JP2972246B2 - Small in vivo movable machine - Google Patents

Description

Description: BACKGROUND OF THE INVENTION (Industrial Application Field) The present invention relates to a micro-in-vivo movable machine, and more particularly to a medical robot which invades a living body to find a special cell and to separate and fuse the cell. Used for

(Prior Art) Conventionally, incision surgery of an affected part has been often used to know the mutation of cells in a living body. However, this method puts a great physical burden on the patient, so that the operation could not be performed on a patient who was already physically tired. Furthermore, it is difficult to apply this method even when the diseased part is widely distributed in the living body because it is observed with the naked eye after the incision, or when it is located in a place where observation is difficult. For this reason, in recent years, in the medical field, a method of examining and treating an affected part by inserting a device into a living body from the mouth or anus of a patient without incising the affected part has been studied. At this time, since the size of the living body is small, it is necessary to reduce the size of the insertion device and to move the insertion device with the same accuracy as the size of the cell. With the rapid development of semiconductor sensors in recent years, it has become possible to manufacture minute sensors for medical use, but the miniaturization of precision actuators that move insertion instruments has been delayed, which has hindered medical progress. Was.

Meanwhile, since about two years ago it was announced that silicon surface micromachining technology could be used to create joints that connect moving mechanical parts to each other on the surface of a silicon substrate, gears, springs, sliders,
Movable mechanical elements such as micro scissors were prototyped. In particular, proceedings of the International Electron Device Meeting (Technical Dijest of International Elec
"IC-P" by LSFan (LSFan) and others described on page 666 of tron Devices Meeting'88 (IEDM'88).
rocessed Electrostatic Micro-motors
It is worth noting that prototypes of micro polysilicon micro-step motors having a diameter of about 0 μm and a thickness of about 1 μm have been described, and it has been confirmed that they actually rotate at a speed of about 550 rpm by electrostatic force. This dimension is almost equal to the size of the cell, so that it is expected that the development of micro precision actuators for medical use will advance using the aforementioned movable mechanical elements including micro motors. became.

FIGS. 3 (a) and 3 (b) show a top view and a sectional view of a polysilicon step motor prototyped by LSFan and the like cited above. This micromotor includes a rotating rotor 1 and a shaft 2 having a cap 4 for covering the center side of the rotor 1 from the upper surface in order to prevent the rotor 1 from coming off, and a stator positioned outside the rotor 1 to apply an electrostatic force to the rotor 1. 3 is composed of three elements. As is apparent from FIG. 2, while the shaft 2 and the stator 3 are fixed to the silicon substrate 6 via the insulating film 5, 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 3 by electrostatic force. When a voltage having the same phase is applied to two stators located 180 degrees opposite to each other, and the phases are sequentially rotated as shown in FIG. 1, Φ1, Φ2, and Φ3, the rotor 1 also rotates accordingly. The rotation of the rotor 1 can be reversed by reversing the direction of rotation of the phase applied to the stator.

Polysilicon movable mechanical elements can be manufactured by the silicon IC process, so that mechanical elements with different shapes can be manufactured at the same time using photolithography on the same silicon substrate, and individual parts have already been assembled The advantage of not requiring a man-hour for assembling, unlike conventional mechanical parts, is expected by the production in a different shape, and future development is expected.

(Problems to be Solved by the Invention) However, as for these small movable mechanical elements, a method for examining and treating by moving in a living body as described above by combining the small movable mechanical elements is disclosed. Nothing is disclosed about the structure of the machine to make it. Furthermore, these small movable mechanical elements are conventionally driven only by externally applied electrostatic force, as exemplified in the above-mentioned micro step motor, and have no function of feedback from the small movable mechanical mechanism. For this reason, even if a minute movable mechanical mechanism is introduced into a living body, it cannot move in response to a delicate signal in the living body, and its function is limited. In addition, the use of electrostatic force as a driving force causes the following problems.

