JP2012225842A - Smell measuring apparatus and smell measuring method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a smell measuring apparatus with high measurement sensitivity capable of detecting and measuring a very small amount of smell molecules and a smell measuring method.SOLUTION: The smell measuring apparatus includes a smell sensor 10 configured in such a manner that a resonance frequency changes by attraction of specified smell molecules, a measurement chamber 20 in which the smell sensor 10 is mounted and a vacuum pump 42 for making the inside of the measurement chamber 20 be at a specific degree of vacuum. The specified smell molecules are supplied into the inside of the measurement chamber 20 where the vacuum is made at the specific degree.

Description

  Some embodiments according to the present invention relate to an odor measuring apparatus and an odor measuring method for measuring a concentration or mass of a predetermined odor molecule.

  Conventionally, as this kind of odor measuring apparatus, a vaporizing means for vaporizing odorous molecules contained in a solution, a dryer for removing moisture in an output gas of the vaporizing means, and an output gas of the dryer are supplied. A device including an odor sensor installed in a sensor cell (see, for example, Patent Document 1) is known.

JP-A-9-273984

  However, as described in Patent Document 1, when moisture contained in the output gas of the vaporizing means is removed with a membrane dryer, not only a few odorous molecules but also water molecules have been removed. For this reason, the odor measuring apparatus described in Patent Document 1 has a problem that the measurement sensitivity of odor molecules is low and odor molecules present in a trace amount in a solution cannot be detected.

  Some aspects of the present invention have been made in view of the above-described problems, and an object thereof is to provide an odor measuring apparatus and an odor measuring method capable of detecting a trace amount of odor molecules.

  An odor measuring apparatus according to the present invention includes an odor sensor configured to change a resonance frequency by adsorption of a predetermined odor molecule, a measurement chamber in which the odor sensor is installed, and a predetermined vacuum inside the measurement chamber. And the above-mentioned predetermined odor molecule is supplied into the measurement chamber having the above-mentioned predetermined degree of vacuum.

  According to such a configuration, a predetermined odor molecule is supplied into the measurement chamber having a predetermined degree of vacuum. Here, if the mean free path of the predetermined odor molecule becomes longer, the probability that the predetermined odor molecule reaches the odor sensor and is adsorbed without colliding with other molecules in the measurement chamber increases. Therefore, the mean free path of a given odor molecule is inversely proportional to the pressure in the measurement chamber. Therefore, by reducing the pressure in the measurement chamber and setting the inside of the measurement chamber to a predetermined degree of vacuum, the measurement chamber is kept for the odor sensor. It becomes a measurement environment in which a substance that becomes a noise component, for example, water molecules is very small (excluded as much as possible), and it becomes possible to install (use) a highly sensitive odor sensor.

  Further, since the amount of change in the resonance frequency is proportional to the square of the resonance frequency, it can be said that the detection sensitivity of the odor sensor is higher (higher sensitivity) as the resonance frequency is higher. On the other hand, if the detection sensitivity of the odor sensor is high, it becomes sensitive to the measurement environment, so that substances other than the odor molecule that is the measurement target may appear as noise components. Therefore, when measuring odor molecules in the atmosphere as in the conventional odor measuring apparatus, for example, a quartz resonator having a resonance frequency of 30 [MHz] in order to obtain a stable detection signal with less noise components from the odor sensor. Was used. As a result, the conventional odor measuring apparatus has measured the odor molecule | numerator of the density | concentration (order) of 100 [ppb] (one billionth).

  On the other hand, in the odor measuring apparatus according to the present invention, the measurement chamber has a measurement environment in which a substance that becomes a noise component for the odor sensor is very small (excluded as much as possible). For example, the resonance frequency is 600 [MHz]. Quartz crystal can be used. Thereby, the odor measuring apparatus of this invention can measure the odor molecule of the density | concentration (order) of 100 [ppt] (one trillion), Compared with the conventional odor measuring apparatus, A measurement sensitivity of about 1000 times can be obtained. Thereby, a measurement sensitivity can be improved and a trace amount odor molecule can be detected and measured.

  Preferably, the apparatus further includes a load lock chamber in which the sample containing the predetermined odor molecule is disposed. The load lock chamber has an openable and closable opening communicating with the measurement chamber. Reduce the pressure inside the lock chamber.

  According to this configuration, the load lock chamber in which a sample containing a predetermined odor molecule is arranged communicates with the measurement chamber and has an opening that can be freely opened and closed. Thus, after the sample is arranged inside the load lock chamber, the opening is opened, so that predetermined odor molecules contained in the sample are supplied to the measurement chamber. Also, when placing a sample in the load lock chamber, the inside of the load lock chamber may be released to the atmosphere (outside air), so the vacuum pump reduces the pressure inside the load lock chamber and By performing evacuation, the degree of vacuum in the measurement chamber is maintained (maintained) even when the opening is opened. Thereby, it is possible to easily realize a load lock chamber for supplying a predetermined odor molecule while maintaining (maintaining) the degree of vacuum inside the measurement chamber.

