Stirrer and analyzer

A stirrer includes a vessel for holding a liquid to be stirred; and a sound wave generator that irradiates the liquid with a sound wave to stir the liquid by the sound wave. The sound wave generator includes a piezoelectric substrate, and a sound generating element provided on the piezoelectric substrate and arranged outside the vessel so as to be adjacent to the liquid across the vessel and the piezoelectric substrate to generate a sound wave for stirring the liquid.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a stirrer and an analyzer.

2. Description of the Related Art

Conventionally, an analyzer analyzes constituent concentrations and the like in a specimen by stirring a liquid sample containing the specimen and a reagent to cause a reaction thereof and analyzing a reaction mixture. As a stirrer for stirring a liquid sample, one that stirs a liquid sample containing a specimen and a reagent in a noncontact fashion by sound waves in order to avoid so-called carry-over is known (See, for example, Japanese Patent Application Laid-open No. 2005-257406).

SUMMARY OF THE INVENTION

A stirrer according to one aspect of the present invention includes a vessel for holding a liquid to be stirred; and a sound wave generator that irradiates the liquid with a sound wave to stir the liquid by the sound wave. The sound wave generator includes a piezoelectric substrate, and a sound generating element provided on the piezoelectric substrate and arranged outside the vessel so as to be adjacent to the liquid across the vessel and the piezoelectric substrate to generate a sound wave for stirring the liquid.

An analyzer according to another aspect of the present invention is for stirring and reacting different liquids to measure an optical property of a reaction liquid, and thus to analyze the reaction liquid. The analyzer uses the stirrer according to the present invention to optically analyze the reaction liquid containing a specimen and a reagent.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of a stirrer and an analyzer of the present invention will be described in detail below with reference to drawings.FIG. 1is an outline configuration diagram showing an automatic analyzer in a first embodiment.FIG. 2is a perspective view showing a portion of a reaction vessel and a reaction wheel used in the automatic analyzer in the first embodiment together with an outline configuration diagram of a stirrer.FIG. 3is a block diagram showing the configuration of the stirrer in the first embodiment together with a perspective view of the reaction vessel.FIG. 4is a perspective view of a surface acoustic wave device to be mounted on a sidewall of the reaction vessel inFIG. 3.

An automatic analyzer1includes, on a work table2as shown inFIG. 1, a specimen table3, a specimen dispensing mechanism5, a reaction wheel6, a photometry device10, a cleaning device11, a reagent dispensing mechanism12, and a reagent table13, and a stirrer20provided therein.

As shown inFIG. 1, the specimen table3is rotated by a drive means in directions indicated by arrows and a plurality of storage chambers3aarranged on an outer circumference along a circumferential direction at equal intervals is provided. In each storage chamber3a, a specimen vessel4housing a specimen is freely detachably stored.

The specimen dispensing mechanism5is a means for dispensing a specimen to a plurality of reaction vessels7held in the reaction wheel6and, as shown inFIG. 1, successively dispenses specimens from a plurality of the specimen vessels4on the specimen table3to a reaction vessel7.

The reaction wheel6is rotated by a drive means that is different from that of the specimen table3in directions indicated by arrows and a plurality of recesses6ais provided on the outer circumference along the circumferential direction at equal intervals. The reaction wheel6has openings6b(SeeFIG. 2) through which a measuring beam passes formed on both sides in a radial direction of each of the recesses6a. The reaction wheel6rotates clockwise by (one round−one reaction vessel)/4 in one cycle and rotates counterclockwise by one recess6ain four cycles. The reaction wheel6has the photometry device10and the cleaning device11arranged on a rotation path and the stirrer20arranged below a position opposite to the cleaning device11in a diameter direction.

The reaction vessel7is a small vessel of several nL (nanoliters) to several tens of μL (microliters) in volume and uses a transparent material that allows to pass 80% or more of light contained in an analytical beam (340 to 800 nm) emitted from a light source of the photometry device10, for example, glass including heat-resistant glass and synthetic resin such as cyclic olefine and polystyrene. As shown inFIG. 2andFIG. 3, the reaction vessel7is a cuvette in a rectangular cylindrical shape forming a liquid holding unit7dwhose horizontal section is square to hold a liquid by sidewalls7aand7band a bottom wall7c(SeeFIG. 5) and having an opening7ein an upper part of the liquid holding unit7d. The reaction vessel7constitutes the stirrer20together with a surface acoustic wave device22mounted on the sidewall7aand inner walls of the liquid holding unit7dare treated to have an affinity for liquids of specimens or reagents. The reaction vessel7is arranged in the recess6awith the sidewall7adirected in the radial direction of the reaction wheel6and the sidewall7bdirected in the circumferential direction of the reaction wheel6.

