JPH03173372A - Movable mechanical micromechanism and driving method thereof - Google Patents

Abstract

PURPOSE:To make a motion control precise and efficient by moving a movable mechanical microelement with an applied force and controlling a fluidic flow with a fluidic control device. CONSTITUTION:A movable mechanically configured micromechanism comprises a fluidic control device 100 and a movable mechanical microelement provided with a shaft 2 having as cap 4 and a rotor 1. The rotor 1 rotates around the shaft 2 via the fluidic control device 100 according to the fluidic flow flowing into the movable mechanical micromechanism. The fluidic control device 100 controls the fluidic flow and amplifies the differential pressure between output tubes 15 and 16 of a final stage in comparison with the one between input tubes 13 and 14 of an initial stage. Also, it is possible to integrate the fluidic control device 100 on a semiconductor substrate and control a fluid, and then the movable mechanical microelement can be controlled efficiently.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a micro movable mechanical mechanism, and particularly when used as an actuator for a medical robot, it is used to separate, fuse and remove microscopic objects such as cells. It will be done.

(Prior Art) In recent years, research has been conducted in the medical field on methods of directly inserting instruments into the living body of a patient to examine and treat affected areas. At this time, since the size of the living body is small, it is necessary to make the inserted instrument small and to move the insertion instrument with precision comparable to the size of the cell. While the rapid development of semiconductor sensors in recent years has made it possible to create microscopic sensors for medical use, the miniaturization of precise actuators that move insertion instruments has lagged behind, and this is hindering medical progress. Ta. However, since it was announced that silicon surface micromachining technology could be used to create joints for joining moving mechanical parts together on the surface of silicon substrates, gears, springs, sliders, and Movable mechanical elements such as micro-scissors were prototyped.

In particular, the International Electron Device Meeting Proceedings (Technical Digest of
International Electron De
vices Meeting '88 (IEDM"8
r IC-P by L, S, Fan et al., described on pages 666 to 669 of 8))
rocessed ElectrostaticMic
In ro-motors J, a prototype of a tiny polysilicon microstep motor with a diameter of about 10011 m and a thickness of about lpm was described, and it was confirmed that it actually rotated at a speed of about 500 rpm due to electrostatic force. is noteworthy. As a result, it is expected that the development of minute precision actuators for medical use will advance by utilizing the aforementioned movable mechanical elements, including micromotors.

As previously cited in Figures 4(a) and (b),
A top view and a cross-sectional view of a polysilicon step motor prototyped by Fan et al. are shown. This micromotor consists of a rotating rotor 1, a shaft 2 with a cap 4 that covers the center side of the rotor 1 from above to prevent the rotor 1 from coming off, and a stator that is located outside the rotor 1 and applies electrostatic force to the rotor 1. It is composed of three elements. As is clear from the figure, the shaft 2 and stator 3 are fixed to the silicon substrate 6 via the insulating film 5, whereas the rotor 1 is free from the silicon substrate 6 and rotates around the shaft 2. can do. When voltages of opposite signs are applied between the rotor 1 and the stator 3, the rotor 1 is attracted to the stator 3E9 by electrostatic force. Applying voltages of the same phase to two stators located 180 degrees opposite each other,
As shown in the figure, 1. ■2. 3, the rotor 1 also rotates accordingly. In addition,
The rotation of the rotor l can be reversed by reversing the direction of rotation of the phase applied to the stator.

Since polysilicon movable mechanical elements can be fabricated using a silicon IC process, mechanical elements with different shapes can be fabricated at the same time on the same silicon substrate using photolithography, and individual parts can be already assembled. By manufacturing it in this way, it has the added advantage of not requiring assembly man-hours like conventional mechanical parts, and is expected to develop in the future.

(Problems to be Solved by the Invention) However, since these minute movable mechanical elements have conventionally been driven only by electrostatic force as exemplified by the microstep motor described above, the following problems have arisen.

