbott Diabetes Care Inc. Sensor insertion devices and methods of use
US12279867B2 (en) 2017-08-18 2025-04-22 Abbott Diabetes Care Inc. Systems, devices, and methods related to the individualized calibration and/or manufacturing of medical devices
US12290359B2 (en) 2020-01-03 2025-05-06 Abbott Diabetes Care Inc. Sensor array systems and methods for detecting multiple analytes
US12385077B2 (en) 2016-03-04 2025-08-12 Abbott Diabetes Care Inc. NAD(P)-dependent responsive enzymes, electrodes and sensors, and methods for making and using the same
US12465251B2 (en) 2020-07-08 2025-11-11 Abbott Diabetes Care Inc. Analyte sensors featuring enhancements for decreasing interferent signal

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US9402544B2 (en) 2009-02-03 2016-08-02 Abbott Diabetes Care Inc. Analyte sensor and apparatus for insertion of the sensor
BRPI1105778A2 (en) 2010-03-24 2016-05-03 Abbott Diabetes Care Inc "medical device inserters and medical device insertion and use processes"

Cited By (24)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4664119A (en) * 1985-12-04 1987-05-12 University Of Southern California Transcutaneous galvanic electrode oxygen sensor
WO1998025138A1 (en) * 1996-12-07 1998-06-11 Central Research Laboratories Limited Electrochemical cell
EP1413881A3 (en) * 1996-12-07 2004-09-01 Central Research Laboratories Limited Electrochemical cell
WO1999024826A1 (en) * 1997-11-10 1999-05-20 Central Research Laboratories Limited A gas sensor
US6454923B1 (en) 1997-11-10 2002-09-24 Central Research Laboratories Limited Gas sensor
DE102004037312A1 (en) * 2004-07-31 2006-03-23 Dräger Safety AG & Co. KGaA Electrochemical gas sensor and method for its production
US7935234B2 (en) 2004-07-31 2011-05-03 Dräger Safety AG & Co. KGaA Electrochemical gas sensor and process for manufacturing same
DE102004037312B4 (en) * 2004-07-31 2015-02-05 Dräger Safety AG & Co. KGaA Electrochemical gas sensor and method for its production
US12274548B2 (en) 2006-10-23 2025-04-15 Abbott Diabetes Care Inc. Sensor insertion devices and methods of use
US11867652B2 (en) 2014-10-23 2024-01-09 Abbott Diabetes Care Inc. Electrodes having at least one sensing structure and methods for making and using the same
US12436127B2 (en) 2014-10-23 2025-10-07 Abbott Diabetes Care Inc. Electrodes having at least one sensing structure and methods for making and using the same
US12385077B2 (en) 2016-03-04 2025-08-12 Abbott Diabetes Care Inc. NAD(P)-dependent responsive enzymes, electrodes and sensors, and methods for making and using the same
US12398413B2 (en) 2016-03-04 2025-08-26 Abbott Diabetes Care Inc. NAD(P)-dependent responsive enzymes, electrodes and sensors, and methods for making and using the same
CN105759022A (en) * 2016-04-25 2016-07-13 盛密科技(上海)有限公司 Gas sensor and detection equipment for percutaneous gas analysis
US12268496B2 (en) 2017-01-23 2025-04-08 Abbott Diabetes Care Inc. Systems, devices and methods for analyte sensor insertion
US12279867B2 (en) 2017-08-18 2025-04-22 Abbott Diabetes Care Inc. Systems, devices, and methods related to the individualized calibration and/or manufacturing of medical devices
US12478296B2 (en) 2017-08-18 2025-11-25 Abbott Diabetes Care Inc. Systems, devices, and methods related to the individualized calibration and/or manufacturing of medical devices
US12290359B2 (en) 2020-01-03 2025-05-06 Abbott Diabetes Care Inc. Sensor array systems and methods for detecting multiple analytes
US12465251B2 (en) 2020-07-08 2025-11-11 Abbott Diabetes Care Inc. Analyte sensors featuring enhancements for decreasing interferent signal
CN111789575A (en) * 2020-07-14 2020-10-20 天津大学 Flexible epidermal electrochemical sensor based on polymer support
CN111789575B (en) * 2020-07-14 2023-10-31 天津大学 Flexible epidermal electrochemical sensor based on polymer support
US12239463B2 (en) 2020-08-31 2025-03-04 Abbott Diabetes Care Inc. Systems, devices, and methods for analyte sensor insertion
US12239442B2 (en) 2020-12-23 2025-03-04 Abbott Diabetes Care Inc. Analyte sensors with reduced interferent signal and methods
CN113827248A (en) * 2021-09-18 2021-12-24 宁波慈溪生物医学工程研究所 A multi-layer composite electrode system for non-contact ECG detection

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Legal Events

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732 Registration of transactions, instruments or events in the register (sect. 32/1977)
PCNP Patent ceased through non-payment of renewal fee

Effective date: 19930105