The photometry device10is arranged, as shown inFIG. 1, near the outer circumference of the reaction wheel6and has the light source emitting the analytical beam (340 to 800 nm) for analyzing a liquid held in the reaction vessel7and a photo detector for receiving the analytical beam after being passed through the liquid by dispersing the analytical beam. The photometry device10is arranged in such a way that the light source and the photo detector are positioned opposite to each other sandwiching the recess6aof the reaction wheel6.

The cleaning device11has a discharging means for discharging liquids and cleaning liquids from the reaction vessel7and a dispensing means for dispensing a cleaning liquid. After discharging a liquid after light measurement from the reaction vessel7after light measurement, the cleaning device11dispenses a cleaning liquid. By repeating an operation of dispensing and discharging of a cleaning liquid two or more times, the cleaning device11cleans an inner part of the reaction vessel7. After being cleaned in this manner, the reaction vessel7is used again for analysis of a new specimen.

The reagent dispensing mechanism12is a means for dispensing a reagent to the plurality of reaction vessels7held by the reaction wheel6and, as shown inFIG. 1, successively dispenses a reagent from a predetermined reagent vessel14of a reagent table13to the reaction vessels7.

The reagent table13is rotated by a drive means that is different from that of the specimen table3and the reaction wheel6in directions indicated by arrows and a plurality of storage chambers13aformed in a fan shape is provided along the circumferential direction. The reagent vessel14is freely detachably stored in each of the storage chambers13a. Each of a plurality of the reagent vessels14is filled with a predetermined reagent corresponding to each inspection item and an information recording medium (not shown) showing information about the housed reagent is attached to an outer surface thereof.

Here, as shown inFIG. 1, a reader15for reading information such as the type of reagent, lots, and term of validity recorded in the information recording medium attached to the reagent vessel14and outputting the information to a control unit16is set up on the outer circumference of the reagent table13.

The control unit16is connected to the specimen table3, the specimen dispensing mechanism5, the reaction wheel6, the photometry device10, the cleaning device11, the reagent dispensing mechanism12, the reagent table13, the reader15, an analysis unit17, an input unit18, a display unit19, and the stirrer20and, for example, a microcomputer equipped with a storage function to store analysis results is used as the control unit16. The control unit16controls actuation of each unit of the automatic analyzer1and, if the lot or term of validity is outside the range of setup based on information read from records in the information recording medium, controls the automatic analyzer1to stop analysis work or issues an warning to the operator.

The analysis unit17is connected to the photometry device10via the control unit16, analyzes constituent concentrations and the like in a specimen from the rate of absorption of a liquid inside the reaction vessel7based on the quantity of light received by the photo detector, and then outputs an analysis result to the control unit16. The input unit18is a part where operations to input inspection items and the like into the control unit16are performed and, for example, a keyboard or a mouse is used as the input unit18. The display unit19displays analysis content, warnings and the like and a display panel or the like is used as the display unit19.

The stirrer20stirs a liquid held in the reaction vessel7by sound waves generated by driving the surface acoustic wave device22and, as shown inFIG. 2andFIG. 3, in addition to the reaction vessel7, has a power transmitter21for supplying power to the surface acoustic wave device22and the surface acoustic wave device22.

The power transmitter21has an RF transmitting antenna21a, a drive circuit21b, and controller21c. The power transmitter21sends power supplied from a high-frequency AC source of several MHz to several hundreds of MHz from the RF transmitting antenna21ato the surface acoustic wave device22as a drive signal. The RF transmitting antenna21ais mounted on the sidewall of the recess6aof the reaction wheel6.

The drive circuit21bhas an oscillating circuit capable of changing oscillating frequencies based on a control signal from the controller21cand outputs a high-frequency oscillating signal of several tens to several hundreds of MHz to the RF transmitting antenna21a. Here, the RF transmitting antenna21aand the drive circuit21bare connected via a contact electrode so that power can still be supplied even if the reaction wheel6rotates. Thus, in the power transmitter21, the RE transmitting antenna21ato which power is supplied via the contact electrode switches as the reaction wheel6rotates and the liquid held in the reaction vessel7of each of the recesses6ais successively stirred. The controller21ccontrols actuation of the drive circuit21band controls, for example, characteristics (characteristics of the frequency, intensity, phase, and waves), waveforms (such as sine waves, triangular waves, rectangular waves, and burst waves), and modulation (amplitude modulation and frequency modulation) of a sound wave emitted by the surface acoustic wave device22. The controller21ccan also switch the frequency of oscillating signal emitted from the drive circuit21baccording to a built-in timer.

