GB2049182A - Method and apparatus for sensing respiration - Google Patents
Method and apparatus for sensing respiration Download PDFInfo
- Publication number
- GB2049182A GB2049182A GB8012439A GB8012439A GB2049182A GB 2049182 A GB2049182 A GB 2049182A GB 8012439 A GB8012439 A GB 8012439A GB 8012439 A GB8012439 A GB 8012439A GB 2049182 A GB2049182 A GB 2049182A
- Authority
- GB
- United Kingdom
- Prior art keywords
- sample
- gas
- cell
- analyser
- analyser cell
- Prior art date
- 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
Links
- 230000029058 respiratory gaseous exchange Effects 0.000 title claims abstract description 14
- 238000000034 method Methods 0.000 title claims abstract description 13
- 238000011010 flushing procedure Methods 0.000 claims abstract description 6
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 claims description 22
- 230000005855 radiation Effects 0.000 claims description 14
- 229910002092 carbon dioxide Inorganic materials 0.000 claims description 11
- 239000001569 carbon dioxide Substances 0.000 claims description 10
- GGYFMLJDMAMTAB-UHFFFAOYSA-N selanylidenelead Chemical compound [Pb]=[Se] GGYFMLJDMAMTAB-UHFFFAOYSA-N 0.000 claims description 2
- 238000010521 absorption reaction Methods 0.000 claims 1
- 241001465754 Metazoa Species 0.000 abstract description 4
- 239000007789 gas Substances 0.000 description 24
- 238000005259 measurement Methods 0.000 description 6
- 230000000243 photosynthetic effect Effects 0.000 description 5
- 230000029553 photosynthesis Effects 0.000 description 4
- 238000010672 photosynthesis Methods 0.000 description 4
- 230000002238 attenuated effect Effects 0.000 description 3
- 230000003287 optical effect Effects 0.000 description 2
- UKUVVAMSXXBMRX-UHFFFAOYSA-N 2,4,5-trithia-1,3-diarsabicyclo[1.1.1]pentane Chemical compound S1[As]2S[As]1S2 UKUVVAMSXXBMRX-UHFFFAOYSA-N 0.000 description 1
- 102100040958 Aconitate hydratase, mitochondrial Human genes 0.000 description 1
- 102100031102 C-C motif chemokine 4 Human genes 0.000 description 1
- 101000965314 Homo sapiens Aconitate hydratase, mitochondrial Proteins 0.000 description 1
- 101150078046 act2 gene Proteins 0.000 description 1
- 239000012080 ambient air Substances 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 239000003054 catalyst Substances 0.000 description 1
- 239000006260 foam Substances 0.000 description 1
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 1
- 239000010931 gold Substances 0.000 description 1
- 229910052737 gold Inorganic materials 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 239000008188 pellet Substances 0.000 description 1
- 230000037039 plant physiology Effects 0.000 description 1
- 239000011819 refractory material Substances 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
- G01N33/48—Biological material, e.g. blood, urine; Haemocytometers
- G01N33/483—Physical analysis of biological material
- G01N33/497—Physical analysis of biological material of gaseous biological material, e.g. breath
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
- G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
- G01N21/35—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light
- G01N21/3504—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light for analysing gases, e.g. multi-gas analysis
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
- G01N33/48—Biological material, e.g. blood, urine; Haemocytometers
- G01N33/483—Physical analysis of biological material
- G01N33/497—Physical analysis of biological material of gaseous biological material, e.g. breath
- G01N33/4977—Metabolic gas from microbes, cell cultures or plant tissues
Landscapes
- Life Sciences & Earth Sciences (AREA)
- Health & Medical Sciences (AREA)
- Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Molecular Biology (AREA)
- Biomedical Technology (AREA)
- General Physics & Mathematics (AREA)
- Pathology (AREA)
- Immunology (AREA)
- General Health & Medical Sciences (AREA)
- Biochemistry (AREA)
- Analytical Chemistry (AREA)
- Medicinal Chemistry (AREA)
- Food Science & Technology (AREA)
- Biophysics (AREA)
- Hematology (AREA)
- Urology & Nephrology (AREA)
- Spectroscopy & Molecular Physics (AREA)
- Investigating Or Analysing Materials By Optical Means (AREA)
- Investigating Or Analysing Biological Materials (AREA)
Abstract
A method of sensing respiration of a plant or animal comprises flushing a known gas through a sample analyser cell, a reference analyser cell, and a sample enclosure in which a sample respires; simultaneously closing the reference analyser cell, and starting closed cycle circulation of gas through the sample enclosure and the sample analyser cell; and subsequently comparing the concentration of a respired gas in the sample analyser cell and the reference analyser cell.
