JPH0810605A - Fluid supply device - Google Patents

Abstract

PURPOSE:To provide a fluid supply device simple in structure, easy to operate at the time of use, enabled in miniaturization and wt. reduction and suitable to carry. CONSTITUTION:Oxygen generated from the anode of a water electrolizing cell is utilized as pressure gas and hydrogen generated from the cathode thereof is occluded by a hydrogen occluding alloy 14 so as not to be discharged to the outside of a fluid supply device. Hydrogen generated from the cathode is introduced into a hydrogen storage container 13 to be immediately occluded by the hydrogen occluding alloy 14. Therefore, a phenomenon such that hydrogen once generated transmits through a cation exchange membrane 6 to reach an oxygen side and is re-bonded to oxygen to return into water can be prevented and, the relation between supply quantity of electricity and the generation amt. of oxygen, in other words, the accurate relation between supply quantity of electricity and the supply amt. of a fluid is kept.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluid feeder for accurately feeding a fluid.

[0002]

2. Description of the Related Art Various infusion pumps are widely used to inject a small amount of a liquid medicine into a human body with high accuracy.

Conventional infusion pumps are syringe pumps, peristaltic (rotor type), depending on the method.
There are four types of pumps: finger pumps and bellows pumps. Of these, all except the bellows pump use a motor such as a stepping motor, a rotary solenoid motor, or a DC motor as a drive source for pushing out the chemical liquid, and employ a complicated mechanism for controlling the chemical liquid discharge amount. Therefore, its weight and size are generally large and expensive. Therefore, it is usually used on the bedside of a hospital and is not suitable for portable or disposable type. Also, the bellows pump is a system that uses the vaporization pressure of freon gas to push the bellows to discharge the chemical solution, but it is difficult to control the vaporization pressure of the freon gas, especially when a small amount of chemical solution is applied for a long time. However, there is a problem in the accuracy of the injection.

On the other hand, one of the inventors of the present application has proposed an apparatus which uses an electrochemical cell for generating a gas when a direct current is passed through it, and performs a pump function and a gas flow rate control at the same time (Japanese Patent No. No. 1214001
issue). Recently, an electrochemical infusion pump utilizing this principle has been proposed (H.R.M.Maguette, US Pat. No. 4,522,698). This electrochemical infusion pump has an electrochemical cell in which porous gas diffusion electrodes are joined to both sides of a water-containing ion exchange membrane that functions as an electrolyte, and hydrogen is supplied to the anode of the electrochemical cell. , Yang
Utilizing the fact that when a direct current is applied between the negative and positive electrodes, hydrogen becomes hydrogen ions at the anode, and the generated hydrogen ions reach the cathode side through the ion exchange membrane, where an electrochemical reaction occurs in which hydrogen is generated. It is a thing. That is, the pressurized hydrogen generated at the cathode is used as a drive source for pushing the piston, diaphragm, bellows and the like.

It is also possible to use oxygen instead of hydrogen as the reactant of this electrochemical cell, and if air is used as the oxygen source to be supplied to the cathode, the structure of the infusion pump will be quite simple. Become.

Further, as a modified version of this electrochemical infusion pump, a method utilizing the electrolysis reaction of water (Japanese Patent Laid-Open No. 2-302264) is such that a cathode is provided on one side of an ion exchange membrane,
Electrolysis of water when the anode is bonded to the other surface or the electrochemical cell in which the cathode and the anode are separated so as to insulate them separately from each other is soaked in water and a direct current is applied to both electrodes. Hydrogen or oxygen generated by the above or a mixed gas of hydrogen and oxygen is used as a pressure source of the infusion pump.

[0007]

The operating principle of an infusion pump of the type that supplies a chemical solution using an electrochemical system is that when a direct current is applied to an electrochemical cell, it is proportional to the amount of electricity supplied according to Faraday's law. Since gas such as oxygen and hydrogen is generated, the pressure of this gas pushes out the chemical solution through the bellows and the diaphragm. Since the amount of gas generated at this time can be controlled extremely precisely by the amount of electricity (current x time) applied to the electrochemical cell portion, there is a feature that the supply amount of a liquid such as a chemical liquid can be accurately determined. .

As an electrochemical cell, in principle, a solid polymer cation exchange membrane, a solid polymer anion exchange membrane, an inorganic proton conductor, an aqueous electrolyte solution, etc. are used as an electrolyte and a direct current is applied. It is possible to use any cell that produces gas.