The surface acoustic wave device22is a sound wave generator for generating sound waves after receiving a drive signal (power) emitted from the RF transmitting antenna21a. As shown inFIG. 3andFIG. 4, the surface acoustic wave device22has a transducer22bas being an interdigital transducer (IDT) and an antenna22cformed on a piezoelectric substrate22amade of, for example, lithium niobate (LiNbO3). The transducer22bis a sound generating element generating sound waves after a drive signal (power) emitted from the RF transmitting antenna21abeing received by the antenna22c. The transducer22bis arranged outside the reaction vessel7adjacent to a liquid held by the reaction vessel7via the reaction vessel7and the piezoelectric substrate22a. That is, as shown inFIG. 5andFIG. 6, the surface acoustic wave device22is mounted on the sidewall7aof the reaction vessel7via an acoustic matching layer23such as epoxy resin and ultraviolet curing resin with the transducer22bdirected outward. The surface acoustic wave device22is schematically depicted ignoring an actual thickness including the thickness of the acoustic matching layer23, in addition to that of the piezoelectric substrate22a, the transducer22b, and antenna22cto clarify the configuration. This also applies to other embodiments.

Here, it is desirable that the reaction vessel7and the piezoelectric substrate22aoverlap with each other and the surface thereof is processed smooth so that the surface roughness of the surface through which sound waves pass becomes smaller than the wavelength of sound waves generated by the transducer22b. If the surface roughness of the surface through which sound waves pass of the reaction vessel7and the piezoelectric substrate22ais larger than the wavelength of sound waves generated by the transducer22b, generated sound waves are scattered by the surface of the reaction vessel7and the piezoelectric substrate22aand, as a result, sound waves will not be emitted in a fixed direction shown inFIG. 6, leading to lower stirring efficiency of a liquid held in the reaction vessel7.

In the automatic analyzer1configured as described above, the reagent dispensing mechanism12successively dispenses reagents to the plurality of reaction vessels7being transported along the circumferential direction by the rotating reaction wheel6from the reagent vessel14. The reaction vessel7to which a reagent has been dispensed is transported along the circumferential direction by the rotating reaction wheel6to successively dispense specimens by the specimen dispensing mechanism5from the plurality of specimen vessels4held on the specimen table3. Then, the reaction vessel7to which a specimen has been dispensed is transported to the stirrer20by the reaction wheel6so that the dispensed reagent and specimen are successively stirred to cause a reaction. A reaction mixture after the specimen and reagent are caused to react in this manner passes through the photometry device10when the reaction wheel6rotates again and an analytical beam emitted from the light source is transmitted. At this point, the reaction mixture of the specimen and reagent inside the reaction vessel7is measured by a light receiving unit and constituent concentrations and the like are analyzed by the control unit16. Then, after the analysis is completed, the reaction vessel7is cleaned by the cleaning device11before being reused for analysis of another specimen.

At this point, in the stirrer20, based on a control signal input from the input unit18in advance via the control unit16, the controller21cinputs a drive signal into the drive circuit21bwhile the reaction wheel6stops. The transducer22bof the surface acoustic wave device22is thereby driven in accordance with the frequency of the input drive signal and, as shown inFIG. 6, a bulk wave Wbis caused. The caused bulk wave Wbis incident on the sidewall7aof the reaction vessel7after propagating through the piezoelectric substrate22aand the acoustic matching layer23and, after propagating through the sidewall7aas shown by arrows, leaks out to a liquid L having a similar acoustic impedance.

As a result, as shown inFIG. 5, not only a flow Fcc obliquely upward from the transducer22b, but also a flow Fcw obliquely downward from the transducer22bis generated in the liquid L inside the reaction vessel7by the leaked-out bulk wave so that the liquid L containing the dispensed reagent and specimen is stirred.

At this point, the stirrer20has the surface acoustic wave device22mounted on the sidewall7aacross the acoustic matching layer23with the transducer22bdirected toward the sidewall7aadjacent to the liquid L. Thus, the stirrer20and the automatic analyzer1can improve stirring efficiency of the liquid L by suppressing attenuation involved in propagation of sound waves because sound waves generated by the transducer22bis incident on the adjacent liquid L through the sidewall7aof the reaction vessel7and thus, the propagation path of sound waves is short. The surface acoustic wave device22has the transducer22barranged outside the piezoelectric substrate22aand the transducer22bis exposed to the air without being covered with a solid body and therefore, excitation of the transducer22bis hard to control so that an energy loss during driving can be reduced to a low level.

