JPS6219379A - Piezoelectric type forcep - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to piezoelectric tweezers suitable for clamping minute objects such as cells or prokaryotes.

[Conventional technology]

Tweezers have been used for a long time as a tool for grasping small objects that cannot be grasped directly, and there are various types depending on the purpose. That is, the structure, dimensions, forming material, etc. are appropriately selected to suit the application, and there are many different types. However, basically, the base end is joined together and the distal end has a pair of clamping legs that can be opened and closed. The pair of clamping legs are normally in an open state due to spring force, and when clamping an object, the tips of the clamping legs are closed by applying clamping force with the fingers. In other words, conventional tweezers require operations such as applying gripping force with the fingers when gripping an object, and releasing the gripping force with the fingers when releasing the object.
Please note that this is done based on the user's will.

On the other hand, when the target object is a cell, as shown in Fig. 9, the cell 2 is injected or aspirated using a microtube 1, which is a glass tube with a hole several μm in diameter at the tip. In some cases, there is a cell manipulation method in which one cell 2 is sucked in, and then inserted into a microtube 1 and a weak current at the cell level is detected through a wire.

Another means of performing TFC cell manipulation is to move the slider 5 by linear motors 3 and 4, as shown in FIG.
As shown by the arrows (X and Y directions), there is a device in which cells are manipulated by sliding in the X and Y directions and manipulating a micropipette 6 attached to one end of the slider 5. 8 is a chassis, 9 is a cell, 10 is an illumination lens, and 11 is an objective lens.

[Problem that the invention seeks to solve]

Conventional bottle sets open and close the clamping legs using the force of the fingers based on the user's will.Next, they can be used to clamp cells in bioenzymes or microscopic objects in the field of high-density semiconductors. Manipulation of minute objects is no longer possible.

In other words, conventional tweezers can only hold objects of a few hundred micrometers at most, and smaller objects such as prokaryotes of several micrometers or fungi of several tens of micrometers can be grasped using conventional tweezers. It is not possible. Even if you can grasp the object with conventional tweezers, the gripping force when holding the object is very unstable, so if the object is something like a cell, it is difficult to grasp the structure of the cell. There is a risk of it being destroyed or deformed. Further, in many cases, when holding and operating such a minute object, an enlarged image of the object is obtained using a microscope, and the tweezers operation is often performed while monitoring the enlarged image.

In such cases, it is originally desirable to perform remote control, but with conventional tweezers, it is necessary to apply a clamping force to the tweezers with one finger, so the finger itself must be within the field of view of the magnified image. There is also the problem that it is easy to get into the system and difficult to operate.

Please note that in the cell manipulation using the micropipette shown in FIG. 9, it is not necessary to apply a clamping force like tweezers. But on the other hand, injection.

The drawback is that only relatively simple operations such as suction can be performed. Furthermore, when performing operations using a microscope, there is a problem in that the hands and fingers must always be placed directly under and near the microscope, making remote control difficult.

Furthermore, the manipulator shown in FIG. 10 and using a near motor has the advantage that depending on how the control voltage is applied to the linear motors 3 and 4, operations with an accuracy on the order of several μm can be performed by remote control. ,
There are the following problems. In other words, when a cell is held and cut with a microneedle, the force that fixes the cell (the suction force of the microneedle in Figure 10) and the pricking force of the microneedle are It is necessary to perform extremely delicate position change control depending on the state of the cell, such as the robustness or internal fluid pressure of the cell.

However, with the conventional manipulator having the configuration shown in FIG. 1O, it is impossible to control the delicate position change as described above, and cells are often destroyed.

Incidentally, the present inventors have developed a piezoelectric bottle set for holding fine objects and have already filed an application as Japanese Patent Application No. 1988-77889.

FIGS. 11(a) and 11(b) are perspective views showing an example thereof.

This is achieved by attaching a piezoelectric element 24.25 between the pair of clamping legs 21.22 and the connecting body 23, and controlling the voltage applied to the piezoelectric element 24.25.
The tip of 2 can be displaced, and the next one is 0.1
A high displacement accuracy of about ˜0.01 μm can be obtained. Furthermore, compared to the above-mentioned or near-motor manipulator, it has the advantage of being able to accurately perform more delicate cell manipulations, etc.

However, unless the cell conditions, such as the robustness of the cell membrane and the internal fluid pressure of the cell, are accurately known beforehand, there is a risk of cell destruction.

