Automatic chemical analysis device and electrical impedance spectroscopy meter

Abstract

The present application provides an automatic chemical analysis device and an electrical impedance spectroscopy device capable of detecting the state of a stirring mechanism before performing a stirring operation. The automatic chemical analysis device dispenses a reagent and a sample as an analysis target into a reaction container (107) and performs stirring by irradiating the reaction container (107) with a sound wave. The automatic chemical analysis device includes a piezoelectric element (201) that generates a sound wave, a plurality of divided electrodes (211) provided on the surface of the piezoelectric element (201), a power amplifier (203) that causes the piezoelectric element (201) to generate a sound wave by applying a voltage to each of the divided electrodes (211), and a host computer and an impedance measurement circuit that measure the electrical impedance spectrum associated with each of the divided electrodes (211) by applying a voltage to each of the divided electrodes (211).

Description

Technical Field

[0001] This invention relates to automated chemical analysis apparatus, and more particularly to a device for stirring reagents and samples within a reaction vessel using acoustic waves. Additionally, this invention relates to an electrical impedance spectroscopy analyzer capable of being connected to such an automated chemical analysis apparatus. Background Technology

[0002] Based on Patent Documents 1-5 and Non-Patent Document 1, a technique for mixing stirred liquids (samples and reagents) in a reaction vessel in a non-contact manner using the effect of acoustic radiation pressure of powerful ultrasound has been developed and put into practical use by installing it in an automated chemical analysis device.

[0003] In this technology, ultrasonic waves are generated by applying a sine wave or a rectangular wave at a frequency near the thickness resonant frequency to the piezoelectric element. The ultrasonic waves are then irradiated from outside the reaction vessel into the stirred liquid, thereby mixing the stirred liquid.

[0004] The automated chemical analysis device equipped with this ultrasonic non-contact stirring technology (hereinafter referred to as "this stirring technology") is intended to be used for many years after its introduction to the user site. Therefore, similar to other mechanisms constituting the automated analysis device (dispensing mechanism, cleaning mechanism, etc.), a function is required to check whether each stirring action is performed properly during the operation of the automated analysis device.

[0005] Specifically, according to Patent Document 4, during the operation of this stirring technology, the current flowing through the piezoelectric element is constantly measured and recorded for each stirring action, and whether proper stirring has been performed is determined by measuring whether a specified current flows. If the specified current does not flow, it is determined that the desired ultrasonic waves have not been generated from the piezoelectric element, which serves as the ultrasonic wave source, and the user is alerted to any abnormality, error, or alarm regarding the stirring action via an automatic analysis device.

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent No. 3641992

[0009] Patent Document 2: Japanese Patent No. 3661076

[0010] Patent Document 3: Japanese Patent No. 4406629

[0011] Patent Document 4: Japanese Patent No. 3746239

[0012] Patent Document 5: Japanese Patent No. 4112228

[0013] Non-patent literature

[0014] Non-patent literature 1: Chemical Engineering Science 60 (2005) pp5519-5528 Summary of the Invention

[0015] The problem that the invention aims to solve

[0016] However, in the existing technology, there is a problem that it is difficult to detect the state of the stirring mechanism before the stirring action is performed.

[0017] For example, in the technology described in Patent Document 4 above, a stirring action is performed, and the waveform and value of the current flowing through the piezoelectric element at this time are compared with a pre-set specified waveform and value to determine whether there is any abnormality in the stirring mechanism. Therefore, this determination is performed after the stirring action.

[0018] If an abnormality in the stirring mechanism cannot be detected before the stirring action, the reagents or samples used in that stirring action may be wasted.

[0019] Furthermore, if an abnormality is detected in the stirring mechanism as a result of the stirring action, there is a possibility that the operation of the automated analysis device may be interrupted. Automated chemical analysis devices that analyze hundreds of samples per hour are mostly used for blood biochemical analysis in the examination departments or examination centers of medium to large-scale hospitals. Therefore, it is particularly important to analyze the desired number of samples within a limited time. Thus, it is undesirable to interrupt the operation of the automated analysis device.

[0020] This invention was made to solve such a problem, and its purpose is to provide an automated chemical analysis device and an electrical impedance spectrometer capable of detecting the state of a stirring mechanism before performing a stirring action.

[0021] Methods for solving problems

[0022] An example of the automated chemical analysis apparatus of the present invention is an automated chemical analysis apparatus that dispenses reagents and a sample as the object of analysis into a reaction vessel, and stirs the reaction vessel by irradiating it with sound waves, wherein...

[0023] The automated chemical analysis device includes:

[0024] A piezoelectric element that generates the sound waves;

[0025] Multiple electrodes disposed on the surface of the piezoelectric element;

[0026] A driver that causes the piezoelectric element to generate the acoustic wave by applying a voltage to each of the electrodes; and

[0027] An electronic circuit that measures the impedance spectrum associated with each of the electrodes by applying a voltage to each of the electrodes.

[0028] An example of the electrical impedance spectroscopy measuring device involved in this invention is an electrical impedance spectroscopy measuring device that can be connected to an automated chemical analysis device, wherein,

[0029] The automated chemical analysis device is equipped with the function of dispensing reagents and the sample to be analyzed into a reaction vessel, and stirring the reaction vessel by irradiating it with sound waves.

[0030] The automated chemical analysis device includes:

[0031] A piezoelectric element that generates the sound waves;

[0032] Multiple electrodes disposed on the surface of the piezoelectric element; and

[0033] A driver that causes the piezoelectric element to generate the sound wave by applying a voltage to each of the electrodes.

[0034] The electrical impedance spectroscopy measuring instrument includes:

[0035] An electronic circuit that measures the electrical impedance spectrum associated with each of the electrodes;

[0036] An input device for inputting action instructions for the electronic circuit;

[0037] A display device that displays information based on the measured electrical impedance spectrum;

[0038] Cables connecting the electronic circuits and the electrodes; and

[0039] A switching device that switches the connections of the electronic circuit and each of the electrodes.

[0040] This specification contains the disclosure of Japanese Patent Application No. 2020-105625, which forms the basis of the priority of this application.

[0041] Invention Effects

[0042] The automated chemical analysis device and electrical impedance spectrometer involved in this invention can detect the state of the stirring mechanism before performing the stirring action.

[0043] For example, as a result of the stirring action, not only can abnormalities be detected, but stable and continuous operation can also be achieved by detecting abnormalities in advance.

[0044] Before stirring, certain malfunctions of the stirring mechanism can be detected. If the stirring action can be delayed, reagents and samples used in the stirring action will not be wasted. Furthermore, if the frequency of these malfunctions and their main causes can be deduced, countermeasures (readjustment, replacement of consumable parts, etc.) can be implemented in advance for the automated chemical analysis device.