(1) The electrostatic force is inversely proportional to the square of the distance of an object acting as is well known as the Clone's law. For this reason, the electrostatic force increases as the distance decreases. On the other hand, since the electrostatic force generated by applying voltages having different signs from the outside from the outside only acts in the attracting direction, if there is no force other than the electrostatic force, the unfixed portion of the movable mechanical element (micromotor In this case, the rotor may stick to the fixed portion (stator). A state in which a moving object moves while being in contact with a fixed object must be avoided because the friction at the contact surface is large, so that the machine is damaged or the energy efficiency is reduced. However, as described above, it is very unstable mechanically to continue moving without contacting the interacting objects only by electrostatic force, and it was necessary to devise a method to reduce the friction while maintaining the mechanical balance. .

(2) Further, the electrostatic force is proportional to the product of the electric charges of the objects acting on each other. When a voltage is applied from the outside, this charge amount is proportional to the cross-sectional area of the surfaces of the object facing each other. The case of FIG. 3 corresponds to the cross-sectional area of the opposing surfaces of the rotor 1 and the stator 3 shown in FIG. As is apparent from this example, since the thickness of the polysilicon film is small (about 1 μm), the cross-sectional area is very small. Therefore, it was necessary to apply a large voltage to obtain a sufficient electrostatic force. In fact, in the previous example, it would take
It was reported that voltages from 0V to 350V were required. This voltage is much higher than the voltage of about 10 V used in normal ICs, and if you want to drive this motor, you will need a coil for raising the voltage in addition to the normal power supply. There was a disadvantage that the device became large.

(3) Mechanical components such as a rotor and a stator to which a voltage is applied are manufactured 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 should be noted that the resistances of the silicon substrate and the insulating film are not infinite, and there are actually finite resistances. As a result, the electric lines of force governing the mechanical balance in the small movable mechanical mechanism become complicated depending on the structure of the entire device, and the analysis of the motion of the mechanical mechanism becomes complicated. Further, since the insulating film has a large dielectric constant, the fact that the lines of electric force vary depending on the type and structure of the insulating film used is also a factor complicating the optimization of the structure of this device.

(4) Further, as a special problem caused by use in a living body, since the liquid in the body contains a large amount of electric field, there is a possibility that the living body may be damaged by affecting electric lines of force and current leaking into the living body. There is.

An object of the present invention is to eliminate the above-mentioned disadvantages of the prior art, to precisely and efficiently control the movement of a micro movable mechanical element in a living body, to obtain information on special cells in the living body, and to treat the same. To provide a new mechanical structure.

(Means for Solving the Problems) A micro-movement mechanical mechanism according to the first invention of the present application controls a micro-movable mechanical element that can move by the action of an applied force and a force acting on the micro-movable mechanical element. A micro movable machine in which a braking element is integrated on the same semiconductor substrate, wherein the movement of the movable mechanical element is controlled by a signal of a sensor recognizing a special cell in a living body. Features.

The micro movable mechanical mechanism of the second invention of the present application is a micro in vivo movable machine characterized in that, in addition to the first invention, an energy generator is provided on the micro movable machine to burn out special cells in the living body. It is characterized by having.

(Function) The micro-in vivo movable machine of the present invention has a braking element for controlling the force acting on the micro-movable mechanical element moving on the semiconductor substrate and a sensor for recognizing special cells in the living body as the micro- movable mechanical element. By controlling the movement of the micro movable mechanical element according to the signal of this sensor, it is possible to detect the abnormality by invading a minute area about the size of a cell in a living body Things. Further, by adding a function such as a heater or a laser, which is an energy generator, to the micro movable mechanical mechanism, abnormal cells at the invading location can be killed one by one.