  Preferably, the sample includes the predetermined odor molecule collected by solid phase extraction.

  According to this configuration, the above-described sample includes predetermined odor molecules collected by solid phase extraction. Thereby, the sample from which molecules other than the predetermined odor molecule are separated is arranged in the load lock chamber, so that the predetermined odor molecule having a high concentration (high purity) can be supplied into the measurement chamber. Thereby, the measurement sensitivity can be further increased, and a trace amount of odor molecules can be detected and measured.

  Preferably, the load lock chamber further includes a heater for heating the sample.

  According to this configuration, the load lock chamber further includes a heater that heats the sample disposed inside the load lock chamber. Thereby, since the predetermined odor molecule contained in the sample is easily released, the probability that the predetermined odor molecule is adsorbed to the odor sensor 10 installed in the measurement chamber can be increased. Thereby, the measurement sensitivity can be further increased, and a trace amount of odor molecules can be detected and measured.

  Preferably, the gas inside the measurement chamber is exhausted at a predetermined speed.

  According to this configuration, the gas inside the measurement chamber is discharged at a predetermined speed. Thereby, the predetermined odor molecule adsorbed on the odor sensor can be removed. Thereby, different odors can be measured continuously.

Preferably, the predetermined degree of vacuum is a pressure of 10 ⁻⁴ Pa or more and 10 ⁻² Pa or less.

According to this configuration, the predetermined degree of vacuum inside the measurement chamber is a pressure of 10 ⁻⁴ [Pa] or higher and 10 ⁻² [Pa] or lower. Thereby, it becomes possible to maintain (maintain) the vacuum state inside a measurement chamber by comprising a vacuum pump with a rotary pump, a turbo-molecular pump, etc., for example. As a result, it is possible to prevent an increase in the size and cost of the apparatus, increase the measurement sensitivity, and easily realize an odor measuring apparatus capable of detecting and measuring a trace amount of odor molecules.

  Preferably, the dimensions inside the measurement chamber are the same or substantially the same as the dimensions of the odor sensor.

  According to this configuration, the dimensions inside the measurement chamber are the same as or substantially the same as the dimensions of the odor sensor. As a result, the inside of the measurement chamber becomes the minimum volume (volume), so that the inside of the measurement chamber can be easily set to a predetermined degree of vacuum, and the odor sensor installed inside the measurement chamber is The probability of adsorbing odor molecules can be increased. Thereby, the measurement sensitivity can be further increased, and a trace amount of odor molecules can be detected and measured.

  Preferably, the odor sensor includes a crystal resonator including a quartz substrate and an adsorption film that adsorbs the predetermined odor molecule, and the adsorption film is formed on at least one surface of the quartz substrate in a vacuum. Is done.

  According to this configuration, the adsorption film is formed on at least one surface of the quartz substrate in a vacuum. Thereby, when the odor sensor is installed in a vacuum, it is possible to prevent a predetermined odor molecule adsorbed on the adsorption film from being released. Thereby, the measurement sensitivity can be further increased, and a trace amount of odor molecules can be detected and measured.

  Preferably, a plurality of the aforementioned odor sensors are provided, and each of the plurality of odor sensors is configured such that the resonance frequency is changed by adsorption of the predetermined odor molecules different from each other.

  According to such a configuration, each of the plurality of odor sensors is configured such that the resonance frequency changes due to adsorption of predetermined odor molecules different from each other. Here, in general, an odor is composed of a plurality of odor molecules, and can be specified (or classified) by the composition ratio (configuration ratio) of each odor molecule. Therefore, by installing a plurality of odor sensors configured to change the resonance frequency due to adsorption of predetermined odor molecules different from each other, the composition ratio (configuration ratio) of the plurality of predetermined odor molecules can be measured. . Thereby, an odor constituted by a plurality of odor molecules can be specified (or classified), and the odor can be identified.

  The odor measurement method according to the present invention includes a step of setting a predetermined degree of vacuum inside a measurement chamber in which an odor sensor whose resonance frequency is changed by adsorption of a predetermined odor molecule is set, Providing an odorant molecule.

  According to such a configuration, a predetermined odor molecule is supplied into the measurement chamber having a predetermined degree of vacuum. Here, if the mean free path of the predetermined odor molecule becomes longer, the probability that the predetermined odor molecule reaches the odor sensor and is adsorbed without colliding with other molecules in the measurement chamber increases. Therefore, the mean free path of a given odor molecule is inversely proportional to the pressure in the measurement chamber. Therefore, by reducing the pressure in the measurement chamber and setting the inside of the measurement chamber to a predetermined degree of vacuum, the measurement chamber is kept for the odor sensor. It becomes a measurement environment in which a substance that becomes a noise component, for example, water molecules is very small (excluded as much as possible), and it becomes possible to install (use) a highly sensitive odor sensor.