Here, since shear elasticity is not generally present in gas flow and liquid flow, sound waves are longitudinal waves propagating as compressional waves. In contrast, in addition to longitudinal waves, transverse waves are also present in solids. If, on the other hand, sound waves are caused in the surface acoustic wave device22in which the transducer22bis arranged outside the piezoelectric substrate22a, sound waves to be generated must be bulk waves so that sound waves propagate from the transducer22binto the piezoelectric substrate22ato be incident on the sidewall7aof the reaction vessel7via the acoustic matching layer23. In such a case, a sound wave (a bulk wave) generated by the surface acoustic wave device22is emitted into the liquid L with a minimum propagation loss to stir the liquid L efficiently.

At this point, a sound wave generated by the transducer22bpropagates through a medium present on the propagation path with a small acoustic impedance difference. Thus, the stirrer20can provide efficient stirring by suitably selecting the medium present on the propagation path of the sound wave generated by the surface acoustic wave device22to make the acoustic impedance difference smaller and control propagation loss. In such a case, a first medium present on the propagation path of a sound wave generated by the transducer22bhas a plurality of sound wave modes and an acoustic impedance of each sound wave mode is substantially equal to at least one of acoustic impedances of a plurality of sound wave modes held by a second medium adjacent to the first medium.

In other words, in the stirrer20, there are the piezoelectric substrate22aas a first medium, the acoustic matching layer23as a second medium, the sidewall7aof the reaction vessel7as a third medium, and the liquid L as a fourth medium on the propagation path of a sound wave generated by the transducer22bof the surface acoustic wave device22. At this point, as materials of these media, lithium niobate is assumed for the piezoelectric substrate22a, ultraviolet curing resin for the acoustic matching layer23, polystyrene resin for the reaction vessel7, and water for the liquid L. Further, it is assumed that the density is ρ, the velocity of longitudinal waves is VL, that of transverse waves is VS, the impedance of longitudinal waves is ZL(=ρ·VL), and that of transverse waves is ZS (=ρ·VS).

In this case, if the transducer22bgenerates a sound wave, sound wave modes as shown inFIG. 7are present in each medium. In the piezoelectric substrate22a, two sound wave modes of longitudinal waves LB (ZLB=22.56 MRayl) and transverse waves SB (ZSB=16.45 MRayl) are present for sound waves. In the acoustic matching layer23, two sound wave modes of longitudinal waves LM(LB), LM(SB) (ZLM=2.99 MRayl) and transverse waves SM(LB), SM(SB) (ZSM=1.23 MRayl) are present for sound waves. In the sidewall7aof the reaction vessel7, two sound wave modes of longitudinal waves LC(LM(LB)), LC(LM(SB)) (ZLC=2.52 MRayl) and transverse waves SC(LM(LB)), SC(LM(SB)) (ZSC=1.12 MRayl) originating from the longitudinal waves LM(LB), LM(SB) in the acoustic matching layer23and longitudinal waves LC(SM(LB)), LC(SM(SB)) (ZLC=2.52 MRayl) and transverse waves SC(SM(LB)), SC(SM(SB) (ZSC=1.12 MRayl) originating from the transverse waves SM(LB), SM(SB) in the acoustic matching layer23. Thus, an acoustic impedance of one sound wave mode held by the acoustic matching layer23becomes substantially equal to at least one of acoustic impedances of the plurality of sound wave modes held by the adjacent reaction vessels7. Such longitudinal waves and transverse waves all become longitudinal waves LWafter entering the liquid L. Here, if the transducer22bis a bidirectional interdigital transducer, longitudinal waves and transverse waves in sound waves pass through the center of the transducer22bto become symmetrical with respect to a line Lsperpendicular to the plate surface of the piezoelectric substrate22ainFIG. 7, but only longitudinal waves and transverse waves above the line Ls are shown to simplify the drawing.