[0045] In addition, because it reduces the possibility of interruptions in the operation of automated analysis devices, it enables stable and continuous operation of automated chemical analysis devices even in examination departments or examination centers of medium or large-scale hospitals. Attached Figure Description

[0046] Figure 1 This is a diagram illustrating a structural example of the automated chemical analysis apparatus according to Embodiment 1 of the present invention.

[0047] Figure 2 It means Figure 1 A diagram illustrating the structure of a stirring mechanism.

[0048] Figure 3 It means Figure 2 A diagram illustrating the structure of an impedance measurement circuit.

[0049] Figure 4 This is a diagram showing an example of the results obtained by measuring the impedance spectrum of a normal piezoelectric element.

[0050] Figure 5 This is a diagram illustrating an example of the results obtained from measuring the impedance spectrum of an abnormal piezoelectric element.

[0051] Figure 6 This is a graph showing an example of the results of impedance spectrum measurements obtained from a normal piezoelectric element.

[0052] Figure 7 This is a diagram illustrating an example of a state where the water level at a constant temperature is at an appropriate position, and there is no stirring liquid inside the reaction vessel, along with an example of the electrical impedance spectroscopy measurement results under this state.

[0053] Figure 8 This is a diagram illustrating an example of a state where the water level is at an appropriate position and the amount of stirred liquid is about one-third of the appropriate amount, along with an example of the electrical impedance spectrum measurement results under this state.

[0054] Figure 9 This is a diagram illustrating an example of a state where the water level is at an appropriate position and the volume of the stirred liquid is approximately two-thirds of the appropriate volume, along with an example of the electrical impedance spectrum measurement results under this state.

[0055] Figure 10This is a diagram illustrating an example of a state where the water level at a constant temperature is at an appropriate position, the amount of stirred liquid exceeds an appropriate amount, and the electrical impedance spectrum measurement results under this state.

[0056] Figure 11 This is a diagram illustrating an example of a state where the volume of the stirred liquid is more than the volume required for mixing, but the water level in the thermostat is lowered, and an example of the electrical impedance spectrum measurement results under this state.

[0057] Figure 12 This is a diagram illustrating an example of the operational sequence of the automated chemical analysis device according to Embodiment 2 of the present invention.

[0058] Figure 13 This is a diagram illustrating the electrical impedance spectroscopy measuring device of Example 2 and its related structural examples. Detailed Implementation

[0059] The following describes embodiments of the present invention. The electronic components used in these embodiments were suitable and readily available at the time of this application; however, there is a high probability that higher-performance components will become available in the future, particularly for electronic components that have undergone significant advancements. Where possible, higher-performance components are sometimes preferred over those used in embodiments of the present invention.

[0060] Example 1

[0061] Figure 1 This illustrates the structure of the automated chemical analysis device of Example 1. Figure 2 This illustrates the structure of the stirring mechanism in Example 1.

[0062] like Figure 1 As shown, the following structure is installed in the automated chemical analysis apparatus of this embodiment.

[0063] - Sample cup 101 that holds the sample to be analyzed

[0064] - Sample tray 102 for setting multiple sample cups 101

[0065] - Reagent bottle 103

[0066] - Reagent cooling tray 104 for refrigerating reagent bottle 103.

[0067] - Sample dispenser 105 for dispensing samples

[0068] - Reagent dispenser 106 for dispensing reagents

[0069] -Reaction vessel 107 containing samples and reagents

[0070] -Reaction disc 108 equipped with reaction vessel 107

[0071] -Stirring mechanism 109 of the stirred liquid inside the stirring reaction vessel 107

[0072] - Absorber 110 for determining the absorbance characteristics within reaction vessel 107

[0073] An automated chemical analysis apparatus dispenses samples and reagents into a reaction vessel 107 via sample dispenser 105 and reagent dispenser 106, respectively. This generates a stirred solution within the reaction vessel 107. The reaction vessel 107, dispensed with samples and reagents, is circumferentially positioned on a reaction disk 108. In this embodiment, the reaction vessel 107 rotates clockwise. The stirred solution within the reaction vessel 107 is stirred and mixed non-contactly in a stirring mechanism 109. The reaction of the mixed sample and reagents is accelerated, and its absorbance characteristics are measured by an absorbance meter 110. After absorbance measurement (i.e., analysis), the reaction vessel 107 is cleaned using a cleaning mechanism (not shown). The next sample is then injected into the cleaned reaction vessel 107, and the aforementioned analytical sequence is repeated.

[0074] Furthermore, in the reaction dish 108, the circumferentially arranged reaction vessel 107 is in contact with constant-temperature water circulating in the constant-temperature bath 111, and the constant-temperature water at a specified temperature is maintained at a constant temperature. In this embodiment, constant-temperature water is used as an example of a liquid mediating sound waves, but in other embodiments, the liquid mediating sound waves is not limited to constant-temperature water, nor is it limited to water.

[0075] The automated chemical analysis device includes a main computer (not shown). The main computer exchanges signals with the sample tray 102, reagent refrigeration tray 104, sample dispenser 105, reagent dispenser 106, reaction tray 108, etc., sending commands to them to control the sequence of actions. Furthermore, the main computer controls the overall operation of the automated chemical analysis device.

[0076] A mainframe computer can be configured as a known type of computer. For example, a mainframe computer has an arithmetic unit for performing calculations and a storage unit for storing information. The arithmetic unit is, for example, a processor, and the storage unit is, for example, a semiconductor memory and a disk drive. Additionally, a mainframe computer may also have an input unit for inputting information, an output unit for outputting information, and a communication unit for sending and receiving information via a communication path. The input unit is, for example, a keyboard and a mouse, the output unit is, for example, a display device and a printer, and the communication unit is, for example, a network interface.

[0077] Figure 2 It includes Figure 1 The cross-sectional view of the stirring mechanism 109 shown is formed by a section parallel to the vertical direction and the radial direction of the reaction disk 108. The electrical circuitry disposed on the host computer side relative to the connector 112 is schematically represented.

[0078] The automated chemical analysis apparatus stirs the reaction vessel 107 by irradiating sound waves onto it using a stirring mechanism 109. Therefore, the automated chemical analysis apparatus possesses the following structural elements.

[0079] - Piezoelectric element 201 that generates sound waves (e.g., ultrasound)

[0080] - Fixture 202 for mounting the piezoelectric element 201 to the thermostatic bath 111

[0081] - A segmented electrode 211 (multiple electrodes) and one or more constant temperature water-side electrodes disposed on the surface of the piezoelectric element 201.

[0082] - A power amplifier 203 (driver) that generates sound waves by driving the piezoelectric element 201 by applying voltage to each electrode.