  Further, since the amount of change in the resonance frequency is proportional to the square of the resonance frequency, it can be said that the detection sensitivity of the odor sensor is higher (higher sensitivity) as the resonance frequency is higher. On the other hand, if the detection sensitivity of the odor sensor is high, it becomes sensitive to the measurement environment, so that substances other than the odor molecule that is the measurement target may appear as noise components. Therefore, when measuring odor molecules in the atmosphere as in the conventional odor measurement method, in order to obtain a stable detection signal with less noise components from the odor sensor, for example, a crystal resonator having a resonance frequency of 30 [MHz] Was used. As a result, the conventional odor measuring method has measured odor molecules having a concentration of the order of 100 [ppb] (parts per billion).

  On the other hand, in the odor measurement method of the present invention, the measurement chamber has a measurement environment in which a substance that becomes a noise component for the odor sensor is very small (excluded as much as possible). For example, the resonance frequency is 600 [MHz]. Quartz crystal can be used. Thereby, the odor measuring method of this invention can measure the odor molecule | numerator of the density | concentration (order) of 100 [ppt] (one trillion), Compared with the conventional odor measuring method, A measurement sensitivity of about 1000 times can be obtained. Thereby, a measurement sensitivity can be improved and a trace amount odor molecule can be detected and measured.

It is a schematic block diagram explaining an example of the odor measuring apparatus which concerns on this invention. It is sectional drawing of the odor sensor shown in FIG. It is a graph explaining an example of the composition ratio of odor. It is a schematic block diagram explaining the other example of the measurement chamber shown in FIG. It is a side view explaining the method of extract | collecting a sample using the SPME holder shown in FIG. It is a figure explaining the state which has arrange | positioned the SPME holder shown in FIG. 5 inside the load lock chamber. It is a figure explaining the state which opened the opening part in FIG. It is a graph explaining an example of the time change of the resonant frequency in the odor sensor shown in FIG. 6 and FIG.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, the drawings are schematic. Therefore, specific dimensions and the like should be determined in light of the following description. Moreover, it is a matter of course that portions having different dimensional relationships and ratios are included between the drawings. In the following description, the upper side of the drawing is referred to as “upper”, the lower side as “lower”, the left side as “left”, and the right side as “right”.

  1 to 8 show an embodiment of an odor measuring apparatus and an odor measuring method according to the present invention. First, the configuration of the odor measuring apparatus will be described with reference to FIGS.

  FIG. 1 is a schematic configuration diagram illustrating an example of an odor measuring apparatus according to the present invention. As shown in FIG. 1, the odor measurement apparatus 100 includes a measurement chamber 20 in which a plurality of odor sensors 10 are installed, a measurement unit 30 electrically connected to each odor sensor 10, and one end of the measurement chamber 20 ( The vacuum unit 40 is attached to the right end portion in FIG. 1 and the load lock chamber 50 is attached to the other end portion (left end portion in FIG. 1) of the measurement chamber.

  FIG. 2 is a cross-sectional view of the odor sensor shown in FIG. As shown in FIG. 2, the odor sensor 10 includes a crystal resonator 11 and an adsorption film 15. The crystal resonator 11 includes a crystal substrate 12, two electrodes 13 disposed on both surfaces (upper surface and lower surface in FIG. 2), and two signal lines 14 each electrically connected to the electrode 13. And comprising.

The crystal unit 11 is, for example, an AT cut type crystal unit. When a voltage is applied between the electrodes 13 provided on both surfaces of the crystal substrate 12, the crystal resonator 11 operates in a so-called thickness-shear vibration mode in which the both surfaces of the crystal substrate 12 vibrate so as to deviate from each other. The resonance frequency (resonance frequency) f ₀ of the crystal unit 11 is inversely proportional to the thickness t of the crystal substrate 12 sandwiched between the electrodes 13 and can be expressed by the following equation (1).
f ₀ = 1670 / t (1)
However, the unit of the thickness t of the quartz substrate 12 is [μm], and the unit of the resonance frequency f ₀ of the quartz crystal resonator 11 is [MHz].

  In the odor sensor 10 using the crystal resonator 11, the relationship between the mass change amount ΔM and the resonance frequency change amount Δf can be expressed by the following Sauerbrey equation (2).

但し、ρは水晶の密度、μは水晶のせん断弾性定数、Ａは有効振動面積であって、略電極面積である。

Where ρ is the density of the crystal, μ is the shear elastic constant of the crystal, A is the effective vibration area, and is approximately the electrode area.

  The adsorption film 15 is made of a material that adsorbs predetermined odor molecules, for example, an organic polymer material. The adsorption film 15 is formed so as to cover both surfaces (the upper surface and the lower surface in FIG. 2) of the quartz substrate 12 including the electrodes 13.

  Examples of the method of forming the adsorption film 15 include a method of applying by spin coating or spraying. More preferably, the adsorption film 15 is formed on at least one surface of the quartz substrate 12 in a vacuum by a method such as vacuum deposition or sputtering. Thereby, when the odor sensor 10 is installed in a vacuum, it is possible to prevent a predetermined odor molecule adsorbed on the adsorption film 15 from being released.

  In the odor sensor 10 configured as described above, when a predetermined odor molecule is adsorbed on the adsorption film 15, the mass of the odor sensor 10 changes, and the resonance frequency changes according to the above-described equation (2).