Therefore, in the stirrer20, if materials of the acoustic matching layer23, the reaction vessel7, and the liquid L are selected as described above, as shown inFIG. 7, mainly the transverse waves SBof sound waves generated by the transducer22bare incident on the acoustic matching layer23from inside the piezoelectric substrate22adue to a difference in acoustic impedance between adjacent media and propagates through the acoustic matching layer23mainly as the longitudinal waves LM(SB) before being incident on the reaction vessel7. Then, after propagating through the sidewall7aof the reaction vessel7, mainly as the longitudinal waves LC(LM(SB)), the sound waves enters the liquid L in longitudinal waves LWmode. In this case, the longitudinal waves LBof sound waves generated by the transducer22balso propagate through the piezoelectric substrate22a, but it is difficult for the longitudinal waves LB to enter the acoustic matching layer23due to a large difference in acoustic impedance. Similarly, the transverse waves SM(SB) propagating through the acoustic matching layer23enters the sidewall7aalso as the longitudinal waves LC(SM(SB)), but it is difficult for the longitudinal waves LC(SM(SB)) to enter sidewall7adue to a large difference in acoustic impedance. Also similarly below, how easily longitudinal waves or transverse waves enter a medium can be determined based on the magnitude of a difference in acoustic impedance.

Here, the stirrer20in the present invention uses an interdigital transducer (IDT) as the transducer22bof the surface acoustic wave device22and thus, the structure thereof is simple and particularly the portion of the transducer22bcan be made thin. The surface acoustic wave device22is also fixed to the reaction vessel7and thus, the stirrer20can easily handle the surface acoustic wave device22together with the reaction vessel7.

Therefore, as shown inFIG. 8, the stirrer20may use the reaction vessel7obtained by embedding the surface acoustic wave device22in a recess7fformed by making the sidewall7athinner across an acoustic matching layer with the transducer22bbeing directed outward from the reaction vessel7. In this case, as shown inFIG. 9, the stirrer20may have two units of the transducer22bof the surface acoustic wave device22mounted on the reaction vessel7. If there are two units, the stirrer20can improve stirring capabilities by using the two transducers22bin various combinations such as driving the two transducers22bin a time-division fashion and driving simultaneously the two transducers22bwith different center frequencies. Therefore, even if the number of liquids held is large, the liquids can be stirred in a short time.

The surface acoustic wave device22can be constructed to be smaller and therefore, the stirrer20may be constructed, like the reaction vessel7shown inFIG. 10, by using the surface acoustic wave device22as a portion of the sidewall7aand embedding the surface acoustic wave device22in an upper part of the sidewall7awith the transducer22bbeing directed outward from the reaction vessel7.

On the other hand, like the reaction vessel7shown inFIG. 11, the stirrer20may have a surface acoustic wave device24mounted on the undersurface of the bottom wall7c. The surface acoustic wave device24has, as shown inFIG. 12, a transducer24bas being an interdigital transducer (IDT) provided in the center of the surface of a substrate24aand an antenna24cto be a receiving means is integrally provided like enclosing the transducer24b. In this case, as shown inFIG. 13, the surface acoustic wave device24is mounted on the bottom wall7cacross the acoustic matching layer23with the transducer24bdirected outward from the reaction vessel7. The stirrer20has the RF transmitting antenna21aof the power transmitter21provided on the bottom wall of the recess6aof the reaction wheel6.

Furthermore, like the reaction vessel7shown inFIG. 14, the stirrer20may use the piezoelectric substrate24aof the surface acoustic wave device24as a bottom wall. In this case, the piezoelectric substrate24aof the surface acoustic wave device24is mounted on a lower part of the sidewall7awith the transducer24bbeing directed outward from the reaction vessel7.

Second Embodiment

Next, a second embodiment of a stirrer and an analyzer of the present invention will be described in detail with reference to drawings. While power is supplied to the surface acoustic wave device by radio in the first embodiment, power is supplied to the surface acoustic wave device through a wire in the second embodiment.FIG. 15is an outline configuration diagram of an automatic analyzer in the second embodiment equipped with a stirrer.FIG. 16is a block diagram showing the configuration of the automatic analyzer inFIG. 15.FIG. 17is a perspective view showing a surface acoustic wave device of the stirrer used in the automatic analyzer inFIG. 15and a reaction vessel on which the surface acoustic wave device is mounted.FIG. 18is a perspective view showing the reaction vessel on which the surface acoustic wave device is mounted and used in the automatic analyzer inFIG. 15together with a power transmitter. Here, in the automatic analyzer in the second embodiment, the stirrer uses the same reaction vessel as the stirrer20in the first embodiment and thus, the same numerals are used to describe the reaction vessel.

An automatic analyzer30has, as shown inFIG. 15andFIG. 16, reagent tables31,32, a reaction wheel33, a specimen vessel transport mechanism37, a photometric system42, a cleaning mechanism43, a control unit45, and a stirrer50.