[0083] Figure 1 The stirring mechanism 109 has Figure 2 The components include connector 112, piezoelectric element 201, clamp 202, segmented electrodes 211, and constant temperature water-side electrode 210. The stirring mechanism 109 is connected to the power amplifier 203 via connector 112. The power amplifier 203 also operates according to instructions from the host computer.

[0084] The automated chemical analysis apparatus includes an impedance measurement circuit 204 for measuring the impedance spectrum (hereinafter sometimes simply referred to as "ImpS") of the piezoelectric element 201. The ImpS of the piezoelectric element 201 is represented, for example, by the set of ImpS associated with each segmented electrode 211 (i.e., the ImpS between each segmented electrode 211 and the constant temperature water-side electrode 210).

[0085] The piezoelectric element 201 is configured such that one side (air side) contacts air, and the other side (constant temperature water side) contacts constant temperature water 209. A segmented electrode 211 is disposed on the air side, and a constant temperature water side electrode 210 is disposed on the constant temperature water side. Furthermore, as... Figure 2 As shown, a portion of the constant temperature water-side electrode 210 is folded back towards the air side along the lower end face of the piezoelectric element 201.

[0086] like Figure 2 As shown by the dashed box in the figure, the dividing electrode 211 is divided vertically. In this embodiment, 14 dividing electrodes 211 are provided (in... Figure 2(Only a portion is shown in the image). The segmenting electrodes 211 are respectively positioned at different heights. The size and shape of each segmenting electrode 211 can be arbitrarily designed, but in this embodiment, the first to thirteenth segmenting electrodes 211 from the top are all of the same shape, with only the fourteenth (lowest) segmenting electrode 211 being slightly longer than the others. Each segmenting electrode 211 is connected one-to-one to a pin of the connector 112.

[0087] The power amplifier 203 includes: a function generation circuit 205 for generating a drive waveform, a final stage amplifier circuit 206 for amplifying the waveform to the desired power, and a current monitor 207 for measuring the current flowing through the piezoelectric element when a voltage is applied. The current monitor 207 can, for example, employ a structure utilizing electromagnetic coupling, an example of which is disclosed in Patent Document 4.

[0088] A relay group 208 is disposed between the power amplifier 203 and the connector 112. The relay group 208 has multiple switches, and the opening and closing of each switch is controlled according to instructions from the host computer. That is, the relay group 208 functions as a switching device for switching the connection between the power amplifier 203 and each segmented electrode 211.

[0089] For example, the main computer detects the liquid level (level) of the stirred liquid inside the reaction vessel 107 (an example of the detection method will be described later). Then, corresponding to the liquid level, one or more appropriate dividing electrodes 211 are selected. Then, the relay group 208 is controlled to apply voltage to the selected dividing electrodes 211. As a result, the position of the ultrasonic waves irradiating the reaction vessel 107 is adjusted.

[0090] A switch 212 and a switch 213 are provided between the power amplifier 203 and the relay group 208 to switch the connection between the piezoelectric element 201 and the power amplifier 203, or between the piezoelectric element 201 and the impedance measuring circuit 204. During stirring, switch 212 is connected to terminal 214 of the power amplifier 203, and switch 213 is connected to terminal 215 (connected to ground terminal 216). On the other hand, during ImpS measurement, switch 212 is connected to the output terminal 217 of the impedance measuring circuit 204, and switch 213 is connected to the input terminal 218 of the impedance measuring circuit 204.

[0091] An information communication unit 219 is provided in the power amplifier 203, through which the host computer controls the power amplifier 203. Similarly, an information communication unit 220 is provided in the impedance measurement circuit 204, through which the host computer controls the impedance measurement circuit 204. In addition, the impedance measurement circuit 204 sends the ImpS measurement results to the host computer via the information communication unit 220.

[0092] With this structure, the impedance measurement circuit 204 and the host computer function as electronic circuits that measure the ImpS of the piezoelectric element 201 by applying voltage to each segmented electrode 211. Furthermore, as... Figure 2 As shown, the impedance measurement circuit 204 does not need to be a separate structural element from the host computer; it can be a single electronic circuit integrating the impedance measurement circuit 204 and the host computer. Furthermore, the operation of the host computer and the impedance measurement circuit 204 can be implemented as the operation of a single electronic circuit.

[0093] Figure 3 yes Figure 2 The impedance measurement circuit 204 described herein is an example of its structure. Inside this circuit, a sinusoidal voltage waveform of arbitrary frequency is generated by a Direct Digital Synthesizer (DDS) 301. This waveform voltage is then amplified by an amplifier 302 and output from the output terminal 303.

[0094] For example, output terminal 303 is connected to segmented electrode 211 via relay group 208, and a sinusoidal voltage is applied to piezoelectric element 201 via segmented electrode 211. Relay group 208 functions as a switching device to switch the connection between the host computer and impedance measurement circuit 204 and each segmented electrode 211.

[0095] The magnitude of the voltage applied here can be appropriately designed by those skilled in the art based on the characteristics of the piezoelectric element 201, but for example, if it is set to a voltage smaller than the voltage applied during stirring (e.g., a voltage referred to as a weak voltage), damage to the piezoelectric element 201 can be prevented. The current flowing through the piezoelectric element 201 when the voltage is applied flows into the input terminal 304 via the constant temperature water side electrode 210 and the relay group 208, and is detected as a voltage value by the detection resistor 305.

[0096] The voltage signal caused by this current is further amplified by a logarithmic amplifier 307 (Log Amp) after being linearly amplified by an operational amplifier 306 with appropriate gain. The voltage applied to the piezoelectric element 201 from the output terminal 303 is input to the microcontroller unit (MCU) 310 via wiring 308. Additionally, the voltage value caused by the current output from the logarithmic amplifier 307 is input to the MCU 310 via wiring 309. Figure 3 In the illustrated embodiment, it is assumed that the resolution of the A / D converter built into the MCU is about 8 to 10 bits, so a logarithmic amplifier 307 is used. However, if an MCU with a higher resolution A / D converter is used, a linear amplifier may be used instead of a logarithmic one.

[0097] The voltage input to MCU310 is converted by an A / D converter. MCU310 sends a control signal 311 to DDS301 to scan the frequency of the generated sine wave within the desired frequency range. The frequency at this time, the applied voltage from output terminal 303, and the measured voltage corresponding to the current flowing through piezoelectric element 201 are stored in the memory within MCU310 and sent to the host computer as ImpS measurement results via information communication unit 220.

[0098] Figure 4 This is an example of the results of measuring ImpS of a normal piezoelectric element. Figure 4 (a) in the figure represents the result when measuring the piezoelectric element in air. Figure 4 (b) in the figure represents the result when the same piezoelectric element is in contact with constant temperature water on one side.