In addition, at least a part of the force acting on the micro movable mechanical element moving on the semiconductor substrate is realized by using a fluid acting force to achieve a mechanical balance, thereby solving the problem associated with the electrostatic force of the conventional example. It is characterized by:

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

FIG. 1 shows a perspective view of an embodiment of the first invention of the present application. 3, the same reference numerals as those in FIG. 3 denote the same components. This micro movable mechanical mechanism includes a braking element for controlling the flow of a fluid, a micro movable mechanical element, and a sensor for detecting the vibration of cells in a living body. The rotor 1 rotates around the shaft 2 according to the flow of the fluid flowing into the micro movable mechanical element via the fluidic element 100, and the rotor 1 converts the rotation into linear motion by the slider 102. This micro movable mechanical mechanism is mounted on a catheter. The braking element comprises a fluidic element 100 and a fluid source 101 for supplying fluid thereto. The fluidic element 100 is a component for controlling the flow of a fluid, and has conventionally been manufactured by assembling a tubular pipe made of a metal or a plastic material. A special feature is set forth in "Measurement and Control" (Vol. 9, No. 3 (March, 1970)) on the conventional configuration and principle application of this fluidic element, and this knowledge can be used. Fluidic device 100 of FIG. 1 is made of the same configuration as the amplifier circuit outlined in page 225 of the document, the pressure P _S of the fluid flowing from the input pipe 12 the pipe 12 and another input tube 13 when when 14 is controlled by the pressure P ₁ and P ₂ of the fluid flowing from flowing out from the output pipe 15 and 16, the tube 15, the pressure P _3, it is a pressure P ₄ in the pipe 16 flows into the micro movable mechanical elements. The pressure difference between P ₃ and P ₄ are proportional constants are determined by the geometry of Furuidiku element 100 as a function of the pressure difference between P ₁ and P _2. Fluidic element shown in the figure
The fluid element has a structure in which the first stage outlet pipes 15 and 16 are connected to the next stage fluid element input tubes 13 and 14, and the differential pressure between the final stage output tubes 15 and 16 is input to the first stage input tube. An example of amplification at 100 times the differential pressure between 13 and 14 is shown on the same page of the above literature. Furthermore, it is possible to reverse the prepared pressure difference between P ₃ and P ₄ by the sign of the pressure difference between P ₁ and P ₂ on the opposite. Therefore, the fluidic element has two input tubes.
13, 14 and two output tubes 15, which produce a signal proportional to the input,
It can be compared to an electric four-terminal circuit having 16 and the function corresponding to the logic circuit or the analog circuit of the electric circuit can be created for the flow of the fluid by combining the fluidic element. By incorporating an actuator such as a flow sensor or a valve in the fluid source 101, the fluid flowing into the fluid element via the input pipes 12, 13, 14 can be controlled. As a result, the fluid output from the output tubes 15 and 16 can be controlled from the fluid source 101.

On the other hand, the micro movable mechanical element has a rotating part composed of components other than the conventional example shown in FIG. Rotor 1
Are disposed at the outlets of the output tubes 15 and 16 of the fluidic element 100, respectively. The rotor 1 rotates around the shaft 2 according to the force of the fluid flowing from the fluidic element 100 acting on the blades of the rotor 1. . The slider 102 linearly moves in the front-rear direction in accordance with the rotation of the rotor. Provided at the outlet of the rotor of the driving force towards the tube 15 provided at the outlet of the tube 16 when towards the pressure P ₃ of the fluid flowing from the output pipe 16 is greater than the pressure P ₄ of the object flowing from the tube 15 As a result, the slider 102 moves away from the cells 103 and 106 in FIG.
Conversely, when P ₄ is larger than P ₃ is a slider 102
Moves toward the cell. In this way, the slider 102 can be linearly moved back and forth according to the rotation of the rotor, and the tip of the slider 102 is
It moves inside.