As shown inFIG. 15, each of the reagent tables31,32holds a plurality of reagent vessels31a,32aarranged in the circumferential direction and transports the reagent vessels31a,32ain the circumferential direction by being rotated by a drive means (not shown) respectively.

As shown inFIG. 15, the reaction wheel33has the plurality of reaction vessels7arranged along the circumferential direction and transports the reaction vessels7by being rotated normally or reversely by a drive means (not shown). Reagents are dispensed to the reaction vessels7by reagent dispensing mechanism35,36provided nearby from the reagent vessels31a,32aof the reagent tables31,32. Here, the reagent dispensing mechanisms35,36have probes35b,36bprovided for dispensing reagents to arms35a,36arotating in arrow directions on a horizontal plane and have a cleaning means for cleaning the probes35b,36bwith washing water respectively.

As shown inFIG. 16andFIG. 17, the reaction vessel7constitutes the stirrer50together with a surface acoustic wave device54mounted on the sidewall7a.

As shown inFIG. 15, the specimen vessel transport mechanism37is a transport means for transporting a plurality of racks39arranged in a feeder38along an arrow direction one by one and transports the rack39step by step. The rack39holds a plurality of specimen vessels39ahousing specimens. Here, each time the step of the rack39transported by the specimen vessel transport mechanism37stops, specimens in the specimen vessels39aare dispensed to each of the reaction vessels7by a specimen dispensing mechanism41having a drive arm41arotating in a horizontal direction and a probe41b. Thus, the specimen dispensing mechanism41has a cleaning means (not shown) for cleaning the probe41bwith washing water.

The photometric system42emits an analytical beam (340 to 800 nm) for analyzing a liquid in the reaction vessel7after a reagent and specimen have reacted and has, as shown inFIG. 15, a light emitting unit42a, a dispersing unit42b, and a light receiving unit42c. An analytical beam emitted from the light emitting unit42apasses through the liquid in the reaction vessel7before being received by the light receiving unit42cprovided at a position opposite to the dispersing unit42b. The light receiving unit42cis connected to the control unit45.

After suctioning and discharging the liquid in the reaction vessel7with a nozzle, the cleaning mechanism43repeatedly injects and discharges a detergent and a cleaning liquid such as washing water through the nozzle43ato clean the reaction vessel7after analysis by the photometric system42is completed.

The control unit45controls actuation of each unit of the automatic analyzer30and also analyzes constituent concentrations and the like in a specimen from the rate of absorption of the liquid inside the reaction vessel7based on the quantity of light emitted by the light emitting unit42aand that received by the light receiving unit42cand, for example, a microcomputer is used as control unit45. As shown inFIG. 15andFIG. 16, the control unit45is connected to an input unit46such as a keyboard and a display unit47such as a display panel.

The stirrer50stirs a liquid held in the reaction vessel7by a sound wave generated by driving the surface acoustic wave device54and has, in addition to the reaction vessel7, as shown inFIG. 15andFIG. 16, a power transmitter51and the surface acoustic wave device54. The power transmitter51is arranged at a position on the outer circumference of the reaction wheel33opposite to the reaction vessel7in the horizontal direction and sends power supplied from a high-frequency AC source of several MHz to several hundreds of MHz to the surface acoustic wave device54. The power transmitter51is equipped with a drive circuit and a controller and, as shown inFIG. 18, has a brush-like contact51ain contact with an electric terminal54dof the surface acoustic wave device54. In this case, as shown inFIG. 15, the power transmitter51is supported by an arrangement determining member52and supplies power from the contact51ato the electric terminal54dwhen the rotation of the reaction wheel33stops.

The arrangement determining member52, whose actuation is controlled by the control unit45, moves the power transmitter51when power is sent from the power transmitter51to the electric terminal54dto adjust the relative configuration of the reaction wheel33relative to the power transmitter51and the electric terminal54din the circumferential and radial directions and, for example, a biaxial stage is used as the arrangement determining member52. More specifically, when the reaction wheel33rotates and no power is supplied from the power transmitter51to the electric terminal54d, actuation of the arrangement determining member52is stopped and maintains the power transmitter51and the electric terminal54dat a fixed distance. When the reaction wheel33stops and power is supplied from the power transmitter51to the electric terminal54d, the arrangement determining member52operates under control of the control unit45to move the power transmitter51to adjust the position along the circumferential direction of the reaction wheel33so that the power transmitter51and the electric terminal54dare positioned opposite to each other and also determines the relative configuration of the power transmitter51and the electric terminal54dby bringing the power transmitter51and the electric terminal54dcloser to bring the contact51ainto contact with the electric terminal54d.