[0099] exist Figure 4 In the figure, the absolute value of the driving frequency versus the impedance |Z| on the horizontal axis is plotted against the phase difference ΔZ between the applied voltage and current values. The ImpS of the piezoelectric element was measured using 13 segmented electrodes of the same shape (same width and length).

[0100] exist Figure 4 In (a), curve group 401 shows the change in the absolute value |Z| and curve group 402 shows the change in the phase difference ΔZ. Both curves show the same change. The frequency at which the absolute value is at its minimum 403 is the resonant frequency 404 of the piezoelectric element. The phase difference at the resonant frequency 404 is approximately zero, representing the point where the piezoelectric element changes from capacitive to inductive.

[0101] At this frequency, the piezoelectric element vibrates significantly compared to when driven at other frequencies, and is considered to be in a resonant state along the thickness direction of the piezoelectric element. Furthermore, during mass production of piezoelectric elements, this resonant frequency deviates by a few percent in each element, but... Figure 4 In the experiment, the invention disclosed in Patent Document 5 was used to solve the problem of individual differences in piezoelectric elements.

[0102] exist Figure 4 In (b), curve group 405 shows the change in the measured absolute value |Z| and curve group 406 shows the change in the phase difference ΔZ.

[0103] Compare Figure 4 The ImpS measurement results in the air shown in (a) are as follows: Figure 4 In the ImpS measurement results shown in (b) with one side in contact with water, the resonant frequency remains almost unchanged, but the impedance value at the resonant frequency becomes 407 in the latter state, which is higher than the former value of 403. Figure 4 In case (b), the vibration of the surface of the piezoelectric element on the side in contact with the constant-temperature water propagates into the water, resulting in ultrasonic waves irradiating the surface of the piezoelectric element. Since the relative acoustic impedance of water to air is more than 3000 times higher, the acoustic impedance is high, thus increasing the acoustic load and consequently, the electrical impedance increases accordingly. In this embodiment, this characteristic is utilized, as described later, to detect the liquid level of the constant-temperature water and the liquid level of the stirred liquid within the reaction vessel.

[0104] Figure 5 This is an example of the ImpS results measured for an abnormal piezoelectric element. This example shows a case where piezoelectricity disappears in a portion of the piezoelectric element. (Compared to...) Figure 4 Similarly, (b) shows the results when the measurement was performed with one side of the piezoelectric element in contact with constant-temperature water.

[0105] The variation curves obtained from the segmented electrode corresponding to the region where piezoelectricity disappears differ from those obtained from the segmented electrode corresponding to the normal region, resulting in a deviation within the set of variation curves. This is especially true in... Figure 5 In the example, regarding the phase difference ΔZ, and Figure 4 Compared to the normal change curve group 406 in (b), change curve group 502 has a larger deviation. Furthermore, in the change curve group 501 for the absolute value |Z|, compared to… Figure 4 Compared to the normal variation curve group 405 in (b), no sharp resonance characteristics are obtained, and the impedance value 504 in the frequency 503, which is considered to be the normal resonance frequency, is higher. Figure 4 The corresponding value in (b) is 407, which means that the current is more difficult to flow and the intensity of the ultrasound is reduced compared to normal.

[0106] In this embodiment, the host computer and impedance measurement circuit 204 are based on... Figure 1 and Figure 2 The structure described herein is used to measure the ImpS of the piezoelectric element, which serves as the sound source for this stirring technology. The malfunction of the piezoelectric element is diagnosed based on this variation curve. Those skilled in the art can appropriately design specific diagnostic methods and criteria; an example of a standard diagnostic method is described below.

[0107] Beforehand, ImpS measurements (i.e., the absolute values ​​of impedance and the spectral variation curves involving phase differences) are collected from each electrode of a normal piezoelectric element test piece, and a statistical population (mother set) is constructed. Based on this statistical population, a variation curve consisting of the average values ​​of the absolute values ​​of impedance and phase differences at each frequency is constructed. Furthermore, a normal range based on the standard deviation σ is defined with this average value as the center. For example, this normal range is set to be within ±2σ of the average value.

[0108] Then, the ImpS of the piezoelectric element being judged is measured, and it is determined whether the ImpS converges to the normal range. As an example of judgment, regarding all segmented electrodes and all frequencies, if the impedance is within the normal range, the piezoelectric element is judged to be normal; otherwise (i.e., for any segmented electrode, at any frequency, if the impedance is too small or too large), the piezoelectric element is judged to be abnormal. Thus, based on the ImpS related to each segmented electrode, the normality of the piezoelectric element is determined.

[0109] The diagnostic method described above is based on the idea of ​​statistical testing, but it can also utilize machine learning. For example, the measurement results obtained by repeatedly performing ImpS measurements on multiple normal piezoelectric element samples can be used as learning data. A learned model can be generated by using a learning model (e.g., the main computer of an automated chemical analysis device) to perform machine learning on the "characteristics of ImpS of normal piezoelectric elements." Using this learned model, it is also possible to determine whether the ImpS variation curve of the piezoelectric element being assessed deviates from the "ImpS variation curve of normal piezoelectric elements."

[0110] The above is an example of a method for diagnosing whether a piezoelectric element is functioning properly. Next, an example of a method for determining whether the stirring mechanism 109 is in a state capable of properly performing stirring actions based on the ImpS measurement results of a piezoelectric element known to be functioning properly will be explained.

[0111] Figure 6 This is an example of ImpS measurement results obtained from a normal piezoelectric element. The vertical axis represents the ID number of the segmented electrodes of the piezoelectric element (numbered 1, 2, ..., 13 sequentially from the topmost segmented electrode). The horizontal axis represents the absolute value of the impedance at resonance of each segmented electrode (denoted as |Z|). r |) The value obtained through standardization (standardization|Z) r |). The reference value used for standardization is the absolute value of |Z| measured in curve group 405 with one side of the piezoelectric element in contact with constant-temperature water. Figure 4The value is obtained by averaging the impedance value 407 of all the segmented electrodes (a total of 13) at resonance.

[0112] By dividing this average value by the |Z| of each segmented electrode r |, The standardized value is the standardized |Z r |. Standardization is represented by a black circle |Z r |Curve 601. In the case of this normal piezoelectric element, the normalized |Z r The range of | (normal range 603) is 0.92 to 1.06.

[0113] Additionally, for the same piezoelectric element, |Z will be measured in air. r The curve 602, obtained through standardization, is... Figure 6 In the graph, this is indicated by white circles. The reference value used in the standardization is the same as that for curve 601. Regarding curve 602, the standardization |Z between each segmented electrode... r The deviation range (range 604 in air) is 0.16 to 0.32. Furthermore, curve 602 (measurement in air) is a lower range than curve 601 (measurement with one side in contact with constant temperature water), for the reason mentioned above, because of the effect of acoustic load on the piezoelectric element.