Therefore, the present invention provides a method for clamping an object, such as an MfJ cell, with an appropriate force that immediately responds to the state of the object, even if the state of the object is not known in advance. It can be operated, and it is possible to perform various operations with precision remotely and with delicate control.
It is an object of the present invention to provide piezoelectric tweezers that can stably manipulate fine objects of several micrometers to several tens of micrometers without causing structural damage.

[Means for solving problems]

The present invention is characterized by taking the following measures in order to solve the above problems and achieve the object. That is, the piezoelectric tweezers of the present invention have a pair of clamping legs that can be freely opened and closed. A first piezoelectric element is attached, a predetermined signal voltage is applied to the first piezoelectric element by a signal voltage applying means to cause a predetermined amount of deviation, and the clamping legs of the tweezers body are used to hold an object. A second piezoelectric element is attached to the tweezers body so that the pressure applied to the clamping legs when the tweezers is clamped can be converted into an electric signal, and the first piezoelectric element is It is characterized in that the signal voltage applied to the piezoelectric element is controlled by a signal voltage control means.

[Effect]

By carefully implementing the above-mentioned measures, the tip of the clamping leg of the tweezers body will be deflected in a predetermined direction by an amount of deflection commensurate with the magnitude of the signal voltage applied to the first piezoelectric element, and the tip of the clamping leg of the tweezers body will be deflected in a predetermined direction with a stable force. The second piezoelectric element is capable of holding an object, and when the object is held, pressure from the object applied to the holding legs is detected by the second piezoelectric element, and a holding force corresponding to this detected pressure is applied to the holding legs. It turns out.

1 and 2 are diagrams illustrating the principle of the present invention. In FIG. 1, 26 is a piezoelectric bimorph that constitutes one of the clamping legs, and 27 is a piezoelectric bimorph that constitutes the other clamping leg. The piezoelectric bimorph 26 acts as a pressure element to generate a force to clamp a minute object such as a cell, and the pressure '1 bimorph 27 clamps the object and then detects the pressure applied to the clamping legs. The two piezoelectric bimorphs 26 and 27 that act as elements may have exactly the same configuration, but
As shown in FIG. 1, a combination of a parallel type piezoelectric bimorph 26 and a series type piezoelectric bimorph 22 is desirable.

The length of the piezoelectric bimorph! , the thickness is t, the electrostriction constant of the piezoelectric ceramic is 1ist, and the applied pressure is V, then the amount of deviation ΔKA when one side of the piezoelectric bimorph is fixed is Δx = 3・12・d3t・V/l” − (1
). Next, at this time, the pressing force at the deflection end PP =
3 wt” dll・Eh-V/41・”
<2) (Eh: Young\A w: Paimole 7 width).

On the other hand, when force F is applied to the piezoelectric bimorph, the generated electric current EE
e is e = 3 trsx ・l-F/2 bt
・(3) becomes. As a reminder, the piezoelectric bimorph is a so-called differential type sensor, and when the force applied to the piezoelectric bimorph and the bending reaction force of the piezoelectric bimorph are in balance with each other, and there is no temporal change in the tr displacement ΔxB, e −=0. Therefore, e is generated by clamping the cell 27 as shown in FIG. The period in which the contact portion is displaced is limited to the period in which the cell itself continues to change over time.

In this way, the piezoelectric bimorph 26 acts as a pressure element,
By using the piezoelectric pyromorph 27 as a detection element, an object 28 such as a cell is clamped and the applied pressure is extracted as an electrical signal. By controlling the pressurizing force of the piezoelectric bimorph 26 as a pressurizing element based on this electric signal, it becomes possible to clamp the object 28 with an optimal clamping force, and it becomes possible to prevent structural destruction of the object 28.

〔Example〕

FIG. 3 is a perspective view showing the first embodiment of the present invention. In FIG. 3, reference numeral 30 denotes a tweezers body, which is composed of a dovetail, a pair of clamping legs 31 and 32, and a connecting body 33. A first and second piezoelectric element 34p35 having a bimorph structure is interposed between the clamping legs 31, 32 and the connecting body 33. Among these piezoelectric elements, the first piezoelectric element 34 is deflected in a predetermined direction according to the signal voltage applied to the signal voltage application terminal 36.37, and opens and closes the clamping legs 31.32. There is. The second piezoelectric element 35 is the clamping leg 3
When an object is held between the ends of the terminals 1 and 32, the pressure is converted into an electrical signal, which is sent to the outside from the terminals 38 and 39.