Description
SPECIFICATION
Method and apparatus for sensing respiration
In this specification the term "respiration" is used in the broad sense, meaning both inspiration and expiration in both animals and plants.
It is often a requirement to make measurements of respiration or of rate of respiration, sometimes in circumstances when mains power is not available. For example, the rate of photosynthesis of a plant may need to be measured in the field. At present techniques are based on infra-red analysers which require mains power, are not easily portable, and are very sensitive to mechanical vibration.
According to the invention, a method of sensing respiration comprising flushing a known gas through a sample analyser cell, a reference analyser cell, and a sample enclosure in which a sample respires; simultaneously closing the reference analyser cell, and starting closed cycle circulation of gas through the sample enclosure and the sample analyser cell; and subsequently comparing the concentration of a respired gas in the sample analyser cell and the reference analyser cell.
It is an advantage of a method according to the invention that the rate of flow of the gas need not be measured; this is a source of error in previous methods.
In one arrangement the time for the concentration of gas in the sample analyser cell to change between a first and a second predetermined level is measured. From such a measurement, photosynthetic rate can be calculated and displayed by suitable circuitry.
Also according to the invention, apparatus for sensing respiration comprises a sample enclosure, a sample analyser cell and a reference analyser cell;
means for simultaneously closing the reference analyser cell, and for causing the sample enclosure and the sample analyser cell to be connected in a closed circuit;
pump means for flushing a gas through said enclosure and cells and for circulating the gas in the closed circuit;
and comparator means for comparing the concentration of a respired gas in the sample analyser cell and the reference analyser cell.
In one embodiment the gas may be carbon dioxide assimilated by a photosynthesising plant leaf in the sample enclosure; conveniently the concentrations of carbon dioxide gas in the analyser cells are compared by passing a beam of infra red radiation through each cell and comparing the attenuation at a suitable wavelength.
The invention will now be described with reference to the accompanying drawings in which Figure 1 shows schematically the optical and gas-flow paths in a photosynthesis meter according to the invention;
Figure 2 shows a suitable electrical circuit; and
Figures 3, 4 and 5 show the form of electrical signals at different parts of the circuit.
In Fig. 1, an infra-red source 10, emitting radiation in all directions, illuminates two gold-coated plane mirrors 12, 1 4 through respective arsenic trisulphide lenses 16, 1 8 which provide collimated beams. The beams are alternately interrupted by a chopper 20.
The mirrors reflect the radiation through a sample analyser cell 22 and an identical reference analyser cell 24 respectively, and, after passage through filters 26, 28 transmitting at 4.26 micrometres, illuminate two concave mirrors 30, 32, which focus the radiation on a sensor 34. Thus the sensor receives alternately radiation attenuated by gas in the sample analyser cell and radiation attenuated by gas in the reference analyser cell. Such a double-beam arrangement is known; the folded optical arrangement illustrated allows a compact instrument but is not essential.
In operation the radiation received by the sensor 34 is attenuated by gas in the analyser cells, and the alternately-received signals are compared by suitable circuitry (not shown in
Fig. 1). Previous calibration allows the measurement of the concentration of a gas such as carbon dioxide which absorbs infra-red radiation.
Considering now the new and inventive features in the gas circulation system the reference analyser cell 24 is connected at one end to a gas supply line 36 and at the other end through a three-way valve 38 to one end of the sample analyser cell 22 through a pump 39 and directly to one end of a sample enclosure 40, the other ends of the cell 22 and enclosure 40 being connected to each other by a pipe 42. The entrance and exit connections to the sample cell 22 are identical to those to the reference cell 24. The pump 39 and three-way valve 32 can be operated either manually, or through a conventional remote control arrangement.
The sample enclosure 40 will usually comprise a compartment hinged at one side 44 and edged with closed-cell flexible foam 46 so that it can be sealed in a gas-tight manner around the stem of a leaf 48 on a living plant without causing damage. Such enclosures are well known in plant physiology.
In operation, valve 38 is set to connect the reference cell 24 to the analyser cell 22, and the sample enclosure 40 is open; the pump 39 draws either ambient air or a known gas or gas mixture through the cells 22, 24 and the flushing gas escapes through the open enclosure 40. Then simultaneously the sample enclosure 40 is closed around the leaf and valve 38 is altered to connect the sample analyser cell 22 to the sample enclosure 40, and the pump 39 circulates gas through this closed circuit. As photosynthesis proceeds in the leaf 48, the concentration of carbon dioxide in the circulated gas alters, and therefore alters the attenuation of infra-red radiation passing through the sample analyser cell 22.