[0114] The following is based on Figure 6 The curves shown illustrate examples of methods for detecting the liquid level of constant-temperature water and the liquid level of the stirred liquid in the reaction vessel. Figures 7-11 Examples showing different liquid surface positions of constant temperature water 209 and 1101 or different liquid surface positions of stirred liquid 801, 901, and 1001.

[0115] Figure 7 (a) shows an example where the liquid level of the constant-temperature water 209 is at a suitable position 701 (e.g., a position corresponding to the maximum liquid volume that the stirring mechanism 109 can stir), and there is no stirred liquid inside the reaction vessel 107. In this embodiment, the frequency of the ultrasonic waves used is approximately several MHz; therefore, in this state, the ultrasonic waves irradiated from the piezoelectric element 201 propagate in the constant-temperature water 209 and reach the outer surface of the wall of the reaction vessel 107. Furthermore, the ultrasonic waves penetrate the wall of the reaction vessel 107 and reach the inner surface 702.

[0116] Figure 7 (b) in the text is to conduct with Figure 6 The ImpS measurement results are obtained using the same method described in the diagram. In curve 703, for the segmented electrode with ID number #13 (hereinafter referred to as "segmented electrode #13", and the same applies to the other segmented electrodes), the standardized |Z r|Within the normal range of 603, or higher. On the other hand, in the other segmented electrodes #1 to #12, the normalized |Z r All are below the normal range of 603.

[0117] Figure 8 Example (a) shows a state where the water level of the constant-temperature water 209 is at the appropriate position 701, and the amount of the stirred liquid 801 is approximately one-third of the appropriate amount. Regarding this state, it is related to... Figure 6 The method described in the text is the same as the key points for determination | Z r The result is Figure 8 (b) in the middle. Figure 8 In curve 802 of (b) in the figure, the standardized |Z r The value of | is large for dividing electrodes #13 and #12, but decreases from dividing electrode #11, and decreases to the intermediate range 803 at dividing electrode #9 and above (i.e., lower than the normal range 603 and higher than the range 604 in air).

[0118] Figure 9 Example (a) shows a state where the water level of the constant-temperature water 209 is at the appropriate position 701, and the amount of the stirred liquid 901 is approximately two-thirds of the appropriate amount. Regarding this state, it is related to... Figure 6 The method described in the text is the same as the key points for determination | Z r The result is Figure 9 (b) in the middle. Figure 9 In curve 902 of (b) in the figure, the standardized |Z r The value of | is relatively large in the dividing electrodes #5 to #13, but begins to decrease above the dividing electrode #5, and decreases to the middle range of 803 in the dividing electrodes #1 to #3.

[0119] Figure 10 (a) in the text represents an example where the liquid level of the constant-temperature water 209 is at the appropriate position 701, and the amount of the stirred liquid 1001 exceeds the appropriate amount. Regarding this state, it is related to... Figure 6 The method described in the text is the same as the key points for determination | Z r The result is Figure 10 (b) in the middle. Figure 10 In curve 1002 of (b) in the figure, the standardized |Z r The value of | exceeds the normal range of 603 for all segmented electrodes.

[0120] The above, if used Figures 6-10 As explained, the standardization of each segmented electrode |Z r |Depending on the amount of stirred liquid in the reaction vessel, it can be standardized based on each segmented electrode|Z rThe amount of the stirred liquid is determined by, for example, the level of the stirred liquid. Thus, the main computer and the impedance measurement circuit 204 detect the level of the stirred liquid based on ImpS associated with each segmented electrode.

[0121] For example, such as Figure 6 As shown in (b) of the standardization, |Z r If all values ​​are within the normal range of 603, the liquid level can be considered appropriate. Additionally, if... Figure 7 (b) Figure 8 (b) and Figure 9 As shown in (b), the standardized |Z| on the upper side of a specific segmented electrode r When the value of | decreases to the middle range of 803, the liquid level position can be inferred from the position of the dividing electrode. Additionally, as... Figure 10 As shown in (b) of the standardization, |Z r If all values ​​exceed the normal range of 603, it can be determined that the liquid level is higher than the appropriate level.

[0122] In addition, the reference values ​​or reference ranges used for judgment (e.g., normal range 603, intermediate range 803, air range 604, etc.) can be measured and stored in advance under specified conditions.

[0123] The detected liquid level position of the stirred liquid can be applied to various controls. As an example, based on the liquid level position (i.e., based on ImpS associated with each segmented electrode), the power amplifier 203 can cause the piezoelectric element 201 to generate sound waves in different ways.

[0124] As a specific example of "different methods," voltages can be applied to different segmented electrodes depending on the liquid level. Those skilled in the art can appropriately design the relationship between the liquid level and the segmented electrodes to which the voltage is applied. For example, in the case of a lower liquid level (e.g., Figure 8 Voltage is applied only to the lower-position segmenting electrodes (e.g., segmenting electrodes #10 to #13) corresponding to the liquid level, while in cases where the liquid level is higher (e.g., ... Figure 9 It can apply voltage to the higher-positioned segmenting electrodes (e.g., segmenting electrodes #4 to #13).

[0125] As another specific example of "different methods," the voltage applied to each segmented electrode can be different depending on the liquid level. For example, in the case of a lower liquid level (e.g., Figure 8 This can reduce voltage, especially when the liquid level is high (e.g., ...). Figure 9 This allows for higher voltage.

[0126] For reference, the following statement is considered to be the occurrence of Figures 6-10 As shown in the figure |Z r One of the reasons for the change. Furthermore, it is assumed that the experimental results described above and the applicability of this embodiment will not be affected if the following explanation is not the primary reason, or if the following explanation is completely inapplicable.

[0127] use Figure 7 The following is an explanation of (a). Ultrasonic waves propagate from the piezoelectric element 201 to the reaction vessel 107 as traveling waves 704. Upon reaching the reaction vessel 107, the ultrasonic waves undergo approximately total reflection at the inner surface 702 of the reaction vessel 107, generating reflected waves 705. Consequently, a standing wave, composed of the traveling wave 704 and the reflected wave 705, is formed between the inner surface 702 and the surface 706 (vibrating surface) of the piezoelectric element 201 that is in contact with the constant-temperature water.

[0128] A standing wave has a sound pressure distribution with antinodes (the parts with the highest or lowest sound pressure) and nodes (the parts with zero sound pressure) arranged along each half wavelength of the sound wave in the direction of sound wave propagation. On the inner surface 702 of the reaction vessel 107, the ultrasonic waves irradiated from the piezoelectric element 201 are almost completely reflected, so the sound pressure is always approximately zero. That is, the sound pressure is reflected at this location as a free end, thus forming nodes on the inner surface 702.