FIG. 4 is a partial cross-sectional view showing the structure of the first piezoelectric element 34. As shown in FIG. As shown in the figure, the first piezoelectric element 34 is made by joining two pieces of piezoelectric ceramics 41 and 42 with an intermediate electrode 43 in between, which are arranged so that their polarization directions are in the same direction as shown by the arrows in the figure. This element has a parallel bimorph structure in which outer electrodes 44, 45 are attached to both sides, and predetermined signal voltages are applied from terminals 36, 37 to the intermediate electrode 43 and outer electrodes 44, 45.

The fifth is a partial cross-sectional view showing the structure of the second piezoelectric element 35. As shown in the figure, the second piezoelectric element 35 is made by bonding two piezoelectric ceramics 51 and 52 arranged with opposite polarization directions as shown by the arrows, and attaching outer electrodes 54 and 55 to both sides of the piezoelectric ceramics 51 and 52. The signal voltage generated at terminals 54 and 55 is taken out to the outside from terminals 38 and 39, and the element has a nine-series bimorph structure.

FIGS. 6(a) and 6(b) are explanatory diagrams of the operation of a piezoelectric element having a bimorph structure. As shown in the figure (&), length l2 width W.

Assuming that the electrical strain coefficient of the piezoelectric element 60 having a bimorph structure with a thickness of t is d31 and the applied voltage is V, the amount of deviation ΔX of the tip 62 when the base end 61 is fixed is as shown in FIG. , as shown in the above equation (1), ΔK = 3"l""dH"v/l".The pressing force P at the deflection end of the piezoelectric element 60 at this time is given by the above equation (2). As shown in (P-3wt-d
H・gh @ V/41. Thus, when a signal voltage having a predetermined polarity and magnitude is applied to the terminals 36 and 37 of the first piezoelectric element 34, one piezoelectric ceramic When the piezoelectric ceramics expand, the other piezoelectric ceramics act to contract, and as a result, the piezoelectric ceramics are bent in the direction of superposition by a displacement amount of ΔX and a pressing force of P.

On the other hand, the generated voltage e when an external force is applied to the piezoelectric element having a bimorph structure is expressed by the above equation (3) and is as follows: K, θ=3 gm*·l−F/2bt. In this way, when pressure is applied from the object to the second piezoelectric element 35, an electric signal having a predetermined polarity and magnitude is generated in the relationship between the displacement direction and the polarization direction of the piezoelectric ceramic, and the electric signal is output from the terminal s8.39. be done. Based on this signal, a signal voltage application terminal (not shown)
By controlling the signal voltage applied to the piezoelectric element 34, the deflection amount ΔX and the pressing force P are automatically changed, and the clamping force is controlled to be t depending on the state of the object.

In this embodiment, since the first piezoelectric element 34 having a parallel bimorph structure is used for pressurization, it has the advantage of low impedance and high operating efficiency. Furthermore, since the second piezoelectric element 35 having a direct-diameter bimorph structure is used for detection, there is an advantage that the capacitance is small and the detection sensitivity is high. In other words, when detecting a converted electrical signal in voltage mode, the generated charge is Q and the capacitance is C.
Then, the generated voltage e is 8 = Q/C. Since the series bimorph structure element can reduce the value of the capacitance C, detection sensitivity increases.

FIG. 7 is a diagram showing a second embodiment of the present invention. This embodiment differs from the first embodiment in that the clamping arms 71.7
2 and the connecting body 73, the first .9 immorph structure has a piezoelectric ceramic bonded onto a non-piezoelectric member. This is because second piezoelectric elements 74 and 75 are interposed.

Figure 8 shows the above 1. It is a partial sectional view of the 2nd piezoelectric element'/4,75. As is clear from FIG. 8, this piezoelectric element has a piezoelectric ceramic 81 bonded onto a non-piezoelectric member 82, and the piezoelectric ceramic 81 is bonded onto a non-piezoelectric member 82.

A signal voltage is applied to the box 81 from the terminals 76 (1B) and 77 (79).

In this second embodiment, when a signal voltage is applied,
Only a single piezoelectric ceramic 81 causes distortion. As a result, due to the relative mechanical relationship with the non-piezoelectric member 82 that does not cause distortion, the same deflection as in the first embodiment will occur. However, the deflection force is smaller than that of the first embodiment. Further, when the object is held between the holding arms 71 and 72, the pressure applied to the holding arms 71 and 72 causes distortion in the piezoelectric ceramic 81, and an electric signal is generated. Therefore, the same clamping force control as in the first embodiment can be performed.