However, an electrochemical cell in which porous electrodes are bonded to both sides of a hydrated cation exchange membrane functioning as an electrolyte is used, and hydrogen is supplied to the anode of this cell and hydrogen generated from the cathode is used as a pressure source. The hydrogen transfer cell used and the oxygen transfer cell that supplies oxygen and air to the cathode and uses oxygen generated from the anode as a pressure source are not very problematic when used with a small current such as supplying a small amount of chemical solution. Although it does not occur, when a large current is passed to generate a large amount of gas in a short time, the overvoltage of the electrochemical cell increases, and the applied voltage must be increased, and if a too high voltage is applied,
It became a water electrolysis cell instead of a hydrogen or oxygen transfer cell, and it was necessary to raise the pressure of the gas to be supplied considerably. In addition, when the gas to be supplied is dry, there is a drawback that the water in the cation exchange membrane evaporates and the resistance of the cation exchange membrane itself increases. To avoid this, the gas to be supplied must be humidified. However, complicated control means were required.

On the other hand, the water electrolysis cell utilizes a very simple reaction in which water is electrolyzed by applying a direct current to generate oxygen from the anode and hydrogen from the cathode. Although hydrogen, oxygen, or a mixed gas of both can be used, it is preferable to use oxygen as the pressurized gas.

However, in this case, hydrogen is released to the outside of the infusion pump. For example, when it is desired to supply 100 ml of chemical liquid per hour, at least 100 ml of oxygen is required, and at this time, 200 ml of hydrogen will be released to the outside. This is 3.33 ml per minute
However, if a large amount of hydrogen is supplied in a short time, a large amount of hydrogen is released at the same time, which is dangerous.

Further, when the hydrogen generated from the cathode stays near the cation exchange membrane which is the electrolyte, hydrogen is much more easily permeated through the cation exchange membrane used for the electrolyte as compared with oxygen. Part of the hydrogen that has passed passes through the cation exchange membrane and reaches the oxygen side, where hydrogen and oxygen recombine due to the catalytic action of the metal used as the electrode and return to the original water, and the amount of electricity supplied and the amount of oxygen generated. In other words, it was difficult to obtain an accurate relationship between the amount of electricity supplied and the amount of chemical solution supplied.

[0013]

The present invention has been made to solve the above-mentioned problems of an electrochemical type infusion pump, and its application is not limited to an infusion pump, and liquids other than chemical liquids and The purpose of the present invention is to provide a device for supplying general fluid such as gas.
An object of the present invention is to provide a fluid supply device that is easy to use and has the advantages of being small and lightweight and suitable for being carried.

In the fluid supply device according to the present invention, oxygen generated from the anode of the water electrolysis cell is used as a pressurized gas, and hydrogen generated from the cathode is occluded in the hydrogen storage alloy, and hydrogen is stored outside the fluid supply device. It is characterized in that it is not released.

The water electrolysis cell that can be used in the present invention includes:
A cell in which a porous metal electrode is bonded to both sides of a solid polymer cation exchange membrane is used, both electrodes are in contact with water, and oxygen generated from the anode upon energization is used as a pressurized gas.
Incidentally, in such a water electrolysis cell, it is common to put water in advance on both the anode side and the cathode side, but the solid polymer ion exchange membrane can absorb a large amount of water inside, As a result, it exerts a proton conductive function and acts as an electrolyte, and it is not always necessary to put water on both the anode side and the cathode side. If water is required for the electrode reaction, water is supplied from the opposite electrode side through the solid polymer ion exchange membrane.

It is also possible to attach a check valve to the fluid supply port.

[0017]

In the fluid supply apparatus according to the present invention, a fluid such as a chemical solution is stored in the fluid storage unit in advance, and both electrodes of the water electrolysis cell or one of the electrodes is brought into contact with water, and an anode and a cathode are connected. When a direct current is applied to the water, electrolysis of water occurs, oxygen is generated from the anode, and hydrogen is generated from the cathode. As a fluid storage unit, a soft bag-like body that can be deformed by the pressure of gas is used, and this is placed in another closed container that does not deform by pressure, and the oxygen generated from the anode of the electrochemical cell is inside the closed container. If you keep it energized, the pressure inside the sealed container will rise,
The pressure is applied to the bag-shaped body containing the fluid such as the chemical liquid, and the bag-shaped body is deformed in the shrinking direction, and as a result, the fluid such as the chemical liquid is supplied from the fluid supply port outside the closed container. .