[0129] On the other hand, when the distance from the surface 706 of the piezoelectric element 201 in contact with the constant-temperature water to the inner surface 702 of the reaction vessel 107 is an odd multiple of half the wavelength, the reflected wave 705 is incident on the surface 706 with the minimum sound pressure. Conversely, when the distance is an even multiple, the reflected wave 705 is incident on the surface 706 with the maximum sound pressure. Since the sound pressure of this reflected wave 705 affects the acoustic load of the piezoelectric element 201, the impedance of the piezoelectric element 201 changes accordingly.

[0130] Thus, when the distance between the surface 706 of the piezoelectric element 201 and the inner surface 702 of the reaction vessel 107 is an integer multiple of half the wavelength, the acoustic load of the piezoelectric element 201 at its surface 706 becomes either maximum or minimum due to the influence of the reflected wave 705. Furthermore, even when this distance is not an integer multiple, the acoustic load of the piezoelectric element 201 varies between maximum and minimum depending on the phase of the reflected wave 705.

[0131] The above is an example of the phenomenon where there is no absorption of sound waves in the constant-temperature water, which serves as the propagation medium for ultrasound, and in the wall of the reaction vessel 107. In reality, the effect of absorption in the propagation medium is not entirely absent, but a near-standing wave sound pressure distribution is formed between the surface 706 of the piezoelectric element 201 and the inner surface 702 of the reaction vessel 107, which affects the impedance of the driven piezoelectric element 201.

[0132] By utilizing this phenomenon, when the liquid level of the constant-temperature water is at the appropriate position 701, the liquid level position, i.e. the liquid volume, of the stirred liquid in the reaction vessel 107 can be detected based on the change in ImpS measured by the segmented electrodes #1 to #13 of the piezoelectric element 201.

[0133] Next, use Figure 11 The method for detecting the liquid level of constant temperature water is explained. Figure 11 Image (a) shows an example where the reaction vessel 107 is filled with a stirred liquid to a level sufficient for mixing, but the water level in the thermostat bath (the liquid level of the thermostat water 1101) is lowered due to some anomaly. Figure 11 (b) shows the standardized |Z in this case. r | curve 1102.

[0134] exist Figure 11 In curve 1102 of (b), the standardized |Z r The value of | is within the normal range of 603 for dividing electrodes #7 to #13, or higher, but begins to decrease above dividing electrode #7, decreasing to the air range of 604 for dividing electrodes #1 to #3. For any dividing electrode, in the standardized |Z r In the case of air within range 604, the position of the constant temperature water 1101 can be estimated based on the position of the dividing electrode. Thus, the liquid level of the constant temperature water 1101 can also be determined based on |Z. r |To test.

[0135] The detected level of the constant-temperature water can be applied to various controls. For example, the level of the water level can be used to determine whether to perform a stirring action. Specifically, the main computer and impedance measurement circuit 204 determine whether the piezoelectric element is correctly contacting the constant-temperature water (i.e., whether the water level is sufficiently high) based on ImpS relative to each segmented electrode. Furthermore, the power amplifier 203 generates sound waves from the piezoelectric element when it is correctly in contact with the constant-temperature water, and does not generate sound waves when it is not in proper contact.

[0136] In addition, as another example, depending on the liquid level of the constant temperature water (i.e., according to ImpS related to each segmented electrode), the power amplifier 203 can cause the piezoelectric element 201 to generate sound waves in different ways.

[0137] As a specific example of "different methods," voltages can be applied to different segmented electrodes depending on the liquid level. Those skilled in the art can appropriately design the relationship between the liquid level and the segmented electrodes to which the voltage is applied. For example, in the case of a lower liquid level (e.g., Figure 11Voltage is applied only to the lower segmenting electrodes (e.g., segmenting electrodes #7 to #13) corresponding to the liquid level, and when the liquid level is higher, voltage can be applied to the higher segmenting electrodes (e.g., segmenting electrodes #4 to #13).

[0138] When the water is not at the specified level and strong ultrasonic waves are applied to perform stirring (i.e., when ultrasonic waves of the required intensity are generated without proper contact between the piezoelectric element and the water), not only will the ultrasonic waves fail to propagate to the reaction vessel, but the vibrational energy will also be stored within the piezoelectric element, potentially causing a rapid temperature rise. If this temperature rises to the point that causes material deformation known as the Curie point, the piezoelectricity of the piezoelectric element will irreversibly disappear.

[0139] Figure 11 The standardized |Z obtained from ImpS measurements is described in the text. r The phenomenon shown by curve 1102 indicates that the automated chemical analysis device can detect the position of the liquid level in constant-temperature water, which is extremely effective in protecting the piezoelectricity of piezoelectric elements. For example, by performing a stirring action beforehand... Figure 11 The measurement described herein can instantly determine whether the liquid level of the constant temperature water is above the position of the dividing electrode used for irradiation.

[0140] in addition, Figures 7-10 The phenomena described and the measurement results are also beneficial to automated chemical analysis devices. Figure 1 The sample dispensed by the sample dispenser 105 and the reagent dispensed by the reagent dispenser 106 are metered and dispensed by a highly precise controlled syringe pump. However, in the event of a slight dispensing error for some reason, resulting in a volume of liquid dispensed into the reaction vessel 107 that differs from the specified value, this conventional automated chemical analysis apparatus does not recognize the dispensing error and instead irradiates an ultrasonic wave at the position corresponding to the pre-specified liquid level.

[0141] At this point, if the actual liquid level is higher than the specified liquid level, the stirring intensity caused by the ultrasound decreases, resulting in insufficient mixing. Conversely, if the actual liquid level is lower than the specified liquid level, in addition to the aforementioned insufficient mixing, other issues may arise, such as... Figure 7 As explained, the ultrasonic waves irradiating the inner surface 702 of the reaction vessel are reflected in a state of near total internal reflection. At this point, even with an intensity high enough for stirring, the possibility of damage to the piezoelectric element itself due to the reflected waves should be considered. According to this embodiment, such a possibility can be avoided.

[0142] Figure 12Here is an example illustrating the operational sequence of the automated chemical analysis apparatus of this embodiment. First, the main computer and impedance measurement circuit 204 apply a predetermined measurement voltage to each segmented electrode to measure the ImpS of the piezoelectric element (step S1). Next, the power amplifier 203 applies a predetermined stirring voltage to each segmented electrode to cause the piezoelectric element to generate sound waves (stirring sound waves) (step S2). Here, the measurement voltage can be set to a voltage smaller than the stirring voltage (e.g., a weak voltage).

[0143] Furthermore, the "stirring voltage" and "measurement voltage" mentioned here do not need to be specific voltages, and can be different voltages depending on certain conditions. In this case, for example, the maximum value of the measurement voltage can be set to a voltage smaller than the minimum value of the stirring voltage.