  The measurement unit 30 shown in FIG. 1 is for detecting a predetermined odor molecule and measuring its mass or its concentration based on the change amount Δf of the resonance frequency of the odor sensor 10. The signal line 14 of each odor sensor 10 is connected to the measurement unit 30, and when a predetermined odor molecule is adsorbed to the odor sensor 10, a detection signal based on the resonance frequency change Δf is input from the odor sensor 10. The

  In the present embodiment, an example in which four odor sensors 10 are installed in the measurement chamber 20 has been described. However, the present invention is not limited to this, and one odor sensor 10 may be installed in the measurement chamber 20. Two, three, or five or more may be installed.

  As shown in FIG. 1, when a plurality of odor sensors 10 are installed in the measurement chamber 20, each of the plurality of odor sensors 10 changes its resonance frequency due to adsorption of different predetermined odor molecules. It is preferable to configure. Specifically, in each odor sensor 10, a material having sensitivity to different predetermined odor molecules may be selected as the adsorption film 15.

  FIG. 3 is a graph for explaining an example of the odor component ratio. FIG. 3 is a graph when the odor of basil is measured using 16 odor sensors 10 expressed as ch1 to ch16, and is plotted based on the above-described resonance frequency change Δf. It is. As shown in FIG. 3, the odor sensor 10 for ch1, ch2, and ch16 detects a large amount of predetermined odor molecules (reacts greatly to odor molecules). On the other hand, the odor sensor 10 for ch8 and ch11 does not detect a predetermined odor molecule (reacts to the odor molecule) or slightly detects a predetermined odor molecule (reacts slightly to the odor molecule). Here, in general, an odor is composed of a plurality of odor molecules, and can be specified (or classified) by the composition ratio (configuration ratio) of each odor molecule. Therefore, for example, by installing 16 odor sensors 10 configured to change the resonance frequency due to adsorption of predetermined odor molecules different from each other, as shown in FIG. The composition ratio (composition ratio) can be measured.

  The vacuum unit 40 shown in FIG. 1 has an exhaust pipe 41 and a vacuum pump 42. The exhaust pipe 41 is a pipe that communicates the measurement chamber 20 with the outside. The vacuum pump 42 is installed in the exhaust pipe 41 and exhausts the gas in the measurement chamber 20 to the outside (in the atmosphere) through the exhaust pipe 41 as indicated by a block arrow in FIG. Thereby, the pressure inside the measurement chamber 20 can be reduced (depressurized), and the inside of the measurement chamber 20 can be set to a predetermined degree of vacuum.

The predetermined degree of vacuum inside the measurement chamber 20 is, for example, a pressure of 10 ⁻⁴ [Pa] or more and 10 ⁻² [Pa] or less. Thereby, the vacuum pump 42 is configured by, for example, a rotary pump, a turbo molecular pump, or the like, so that the vacuum state inside the measurement chamber 20 can be maintained (maintained).

  In addition, a predetermined odor molecule is supplied from the load lock chamber 50 to the inside of the measurement chamber 20 having a predetermined degree of vacuum, as will be described later.

Here, in the measurement chamber 20, the mean free path λ of a predetermined odor molecule is expressed by the following equation using the temperature T of the measurement chamber 20, the pressure P of the measurement chamber 20, and the diameter D of the predetermined odor molecule. It is represented by (3).
λ = 3.11 × 10 ⁻²⁴ × T / (P × D) (3)
However, the unit of the temperature T of the measurement chamber 20 is [K], the unit of the pressure P of the measurement chamber 20 is [Pa], the unit of the diameter D of the predetermined odor molecule is [m], and the predetermined unit The unit of the mean free path λ of the odorant molecule is [m].

  If the mean free path λ of a predetermined odor molecule becomes longer, the probability that the predetermined odor molecule reaches the odor sensor 10 and is adsorbed without colliding with other molecules in the measurement chamber 20 increases. Therefore, as expressed in the above-described equation (3), the mean free path λ of a predetermined odor molecule is inversely proportional to the pressure P in the measurement chamber 20, so that the pressure P in the measurement chamber 20 is reduced and the measurement chamber 20 By setting the inside of the chamber 20 to a predetermined degree of vacuum, the inside of the measurement chamber 20 becomes a measurement environment in which a substance that becomes a noise component for the odor sensor 10, such as water molecules, is very small (excluded as much as possible). It becomes possible to install (use) the sensitive odor sensor 10.

Here, as expressed in the above-described equation (2), the amount of change Δf of the resonance frequency is proportional to the square of the resonance frequency f ₀ of the crystal unit 11, so that the detection sensitivity of the odor sensor 10 is It can be said that the higher the resonance frequency f ₀ of the quartz crystal resonator 11 is, the higher the sensitivity is. On the other hand, when the detection sensitivity of the odor sensor 10 is high, it becomes sensitive to the measurement environment, so that substances other than the odor molecule that is the measurement target may appear as noise components. Therefore, when measuring odor molecules in the atmosphere as in the conventional odor measurement apparatus and odor measurement method, in order to obtain a stable detection signal with less noise components from the odor sensor, for example, the resonance frequency is 30 [MHz]. The quartz crystal was used. As a result, the conventional odor measuring apparatus and odor measuring method have measured odor molecules having a concentration in the order of 100 [ppb] (parts per billion).