(1) Electrostatic force is inversely proportional to the square of the distance between the objects acting on it, as is well known as Coulomb's law. Therefore, as the distance becomes smaller, the electrostatic force becomes larger. On the other hand, since the electrostatic force generated by applying voltages of different signs from the outside acts only in the direction of attraction, if there is no force other than the electrostatic force, the unfixed part of the movable mechanical element (micromotor) In some cases, the rotor) may stick to a fixed part (stator). A situation in which a moving object moves while in contact with a fixed object must be avoided because the friction on the contact surface is large, causing damage to the machine and poor energy efficiency. However, as mentioned earlier, it is mechanically very unstable to continue moving without contacting objects that interact with each other using electrostatic force alone, so it was necessary to find a way to reduce friction while maintaining mechanical equilibrium. .

(2) Furthermore, electrostatic force is proportional to the product of the charges of objects that interact with each other. When a voltage is applied from the outside, the amount of charge is proportional to the cross-sectional area of opposing surfaces of the object. In the case of FIG. 4, this corresponds to the cross-sectional area of the opposing surfaces of the rotor 1 and stator 3 shown in FIG. 4(b). As is clear from this example, since the polysilicon film is thin (about lpm), the cross-sectional area is extremely small. Therefore, it was necessary to apply a large voltage to obtain sufficient electrostatic force. In fact, in the previous example, it takes 20
It has been reported that voltages ranging from 0V to 350V were required. This voltage is I
This is very large compared to the voltage of about OV, and if you try to drive this motor, you will need an external power coil in addition to the normal power supply, which has the disadvantage that the entire device will be large.

(3) Mechanical parts such as a rotor and a stator to which a voltage is applied are fabricated on a silicon substrate, and are usually electrically insulated from the silicon substrate 6 by an insulating film 5 as shown in FIG. However, it must be noted that in reality, the resistance of the silicon substrate and the insulating film is not infinite but finite. As a result, the lines of electric force that govern the mechanical equilibrium within the micro-movable mechanical mechanism become complex depending on the structure of the entire device, making analysis of the motion of the mechanical mechanism complicated. Furthermore, since the insulating film has a large dielectric constant, the lines of electric force change depending on the type and structure of the insulating film used, which is another factor that makes it difficult to optimize the structure of this device.

All of the above-mentioned difficulties arise from trying to control the motion of minute movable mechanical mechanisms only by electrostatic force.
A new device structure and driving method that solves this problem has been desperately desired.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the drawbacks of the prior art described above and to provide a new structure and driving method for precisely and efficiently controlling the movement of minute movable mechanical elements fabricated on a semiconductor substrate.

(Means for Solving the Problems) The micro-movable mechanical mechanism of the first invention of the present application includes a micro-movable mechanical element that can be moved by the action of an applied force, and at least a portion of the force that acts on the micro-movable mechanical element. It is characterized by being equipped with a full-deck element that controls the flow of fluid that mediates the flow of fluid.

A method for driving a micro movable mechanical mechanism according to the second invention of the present application controls the motion of at least a portion of the force acting on micro movable mechanical elements integrated on a substrate by using the force exerted by a fluid flow, and The feature is that the flow of water can be controlled by a fluidic element.

(Function) The micro-movable mechanical mechanism of the present invention is characterized in that it achieves mechanical equilibrium by using fluid force for at least part of the force acting on the micro-movable mechanical element moving on the substrate, and further , a mechanism with functions similar to those conventionally called fluidic elements is integrated on a semiconductor substrate using semiconductor process technology, making it possible to control the movement of this fluid.

(Example) Next, the first invention will be described with reference to the drawings.

FIG. 1 shows a top view of the first embodiment of the present application. In this figure, the same numbers as the constituent elements in FIG. 4 indicate the same constituent elements. This minute movable mechanical mechanism is
It is composed of a micro movable element consisting of a fluidic element 100, a shaft 2 with a cap 4, and a rotor 1, and the rotor 1 moves around the shaft 2 according to the flow of fluid that flows into the micro movable mechanical mechanism via the fluidic element 100. It rotates. The fluidic element 100 is a component for controlling the flow of fluid, and conventionally,
It was made by assembling tubular pipes made of metal and plastic materials. It should be noted that it is in accordance with the present invention that the fluidic element is used to control the fluid acting on the micro-movable mechanical element. You can make use of this knowledge as there is a special feature in "Measurement and Control" (Vol. 9, No. 3 (March 1972)) about the conventional configuration and principle applications of this fluidic element. 1st
The fluidic element 100 shown in the figure has the same configuration as the amplifier circuit outlined on page 225 of the same document, and has an input tube 1.
When the pressure Ps of the fluid flowing in from the input pipe 12 and the other input pipes 13 and 14 is controlled by the pressure P1 and P2 of the fluid flowing in from the output pipes 15 and 16, the pressure Ps becomes P and P. Microscopic 4 Flows into the moving mechanical element. The differential pressure between P3 and P4 is P
A constant of proportionality is determined by the geometry of the fluidic element 100 as a function of the differential pressure between l and P2. Four fluidic elements 100 shown in the same figure are arranged in series, and the output tube 1 of the first stage is
5.16 is connected to the next stage full-day element input tube 13゜14, and the fluidic element is the final stage output tube 1.
The differential pressure between 5 and 16 is 10
An example of 0-fold amplification is shown on the same page of the previous document. Furthermore, by reversing the sign of the pressure difference between Pl and P2, the pressure difference between P3 and P4 can be easily reversed.