The concentration at any time can be measured as described above, without measurement of the gas flow rate.
It is a further advantage of the use of this novel method of measurement that the photosynthetic rate of a leaf can be calculated and displayed by suitable circuitry. If the change in carbon dioxide concentration between times t, and t2 is act2, then -photosynthetic rate R is:- R = - A CO2 v
t2 - ti Usually, ACOz will be constant, and rate R will be inversely proportional to the time interval.
The apparatus will be calibrated using the volume ('4of the closed circwit:and the sensitivity of the gas analyser and a simple time measurement will allow photosynthetic rate to be displayed. Time t1-can either be the time when the closed-cycle circulation was started, or a time when carbon dioxide concentration in the sample cell has reached a predetermined level.
A suitable source 10 of infra-red radiation is a "pellistor", that.is, a coil of metal wire embedded in a pellet of a refractory material; such a pellistor, when coated with a catalyst, is intended for use in a gas sensor, see UK
Patent No. 892,530, but it has been found to emit infra-red radiation when supplied with low electrical power.
An example of a suitable electrical circuit is shown in Fig. 2. A lead selenide infra-red detector assembly 34 is connected to an-a.c.
coupled high input impedance balanced amplifier 50; the amplifier output signal is passed through a further amplifier 52 and an a.c. coupled buffer 54, which removes any d.c. signal, to a phase sensitive detector (PSD) 56. An idealised output from amplifier 50 is shown in Fig. 3; the change in maximum signal level corresponds to the difference in attenuation in the sample and reference analyser cells. The PSD is also supplied with a reference signal, shown in Fig. 4, from a reference photocell 58 and squarer 60. The
PSD output, illustrated in Fig. 5, feeds a low pass filter 62; the filtered product is proportional to the difference between the signals received after passage through the two analyser cells and therefore to ACO2, provided the concentration change is small. A suitable display 64 can be provided.
To determine photosynthetic rate, additional circuitry is provided and is shown by dotted lines; two threshold detectors 66, 68 are connected to the output of filter 62 and, through a gate 70, supply start and stop signals to a digital timer 72. With this arrangement, a suitable display of photosynthetic rate can be provided.
The instrument described may be handportable and battery operated for use in the field.
While the apparatus has been described with reference to a photosynthesis meter which senses carbon dioxide assimilated by a plant leaf in the sample enclosure, the invention may also be used to sense carbon dioxide expired by an animal, either enclosed in the sample enclosure or connected to that enclosure by breathing apparatus. By use of suitable sensors, oxygen inspired by an animal or expired by a plant may also be sensed.
Claims (8)
1. A method of sensing respiration comprising flushing a known gas through a sample analyser cell, a reference analyser cell, and a sample enclosure in which a sample respires;
simultaneously closing the reference analyser cell and starting closed-cycle circulation of gas through the sample enclosure and the sample analyser cell;
and subsequently comparing the concentration of the respired gas in the sample analyser cell and the reference analyser cell.
2. A method of sensing rate of respiration comprising sensing respiration by a method according to Claim 1, and determining the time for the concentration of the respired gas in the sample analyser cell to change between two predetermined values.
3. A method according to Claim 1 or
Claim 2 in which the gas is carbon dioxide assimilated by a plant in the sample enclosure, and the concentration of carbon dioxide gas in the two analyser cells is compared by the technique of infra-red absorption.
4. Apparatus for sensing respiration com
prises a sample enclosure, a sample analyser cell and a reference analyser cell;
means for simultaneously closing the reference analyser cell, and for causing the sample enclosure and the sample analyser cell to be connected in a closed circuit;
pump means for flushing the gas through said enclosure and cells and for circulating the gas in the closed circuit;
and comparator means for comparing the
concentration of a respired gas in the sample
analyser cell and the reference analyser cell.
5. Apparatus according to Claim 4 further
comprising timing means for determining the time for the concentration of the respired gas
in the sample analyser cell to change between two predetermined values.
6. Apparatus according to Claim 4 or
Claim 5 in which the comparator means com prises means for comparing the intensities of two beams of infra-red radiation which have passed respectively through the sample analyser cell and the reference analyser cell.
7. Apparatus according to Claim 6 in which the sensor of infra-red radiation is a lead selenide detector, and further comprising as a source of infra-red radiation a pellistor as hereinbefore described.