[0144] The automated chemical analysis device corresponding to the measured ImpS operates as described above. For example, the liquid level of the stirred liquid in the reaction vessel is detected before the stirring action begins. If the error in the liquid level position (the difference between the liquid level position of the specified liquid volume and the actual liquid level position) is within the acceptable range from a chemical analysis point of view, the main computer of the automated chemical analysis device automatically determines or changes the dividing electrode to be driven, enabling ultrasonic irradiation corresponding to the actual liquid level position.

[0145] Therefore, by performing ImpS measurement of the piezoelectric element of this embodiment on an automated chemical analysis device in operation, not only can abnormalities of the piezoelectric element be detected, but also its detection can be prevented, and the failure of this automated chemical analysis device caused by the stirring mechanism 109 can be greatly suppressed.

[0146] In addition, by pre-saving the results of each ImpS measurement and analyzing the changes or shifts in the measurement results, for example, in cases where the measurement results are obtained by chance and do not occur, it is possible to detect signs of abnormality or malfunction of the stirring mechanism 109.

[0147] The above describes Embodiment 1 of the present invention. Furthermore, the automated chemical analysis apparatus of Embodiment 1 includes functions for determining whether the piezoelectric element is functioning properly, detecting the liquid level of the stirred liquid, and detecting the liquid level of the constant-temperature water; however, as a variation, some of these functions may be omitted.

[0148] Furthermore, these functions are merely examples of utilizing the ImpS function of piezoelectric elements. They can also be configured to perform other functions besides those already implemented, or based on the ImpS function of piezoelectric elements. For example, using a precision pipette, a certain volume of liquid can be precisely dispensed into a reaction vessel manually. By determining the position of the liquid level corresponding to that volume within the reaction vessel, it can be determined whether the piezoelectric element and the reaction vessel are in the appropriate relative position.

[0149] [Example 2]

[0150] In Example 1, a measuring device is mounted on the automated chemical analysis apparatus. Figure 3 The electronic circuit for impedance spectroscopy (main computer and impedance measurement circuit 204; hereinafter referred to as "ISMC"). Example 2 relates to an ImpS meter (impedance spectroscopy meter) that can be connected to an automated chemical analysis device (e.g., an existing automated chemical analysis device) that does not have an ISMC. Hereinafter, the differences from Example 1 will be described.

[0151] The ImpS measuring instrument described in Example 2 can be used as a maintenance tool for existing automated chemical analysis devices.

[0152] In Example 1, ISMC ( Figure 3 In the ISMC, the DDS301, MCU310, and logarithmic amplifier 307 are the main components, but these components can now be packaged in ICs smaller than 10mm. Therefore, the circuitry of an ISMC can be constructed on a substrate of, for example, 5cm × 9cm (business card size) or smaller. The overall thickness of the ISMC can be less than 10mm. This compact design makes the ImpS meter portable and improves convenience.

[0153] Figure 13 This section illustrates a structural example related to the ImpS measuring device and its connections in this embodiment. Figure 13 Example (a) shows a structural example of an ImpS measuring device. Using a portable housing 1201, an ISMC with the same functions as in Example 1 is constructed. That is, the ImpS measuring device includes a main computer, an impedance measurement circuit 204, and a relay group 208.

[0154] Furthermore, the ImpS measuring device according to Embodiment 2 includes a keypad operation button 1202 and a display device 1203. The keypad operation button 1202 is an example of an input device for inputting operation instructions to the host computer and the impedance measurement circuit 204. The display device 1203 displays information based on the measured ImpS, under the control of the host computer.

[0155] The display device 1203 can display information indicating whether a stirring action can be performed (i.e., whether the stirring mechanism 109 is in a state where it can properly perform a stirring action). As a specific example, when the piezoelectric element is in correct contact with the constant-temperature water, information indicating that a stirring action can be performed is displayed. Figure 13 In example (a), the message "ALL OK!!" is displayed as an example of information indicating that the stirring action can be performed.

[0156] In addition, the display device 1203 can display information indicating the level of the stirred liquid within the reaction vessel. Furthermore, the display device 1203 can display information indicating the level of the constant-temperature water. The display device 1203 can display other information as well.

[0157] The ImpS tester includes a cable 1204. One end of the cable 1204 is connected to the housing 1201, and the other end is connected to a connector 1205. The cable 1204 connects the main computer and the impedance measurement circuit 204 to the individual electrodes via the connector 1205.

[0158] like Figure 13 As shown in (b), a conventional automated chemical analyzer includes a connector 112x and a stirring mechanism 109x. The connector 1205 of the ImpS analyzer can be connected to the connector 112x of the automated chemical analyzer. Thus, the host computer and the impedance measurement circuit 204 can control the segmented electrodes of the automated chemical analyzer via the connector 1205.

[0159] Based on this structure, the functions described in Embodiment 1 can also be implemented in Embodiment 2. For example, conventional automated chemical analysis devices can also perform functions such as determining whether the piezoelectric element is functioning properly, detecting the liquid level of the stirred liquid, and detecting the liquid level of the constant-temperature water. Therefore, the same effects as in Embodiment 1 can be obtained.

[0160] In Embodiment 2 described above, the ImpS meter is a portable structure using a housing 1201. The main computer, impedance measurement circuit 204, key operation buttons 1202, display device 1203, and relay group 208 are housed within the portable housing 1201. Here, "portable" refers to dimensions of, for example, 5cm × 9cm × 10mm or less. However, as a variation, a larger portable housing can also be used. Alternatively, a non-portable ImpS meter can also be constructed (e.g., a mountable ImpS meter).

[0161] Explanation of reference numerals in the attached figures

[0162] 101…sample cup

[0163] 102… Sample tray

[0164] 103… reagent bottle

[0165] 104…Reagent Refrigeration Tray

[0166] 105… Sample dispenser

[0167] 106…Reagent Dispenser

[0168] 107…Reaction Vessel

[0169] 108…reaction disk

[0170] 109…Stirring mechanism

[0171] 110… Absorbance meter

[0172] 111…Thermostatic Bath

[0173] 112… connector

[0174] 201…Piezoelectric elements

[0175] 202… Fixture

[0176] 203…Power Amplifier (Driver)

[0177] 204…Impedance Measurement Circuit (Electronic Circuit)

[0178] 205… Function Generation Circuit

[0179] 206… Final Amplifier Circuit

[0180] 207… Current Monitor

[0181] 208…Relay group (switching device)

[0182] 209…Constant-temperature water (a liquid that mediates sound waves)

[0183] 210…Constant Temperature Water Side Electrode

[0184] 211…Segmented Electrode (Multiple Electrodes)