Note that the non-piezoelectric member 82 is a clamping arm 71 of tweezers.
Instead of being provided separately from the clamping arms 71.72, the extensions of the clamping arms 71.22 may also be used, and the pressure-1 ceramics can be attached to the clamping arms 71.72.
It may be attached to the outer or inner surface of 72.

Note that the present invention is not limited to the above embodiments. For example, in the above embodiment, the first piezoelectric element for pressurization is attached to one clamping arm, and the second piezoelectric element for detection is attached to the other clamping arm. The first one is for pressurization and detection. The second piezoelectric elements may be attached one set at a time. Further, a piezoelectric element having a laminated structure may be used as the piezoelectric element for pressurization, and this piezoelectric element may be interposed between the base end portions of the pair of clamping arms, also serving as a connecting body. Furthermore, in the first embodiment, an element with a parallel bimorph structure is used as the f41 piezoelectric element for pressurization, and an element with a series bimorph structure is used as the second piezoelectric element for detection. 1. A piezoelectric element having a parallel or series piezoelectric structure may be used as all of the second piezoelectric elements.

In this case, the efficiency and sensitivity are inferior to those of the first embodiment, but since the same structure is used, it is easy to make a duplicate, and there is no risk of misuse of the two during use. It has the advantage of being highly flexible in use. It goes without saying that various other modifications can be made without departing from the gist of the present invention.

〔Effect of the invention〕

According to the present invention, the tip of the clamping leg of the tweezers main body is deviated in a predetermined direction by the amount of mental deviation commensurate with the magnitude of the signal voltage applied to the first piezoelectric element, stably and volitionally holding the object The second piezoelectric element detects the pressure from the object applied to the clamping arms when the object is clamped, and the clamping force is applied to the clamping arms in accordance with this detected pressure. Therefore, even if you do not know in advance the state of an object such as a cell,
It is possible to clamp and operate an object with an appropriate force that immediately responds to the condition of the object, and various operations can be performed with precision with delicate remote control, and within a few micrometers.
It is possible to provide piezoelectric tweezers that can stably manipulate fine objects with a size of about 100 μm to several tens of μm without causing structural damage.

[Brief explanation of the drawing]

1 and 2 are detailed diagrams for explaining the present invention in detail, FIG. 1 is a diagram showing the basic structure, and FIG. 2 is an explanatory diagram of the operation. 3 to 6(a) and 6(b) are views showing the first embodiment of the present invention, in which FIG. 3 is a perspective view showing the configuration, and FIGS. 4 and 5- are views showing the first embodiment. Partial cross-sectional views showing the structure of the second bimorph piezoelectric element, FIGS. 6(a) and 6(b)
FIG. 2 is an explanatory diagram of the operation of a piezoelectric element having a bimorph structure. 7th
8 and 8 are diagrams showing a second embodiment of the present invention, FIG. 7 is a perspective view showing the structure, and FIG. 8 is a partial sectional view showing the structure of a piezoelectric element having a bimorph structure. Figures 9 and 10 are diagrams for explaining the conventional technology, respectively.
Figures 1(a) and 1(b) are perspective views illustrating the problem to be solved. 1.6... Myphropith, 2,9... Cell, 3
．． 4... Linear motor, 5 river slider, 7... Stage, 8... Chassis, 10... Lighting lens, 11
...Objective lens, 20...Tweezers body, 21.
22, 31. 32. 77. 72... clamping leg, 2s, s
3.73...connector, 24, 34. 74...First piezoelectric element, 25,35.75...Second piezoelectric "bare hand", 26.27...Piezoelectric bimorph,
28...Object, 41.42.51.52°81...
・Piezoelectric ceramics, 44, 45.54°55...electrode plate. Applicant's representative Patent attorney Jun Tsuboi Figure 1 Figure 2 N3r! ! ! I Figure 4 Figure 5 Figure 6 Figure 8 Figure 9 Figure 10 Prisoner Figure 11

Claims (1)

[Claims] A tweezers body having a pair of clamping legs that are provided so as to be freely opened and closed; and a first piezoelectric element that is attached to the tweezers body so as to be able to apply a deflecting force in the direction of the opening and closing legs to the clamping legs of the tweezers body. an element, a signal voltage applying means for applying a signal voltage to the first piezoelectric element to cause a predetermined amount of deviation, and a pressure applied to the clamping legs when an object is clamped by the clamping legs of the tweezers body A second piezoelectric element is attached to the tweezers body so as to be convertible into an electric signal, and a signal voltage applied to the first piezoelectric element is controlled based on the electric signal taken out from the second piezoelectric element. Piezoelectric tweezers characterized by comprising signal voltage control means.