Since the amount of oxygen generated at a constant pressure due to the electrolysis of water is determined by the amount of electricity supplied (current x time),
When a constant current is applied, the supply amount of the fluid per unit time becomes constant, and an arbitrary supply amount of the fluid can be obtained by changing the magnitude of the applied current.

On the other hand, hydrogen generated from the cathode of the electrochemical cell is introduced into a hydrogen storage container equipped with a hydrogen storage alloy, and is stored therein by reacting with the hydrogen storage alloy, and hydrogen is stored outside the fluid supply device. Will not be released at all.

As is well known, in a hydrogen storage alloy, the equilibrium of metal-hydrogen system is represented by an isotherm diagram of dissociation pressure and composition of metal hydride. Hydrogen storage alloy,
When kept at a certain temperature and a certain hydrogen pressure, a metal hydride with a constant composition is produced. For example, lanthanum metal hydride - if using nickel 5 hydride (LaNi ₅ H), the hydride 25 ° C., Keeping in equilibrium with the 2 atm hydrogen, a LaNi ₅ H _6. That is, 1 mol of LaN
About 5 g of hydrogen is occluded with i5H (433.5 g). This hydrogen is equivalent to about 61.1 liters at 1 atmosphere and 25 ° C.

Now, considering a fluid supply device for supplying 100 ml of chemical liquid per hour for 5 hours, the minimum required amount of oxygen is 500 ml at 25 ° C. and 1 atm, and at this time, 1 liter of hydrogen is simultaneously generated. Therefore, the LaNi ₅ H required to store this hydrogen is about 7 g. In this way, a small amount of metal hydride can store a large amount of hydrogen and prevent hydrogen from being released to the outside.

Although a chemical liquid is usually considered as a fluid to be supplied, the application of the fluid supply device of the present invention is not limited to the supply of a chemical liquid, and any fluid such as liquid or gas can be used. It goes without saying that it can be used to supply

[0023]

The structure and method of use of the fluid supply device according to the present invention will be described in detail with reference to preferred embodiments.

[Example 1] A bag-shaped body as a fluid storage section,
A fluid supply device using lanthanum-nickel pentahydride as a hydrogen storage alloy was produced. FIG. 1 shows its cross-sectional structure. In the figure, reference numeral 1 is a soft neoprene rubber bag as a fluid storage unit, the bag portion has a thickness of 0.2 mm and an internal volume of 130 ml at the maximum. A fluid supply port 2 is attached to the. Reference numeral 3 denotes an acrylic case, which is a cylindrical shape having a thickness of 3 mm, an outer diameter of 60 mm, and a length of 70 mm, which is not deformed even when a pressure of several atmospheres is applied, and has a rubber bag 1 as a fluid storage unit therein. It is stored.
4 is a target fluid to be supplied, and 100 ml of physiological saline was used here. Reference numeral 5 is a thin tube, and 6 is an injection needle.
Reference numeral 7 is an electrochemical cell portion as a gas generating portion, and 8 is a cation exchange membrane functioning as an electrolyte.
A Nafion 117 membrane having a water content of 40 mm and a diameter of 40 mm was used. Reference numeral 9 is an anode, and 10 is a cathode, both of which are porous platinum electrodes having a diameter of 30 mm joined to both surfaces of a cation exchange membrane by electroless plating. 11 is the water in contact with the cation exchange membrane. Reference numeral 12 is a DC constant current power source in which a battery and a constant current circuit are combined. Reference numeral 13 denotes a stainless steel hydrogen storage container, which has a cylindrical shape with an outer diameter of 60 mm and a length of 10 mm, and is filled with 5 g of lanthanum-nickel 5 hydride (LaNi ₅ H) as a hydrogen storage alloy 14. deep. However, the hydrogen storage metal and the cathode of the electrochemical cell are arranged so as not to come into direct contact with each other.

In using this fluid supply device, the DC constant current power supply 12 is used to connect the anode 9 and the cathode 10 to
When a direct current of 50 mA is applied, an electrolysis reaction of water occurs in the electrochemical cell section 7, and oxygen 15 is emitted from the anode.
Further, hydrogen 16 is generated from the cathode. The oxygen 15 accumulates in the space 17 between the rubber bag 1 and the case 3, the rubber bag 1 is deformed in a contracting direction, and the physiological saline 4 passes through the fluid supply port 2 and the thin tube 5, It is supplied from the injection needle 6. If electricity is continued, physiological saline will be 100 ml in 1 hour.
It was supplied, and the amount of supply every 5 minutes was always kept constant, showing that the accuracy of the relationship between the amount of electricity supplied and the amount of electricity supplied was extremely good.