Here, the stirrer50may use the control unit45of the automatic analyzer30as an arrangement determination means to adjust the relation configuration of the power transmitter51and the electric terminal54dalong the circumferential direction of the reaction wheel33by controlling a drive means such as a motor rotary driving the reaction wheel33by the control unit45. As mentioned above, it is only necessary for the arrangement determining member52to be able to at least adjust the relative configuration of the power transmitter51and the electric terminal54dalong the circumferential direction of the reaction wheel33so that the power transmitter51and the electric terminal54dare positioned opposite to each other. On the other hand, the relative configuration of the power transmitter51and the electric terminal54dis detected, for example, by providing a reflection sensor on the power transmitter51side and using reflection from reflectors provided at specific positions of the reaction vessel7or the surface acoustic wave device54. At this point, data of the detected relative configuration is entered in the control unit45.

As shown inFIG. 17andFIG. 19, the surface acoustic wave device54is a sound wave generating means in which a transducer54bas being an interdigital transducer (IDT) is provided on one surface of a piezoelectric substrate54aand a bus bar54cis extended to the surface on the other side with electric terminals54dprovided at ends of the bus bar54c. The transducer54bis a sound generating element generating sound waves by power supplied from the power transmitter51. The surface acoustic wave device54is mounted on the sidewall7aof the reaction vessel7so that when the reaction vessel7is set to the automatic analyzer30, a plurality of comb-like electrodes constituting the transducer54bis arranged in a vertical direction. The surface acoustic wave device54is mounted on the sidewall7aof the reaction vessel7across an acoustic matching layer55(SeeFIG. 20) such as epoxy resin and ultraviolet curing resin with the transducer54bdirected outward from the reaction vessel7.

At this point, as shown inFIG. 17, the surface acoustic wave device54including the electric terminals54dto be a receiving means is arranged at an intermediate position in the vertical direction by avoiding a lower part of the sidewall7ato be a window for light measurement so that light measurement by the photometric system42is not prevented. The surface acoustic wave device54uses an interdigital transducer (IDT) as the transducer54band thus, the structure thereof can be made simple with reduced size. Here, instead of lead zirconate titanate (PZT) attached with an interdigital transducer (IDT), PZT with electrodes on both sides may also be used for the transducer54b.

In the automatic analyzer30configured as described above, the reagent dispensing mechanisms35,36successively dispense reagents to the plurality of reaction vessels7operating under control of the control unit45and being transported along the circumferential direction by the rotating reaction wheel33from the reagent vessels31a,32a. Specimens are successively dispensed to the reaction vessels7to which reagents have been dispensed by the specimen dispensing mechanism41from the plurality of specimen vessels39aheld in the rack39. Then, each time the reaction wheel33stops, the reaction vessels7to which reagents and specimens have been dispensed are successively stirred by the stirrer50to cause a reaction between reagents and specimens. When the reaction wheel33rotates again, the reaction vessels7pass through the photometric system42. At this point, the liquid inside the reaction vessels7is measured photometrically by the light receiving unit42cand constituent concentrations and the like are analyzed by the control unit45. Then, after the analysis is completed, the reaction vessel7is cleaned by the cleaning mechanism43before being reused for analysis of another specimen.

At this point, in the stirrer, when the reaction wheel33stops, the power transmitter51supplies power from the contact51ato the electric terminal54d. The transducer54bof the surface acoustic wave device54is thereby driven to cause sound waves. The caused sound waves propagate from the acoustic matching layer55into the sidewall7aof the reaction vessel7before being leaked to a liquid having a similar acoustic impedance. As a result, as shown by arrows inFIG. 20, a flow Fccobliquely upward and a flow Fcwobliquely downward arise from a position corresponding to the transducer54bin the liquid L as a starting point inside the reaction vessel7. The liquid L held inside the reaction vessel7is stirred by these two flows. At this point, the stirrer50brings the power transmission body51closer to the electric terminal54dthrough the arrangement determining member52and also adjusts the positions so that the power transmitter51and the electric terminal54dare opposite to each other and therefore, power transmission from the power transmitter51to the electric terminal54dproceeds smoothly.

The reaction vessel7has the surface acoustic wave device54mounted on the sidewall7aacross the acoustic matching layer55(SeeFIG. 20) with the transducer54bdirected toward the sidewall7aadjacent to the liquid L. Thus, in the stirrer50and the automatic analyzer30, a sound wave generated by the transducer54benters the adjacent liquid L after passing through the sidewall7afrom the acoustic matching layer55. Therefore, the stirrer50and the automatic analyzer30can improve stirring efficiency of the liquid L because the propagation path of sound waves is short and attenuation of sound waves involved in propagation can be suppressed.

