Surgery – Means for introducing or removing material from body for... – Treating material introduced into or removed from body...
Reexamination Certificate
2000-03-14
2003-04-29
Rivell, John (Department: 3753)
Surgery
Means for introducing or removing material from body for...
Treating material introduced into or removed from body...
C604S540000, C415S073000, C029S889000
Reexamination Certificate
active
06554799
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a pump for sucking or injecting a liquid from or into a living tissue, and in particular, to a precision screw pump suitable for sucking or injecting a viscous tissue fluid while minimizing invasion into the human body.
BACKGROUND OF THE INVENTION
Conventional methods for sucking a biological tissue fluid from or injecting a liquid into a living body transfer a liquid by applying a negative pressure to a pipe to suck the liquid or applying a positive pressure to the pipe to extrude the liquid.
A recent growing demand for treatment methods with less invasion requires reduction in the diameter of a pipe inserted into a living body. On the other hand, the pipe frictional resistance increases in proportion to the viscosity of a liquid while decreasing in proportion to the pipe diameter, and a driving force for transfer further decreases in proportion to the square of the decrease in pipe diameter. Thus, it is difficult to use a pipe of a small diameter to transfer a viscous liquid inherently having a large pipe frictional resistance (FIG.
1
).
Thus, small-diameter pipes can inevitably be used only for liquids of a low viscosity, and large-diameter pipes must still be used to suck or inject viscous tissue fluids.
If, however, a large-diameter pipe is used, for example, to treat tympanitis, a large amount of eardrum is disadvantageously incised upon insertion of the suction pipe. Besides, the large diameter of the suction pipe limits sites from which viscous pus can be sucked.
Likewise, when a large pressure is required in injecting a liquid, for example, the cerebrospinal fluid, a thick pipe must pierce through the body in order to obtain a high pressure sufficient to press the liquid surface.
According to the prior art, the pipe frictional resistance increases relatively with a decrease in pipe diameter, whereby it has been very difficult to reduce the diameter of the pipe to the extent that invasion into the living body can be minimized while maintaining an effective amount of liquid transferred. In particular, since it has been almost impossible to suck or inject a viscous liquid, which requires a high pressure for suction or injection, using a pipe of a very small diameter, suction or injection of a viscous liquid with less invasion is very significant.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a suction and injection pump that can transfer a sufficient amount of viscous liquid despite the use of a very thin suction and injection pipe in order to provide means for enabling a viscous liquid to be sucked or injected while minimizing invasion into the human body.
Having made research to achieve this object, the inventors have found that introduction of a screw pump structure enables a liquid to be transferred only by means of the rotation of a rotor without depending on a pressure for sucking or pressing the liquid, that a viscous liquid can be moved by increasing the number of rotations of the rotor, and that the pipe diameter can be reduced by twisting up a plurality of very thin filaments to obtain a rotor of a very small diameter that can be rotatably housed in a thin pipe.
The present invention was made based on the findings that the transfer capability improves consistently with a decrease in friction between an inner wall of a needle and a transferred liquid or between the rotor and the liquid and that the screw pump prevents the amount of liquid transferred from being affected by a large gap between an outer periphery of the rotor and the inner wall of the needle, as long as the liquid has a certain degree of high viscosity.
The present invention provides a pump capable of minimizing invasion into human bodies by housing a very thin rotor in a cylindrical needle and positively transferring a liquid based on the mechanical configuration of the rotor so as to effectively suck or inject a viscous liquid while using this configuration to reduce the pipe diameter.
More specifically, the present invention provides a precision screw pump for injecting or ejecting a liquid into or from a biological tissue, as described below.
(1) A needle-shaped precision screw pump of a very small diameter for injecting or ejecting a liquid into or from a biological tissue.
(2) A precision screw pump in an instrument for injecting or ejecting a liquid into or from a biological tissue, comprising a cylindrical thin needle having an introduction port at one end and a discharge port at the other end, and a cylinder connected to one end of the needle and having a larger diameter than the needle, wherein
said cylindrical needle is a screw pump comprising a rotor housed in said needle for rotation along an axial direction thereof and a driver housed in said cylinder and connected to one end of said rotor for rotating the rotor, wherein
said rotor is a rotor obtained by twisting up a plurality of filaments and is rotated in synchronism with the rotation of said driver to transfer a liquid through said thin pipe from said introduction port to said discharge port.
(3) The precision screw pump according to (2) wherein said cylindrical needle comprises a smooth-surface substance having a predetermined strength.
(4) The precision screw pump according to (2) or (3) wherein the filaments constituting said rotor are covered with the smooth-surface substance.
(5) The precision screw pump according to any one of (2) to (4) wherein said rotor has a screw angle set between 15 and 35° relative to a rotational center axis.
In addition, the present invention provides a rotor for a screw pump as described below.
(6) A rotor for a screw pump manufactured by twisting up a plurality of filaments into a screw.
Further, the present invention includes the following method for producing a photocurable resin the above rotor for a screw pump.
(7) A method for producing the rotor for a screw pump rotor according to (6), the method comprising
providing a plurality of filaments,
coating an adhesive on the filaments,
twisting up the filaments, and
curing the adhesive to give a screw pump rotor.
(8) The method according to (7), wherein the adhesive is a photocurable resin.
In addition, a basic concept of the present invention is a biological liquid injection and ejection instrument as described below.
(9) A biological liquid injection and ejection instrument comprising a micro screw pump formed of a hollow needle.
(10) A biological liquid injection and ejection instrument wherein a micro screw pump is formed of a hollow needle so that the hollow needle has a small diameter.
(11) A method of making a diameter of a hollow needle small, the method comprising making a hollow needle in the form of a micro screw pump.
DEFINITION OF TERMINOLOGY
The “needle-shaped or needle” constituting the present screw pump can be shaped like a hollow cylinder and may have a flat or sharp tip, as shown in
FIGS. 2A and 2B
, respectively.
The “introduction or discharge port” of the needle is not necessarily limited to predetermined one end. In other words, for liquid suction, a tip portion of the needle which is contacted with the surface of a liquid to be sucked is the introduction port, whereas a cylinder side of the needle is the discharge port. On the contrary, for liquid injection, one end of the needle which is connected to the cylinder is the introduction port, while another end of the needle which is inserted into a living body is the discharge port.
The liquid to be transferred by the present screw pump can improve its own fluidity in the needle when the rotor is moved, and includes not only a solated liquid, which has low viscosity but also a gelled liquid, which has high viscosity.
The “screw pump” constituting the present invention is comprised of a casing and a rotor so as to transfer a liquid by rotating the rotor. The “rotor” is any rotor having a structure such as a “thread” or a “screw structure,” which can rotate a shaft to transfer the liquid in a fixed direction.
The “plurality of filaments” constituting the rotor according to the present inventio
Hatamura Yotaro
Nakao Masayuki
Okusa Takenori
Center for Advanced Science and Technology Incubation, Ltd.
Nixon & Peabody LLP
Rivell John
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