Therefore, a fluidic element can be likened to an electrical four-terminal circuit with two input tubes 13.14 and two output tubes 15.16 producing a signal proportional to the input, and by combining fluidic elements, an electrical It is possible to create a function corresponding to a logic circuit or an analog circuit for fluid flow. As a result, it has become possible to control fluids using fluidic elements.

On the other hand, the minute movable element consists of the same components as the conventional example except for the stator 3 (FIG. 4), and the fluidic element 10
The rotor 1 rotates around the shaft 2 due to the force exerted by the fluid flowing in from the rotor 1 on the blades of the rotor 1. When the pressure P3 of the fluid flowing in from the pipe 16 is greater than the pressure P4 of the fluid flowing in from the pipe 15, the micro movable element shown in the figure rotates clockwise at a rotation speed corresponding to the differential pressure between P3 and P4. do. When P4 is greater than P3, it rotates counterclockwise. In this way, it is possible to control the movement of micro-movable mechanical elements using fluidic elements. The feedback tube 11 is provided to prevent the fluid flow within the fluidic element 100 from becoming unstable when the differential pressure between Pl and P2 exceeds 20% of Ps.

Furthermore, this conduction tube 10 passes through the semiconductor substrate at an outlet for excess fluid and communicates with the outside world. By keeping constant the difference between the pressure of the fluid flowing through the conduction pipe and the pressure Ps of the fluid flowing into the fluidic element, the operation of the fluidic element can be further stabilized.

The fluidic element shown in the figure can be manufactured on a semiconductor substrate using semiconductor IC process technology.

The shape of a fluidic element can be molded by lithography into an insulating thin film such as polysilicon deposited on a semiconductor substrate, and a hole for a fluidic element can be formed in the thin film by an etching technique such as dry etching. Alternatively, it can also be produced by etching the semiconductor substrate with an anisotropic etching solution such as FDP. These processes are compatible with the processes used to fabricate micro-movable mechanical elements, and when configured to fabricate fluidic elements in thin films, they can be fabricated simultaneously with the process for micro-movable mechanical elements without the need for extra steps. The advantage is that it doesn't. After the fluidic element and the micro movable mechanical element are fabricated on the semiconductor substrate, a glass substrate is bonded to the semiconductor substrate so as to cover the mechanical mechanism so that the fluid flows along the semiconductor surface to form a fluid passage.

FIG. 2 shows another embodiment of the invention. In the figure, components having the same numbers as in FIG. 1 indicate the same components. This embodiment differs from the embodiment shown in FIG. 1 only in the shape of the gear of the rotor 20, which is a minute movable mechanical element. When the surface shape placed in the fluid flow is convex, the fluid speed increases, whereas when the surface shape is concave, the fluid speed slows down.

This difference in velocity of the fluid generates a force in the direction from a location of low velocity to a location of high velocity. In this embodiment, the minute movable mechanical element is more likely to rotate in the clockwise direction. It is clear that the rotation of the minute movable mechanical element can also be adjusted here by the pressure of the fluids P3 and P4.