Thus, the stirrer50is superior in propagation efficiency of sound waves generated by the surface acoustic wave device54and has a simple structure. As a result, the automatic analyzer30has an advantage that the automatic analyzer30can be reduced in size compared with conventional analyzers and maintenance thereof is made easier. The surface acoustic wave device54has the transducer54barranged outside the piezoelectric substrate54aand the transducer54bis exposed to the air without being covered with a solid body and therefore, excitation of the transducer54bis hard to control so that an energy loss during driving can be reduced to a low level.

The stirrer50in the second embodiment is constructed so that power is sent to the surface acoustic wave device54by the brush-like contact51abeing abutted the electric terminal54dby the power transmitter51. However, with respect to the stirrer50, it may also be constructed that when power is sent to the surface acoustic wave device54, the power transmitter51abuts the reaction vessel7with the arrangement determining member52having racks and pinions after the reaction wheel33stops and, as shown inFIG. 21, such as a spring terminal51bprovided in the power transmitter51abuts the electric terminal54d. If this configuration is adopted, when the reaction vessels7are transported by rotating the reaction wheel33, with the respect to the automatic analyzer30, the power transmitter51is moved away from the reaction vessels7through the arrangement determining member52so that the spring terminal51bshould not interfere with the surface acoustic wave device54.

The configuration of the stirrer50in which power is sent to the surface acoustic wave device54by the contact51aabutting the electric terminal54dby the power transmitter51may be changed and, for example, as shown inFIG. 22, an arm member57may be provided in the power transmitter51with a surface acoustic wave device58provided at a tip of the arm member57so that the surface acoustic wave device58comes into contact with the sidewall7aof the reaction vessel7by the arm member57protruding when the liquid should be stirred. With this configuration, the stirrer allows to suitably change the target on which a surface acoustic wave device should be mounted to the arm member57or the reaction vessel7in accordance with design, increasing design flexibility.

In this case, a drive arm57bof the arm member57is freely appearingly/disappearingly supported by a support cylinder57a. The surface acoustic wave device58has a transducer58bformed on one surface of a piezoelectric substrate58a, is glued to an end face of the drive arm57bby an adhesive Adwith the transducer58bdirectly inward, and is driven by power supplied by a power line wired inside the support cylinder57aand the drive arm57b.

With the configuration as described above, for stirring by the surface acoustic wave device58, as shown inFIG. 23, the stirrer50under control of the control unit45discharges an acoustic matching liquid Lmto the surface acoustic wave device58from a nozzle59held by an acoustic matching liquid dispensing mechanism. Next, as shown inFIG. 24, the stirrer50under control of the control unit45protrudes the drive arm57bto bring the surface acoustic wave device58on the end face of the drive arm57binto contact with the sidewall7aof the reaction vessel7.

Accordingly, a sound wave (bulk wave) generated by the transducer58bof the surface acoustic wave device58leaks out from the sidewall7aof the reaction vessel7into the liquid L via a thin film of the acoustic matching liquid Lm arranged between the surface acoustic wave device58and the sidewall7a. As a result, not only a flow Fcc obliquely upward from the transducer58b, but also a flow Fcw obliquetly downward from the transducer58barises in the liquid L by the leaked-out sound wave (bulk wave) so that the liquid L is stirred.

At this point, the stirrer50can improve stirring efficiency by suppressing attenuation of sound waves because the propagation path between where the surface acoustic wave device58comes into contact with the sidewall7avia the acoustic matching liquid Lm and where the liquid L is irradiated with a sound wave (bulk wave) is short. Then, when stirring of the liquid L is completed, the stirrer50under control of the control unit45pulls back the drive arm57bto end contact between the surface acoustic wave device58and the sidewall7aof the reaction vessel7.

The configuration of the stirrer50in which a surface acoustic wave device is abutted the sidewall7aof the reaction vessel7to stir a liquid by the surface acoustic wave device is also applicable to the stirrer20in the first embodiment. In case of adopting such a configuration, it is necessary for the stirrer20to arrange the arm member57mounted the surface acoustic wave device22near the outer circumference of the reaction wheel6, and also to form a contact opening above the opening6bthrough which the drive arm57bis inserted to make the surface acoustic wave device22abut the sidewall7aof the reaction vessel7.