On the other hand, in the odor measuring apparatus 100 and the odor measuring method of the present invention, the inside of the measurement chamber 20 is a measurement environment in which a substance that becomes a noise component for the odor sensor 10 is very small (excluded as much as possible). A crystal resonator having a resonance frequency f ₀ of 600 [MHz] can be used. Thus, the odor measuring apparatus 100 and the odor measuring method of the present invention can measure odor molecules having a concentration of the order of 100 [ppt] (one trillionth), and the conventional odor measuring apparatus. Compared with the odor measurement method, measurement sensitivity about 1000 times can be obtained.

  FIG. 4 is a schematic configuration diagram for explaining another example of the measurement chamber 20 shown in FIG. In addition, the vertical, horizontal, and height dimensions inside the measurement chamber 20 are the same as the vertical, horizontal, and height dimensions of the plurality of odor sensors 10, or as shown in FIG. It is preferable that they are slightly the same and substantially the same. Thereby, since the inside of the measurement chamber 20 becomes the minimum volume (volume), the inside of the measurement chamber can be easily set to a predetermined degree of vacuum, and the odor sensor 10 installed in the inside of the measurement chamber 20. However, the probability of adsorbing a predetermined odor molecule can be increased.

  Note that when one odor sensor 10 is installed inside the measurement chamber 20, the vertical, horizontal, and height dimensions inside the measurement chamber 20 are similarly set to the vertical, horizontal, and vertical dimensions of one odor sensor 10. And the height dimension is preferably the same or slightly larger.

  The load lock chamber 50 shown in FIG. 1 is for taking in and out (exchange) a sample containing a predetermined odor molecule while keeping (maintaining) the inside of the measurement chamber 20 in a vacuum. On the other hand, an SPME (Solid Phase Micro Extraction) holder 60 shown in FIG. 1 has an SPME fiber 61 on which a sample containing a predetermined odor molecule is adsorbed. By installing the SPME holder 60 inside the load lock chamber 50, a sample containing a predetermined odor molecule is arranged inside the load lock chamber 50.

  The load lock chamber 50 has an opening 51 and an exhaust pipe 52. The opening 51 is provided at a connection portion between the load lock chamber 50 and the measurement chamber 20, and communicates the load lock chamber 50 and the measurement chamber 20. The opening 51 is configured to be openable and closable, and is opened and closed based on a control signal from a control unit (not shown). Thus, after the sample is arranged inside the load lock chamber 50, the opening 51 is opened, so that predetermined odor molecules contained in the sample are supplied to the measurement chamber 20.

  The exhaust pipe 52 is connected to the vacuum pump 42 described above. The vacuum pump 42 reduces (depressurizes) the pressure inside the load lock chamber 50 to make the inside of the load lock chamber 50 in a vacuum state. Thereby, when the sample is placed in the load lock chamber 50, the inside of the load lock chamber 50 may be released to the atmosphere (outside air), so the vacuum pump 42 reduces the pressure inside the load lock chamber 50. By vacuuming from the atmospheric pressure, the degree of vacuum in the measurement chamber 20 is maintained (maintained) even when the opening 51 is opened.

  In the present embodiment, an example in which the load lock chamber 50 includes the exhaust pipe 52 has been described, but the present invention is not limited to this. For example, the load lock chamber 50 may include a pump for reducing the pressure inside the load lock chamber 50, in addition to the vacuum pump 42.

  The load lock chamber 50 further includes a heater 53. The heater 53 heats the sample disposed inside the load lock chamber 50. Thereby, since the predetermined odor molecule contained in the sample is easily released, the probability that the predetermined odor molecule is adsorbed to the odor sensor 10 installed in the measurement chamber 20 can be increased.

  Next, a method for measuring the concentration of a predetermined odor molecule will be described with reference to FIGS.

  FIG. 5 is a side view for explaining a method of collecting a sample using the SPME holder 60 shown in FIG. First, the vacuum pump 42 shown in FIG. 1 discharges the gas inside the measurement chamber 20 and sets the inside of the measurement chamber 20 to a predetermined degree of vacuum in advance. On the other hand, as shown in FIG. 5, an odor substance A that emits odor is enclosed in a container 70 made of glass or the like that does not leave odor (less adsorbed). Next, the tip of the SPME holder 60 including the SPME fiber 61 is inserted into the container 70. When a certain time, for example, about 1 to 60 minutes elapses, the predetermined odor molecule emitted from the odor substance A is sufficiently adsorbed to the SPME fiber 61, and the predetermined odor molecule is solidified and extracted (solidified). Samples that have been phase extracted) can be collected. As a result, the sample from which molecules other than the predetermined odor molecules are separated is arranged in the load lock chamber 50, so that the predetermined odor molecules with a high concentration (high purity) can be supplied into the measurement chamber 20. .