As mentioned above, we have found that the motion of minute movable mechanical elements can be controlled by the flow of fluid, but when it is desired to control the motion of microscopic mechanical elements at very high speeds, it is possible to Since the flow is much faster, it occurs that the method of motion control using electrostatic force has superior response characteristics. FIG. 3 shows another embodiment of the present invention, in which components having the same numbers as in FIG. 1 indicate the same components. This embodiment differs from the embodiment shown in FIG. 1 only in that a stator 30 is added to the minute movable mechanical elements. The movement of the rotor 1 is controlled by applying an alternating current voltage to the stator 30, as in the conventional example. However, in the case of Fig. 3, the movement of the rotor 1 is mainly performed by the acting force of the fluid, and the control by electrostatic force can be separated only into control of the delicate movement of the rotor 1. There is no need to apply voltage.

Moreover, as a result of adding electrostatic force control by the stator 30,
The movement of the movable mechanical element can now be controlled in a shorter time than the method shown in FIG. In the example shown in Fig. 3, control by electrostatic force is added to control by fluid by applying voltage to the stator 30, but it is also possible to add control by electromagnetic force to control by fluid by using the stator 30 as a coil or magnet. This method is also included in the present invention because it can achieve the effect of lifting and softening even if it is used.

In the embodiments shown in FIGS. 1 to 3 described above, the fluidic element and the micro movable mechanical element are integrated on the same semiconductor substrate, but the present invention is not limited to this structure. The present invention also covers general methods of controlling the movement of movable mechanical elements by controlling fluids using fluidic elements, such as forming a fluidic element on a substrate separate from the mechanical element and connecting the two with a tube. It is.

Furthermore, the minute movable mechanical elements are not limited to the rotating rotor shown in the present invention, but also include mechanical components such as sliders that move linearly, cranks that convert linear movement into rotational movement, and mechanical components such as springs. Includes all combined components.

(Effects of the Invention) Since the micro movable mechanical mechanism of the present invention uses fluid as the main power source, it is possible to significantly reduce the influence of troubles caused by the electrostatic force described above. That is, the force due to the pressure difference between the fluids is not a force that attracts each other like electrostatic force, so it is possible to stably create a dynamic equilibrium state without contacting an object. Next, as described in the previous embodiment, it is possible to control the pressure difference of the fluid by adding the structure of the fluidic element, and there is no need to increase the voltage as in the conventional example. Finally, the fluid depends on the geometry of the passageway through which it flows and not on the overall structure other than the passageway. Furthermore, since it is not affected by the material of the passage, there is no need to consider the difference even if the mechanical structure is made using different materials, and as a result, the design of the mechanical structure becomes easier. Another great advantage of this method is that the fluid force does not interact with electrostatic force or electromagnetic force, so these forces can be analyzed independently. A further advantage is that when the fluidic element is manufactured on the same semiconductor substrate as the micro movable mechanical element, the complicated steps of miniaturizing the structure and assembling micro parts are not required. These effects are remarkable and the present invention is effective.

[Brief explanation of the drawing]

FIG. 1 is a top view of an embodiment of the first and second inventions of the present application;
FIG. 2 is a top view of another embodiment, FIG. 3 is a top view of one embodiment described in the third and fourth claims of the present invention, and FIG.
a), (b) show a top view and a sectional view of a conventional structure. In the figure, 1...rotor, 2...shaft, 3...
... Stator, 4... Cap, 5... Insulating film, 6
...Silicon substrate, 101.・Conduction hole, 11... Feedback tube, 12.13° 14... Input tube, 15
．． 16... Output tube, 20... Rotor, 30... Stator, 100... Fluidic element.

Claims (4)

[Claims] (1) A micro-movable mechanical element that can be moved by the action of an applied force, and a fluidic element that controls the flow of a fluid that mediates at least a portion of the force that acts on the micro-movable mechanical element. Features a microscopic movable mechanical mechanism. (2) A micro-movable mechanical mechanism that controls the movement of at least a portion of the force acting on micro-movable mechanical elements integrated on a substrate by using the force exerted by a fluid flow, and controls the flow of the fluid using a fluidic element. driving method. (3) A method for driving a micro-movable mechanical mechanism according to claim 2, which utilizes the resultant force of electrostatic force and fluid force as the force acting on the micro-movable mechanical mechanism. (4) A method for driving a micro movable mechanical mechanism according to claim 2, which utilizes the resultant force of electromagnetic force and fluid force as the force acting on the micro movable mechanical mechanism.