[0185] 212, 213… switches

[0186] 214, 215... terminals

[0187] 216…Grounding terminal

[0188] 217… Output Terminal

[0189] 218… Input Terminals

[0190] 219, 220… Information and Communication Units

[0191] 301…Direct Digital Broadcasting (DDS)

[0192] 302…Amplifier

[0193] 303… Output Terminal

[0194] 304… Input Terminal

[0195] 305…Sense Resistor

[0196] 306…Operational Amplifier

[0197] 307… Logarithmic Amplifier

[0198] 308, 309… wiring

[0199] 310…MCU

[0200] 311… Control signal

[0201] 401, 402, 405, 406, 501, 502… change curve group

[0202] 404…resonance frequency

[0203] 603…Normal range

[0204] 604…Airborne range

[0205] 701…appropriate position

[0206] 702…Inner surface of the reaction vessel

[0207] 704…Traveling Wave

[0208] 705…Reflected wave

[0209] 706… The side of the piezoelectric element that comes into contact with constant-temperature water.

[0210] 801, 901, 1001… the stirred liquid

[0211] 803…Middle range

[0212] 1101…Constant-temperature water (a liquid that mediates sound waves)

[0213] 1201…Portable case

[0214] 1202…Buttons for key operation (input device)

[0215] 1203… Display device

[0216] 1204… cable

[0217] 1205… connector.

[0218] All publications, patents and patent applications referenced in this specification are incorporated herein by direct reference.

Claims

1. An automated chemical analysis apparatus, comprising dispensing reagents and a sample as the object of analysis into a reaction vessel, and stirring the reaction vessel by irradiating it with sound waves, characterized in that, The automated chemical analysis device includes: A constant temperature bath, which keeps the reaction vessel in contact with constant temperature water; A piezoelectric element is mounted on the constant temperature bath via a clamp to contact the constant temperature water on the water side and the air on the air side, and to generate the sound wave. One or more constant temperature water side electrodes are disposed on the constant temperature water side surface of the piezoelectric element and multiple electrodes are disposed on the air side surface of the piezoelectric element. A portion of the constant temperature water side electrode is folded back along the lower end face of the piezoelectric element to the air side. The multiple electrodes on the air side are respectively arranged at different height positions in the vertical direction, and the lowermost electrode is formed to be slightly longer than the other electrodes. A driver that causes the piezoelectric element to generate the sound waves by applying a voltage to each of the electrodes; An electronic circuit that measures the resistance associated with each of the electrodes by applying a voltage to each of the electrodes. Anti-spectrum; as well as The main computer controls the drivers and the electronic circuitry. The main computer enables the electronic circuitry to detect the liquid surface position of the stirred liquid based on the absolute value of the impedance at resonance of each electrode, and the main computer performs the following processing: When all the absolute values ​​related to the electrodes are within the specified normal range, the liquid level position is determined to be appropriate. Regarding the electrode above a specific electrode, when the absolute value is in the middle range below the normal range, the liquid level position is estimated based on the position of that specific electrode. When the absolute values ​​associated with all of the electrodes exceed the normal range, the liquid level is determined to be above the appropriate position. When the absolute value of any of the electrodes is below the intermediate range, the surface position of the constant-temperature water in the constant-temperature bath is estimated. The host computer controls the driver to generate the sound waves by applying voltage to the electrodes at and below the liquid level and at the surface of the constant-temperature water in the constant-temperature bath, in a manner that varies according to the impedance spectrum associated with each of the electrodes.

2. The automated chemical analysis device according to claim 1, characterized in that, The electronic circuit determines whether the piezoelectric element is functioning properly based on the impedance spectrum associated with each of the electrodes.

3. The automated chemical analysis device according to claim 1, characterized in that, Before the driver causes the piezoelectric element to generate the acoustic wave, the electronic circuit measures the impedance spectrum associated with each of the electrodes.

4. The automated chemical analysis device according to claim 1, characterized in that, The driver applies a predetermined stirring voltage to each of the electrodes, causing the piezoelectric element to generate the sound wave. The electronic circuit applies a measurement voltage smaller than the stirring voltage to each of the electrodes to measure the electrical impedance spectrum.

5. A resistivity spectroscopy measuring instrument, capable of being connected to an automated chemical analysis device, characterized in that, The automated chemical analysis device is equipped with the function of dispensing reagents and the sample to be analyzed into a reaction vessel, and stirring the reaction vessel by irradiating it with sound waves. The automated chemical analysis device includes: A constant temperature bath, which keeps the reaction vessel in contact with constant temperature water; A piezoelectric element is mounted on the constant temperature bath via a clamp to contact the constant temperature water on the water side and the air on the air side, and to generate the sound wave. One or more constant-temperature water-side electrodes are disposed on the constant-temperature water-side surface of the piezoelectric element, and multiple electrodes are disposed on the air-side surface of the piezoelectric element. A portion of the constant-temperature water-side electrode is folded back along the lower end face of the piezoelectric element to the air-side surface. The multiple electrodes on the air-side surface are respectively arranged at different heights in the vertical direction, and the lowermost electrode is formed to be slightly longer than the other electrodes. A driver that causes the piezoelectric element to generate the sound wave by applying a voltage to each of the electrodes. The electrical impedance spectroscopy measuring instrument includes: An electronic circuit that measures the electrical impedance spectrum associated with each of the electrodes by applying a voltage to each of the electrodes; The main computer controls the drivers and the electronic circuitry; An input device for inputting action instructions for the electronic circuit; A display device that displays information based on the measured electrical impedance spectrum; A cable that connects the electronic circuit and each of the electrodes; as well as A switching device that switches the connections of the electronic circuit and each of the electrodes. The host computer enables the electronic circuitry to detect the liquid surface position of the stirred liquid based on the absolute value of the impedance at resonance of each electrode, and the host computer performs the following processing. When all the absolute values ​​related to the electrodes are within the specified normal range, the liquid level position is determined to be appropriate. Regarding the electrode above a specific electrode, when the absolute value is in the middle range below the normal range, the liquid level position is estimated based on the position of that specific electrode. When the absolute values ​​associated with all of the electrodes exceed the normal range, the liquid level is determined to be above the appropriate position. When the absolute value of any of the electrodes is below the intermediate range, the surface position of the constant-temperature water in the constant-temperature bath is estimated. The host computer controls the driver to generate the sound waves by applying voltage to the electrodes at and below the liquid level and at the surface of the constant-temperature water in the constant-temperature bath, in a manner that varies according to the impedance spectrum associated with each of the electrodes.

6. The electrical impedance spectroscopy measuring instrument according to claim 5, characterized in that, The electronic circuitry, the input device, the display device, and the switching device are housed in a portable case.

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