In the present embodiment, a sensor 104 for detecting a cell signal is mounted at the tip of the slider 102. This sensor, for example ISFET (I on S ensitive F ield E ffect T ransis
tor) can be used. An enzyme film is formed as a gate insulating film of the ISFET and moves in a living body. Since the output of the ISFET is considered to be different between the place where only the normal cells 103 are present and the place where the abnormal cells 106 are present, if the output is detected, when this sensor 104 comes close to the abnormal cells 106 You can know it and emit a signal. The signal is fed back to the fluid source 101 to control the movement of the micro mechanical element. Note that multiple sensors are provided and
If the type of T enzyme film is changed, a plurality of types of abnormal cells corresponding to the type can be detected. In response to this minute movement, the sensor is passed through a catheter equipped with a micro movable machine.
The output of 104 can be taken out. as a result,
Abnormalities inside the living body can be inspected on a cell-by-cell basis.
As this mounting method, it is also possible to use a telemetry technique other than the catheter. Thus the sensor 10
By mounting 4 on the movable mechanical mechanism, it is possible to control the movement of the minute movable mechanical element via the fluidic element 100, for example. The feedback tube 11 is
Furuidiku element when pressure difference P ₁ and P ₂ exceeds 20% of P _S
This is provided to prevent the flow of the fluid in 100 from becoming unstable. Further, the conduit 10 penetrates the semiconductor substrate at the outlet of the extra fluid and communicates with the outside world. The operation of Furuidiku element by the difference between the pressure P _S of the fluid flowing into the pressure and Furuidiku element of the fluid flowing through the conduit at a constant can be further stabilized. semiconductor
By using the IC process technology, it is possible to manufacture the fluidic device illustrated in FIG. 1 on a semiconductor substrate. The shape of the fluidic element is formed by lithography on a thin film of polysilicon or SiO ₂ deposited on a semiconductor substrate, and a hole of the fluidic element is formed in the thin film by an etching technique such as dry etching. Alternatively, a semiconductor substrate
This can also be produced by etching with an anisotropic etching solution such as EDP (ethylenediamine pyrocatechol). These processes are compatible with the processes used to make micro-movable mechanical elements,
When a fluidic element is manufactured in a thin film, it can be manufactured simultaneously with the process of the micro movable mechanical element, and has an advantage that an extra step is not required. After fabricating a fluidic element and a micro movable mechanical element on a semiconductor substrate,
In order for the fluid to flow along the semiconductor surface, the glass substrate is bonded to the semiconductor substrate so as to cover the mechanical mechanism to form a fluid passage.

The rotation of the rotor can also be controlled by providing irregularities on the sides of the gear blades of the rotor 1 of the micro movable mechanical element. The velocity of the fluid increases when the surface of the object placed in the flow of the fluid is convex, whereas the velocity of the fluid decreases when the surface is concave, and the velocity is small due to the velocity difference of the fluid. This is because a force is generated in a direction from a place to a place with a high speed.

As described above, it has been found that the movement of the micro movable mechanical element can be controlled by the flow of the fluid, but when it is desired to control the movement at a very high speed, the movement of the electrons in the object is more than the flow of the fluid. Since the flow is much faster, the method of motion control by electrostatic force has better response characteristics. Therefore, it is possible to control the movement of the rotor 1 by applying an AC voltage to the rotor from the outside, as in the conventional example. However, in the case of a structure in which the force of the fluid is also used at the same time, it is possible to use the method in which the movement of the rotor 1 is mainly performed by the acting force of the fluid, and the control by the electrostatic force is separated into only the control of the subtle movement of the rotor 1. is there. As a result, it is no longer necessary to apply a large voltage. It should be noted that, besides performing control by electrostatic force by applying a voltage, the same effect as above can be obtained by adding control by electromagnetic force using a coil or magnet to control by the above fluid, so this method is also included in the present invention. .