On the other hand, about 2 generated from the cathode at this time
00 ml of hydrogen is introduced into the hydrogen storage container 13, where it is stored in the hydrogen storage alloy LaNi ₅ H. LaNi ₅
When H comes in contact with hydrogen at 25 ° C and 2 atm, it is about 1 per 1g.
Since 40 ml of hydrogen can be occluded, if 5 g of LaNi ₅ H is put in the hydrogen storage container 13 in advance, all the hydrogen generated from the cathode can be occluded, and it will not go out of the fluid supply device. There wasn't.

[Embodiment 2] The structure is exactly the same as that of Embodiment 1, except that the hydrogen storage alloy is replaced by a misch metal alloy [Mm (Ni ₄ M
n _{0 . 2} Al _0.2 Co _0.6 )] was used. 5 g of misch metal type gold was used.
This misch metal alloy can store about 150 ml of hydrogen per 1 g at 25 ° C. and 1.5 atmospheric pressure. When a direct current of 450 mA was applied to the electrochemical cell section in the same manner as in Example 1, 100 ml of physiological saline was supplied per hour, and the amount of supply every 5 minutes was always kept constant.
The accuracy of the relationship between the amount of electricity supplied and the amount of electricity supplied was extremely good, and 200 ml of hydrogen generated at the same time was occluded in the misch metal alloy and did not flow out of the fluid supply device.

[Embodiment 3] The structure is exactly the same as that of Embodiment 1, but L which is a hydrogen storage alloy in a hydrogen storage container is used.
aNi ₅ H was directly attached to the cathode of the electrochemical cell, and the hydrogen storage alloy and the electrolyte were not in contact with each other.
A fluid supply device was produced. The sectional structure is shown in FIG.
The symbols 1 to 17 in the figure are the same as those in the first embodiment. Here, 5 g of LaNi ₅ H was used.

As in Example 1, the electrochemical cell was
When a direct current of mA is applied, 100 ml of physiological saline is supplied for one hour, the amount of supply every 5 minutes is always kept constant, and the relationship between the amount of electricity supplied and the amount of electricity supplied is extremely accurate and occurred simultaneously. 200 ml of hydrogen was stored in the hydrogen storage alloy LaNi ₅ H and did not go out of the fluid supply device.

[Embodiment 4] Instead of the rubber bag-like body described in Embodiment 1 as the fluid storage portion, an outer cylinder of a commercially available disposable syringe for 100 ml and a rubber piston at the tip of the sucker are used. The fluid supply device used was made. Its sectional structure is shown in FIG. In the figure, 2 to 17 show the same thing as Example 1, and used the outer cylinder 18 of the syringe and the rubber piston 19 of the tip of the sucker as a fluid storage part.
20 is the tip of the syringe. The length of the acrylic cylinder 3 is 140 mm, and the tip portion 20 of the syringe is inserted into the fluid supply port 2.

When a constant DC current of 600 mA is applied to the electrochemical cell, the rubber piston 19 at the tip of the sucker moves in the direction of being pushed into the outer cylinder 18 of the syringe, and as in Example 1, 1 100 ml of physiological saline is supplied per hour, and the supply amount every 5 minutes is always kept constant, and the accuracy of the relationship between the amount of electricity supplied and the supply amount is extremely good. In this case, since there is frictional resistance between the rubber piston 19 at the tip of the sucker and the outer cylinder 18 of the syringe, in order to supply the physiological saline solution at the same speed as in the first embodiment, Since a larger pressure than that in Example 1 is required, a large current of 600 mA needs to be passed.

[Embodiment 5] With the same structure as in Embodiment 1,
A fluid supply device having a check valve attached to the fluid supply port was manufactured. In this device, there was no liquid leakage from the fluid supply port when not in use, and the liquid supply was stopped even if the pressure outside the fluid supply port was reduced during use. With this structure, it is also possible to use gas as a fluid instead of liquid.

[0033]

In the fluid transporter according to the present invention, since the water electrolysis cell is used as the electrochemical cell, the current to be applied is small as in the case of the hydrogen transfer cell or the oxygen transfer cell. There is no concern that the resistance will be increased due to the limitation of the range or the drying of the ion exchange membrane that acts as an electrolyte, and a complicated control mechanism such as pressurization and humidification of gas for solving these is unnecessary. Also, the amount of supply of the target fluid is determined by the gas generated from the electrochemical cell. The amount of gas generated is the amount of energizing electricity, in other words (current x
It can be set by time), the supply amount per unit time is the value of current, and when a constant current is applied, the total supply amount can be determined by time,
The fluid can be accurately supplied over a long period of time by a very simple method.