  Note that when the tip of the SPME holder 60 is inserted into the container 70, the temperature in the container 70 is set to a temperature suitable for adsorbing the predetermined odorant molecules emitted from the odorant substance A to the SPME fiber 61, for example, You may set to the temperature below room temperature and below 80 [degreeC].

  Examples of the material of the SPME fiber 61 include polydimethylsiloxane (PDMS), polyacrylate (PA), divinylbenzene (DVB), polyethylene glycol (PEG), or a combination thereof. The material of the SPME fiber 61 is selected according to a predetermined odor molecule to be extracted.

  FIG. 6 is a view for explaining a state in which the SPME holder 60 shown in FIG. 5 is arranged inside the load lock chamber 50. Next, as shown in FIG. 6, the SPME holder 60 in which a sample containing a predetermined odor molecule is adsorbed to the SPME fiber 61 is installed inside the load lock chamber 50. At this time, the temperature inside the load lock chamber 50 is room temperature, and the opening 51 is closed. Further, the vacuum pump 42 reduces the pressure inside the load lock chamber 50 and performs evacuation from the atmospheric pressure.

  Next, the heater 53 moves the SPME holder 60 installed inside the load lock chamber 50, particularly the SPME fiber 61 on which a sample containing a predetermined odor molecule is adsorbed, for example, 200 [° C.] to 350 [° C.]. Heat at the following temperature.

  FIG. 7 is a diagram for explaining a state in which the opening 51 is opened in FIG. Next, the opening 51 is opened, and a predetermined odor molecule is supplied from the load lock chamber 50 into the measurement chamber 20. Note that before the opening 51 is opened, the vacuum pump 42 discharges the gas inside the measurement chamber 20 and keeps the inside of the measurement chamber 20 at a predetermined degree of vacuum. Further, the vacuum pump 42 continues to discharge the gas inside the measurement chamber 20 after opening the opening 51.

  When a predetermined odor molecule moving inside the measurement chamber 20 is adsorbed to the adsorption film 15 of the odor sensor 10, a detection signal based on the change amount Δf of the resonance frequency is input to the measurement unit 30 via the signal line 14. . The measurement unit 30 measures (calculates) the concentration of a predetermined odor molecule based on this detection signal.

  After measuring the concentration of a predetermined odor molecule, the opening 71 is closed as shown in FIG. Note that the vacuum pump 42 continues to discharge the gas inside the measurement chamber 20 even after the opening 51 is closed. At this time, the vacuum pump 42 preferably discharges the gas inside the measurement chamber 20 at a predetermined speed or flow rate, for example, 60 [sccm]. Thereby, the predetermined odor molecule adsorbed on the odor sensor 10 can be removed.

FIG. 8 is a graph for explaining an example of a temporal change in the resonance frequency in the odor sensor 10 shown in FIGS. 6 and 7. As shown in FIG. 8, at time t ₁ , when the opening 51 is opened and a predetermined odor molecule is supplied to the inside of the measurement chamber 20, the odor sensor 10 adsorbs the predetermined odor molecule to a predetermined value f. The resonance frequency of the odor sensor 10 which was ₁ , changes from time t ₁ to time t ₂ . At time t ₂ , when the opening 51 is closed and the gas inside the measurement chamber 20 is discharged at a predetermined speed, the predetermined odor molecule adsorbed on the odor sensor 10 is removed. As a result, the resonance frequency of the odor sensor 10 is changed from the another predetermined value f _2.

  Thus, according to the odor measuring apparatus 100 of this embodiment, a predetermined odor molecule | numerator is supplied into the inside of the measurement chamber 20 made into the predetermined vacuum degree. Here, if the mean free path λ of a predetermined odor molecule becomes longer, the probability that the predetermined odor molecule reaches the odor sensor 10 and is adsorbed without colliding with other molecules in the measurement chamber 20 increases. . Therefore, as expressed in the above-described equation (3), the mean free path λ of a predetermined odor molecule is inversely proportional to the pressure P in the measurement chamber 20, so that the pressure P in the measurement chamber 20 is reduced and the measurement chamber 20 By setting the inside of the chamber 20 to a predetermined degree of vacuum, the inside of the measurement chamber 20 becomes a measurement environment in which a substance that becomes a noise component for the odor sensor 10, such as water molecules, is very small (excluded as much as possible). It becomes possible to install (use) the sensitive odor sensor 10.

Further, as expressed in the above-described equation (2), the amount of change Δf in the resonance frequency is proportional to the square of the resonance frequency f ₀ of the crystal resonator 11, and therefore the detection sensitivity of the odor sensor 10 is the crystal. It can be said that the higher the resonance frequency f ₀ of the vibrator 11, the higher (higher sensitivity). On the other hand, when the detection sensitivity of the odor sensor 10 is high, it becomes sensitive to the measurement environment, so that substances other than the odor molecule that is the measurement target may appear as noise components. Therefore, when measuring odor molecules in the atmosphere as in the conventional odor measuring apparatus, for example, a quartz resonator having a resonance frequency of 30 [MHz] in order to obtain a stable detection signal with less noise components from the odor sensor. Was used. As a result, the conventional odor measuring apparatus has measured the odor molecule | numerator of the density | concentration (order) of 100 [ppb] (one billionth).

In contrast, in the odor measurement device 100 of the present invention, the measurement chamber 20, since the material becomes a noise component for odor sensor 10 is very small (as much as possible eliminated) the measurement environment, for example, the resonance frequency f ₀ Can use a crystal resonator of 600 [MHz]. Thereby, the odor measuring apparatus 100 of this invention can measure the odor molecule | numerator of the density | concentration (order) of 100 [ppt] (one trillion), compared with the conventional odor measuring apparatus. , About 1000 times the measurement sensitivity can be obtained. Thereby, a measurement sensitivity can be improved and a trace amount odor molecule can be detected and measured.

  Further, according to the odor measuring apparatus 100 of the present embodiment, the load lock chamber 50 in which a sample containing a predetermined odor molecule is disposed communicates with the measurement chamber 20 and has an opening 51 that can be freely opened and closed. Thus, after the sample is arranged inside the load lock chamber 50, the opening 51 is opened, so that predetermined odor molecules contained in the sample are supplied to the measurement chamber 20. Further, when the sample is placed in the load lock chamber 50, the inside of the load lock chamber 50 may be released to the atmosphere (outside air), so the vacuum pump 42 reduces the pressure inside the load lock chamber 50, By performing evacuation from the atmospheric pressure, the degree of vacuum in the measurement chamber 20 is maintained (maintained) even when the opening 51 is opened. Accordingly, it is possible to easily realize the load lock chamber 50 that supplies a predetermined odor molecule while maintaining (maintaining) the degree of vacuum inside the measurement chamber 20.

  Moreover, according to the odor measuring apparatus 100 of this embodiment, the sample mentioned above contains predetermined odor molecules collected by solid phase extraction. As a result, the sample from which molecules other than the predetermined odor molecules are separated is arranged in the load lock chamber 50, so that the predetermined odor molecules with a high concentration (high purity) can be supplied into the measurement chamber 20. . Thereby, the measurement sensitivity can be further increased, and a trace amount of odor molecules can be detected and measured.

  Further, according to the odor measuring apparatus 100 of the present embodiment, the load lock chamber 50 further includes the heater 53 that heats the sample disposed inside the load lock chamber 50. Thereby, since the predetermined odor molecule contained in the sample is easily released, the probability that the predetermined odor molecule is adsorbed to the odor sensor 10 installed in the measurement chamber 20 can be increased. Thereby, the measurement sensitivity can be further increased, and a trace amount of odor molecules can be detected and measured.

  Moreover, according to the odor measuring apparatus 100 of this embodiment, the gas inside the measurement chamber 20 is discharged at a predetermined speed. Thereby, the predetermined odor molecule adsorbed on the odor sensor 10 can be removed. Thereby, different odors can be measured continuously.

Further, according to the odor measuring apparatus 100 of the present embodiment, the predetermined degree of vacuum inside the measurement chamber 20 is a pressure of 10 ⁻⁴ [Pa] or more and 10 ⁻² [Pa] or less. Thereby, the vacuum pump 42 is configured by, for example, a rotary pump, a turbo molecular pump, or the like, so that the vacuum state inside the measurement chamber 20 can be maintained (maintained). Accordingly, it is possible to prevent an increase in the size and cost of the apparatus, increase the measurement sensitivity, and easily realize the odor measuring apparatus 100 capable of detecting and measuring a trace amount of odor molecules. .

  Further, according to the odor measuring apparatus 100 of the present embodiment, the dimensions inside the measurement chamber 20 are the same as or substantially the same as the dimensions of the odor sensor 10. Thereby, since the inside of the measurement chamber 20 becomes the minimum volume (volume), the inside of the measurement chamber 20 can be easily set to a predetermined degree of vacuum, and the odor sensor installed inside the measurement chamber 20 10 can increase the probability of adsorbing a predetermined odor molecule. Thereby, the measurement sensitivity can be further increased, and a trace amount of odor molecules can be detected and measured.

  Moreover, according to the odor measuring apparatus 100 of this embodiment, the adsorption film 15 is formed on at least one surface of the quartz substrate 12 in a vacuum. Thereby, when the odor sensor 10 is installed in a vacuum, it is possible to prevent a predetermined odor molecule adsorbed on the adsorption film 15 from being released. Thereby, the measurement sensitivity can be further increased, and a trace amount of odor molecules can be detected and measured.

  In addition, according to the odor measuring apparatus 100 of the present embodiment, each of the plurality of odor sensors 10 is configured such that the resonance frequency is changed by adsorption of different predetermined odor molecules. Here, in general, an odor is composed of a plurality of odor molecules, and can be specified (or classified) by the composition ratio (configuration ratio) of each odor molecule. Therefore, for example, by installing 16 odor sensors 10 configured to change the resonance frequency due to adsorption of predetermined odor molecules different from each other, as shown in FIG. The composition ratio (composition ratio) can be measured. Thereby, an odor constituted by a plurality of odor molecules can be specified (or classified), and the odor can be identified.

  In addition, according to the odor measurement method of the present embodiment, predetermined odor molecules are supplied into the measurement chamber 20 that has a predetermined degree of vacuum. Here, if the mean free path λ of a predetermined odor molecule becomes longer, the probability that the predetermined odor molecule reaches the odor sensor 10 and is adsorbed without colliding with other molecules in the measurement chamber 20 increases. . Therefore, as expressed in the above-described equation (3), the mean free path λ of a predetermined odor molecule is inversely proportional to the pressure P in the measurement chamber 20, so that the pressure P in the measurement chamber 20 is reduced and the measurement chamber 20 By setting the inside of the chamber 20 to a predetermined degree of vacuum, the inside of the measurement chamber 20 becomes a measurement environment in which a substance that becomes a noise component for the odor sensor 10, such as water molecules, is very small (excluded as much as possible). It becomes possible to install (use) the sensitive odor sensor 10.

Further, as expressed in the above-described equation (2), the amount of change Δf in the resonance frequency is proportional to the square of the resonance frequency f ₀ of the crystal resonator 11, and therefore the detection sensitivity of the odor sensor 10 is the crystal. It can be said that the higher the resonance frequency f ₀ of the vibrator 11, the higher (higher sensitivity). On the other hand, when the detection sensitivity of the odor sensor 10 is high, it becomes sensitive to the measurement environment, so that substances other than the odor molecule that is the measurement target may appear as noise components. Therefore, when measuring odor molecules in the atmosphere as in the conventional odor measurement method, in order to obtain a stable detection signal with less noise components from the odor sensor, for example, a crystal resonator having a resonance frequency of 30 [MHz] Was used. As a result, the conventional odor measuring method has measured odor molecules having a concentration of the order of 100 [ppb] (parts per billion).

In contrast, in the odor measuring method of the present invention, the measurement chamber 20, since the material becomes a noise component for odor sensor 10 is very small (as much as possible eliminated) the measurement environment, for example, the resonance frequency f ₀ A 600 [MHz] crystal resonator can be used. Thereby, the odor measuring method of this invention can measure the odor molecule | numerator of the density | concentration (order) of 100 [ppt] (one trillionth), Compared with the conventional odor measuring method, A measurement sensitivity of about 1000 times can be obtained. Thereby, a measurement sensitivity can be improved and a trace amount odor molecule can be detected and measured.

  Note that the configurations of the above-described embodiments may be combined, or some components may be replaced. The configuration of the present invention is not limited to the above-described embodiment, and various modifications may be made without departing from the gist of the present invention.

  DESCRIPTION OF SYMBOLS 10 ... Odor sensor, 20 ... Measurement chamber, 30 ... Measurement part, 42 ... Vacuum pump, 50 ... Load lock chamber, 51 ... Opening part, 53 ... Heater, 60 ... SPME holder, 100 ... Odor measurement apparatus

Claims (10)

An odor sensor configured to change a resonance frequency by adsorption of a predetermined odor molecule;
A measurement chamber in which the odor sensor is installed;
A vacuum pump for setting the inside of the measurement chamber to a predetermined degree of vacuum,
The odor measuring apparatus, wherein the predetermined odor molecule is supplied into the measurement chamber having a predetermined degree of vacuum. A load lock chamber in which a sample containing the predetermined odor molecule is disposed;
The load lock chamber has an openable / closable opening communicating with the measurement chamber,
The odor measuring apparatus according to claim 1, wherein the vacuum pump reduces a pressure inside the load lock chamber. The odor measurement apparatus according to claim 2, wherein the sample includes the predetermined odor molecule collected by solid phase extraction. The odor measuring apparatus according to claim 2 or 3, wherein the load lock chamber further includes a heater for heating the sample. The odor measurement apparatus according to any one of claims 1 to 4, wherein the gas inside the measurement chamber is discharged at a predetermined speed. The odor measuring apparatus according to claim 1, wherein the predetermined degree of vacuum is a pressure of 10 ⁻⁴ Pa or more and 10 ⁻² Pa or less. The odor measuring apparatus according to any one of claims 1 to 6, wherein a dimension inside the measurement chamber is the same as or substantially the same as a dimension of the odor sensor. The odor sensor includes a crystal resonator including a crystal substrate, and an adsorption film that adsorbs the predetermined odor molecule,
The odor measuring apparatus according to claim 1, wherein the adsorption film is formed on at least one surface of the quartz substrate in a vacuum. A plurality of the odor sensors;
9. The odor measuring apparatus according to claim 1, wherein each of the plurality of odor sensors is configured to change a resonance frequency by adsorption of the predetermined odor molecules different from each other. . The inside of the measurement chamber in which the odor sensor whose resonance frequency is changed by adsorption of a predetermined odor molecule is set to a predetermined vacuum degree;
Supplying the predetermined odor molecule to the measurement chamber. The odor measurement method, comprising:

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