FIG. 2 shows a top view of one embodiment of the second invention of the present application. In the figure, the same numbers as the components in FIG. 1 indicate the same components. This embodiment is obtained by adding a heater 105 as an energy generator to the embodiment shown in FIG. When the tip of the slider 102 approaches the abnormal cell 106 in the body, the signal of the cell is received by the sensor 104, an electric current is applied to the heater 105, and the heater 105 has a function of burning and burning the abnormal cell 106. The same effect can be obtained by mounting a device that outputs energy such as a laser in addition to the heater. The micro movable mechanical element is not limited to the combination of the rotating rotor and the slider exemplified in the present invention, but includes a slider that performs a linear motion, a crank that converts a linear motion into a rotary motion, and a mechanical configuration such as a spring. All configurations combining elements are included.

(Effects of the Invention) The small in-vivo movable machine of the present invention can directly invade a living body because of its small components. Furthermore, since it has its own sensor and motion control system, it can autonomously move based on local signals in the living body. Further, by having a mechanism for emitting energy such as a heater or a laser, it is possible to remove abnormal cells in a living body at a level of one by one. When a fluid is mainly used as a power source, the influence of the trouble caused by the electrostatic force described above can be significantly reduced. That is, since the force due to the pressure difference of the fluid is not a force that attracts each other like an electrostatic force, a dynamic equilibrium state can be stably formed without contacting an object. Next, as described in the previous embodiment, it is possible to control the pressure difference of the fluid by changing the structure of the fluidic element, and it is not necessary to increase the voltage as in the conventional example. Finally, the fluid depends on the geometry of its flowing passage and not on the overall structure other than the passage. Further, since it is not affected by the material of the passage, it is not necessary to consider the difference even if the mechanical structure is manufactured using different materials, and as a result, the design of the mechanical structure is prepared. It is also a great advantage of the method that fluid forces do not interact with electrostatic or electromagnetic forces and that these forces can be analyzed independently. Further, when the fluidic element is manufactured on the same semiconductor substrate as the micro movable mechanical element, there is an added advantage that the complicated steps of miniaturizing the structure and assembling the micro parts are not required. These effects are remarkable, and the present invention is effective.

[Brief description of the drawings]

FIG. 1 is a top view of one embodiment of the first invention of the present application, FIG. 2 is a top view of a second embodiment of the present invention, and FIGS. 3 (a) and (b) are top views of a conventional structure, respectively. FIG. 1 ... rotor, 2 ... shaft, 3 ... stator, 4 ...
... cap, 5 ... insulating film, 6 ... silicon substrate, 10 ...
... Conduction hole, 11 ... Feedback tube, 12, 13, 14 ... Input tube, 15, 16 ... Output tube, 20 ... Rotor, 30 ... Stator, 100 ... Fluidic element, 101 ... Fluid source , 102 ...
… Slider, 103… In vivo cells, 104… Sensor, 10
5 ... heater, 106 ... abnormal cells

Claims (5)

(57) [Claims] A micro movable machine having a micro movable mechanical element capable of moving by the action of an applied force and a braking element for controlling a force acting on the micro movable mechanical element. The movement of the movable mechanical element is controlled by a signal of a sensor that recognizes a cell, and the minute movable mechanical element, the braking element, and the sensor are formed on the same semiconductor substrate. In vivo movable machine. 2. The micro in-vivo movable machine according to claim 1, wherein at least a part of the force acting on the micro movable mechanical element integrated on the substrate is subjected to motion control by utilizing the acting force of a fluid flow. , A small in vivo movable machine that controls the flow of the fluid by a fluidic element. 3. The sensor is an ISFET in which an enzyme film is used as a gate insulating film, and the ISFET has a different output between a place where the special cells are present and a place where only normal cells are present. The micro living body movable machine according to claim 1 or 2, characterized in that: 4. A plurality of ISFEs having a plurality of sensors, wherein the plurality of sensors use different enzyme films for a gate insulating film.
3. The in vivo micro-organism according to claim 1 or 2, wherein the plurality of ISFETs have different outputs between a place where specific cells are present and a place where only normal cells are present. Moving machinery. 5. The small in vivo movable machine according to claim 1, wherein an energy generator is provided on the small movable machine to burn out special cells in the living body.