In the fluid supply device according to the present invention for supplying the fluid by pushing the fluid storage portion with the gas generated from the electrochemical cell, it is critically important to use oxygen generated from the anode as the pressurized gas. is there. That is, the hydrogen generated from the cathode is introduced into the hydrogen storage container and immediately stored therein by the hydrogen storage alloy. Therefore, it is possible to prevent the phenomenon that hydrogen once generated permeates the cation exchange membrane and reaches the oxygen side, where it recombines with oxygen and returns to water. Relationship, in other words, an accurate relationship is maintained between the amount of electricity supplied and the amount of fluid supply. Of course, it is possible to eliminate the risk of hydrogen leaking to the outside during use of the fluid supply device, and since only oxygen is accumulated in the fluid supply device after using the fluid supply device, it is possible to eliminate There is no danger at all.

As the hydrogen storage alloy, in addition to the lanthanum-nickel pentahydride and the misch metal hydride described in the examples, all kinds of hydrogen storage alloys such as titanium-nickel hydride can be used. Is. Further, the hydrogen storage alloy may be separated from the cathode of the electrochemical cell as described in Example 1, or may be directly attached to the cathode or may be porous as described in Example 3. It may be attached to the cathode via a sheet, but in any case, it is kept out of contact with the solid polymer ion exchange membrane as the electrolyte.

Further, in the fluid supply apparatus according to the present invention, since the rubber bag-shaped body or the disposable syringe is used as the fluid storage section, the gas generation section can be repeatedly used. When the bag-shaped body is used for the fluid storage unit, the material of the bag-shaped body is not limited to the rubber described in the first embodiment, but may be soft plastic or a bag made of thin metal or a bellows-like container depending on the pressure of gas. Any deformable container may be used. Further, as the fluid storage unit, a commercially available disposable plastic syringe or a glass syringe can be used as they are, and in the case of further miniaturization, the syringe as described in the fourth embodiment is used. It is possible to use the one composed only of the outer cylinder and the piston. In this case, for the piston,
As described in Example 4, the piston at the tip of the sucker of a commercially available syringe may be used as it is, or a cylindrical piston having an O-ring separately attached may be used in various shapes and materials. It is possible.

Further, by providing the backflow prevention valve at the fluid supply port of the fluid storage unit, there is no fear of leakage of the chemical liquid or the like when not in use, and it is possible to use gas as the supply fluid.

Further, the entire fluid supply device according to the present invention has a simple structure, can be made small and lightweight, can be carried around, and can be easily operated during use. When used for, it is extremely easy for the patient to use.

As described above, the fluid supply device according to the present invention has a simple structure, is inexpensive, and makes it possible to make the fluid supply unit disposable, and uses the conventional bellows, diaphragm or electrochemical method. It can eliminate the drawbacks of the existing infusion pumps, and its industrial value is extremely large.

[Brief description of drawings]

FIG. 1 is a diagram showing a cross-sectional structure of a fluid supply device according to a first embodiment of the present invention.

FIG. 2 is a view showing a sectional structure of a fluid supply device according to a third embodiment of the present invention.

FIG. 3 is a view showing a sectional structure of a fluid supply device according to a fourth embodiment of the present invention.

[Explanation of symbols]

 1 Rubber Bag 3 Acrylic Case 4 Saline 7 Electrochemical Cell 6 Cation Exchange Membrane 13 Hydrogen Storage Container 14 Hydrogen Storage Alloy

Claims (3)

[Claims] 1. A fluid storage part comprising a gas generation part having a water electrolysis cell and a fluid storage part deformable by the pressure of the gas, and oxygen generated from the anode when a direct current is applied to the water electrolysis cell. A fluid supply device, characterized in that it is configured to pressurize a fluid to push out a fluid and occlude hydrogen generated from the cathode of the water electrolysis cell in a hydrogen storage alloy. 2. The fluid supply device according to claim 1, wherein the hydrogen storage alloy is housed in a hydrogen storage container. 3. A hydrogen storage alloy is attached to the cathode of an electrochemical cell directly or through a porous sheet,
The fluid supply device according to claim 1.