8. Apparatus for sensing rate of a respiration substantially as hereinbefore described with reference to Figs. 1 and 2 of the accompanying drawings.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8012439A GB2049182B (en) | 1979-04-20 | 1980-04-15 | Method and apparatus for sensing respiration |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB7913929 | 1979-04-20 | ||
| GB8012439A GB2049182B (en) | 1979-04-20 | 1980-04-15 | Method and apparatus for sensing respiration |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB2049182A true GB2049182A (en) | 1980-12-17 |
| GB2049182B GB2049182B (en) | 1983-03-16 |
Family
ID=26271292
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB8012439A Expired GB2049182B (en) | 1979-04-20 | 1980-04-15 | Method and apparatus for sensing respiration |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2049182B (en) |
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3209013A1 (en) * | 1982-03-12 | 1983-10-20 | Beckenkamp, Hermann, Prof.Dr., 6601 Schafbrücke | Method and device for determining and monitoring the effects of pollutant combinations in the air |
| DE3530669A1 (en) * | 1985-08-28 | 1986-01-16 | Heinz Walz Meß- und Regeltechnik, 8521 Effeltrich | Method and device for recording gas exchange processes in intact plants |
| EP0372429A2 (en) * | 1988-12-01 | 1990-06-13 | Czekajewski, Jan doing business under The Trading Style Columbus Instruments Division of INTERNATIONAL INSTRUMENT COMPANY | Method and apparatus for measuring respiration, oxidation and similar interactions between a sample and a selected component of a fluid medium |
| CN100386626C (en) * | 2003-07-29 | 2008-05-07 | 中国科学院沈阳应用生态研究所 | Method for measuring tree stem respiratory |
| CN101241117B (en) * | 2008-03-12 | 2011-05-18 | 福建师范大学 | Air cell for determining trunk respiration |
| WO2012040439A2 (en) | 2010-09-23 | 2012-03-29 | Li-Cor, Inc. | Gas exchange system flow configuration |
| EP2477025A3 (en) * | 2011-01-13 | 2012-11-28 | Li-Cor, Inc. | Off-set compensation technique for dual analyzer gas exchange systems |
-
1980
- 1980-04-15 GB GB8012439A patent/GB2049182B/en not_active Expired
Cited By (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3209013A1 (en) * | 1982-03-12 | 1983-10-20 | Beckenkamp, Hermann, Prof.Dr., 6601 Schafbrücke | Method and device for determining and monitoring the effects of pollutant combinations in the air |
| DE3530669A1 (en) * | 1985-08-28 | 1986-01-16 | Heinz Walz Meß- und Regeltechnik, 8521 Effeltrich | Method and device for recording gas exchange processes in intact plants |
| EP0372429A2 (en) * | 1988-12-01 | 1990-06-13 | Czekajewski, Jan doing business under The Trading Style Columbus Instruments Division of INTERNATIONAL INSTRUMENT COMPANY | Method and apparatus for measuring respiration, oxidation and similar interactions between a sample and a selected component of a fluid medium |
| US4947339A (en) * | 1988-12-01 | 1990-08-07 | Jan Czekajewski | Method and apparatus for measuring respiration, oxidation and similar interacting between a sample and a selected component of a fluid medium |
| EP0372429A3 (en) * | 1988-12-01 | 1991-09-18 | Czekajewski, Jan doing business under The Trading Style Columbus Instruments Division of INTERNATIONAL INSTRUMENT COMPANY | Method and apparatus for measuring respiration, oxidation and similar interactions between a sample and a selected component of a fluid medium |
| CN100386626C (en) * | 2003-07-29 | 2008-05-07 | 中国科学院沈阳应用生态研究所 | Method for measuring tree stem respiratory |
| CN101241117B (en) * | 2008-03-12 | 2011-05-18 | 福建师范大学 | Air cell for determining trunk respiration |
| WO2012040439A2 (en) | 2010-09-23 | 2012-03-29 | Li-Cor, Inc. | Gas exchange system flow configuration |
| EP2619548A4 (en) * | 2010-09-23 | 2018-01-17 | Li-Cor, Inc. | Gas exchange system flow configuration |
| EP2477025A3 (en) * | 2011-01-13 | 2012-11-28 | Li-Cor, Inc. | Off-set compensation technique for dual analyzer gas exchange systems |
Also Published As
| Publication number | Publication date |
|---|---|
| GB2049182B (en) | 1983-03-16 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |