JP2006322791A - System for measuring degree of swelling, and its method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a swelling degree measuring system capable of accurately measuring the degree of swelling of polymer gels in solutions. <P>SOLUTION: The swelling degree measuring system comprises a piezoelectric transducer 4, provided with both a beam part 2 having a fixed end part and capable of fixing a polymer gel 6 to be measured, and a piezoelectric element 3 provided for part of the beam part 2; an immersion tank 7, in which a solution 8 for immersing the polymer gel 6 is stored; a power supply part 11 for oscillating the piezoelectric element 3; an admittance-measuring part 14 for measuring the admittance of the piezoelectric element 3; a swelling degree analysis part 16 for analyzing the degree of swelling of the polymer gel 6, on the basis of admittance measurement data 23 measured by the admittance measuring part 14; and an output part 17 for outputting swelling degree analysis data 25 of the polymer gel 6, acquired by the swelling degree analysis part 16. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  In the present invention, a polymer gel is fixed to a piezoelectric transducer equipped with a piezoelectric element, immersed in a solution, and the admittance of the piezoelectric element is measured to measure the degree of swelling of the polymer gel with high accuracy in real time. The present invention relates to a measurement system and method.

Among the polymer gels, the external stimulus-responsive polymer gel is highly expected as a material for the next-generation device because its characteristics are greatly changed by the external stimulus. In particular, the temperature-responsive polymer gel has an interesting property that the degree of swelling varies with temperature. Using this property, temperature control of the substance permeability in the gel can be used for drug delivery systems, chemical valves for micro chemical chips, and the hydrophilicity of the gel can be controlled for cell culture sheets and separation membranes for water treatment. The application of is considered.
In designing a material in which such a temperature-responsive gel is optimized for various application fields, it is strongly required to measure the degree of swelling with respect to a temperature change of the gel accurately and in real time.
However, in measuring the degree of swelling of a temperature-responsive polymer gel, an electronic balance is often used to measure and evaluate the hydrophilicity of the prepared polymer film. As a specific measuring method, the adjusted polymer film is cut into a certain size, immersed in a solution having a constant temperature for a predetermined time, taken out, and weighed with a balance. The degree of swelling of the membrane is calculated from its weight, membrane and water density.
On the other hand, a piezoelectric element is an element widely used from an ignition device such as a lighter to a speaker, a microphone, an oscillation circuit, a driving device, and the like. For example, Patent Document 1 discloses a pollutant measuring apparatus that measures the amount of fouling adhered to the surface of an outdoor structure equipped with the piezoelectric element using a change in vibration characteristics.

In the invention disclosed in Patent Document 1, a piezoelectric element is mounted on the surface of an outdoor structure, a plurality of vibration electrodes are provided on the piezoelectric element, and a voltage is applied between the electrodes to vibrate the piezoelectric element. The vibration characteristic of the piezoelectric element is detected, the amount of adhered fouling on the surface of the outdoor structure is obtained based on the change of the vibration characteristic, and the heating current is supplied to at least one of the electrodes to evaporate the moisture. It is something to be made.
In the pollutant measuring apparatus configured as described above, the amount of the pollutant attached to the surface of the outdoor structure can be directly obtained as a change with time.
In addition, as an apparatus using a piezoelectric element, Patent Document 2 uses vibration generated when a piezoelectric element is vibrated as a sound wave generation source in an automatic analyzer having means for stirring an object to be stirred with sound waves. Yes.
Furthermore, Patent Document 3 discloses a sound pressure measuring device, in which a piezoelectric element is incorporated in a sensor unit, and a receiving rod that receives ultrasonic waves transmitted from an ultrasonic transducer via pure water. 1 is used to piezoelectrically convert the received ultrasonic vibration.

However, in the method for measuring the degree of swelling of the polymer gel described above, (1) real-time measurement is impossible, (2) the measurement accuracy depends on the accuracy of the balance, (3) the gel needs to be taken out from the solution once, There were problems such as large measurement error and (4) unsuitable for measurement of thin film and small size gel. In addition, there are a method for calculating the degree of swelling from the change in gel size and a measurement method using buoyancy while the membrane is immersed in the solution, but the former has a low accuracy in measuring the gel size, so accurate measurement is possible. There is a problem that the latter is difficult to measure in real time.
In the invention disclosed in Patent Document 1, the amount of fouling substances adhering to the surface of an outdoor structure can be obtained in real time, but the polymer gel is immersed in a solution and the degree of swelling with respect to the solution is measured. There was a problem that it was not possible.
In the invention disclosed in Patent Document 2, a piezoelectric element is used as a sound wave generation source, and some amount is not measured using a change in the vibration frequency of the piezoelectric element. There was a problem that the degree could not be measured.
Also in the invention disclosed in Patent Document 3, the piezoelectric element is used for piezoelectric conversion of ultrasonic vibration, and there is a problem that the degree of swelling of the polymer gel cannot be measured.
JP-A-8-193825 JP 2002-71697 A JP 2004-251845 A

  The present invention has been made in view of such a conventional situation, and an object of the present invention is to provide a swelling degree measuring system capable of measuring the swelling degree of a polymer gel accurately and in real time in a solution.

In order to achieve the above object, a swelling degree measuring system according to the first aspect of the present invention includes a beam portion capable of fixing a polymer gel to be measured by fixing an end portion thereof, and a piezoelectric element provided in a part of the beam portion. A piezoelectric transducer comprising: a dipping tank storing a solution in which the polymer gel is immersed; a power supply unit that vibrates the piezoelectric element; an admittance measuring unit that measures admittance of the piezoelectric element; and an admittance measured by the admittance measuring unit A swelling degree analysis unit that analyzes the swelling degree of the polymer gel based on the measurement data and an output unit that outputs the swelling degree analysis data of the polymer gel obtained by the swelling degree analysis unit are provided.
In the swelling degree measuring system having the above configuration, the admittance measuring unit measures the admittance while vibrating the piezoelectric element while immersing the beam part capable of fixing the polymer gel in the immersion tank, and the degree of swelling is determined based on the amount of change in admittance. The analysis unit has an effect of analyzing the degree of swelling of the polymer gel.
In the invention disclosed in Patent Document 1 as well, the quartz diaphragm as a piezoelectric element is vibrated to detect the amount of fouling substances adhering to the detection surface, but in order to measure the swelling degree of the polymer gel It is necessary to immerse in a solution, and the configuration as disclosed in Patent Document 1 cannot exhibit an action related to swelling.
In addition, in the configuration in which the piezoelectric element is provided in the beam part, the vibration of the piezoelectric element is transmitted to the polymer gel through the beam part to generate a mechanical impedance change, and the change is again transmitted through the beam part through the piezoelectric part. The action of measuring the admittance of the element and analyzing the swelling degree of the polymer gel based on the change of the admittance is different from the action of the invention disclosed in Patent Document 1.

According to a second aspect of the present invention, there is provided the swelling degree measuring system according to the first aspect, wherein the polymer gel is fixed to a probe that is detachably attached to the beam section instead of the beam section. It is what is done.
The operation of the swelling degree measuring system according to such a configuration is substantially the same as the operation of the invention described in claim 1, but the polymer gel is attached to a probe separate from the beam portion and managed individually. It has the action.

A swelling degree measuring system according to a third aspect of the invention is the swelling degree measuring system according to the first aspect, wherein at least two beam portions are provided in parallel, and one of the beam portions has a known characteristic. A certain polymer gel can be fixed.
In the swelling degree measuring system according to such a configuration, at least two beam portions are provided in parallel, a polymer gel having a known characteristic is fixed to one of the beam portions, and a polymer to be measured is attached to another beam portion. The gel can be fixed and simultaneously vibrated by the piezoelectric element, and it has an effect of providing a real-time measurement control section.

Furthermore, the swelling degree measuring system according to the invention of claim 4 is the swelling degree measuring system according to any one of claims 1 to 3, wherein a temperature measuring unit capable of measuring the solution temperature of the immersion bath; A temperature adjusting unit capable of adjusting the solution temperature.
Such a swelling degree measuring system has an effect of measuring the swelling degree while measuring and adjusting the solution temperature of the immersion bath.

Furthermore, the swelling degree measuring system according to the invention of claim 5 relates to the characteristics of the solution immersed in order to swell the polymer gel in the swelling degree measuring system according to any one of claims 1 to 4. An input database for readable storage of solution data, polymer gel data relating to polymer gel characteristics, beam section and / or piezoelectric element characteristics, and solution data and polymer gel in advance in the input database An input unit for inputting data and measurement system data, and an output database for readable storage of admittance measurement data and / or swelling degree analysis data are provided.
In such a swelling degree measurement system, each data is stored in the input database via the input unit in advance, so that the swelling degree analysis unit reads these data from the input database and analyzes the swelling degree. In addition, the measurement result and the analysis result are stored in the output database and read out by the output unit.

Further, the swelling degree measuring method according to the invention described in claim 6 is based on the invention described in claim 1 as a method invention, and is highly applicable to a piezoelectric transducer including a piezoelectric element that vibrates by an AC power source. The molecular gel is fixed and immersed in a solution, the admittance of the piezoelectric element is measured before and after the swelling of the polymer gel to calculate the admittance change, and the admittance change of the piezoelectric element before and after the swelling and the polymer gel are measured. The mass change amount of the polymer gel is calculated based on the relationship of the mass change amount of the polymer gel to calculate the degree of swelling of the polymer gel.
Such a method for measuring the degree of swelling has the same action as the invention described in claim 1.

  In the swelling degree measuring system according to claims 1 to 5 of the present invention and the swelling degree measuring method according to claim 6, the solution is stored in a dipping bath and the polymer gel is immersed in the solution, Since the piezoelectric element is vibrated through the beam portion, it is possible to accurately measure the polymer gel in a swollen state under a constant vibration condition in real time.

  Moreover, in particular, in the swelling degree measuring system according to claim 2, since the probe for fixing the polymer gel is provided, the polymer gel which is the measurement target of the swelling degree is attached to a plurality of probes for management. It is possible. Moreover, since the temperature characteristics may change when the polymer gel is dried, it is desirable to store it in water. However, in this case as well, the polymer gel may be fixed to the probe and separated from the piezoelectric transducer for management. it can.

  Further, particularly in the swelling degree measuring system according to claim 3, since the polymer gel having a known characteristic is fixed to at least one beam portion, the change in the admittance of the piezoelectric element with respect to the polymer gel to be measured in real time. It is possible to compare or calibrate the measurement results of the amount and the degree of swelling, and to improve the measurement accuracy.

  In particular, in the swelling degree measuring system according to claim 4, since the swelling degree can be measured while measuring and adjusting the solution temperature of the immersion bath, the swelling degree of the polymer gel having temperature dependency is measured. Can be carried out with higher accuracy.

  In the swelling degree measuring system according to claim 5, by storing each data in the input database, it is not necessary to sequentially input the data for analyzing the swelling degree, and the swelling degree analyzing unit stores these data. And the degree of swelling can be easily analyzed. In addition, the measurement results and analysis results are stored in an output database and can be easily managed. Furthermore, the data can be stored in the output database and read out via the output unit.

Hereinafter, an embodiment of a swelling degree measuring system according to the present invention will be described with reference to FIG. (In particular, corresponding to claims 1, 2, 4 and 5)
FIG. 1 is a configuration diagram of a swelling degree measuring system according to the present embodiment. The degree-of-swelling measuring system 1 is attached to the end of the beam unit 2 and a piezoelectric transducer 4 comprising a beam unit 2 suspended from the transducer support unit 12 and a piezoelectric element 3 attached to the beam unit 2. A polymer gel membrane probe 5 is provided.
The polymer gel membrane probe 5 is plate-like and has a polymer gel membrane 6 fixed on both sides thereof, and is immersed in a solution 8 stored in an immersion tank 7. A portion within a dotted line indicated by A in the figure is a polymer gel film probe 5 attached to the beam portion 2 from the direction of arrow B in the figure, and a polymer gel film 6 fixed to the polymer gel film probe 5. This relationship is schematically shown.
The immersion tank 7 is provided with a temperature adjusting unit 9, and the temperature of the solution 8 can be kept constant.
An AC power supply 11 that supplies a voltage applied to the piezoelectric element 3 is connected to the piezoelectric element 3, and an output voltage Vout with respect to the input voltage Vin is input to the admittance measuring unit 14, and the admittance of the piezoelectric element 3 is measured. Note that admittance is the reciprocal of impedance.
Further, the temperature of the solution 8 in the immersion bath 7 is measured by the temperature measuring unit 15 through the temperature measuring unit 10. The admittance measurement unit 14 stores the measurement result as admittance measurement data 23 and the temperature measurement unit 15 stores the measurement result as temperature measurement data 24 in a readable manner in the output database 19.

The swelling degree analysis unit 16 analyzes the degree of swelling of the polymer gel film 6 swollen by the solution 8 and stores the analysis result in the output database 19 so as to be readable as the swelling degree analysis data 25.
For the analysis in the swelling degree analysis unit 16, the solution data 20 regarding the swollen solution 8, the polymer gel film data 21 of the polymer gel film 6 in the swollen state, and the piezoelectric transducer 4 and the AC power supply 11 are preliminarily used. Since the measurement system data 22 based on the characteristics is required, the data is stored in advance in the input database 18 via the input unit 13 in a readable manner.

  The solution data 20 specifically includes the component and type of the solution, the density of the solution, and the polymer gel film data 21 includes the type of polymer gel film, the mass of the polymer gel film during drying, Density, dimensions, Young's modulus, Poisson's ratio, and the admittance response peak frequency during drying with the temperature described later as parameters are included. The measurement system data 22 includes the Young's modulus, Poisson's ratio, density, etc. of the beam portion 2 of the piezoelectric transducer 4 and the density, elastic coefficient, relative dielectric constant, piezoelectric constant, etc. of the piezoelectric element 3, which will be described later. The coefficient k representing the relationship between the shift amount Δf of the peak frequency of the admittance response and the mass change Δm of the polymer gel film 6 is also included.

  The temperature adjustment unit 9 adjusts the temperature adjustment unit 9 so as to obtain a preset water temperature of the solution 8 while receiving a signal related to the water temperature of the solution 8 measured by the temperature detection unit 10 and the temperature measurement unit 15. It is good to do so. Further, in the present embodiment, the transducer support portion 12 supports the piezoelectric transducer 4, but the transducer support portion 12 is not particularly provided, for example, the periphery of the immersion bath 7 is provided high, and the piezoelectric transducer is provided on this. 4 may be fixed. That is, the transducer support portion 12 does not need to be provided as an independent element, and any transducer can be used as long as the piezoelectric transducer 4 can be supported.

Next, the principle of swelling degree measurement of the swelling degree measuring system according to the present embodiment will be described with reference to FIGS.
FIG. 2A is a side view showing the dimensions of the piezoelectric transducer 4, the polymer gel film probe 5, and the polymer gel film 6 extracted from the swelling degree measurement system according to the present embodiment, and FIG. It is a front view.
The piezoelectric transducer 4 has a structure in which a ceramic piezoelectric element 3 having a size of 10 × 5 × 0.3 mm is fixed to an aluminum cantilever beam portion 2 having a length l = 75 mm. The polymer gel membrane probe 5 is for immobilizing a 10 × 5 mm polymer gel membrane 6 on a 30 × 5 × 0.5 mm aluminum plate. The dimensions in the present swelling degree measuring system 1 are used as an analysis model, and are a size that can be prototyped in a laboratory, and are not particularly limited to these dimensions.
First, numerical simulation of the piezoelectric transducer 4 shown in FIG. 2 is performed using a finite element method. The physical property values in the analysis are shown in Table 1.

In addition, in order to measure changes in the mass and volume of the polymer gel film 6 with changes in impedance of the piezoelectric element 3, an input voltage (v _in ) is applied to the piezoelectric element 3 via a resistor as shown in FIG. did. Here, when the input voltage is represented by equation (1), the admittance Y of the piezoelectric element 3 is represented by equation (2). In the specification of the present application, when the input voltage is a function of time, it is lowercase (including italics), and when it is a function of frequency or constant (for example, amplitude), it is uppercase (including italics).

In the numerical simulation in the swelling degree measuring system according to the present embodiment, the input voltage amplitude is set to A = 1V, and the resistance value is set to R = 1000Ω.
The polymer gel film 6 swells by absorbing moisture when immersed in warm water. In that case, both the mass and volume of the polymer gel film 6 change. Therefore, when the mass change of water absorbed by the polymer gel film 6 is Δm, the density of water is d _w , and the volume change is ΔV = Δm / d _w , the thickness of the polymer gel film 6 is expressed by the equation (3). expressed.

In the formula (3), S is the area of the polymer gel film 6. On the other hand, in the numerical analysis, since the physical property value of the polymer gel film 6 is given by the thickness and density of the film, a method of giving the mass change Δm due to moisture to the equivalent density of the film is adopted. If the mass of the polymer gel film 6 at the time of drying is m and the density is dm, the equivalent density d _Δm of the polymer gel film 6 is given by equation (4).

The frequency response of the piezoelectric transducer 4 was simulated while changing the mass change Δm of the polymer gel film 6 from 0 to 10 mg. The obtained piezoelectric admittance response is shown in FIG. As shown in FIG. 4, the peak frequency shifts to the left and the amplitude tends to decrease due to the mass change of the polymer gel film 6.
Further, FIG. 5 shows the relationship between the peak frequency shift amount Δf and the mass change Δm of the polymer gel film 6. According to FIG. 6, it is understood that the amount of water infiltrated into the polymer gel film 6 is proportional to the shift amount of the peak frequency of the piezoelectric transducer 4 and has a substantially linear relationship. Moreover, the coefficient is obtained by linear approximation.

As a result, k = 45 [Hz / mg] was calculated.
Using this coefficient k, the mass change (Δm) that caused the swelling degree change is obtained from the admittance response (Δf) measured by the admittance measuring unit 14, and finally the swelling degree is obtained.
Here, a method for deriving the admittance of the piezoelectric element 3 measured by the admittance measuring unit 14 will be described with reference to FIGS. 6 and 7.
In general, the sine wave voltage v (t) can be expressed by the following equation using the amplitude V _a , the phase θ, the angular frequency ω, and the offset voltage V _off .

  further,

Then, equation (6) becomes

And can be linearized. The most probable values A ₀ , B ₀ , and C _{0 of} A, B, and C are obtained by applying the least square method to Equation (8), and the amplitude V _a is expressed by the following equation using A ₀ and B _0. I can express.

Discrete data V _F (n), V _Z (n) obtained by the AD converter by the above method and V _P (n) = V _F (n) −V _Z (n) applied to both ends of PZT (piezoelectric element). , n = 1, 2, 3,..., X, the amplitude values V _Fa , V _Za , and V _Pa are obtained. Next, a method of calculating the real part R _e (Y) of the PZT admittance value using these amplitude values will be considered. As shown in FIG. 7, when the voltage signals V _F , V _Z and V _P are expressed as vectors and the phase angle β and V _P are used to determine _Re (V _P ),

It becomes. If the additional impedance Z of the circuit shown in FIG. 6 is a resistance R [Ω], the current I flowing through the circuit is

And the admittance real part R _e (Y) of PZT is

It becomes. Substituting Equation (10) and Equation (11) into this

It becomes. Furthermore, from the relationship of FIG.

Is substituted into the equation (13), the piezoelectric element admittance real part R _e (Y) is obtained as follows. These calculations are executed by the admittance measurement unit 14.

Next, an analysis processing method in the admittance measuring unit 14, the temperature measuring unit 15, and the swelling degree analyzing unit 16 of the swelling degree measuring system according to the present embodiment will be described. (In particular, corresponding to claim 6)
FIG. 8 is a flowchart showing analysis procedures of the admittance measurement unit, temperature measurement unit, and swelling degree analysis unit according to the present embodiment. In this figure, since these three measurement units and analysis units will be described in detail, as a previous step, the piezoelectric transducer 4 having the piezoelectric element 3 that vibrates by the AC power source is directly or via the polymer gel film probe 5. The step of fixing the polymer gel film 6 and immersing it in a solution for swelling to stabilize the temperature at a constant value is included.
In FIG. 8, the admittance measurement unit 14 measures the admittance response waveform of the piezoelectric element 3 provided in the piezoelectric transducer 4 in step S1, and measures its peak frequency. The measured peak frequency is stored in the output database 19 as admittance measurement data 23.

Next, the temperature measurement unit 15 measures the temperature of the solution in which the polymer gel film 6 is immersed in step S3, and stores the temperature measured in step S4 in the output database 19 as temperature measurement data 24. In FIG. 8, the step in the temperature measurement unit 15 is a step after the admittance measurement unit 14, but may be performed simultaneously or as a step before steps S <b> 1 and S <b> 2. Thus far, admittance measurement and temperature measurement for analysis of the degree of swelling have been performed.
The swelling degree analysis unit 16 reads the obtained admittance measurement data 23 from the output database 19 (step S5), and calculates the amount of change from the response peak frequency of the dried polymer gel film 6 (step S6). The response peak frequency of the dried polymer gel film 6 may be stored in advance in the input database 18 as the polymer gel film data 21 and read from the input database 18 simultaneously with the admittance measurement data 23.

Once the admittance change amount is calculated, in step S7, the mass change amount of the polymer gel film is calculated using the coefficient k expressed by the above-described equation (5). Since this equation (5) is stored in advance in the input database 18 as part of the measurement system data 22, it may be read from the input database 18 and used.
Thereafter, in step S8, the degree of swelling is calculated from the change in mass of the polymer gel film obtained in step S7 using equation (5). In step S9, the calculated degree of swelling is used as swelling degree analysis data 25. Store in the output database 19.
Of course, the data may be output directly to the output unit 17 shown in FIG. 1 without being stored in the output database 19, or may be output from the output unit 17 via the output database 19.

Next, the creation of a swelling degree measurement system including the piezoelectric transducer 4 as shown in FIG. 2 and the results of experiments performed using the system will be described with reference to FIGS.
In the present embodiment, the temperature-responsive polymer gel membrane probe 5 is fixed to the aluminum plate having the dimensions described above using N-isopropylacrylamide as the polymer gel membrane 6.
Two methods were used for fixing the polymer gel film 6. One is a method in which a polymer solution is cast, dried to form a solid film, and then attached to an aluminum plate. This film is used as an adhesive polymer gel film 6. The other is a method in which the produced polymer solution is applied to an aluminum plate and dried, and this film is used as a coating gel film. In the latter case, the coating gel film was fixed to an aluminum plate, and then the entire aluminum plate was heat-treated at 160 ° C. for 20 minutes, and subjected to a cross-linking treatment with a 0.025 vol% glutamine aldehyde aqueous solution for 1 day. In the former case, the adhesive gel film was subjected to the same cross-linking treatment and then pasted on an aluminum plate using an aqueous polyvinyl alcohol (PVA) solution as an adhesive.
When these polymer gel films 6 are bonded to the polymer gel film probe 5, the polymer gel film 6 is formed by opening six holes with a diameter of 1 mm in the range of the tip of the polymer gel film probe 5 to 10 mm. It connects through these holes, and it is devised so that the adhesive force of the polymer gel film 6 to the polymer gel film probe 5 is strengthened.

FIGS. 9A and 9B show the state of the polymer gel membrane fixed to the polymer gel membrane probe according to the present embodiment, divided into the two methods described above. Is a pasted gel membrane pasted into a solid membrane (pasted gel membrane), and (b) is a coated gel membrane dried and immobilized (coating gel membrane). FIG. 9C shows the piezoelectric transducer according to the present embodiment. The hole drilled in the range of 10 mm tip of the polymer gel membrane probe 5 is particularly as shown in FIG. 9B.
In the present embodiment, the polymer gel membrane probe 5 is fixed to the piezoelectric transducer 4 by using a double-sided tape, and the polymer gel membrane probe 5 can be easily removed. Of course, other than double-sided tape, for example, fixing with bolts and nuts is desirable because it is easy to position and firmly fixed, but it is not easy to replace the polymer gel membrane probe 5 when welded. It is necessary to keep in mind.
The swelling degree of the polymer gel film is measured using the piezoelectric transducer 4 configured as described above. Hereinafter, the measurement method will be described.
For example, when a polymer gel film is immersed in water, the film swells, and the mass of the film changes due to moisture infiltrated therein. This mass change causes a change in the mechanical impedance of the piezoelectric transducer 4, and therefore, the change in the mechanical impedance can be measured with high accuracy by measuring the electrical impedance of the piezoelectric element. .

A concrete method will be described as an example with reference to FIG.
When the polymer gel film 6 of the polymer gel film probe 5 is immersed in water and the water temperature is changed, the mass change of the film due to swelling of the polymer gel film 6 is changed. And the temperature change of the water content of the polymer gel film 6 is examined.
An admittance analyzer is used as the admittance measurement unit 14 to measure the admittance response of the piezoelectric transducer 4 while sweeping a sine wave of a constant voltage to the piezoelectric element 3.
First, the frequency response of admittance is measured for both the case where only the aluminum substrate of the polymer gel film probe 5 is installed on the piezoelectric transducer 4 and the case where the polymer gel film 6 is fixed to the polymer gel film probe 5. The operation characteristics of 4 were investigated.

FIG. 10 is a graph showing the operating characteristics of the piezoelectric transducer 4. In the figure, the spectrum indicated by the dotted line is the result of the polymer gel membrane probe 5 alone, and the spectrum indicated by the solid line is the result when the polymer gel membrane 6 is fixed to the polymer gel membrane probe 5.
In order to grasp the entire characteristics, the sweep frequency range is 0 to 40 kHz, and the sweep frequency step is 50 Hz. From the figure, it can be seen that when the polymer gel film 6 is fixed, the admittance frequency response waveform is shifted to the left side, that is, to the low frequency side as compared with the case where the polymer gel film 6 is not fixed. This difference is considered to be due to an increase in mass of the polymer gel membrane probe 5 due to the polymer gel membrane 6 being fixed.
Although it is possible to perform the mass evaluation of the gel using the admittance waveform of the whole region of 0 to 40 kHz, since the measurement takes a long time, the mass change of the film is evaluated using the single peak waveform.
Considering the response of the one-degree-of-freedom system, both the resonance frequency and the maximum amplitude decrease due to an increase in mass. However, since the waveform in which this feature appears remarkably is a waveform around 25 kHz, the measurement is around this 25 kHz. I decided to do it.
Before measuring the characteristics of the polymer gel film 6, it is necessary to examine the influence of the temperature on the piezoelectric transducer 4 itself. Therefore, only the aluminum substrate of the polymer gel film probe 5 that does not fix the polymer gel film 6 is used. The admittance response of the piezoelectric transducer 4 was measured by changing the water temperature while the tip of the polymer gel membrane probe 5 was immersed in water. As described above, it is known from the characteristics of the resonance frequency and the maximum amplitude that a waveform in the vicinity of 25 kHz is desirable. Therefore, the surrounding frequency range of 23 kHz to 27 kHz is set as the measurement frequency range, and the sweep frequency step is set to 5 Hz. The water temperature was changed from 15 ° C to 50 ° C.

The measurement results are shown in FIG. As shown in FIG. 11, it was confirmed that the change in the water temperature has almost no influence on the admittance frequency response of the piezoelectric transducer 4.
Next, measurement of the degree of swelling of the polymer gel film 6 in this example will be described.
The degree of swelling He of the polymer gel film 6 is expressed by the formula (5).

Here, Δm and Δf are the amount of water infiltrated by the polymer gel film 6 and the peak frequency shift amount of the admittance waveform of the piezoelectric element 3, respectively, and V _m and d _w are respectively the polymer gel film 6 at the time of drying. Volume and density of water.
The degree of swelling was measured by immersing the polymer gel membrane probe 5 having the polymer gel membrane 6 fixed in the immersion tank 7 and using water as the solution 8 to change the water temperature from a low temperature to a high temperature.
At first, the water temperature was set to 20 ° C., and thereafter the admittance response of the piezoelectric element 3 was measured by the admittance measuring unit 14 while increasing the temperature by 6 ° C. to finally 50 ° C.
In addition, since it carried out in the immersion tank 7 which is not equipped with the temperature control part 9 in a present Example, since it performed by adding high temperature warm water to temperature rising, water was discharged | emitted with the syringe in order to keep a water level constant.

The measurement by the admittance measurement unit 14 was performed after the waiting state was stabilized for 5 minutes after reaching the target temperature. A graph obtained by repeatedly measuring the admittance response from 20 ° C. to 50 ° C. is shown in FIG.
In FIG. 12, the vertical axis represents admittance, and the horizontal axis represents the frequency of the admittance waveform. It can be seen that the frequency increases as the water temperature increases. Table 2 shows the difference from the reference frequency (24.5 kHz) for each water temperature.

Further, both the pasted gel membrane 6 (pasted gel membrane) and the one coated and dried and immobilized (coating gel membrane) are swollen using the formula (5). The degree was calculated. The result is shown in FIG. 13 while comparing with the degree of swelling calculated using an electronic balance.
In FIG. 13, the horizontal axis indicates the temperature of water subjected to swelling, and the vertical axis indicates the degree of swelling. Although there is a slight difference in the degree of swelling between what was applied later as a solid film and what was applied and dried and fixed, the value was almost the same as the degree of swelling of the polymer gel film obtained with an electronic balance. It turns out that it is obtained.

In the present embodiment configured as described above, the degree of swelling of the polymer gel film can be accurately measured in real time in the solution without taking it out of the solution.
Next, an example relating to the combination of the piezoelectric transducer and the polymer gel film probe of the swelling degree measuring system according to the present embodiment will be described with reference to FIG.
14A is a diagram showing a configuration of a basic combination of the piezoelectric transducer 4 and the polymer gel film probe 5 to which the polymer gel film 6 described in FIGS. 1 to 3 is fixed. In contrast to this configuration, (b) is different from the side where the polymer gel film 6 is directly fixed to the beam portion 2 a without providing the polymer gel film probe 5 and the piezoelectric element 3 is fixed to the polymer gel film 6. It is provided at the end, and is clamped by the fixing members 29a and 30a and fixed by the position adjusting tool 26 so as to be adjustable.

In the embodiment shown in (b), a hole (not shown) through which the position adjusting tool 26 can be inserted is formed in the beam portion 2a on the side where the piezoelectric element 3 is provided, and the position adjusting tool 26 is fixed. An operation is performed in which the position of the beam portion 2a is adjusted by loosening it in relation to the materials 29a and 30a, and the position adjusting tool 26 is fastened and fixed again after the adjustment.
By doing in this way, it is possible to always make the longitudinal position of the beam portion 2a constant, and it is also possible to adjust the positional relationship with the polymer gel film 6. It is possible to adjust the effect of the change in mechanical impedance generated in the beam portion 2a by the polymer gel film 6 by adjusting the position of the beam portion 2a, thereby improving the accuracy of measurement of the degree of swelling of the polymer gel film 6. It becomes possible. Further, the beam portion 2a can be easily exchanged, and the need to store the polymer gel membrane probe 5 as a unit can be reduced. In FIG. 14B, the piezoelectric element 3 is shown to be sandwiched between the fixing members 29a and 30a. However, the piezoelectric element 3 is not necessarily provided with a hole through which the position adjusting tool 26 is inserted. Needless to say, the position of the piezoelectric element 3 and the position of the hole may be shifted.

Next, the embodiment shown in FIG. 14C will be described. (In particular, corresponding to claim 3)
In the embodiment shown in (c), the polymer gel film 6a having a known characteristic and the polymer gel film 6 to be measured are fixed to the ends of the two beam portions 2b and 2c, respectively, and the piezoelectric element is fixed. 3 can be simultaneously vibrated, and the data of the polymer gel film 6a having known characteristics can be compared with the data of the polymer gel film 6 to be measured.
Also in this embodiment, the polymer gel membrane probe 5 is not used as in the embodiment shown in (b).
In the present embodiment, the two beam portions 2b and 2c are configured in parallel, and the fixing member 30b is fixed by the fasteners 28a and 28a while the piezoelectric elements 3 are arranged inside the key-shaped upper portion. The fixing member 30b and the fixing member 29b provided on the upper portions of the beam portions 2b and 2c are fixed by the fastener 28b via the buffer member 27. Since the two beam portions 2b and 2c are independent and independent, and the piezoelectric elements 3 and 3 that vibrate them are also independent and independent, it is possible to avoid resonance due to mutual vibration.
The polymer gel film 6a directly fixed to the lower end of the beam portion 2c is a film material whose swelling degree characteristic is known, and based on this, the polymer gel film 6 to be measured is applied to the solution in the same immersion bath. By soaking, the obtained measurement results can be compared.

Furthermore, it is also possible to use for the calibration of the swelling degree measuring system by using a film material having a known characteristic.
For example, in the degree-of-swelling measurement system 1 shown in FIG. 1, the piezoelectric element under a certain condition obtained by using the beam portions 2b and 2c shown in FIG. 14C and using the polymer gel film 6a in advance. When the polymer gel film 6 to be measured is actually fixed to the beam portion 2b with the admittance response value of 3 as a reference, the admittance response of the piezoelectric element 3 of the beam portion 2c becomes a previously determined admittance response value. In addition, it is conceivable to measure the beam portion 2b.
By adopting the embodiment according to (c) in the swelling degree measuring system, it is possible to carry out the swelling degree measurement with higher accuracy.

  As described above, the inventions described in claims 1 to 5 of the present invention can accurately measure the swelling degree of the polymer gel film in real time. A chemical valve for micro chemical chips, and a device for measuring the degree of swelling of the membrane used as a material in test devices and evaluation tests for material design when applied to cell culture sheets and separation membranes for water treatment Can be used.

It is a block diagram of the swelling degree measuring system which concerns on embodiment of this invention. (A) is a side view which extracts the piezoelectric transducer, the polymer gel film | membrane probe, and polymer gel film | membrane of the swelling degree measuring system which concern on this Embodiment, and shows the dimension, (b) is a front view. It is a conceptual diagram for demonstrating the relationship between the input voltage of a piezoelectric transducer of the swelling degree measuring system which concerns on this Embodiment, and an output voltage. It is a graph which shows the result of having simulated the frequency response of the piezoelectric transducer of the swelling degree measuring system which concerns on this Embodiment. 6 is a graph showing a relationship between a peak frequency shift amount Δf and a mass change Δm of the polymer gel film 6 obtained by simulation. It is a conceptual diagram of the admittance measurement circuit of the piezoelectric element which concerns on this Embodiment. It is a conceptual diagram expressing the output voltage of a piezoelectric element with a vector. It is a flowchart which shows the procedure of the analysis of the admittance measurement part, temperature measurement part, and swelling degree analysis part which concern on this Embodiment. (A), (b) is the photograph which shows the state of the polymer gel film | membrane fixed to the polymer gel film | membrane probe which concerns on this Embodiment divided into two methods, (a) is a solid film and Pasted (membrane pasted), (b) is applied, dried and fixed (coating gel membrane), (c) shows the piezoelectric transducer according to the present embodiment It is a photograph. It is a graph which shows the operating characteristic of the piezoelectric transducer of the swelling degree measuring system which concerns on this Embodiment. It is a graph which shows the result of having measured the admittance response in the state without the polymer gel film | membrane of the piezoelectric transducer of the swelling degree measuring system which concerns on this Embodiment. It is a graph which shows the result of having measured the admittance response in the state with a polymer gel film of the piezoelectric transducer of the swelling degree measuring system which concerns on this Embodiment. The swelling degree measured in the swelling degree measuring system according to the present embodiment was obtained by using an electronic balance by dividing it into a solid film and affixed after being applied and dried and fixed. It is a graph which shows temperature as a parameter compared with a value. FIG. 4 is a schematic structural diagram showing an example of a combination of a probe or a beam unit for fixing a piezoelectric transducer and a polymer gel film in the swelling degree measuring system according to the present embodiment, and (a) is a basic structure shown in FIGS. 1 to 3. (B) is an embodiment in which a polymer gel film is directly fixed to a beam portion without providing a probe, and the position of the beam portion can be adjusted, and (c) is also a beam portion without providing a probe. A comparative example is shown in which a polymer gel membrane is fixed to the membrane and another membrane material with known properties is used as a reference.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Swelling degree measuring system 2, 2a-2c ... Beam part 3 ... Piezoelectric element 4 ... Piezoelectric transducer 5 ... Polymer gel film probe 6 ... Polymer gel film 7 ... Immersion tank 8 ... Solution 9 ... Temperature control part 10 ... Thermometry 11: AC power supply 12: Transducer support unit 13 ... Input unit 14 ... Admittance measurement unit 15 ... Temperature measurement unit 16 ... Swelling degree analysis unit 17 ... Output unit 18 ... Input database 19 ... Output database 20 ... Solution data 21 ... polymer gel film data 22 ... measurement system data 23 ... admittance measurement data 24 ... temperature measurement data 25 ... swelling degree analysis data 26 ... position adjusting tool 27 ... buffer material 28a, 28b ... fastener 29a, 29b ... fixing material 30a, 30b ... Fixing material

Claims (6)

  A beam part capable of fixing a polymer gel to be measured with a fixed end part, a piezoelectric element provided in a part of the beam part, an immersion tank storing a solution in which the polymer gel is immersed, A power supply unit that vibrates the piezoelectric element, an admittance measuring unit that measures the admittance of the piezoelectric element, and a swelling degree analysis that analyzes the degree of swelling of the polymer gel based on the admittance measurement data measured by the admittance measuring unit And a polymer gel swelling degree measuring system, comprising: an output part for outputting swelling degree analysis data of the polymer gel obtained by the swelling degree analyzing part.   The swelling degree measuring system according to claim 1, wherein the polymer gel is fixed to a probe detachably provided on the beam portion instead of the beam portion.   2. The swelling degree measuring system according to claim 1, wherein at least two of the beam portions are provided in parallel, and a polymer gel whose characteristics are known can be fixed to one of the beam portions.   The degree of swelling according to any one of claims 1 to 3, further comprising: a temperature measuring unit capable of measuring the solution temperature of the immersion bath; and a temperature adjusting unit capable of adjusting the solution temperature. Measuring system.   For input to store readable data on solution data regarding the characteristics of the solution immersed to swell the polymer gel, polymer gel data regarding the characteristics of the polymer gel, and beam system and / or piezoelectric element characteristics A database, an input unit that inputs the solution data, polymer gel data, and measurement system data in advance to the input database, and an output database that stores the admittance measurement data and / or swelling degree analysis data in a readable manner The swelling degree measuring system according to any one of claims 1 to 4, wherein the swelling degree measuring system is provided.   A polymer gel is fixed to a piezoelectric transducer having a piezoelectric element that is vibrated by an AC power source and immersed in a solution, and the admittance of the piezoelectric element is measured before and after swelling of the polymer gel to calculate an admittance change amount. Calculating the degree of swelling of the polymer gel by calculating the amount of mass change of the polymer gel based on the relationship between the measured admittance change amount of the piezoelectric element before and after the swelling and the mass change amount of the polymer gel; A method for measuring the swelling degree of a polymer gel.