Patent Application
20100040490
The invention relates generally to the field of medial devices and more particularly to a portable self-contained medical pump capable of delivering precise doses.
The field of medical pumps has seen many improvements over the years, with numerous designs for specific types of uses. Examples includes pumps for the delivery of insulin, artificial heart pumps and many non-specific pump designs. Some of these designs incorporate electromagnets to produce the pump effect or utilize a removable medicine camber.
For example, U.S. Pat. No. 4,786,240 to Koroly et al. discloses a two chamber pump that utilizes an electromagnet within the chamber. Permanent magnets are placed at either ends of a chamber and an electromagnet is embedded within a flexible septum in the chamber. The polarity of the electromagnet is flipped thus alternately moving the electromagnet between the two permanent magnets, thus pumping fluid into and out of either side of the two pumping chambers created by the septum.
Another prior pump design is disclosed in U.S. Pat. No. 4,915,017 to Perlov. In this design diaphragms of various flexibility are utilized to create multi-chamber pumps. In some versions of the disclosed pump magnetic coils are utilized, along with a magnet in the diaphragm to count the number of time the pump has cycled and thus track the total flow of fluid through the pump.
In a third design, an electromagnetic pump is disclosed in U.S. Pat. No. 5,607,292 to Rao. In this design a single electromagnet is used in conjunction with elastromeric spring seals to pump fluid in and out of a chamber.
A final prior art pump design is disclosed in U.S. Pat. No. 7,377,907 to Shekalim. In this design a complex labyrinth is utilized to regulate flow from the pump and includes a removable cartridge to house the labyrinth and a fluid reservoir for the fluid to be delivered by the pump.
In a first embodiment, an electromagnetic pump has a housing including first and second spaced apart electromagnets. A controller for controlling the magnets and a power source for powering the electromagnets within the housing. A removable cassette is in engagement with the housing between the first and second electromagnets and includes a cavity. The pump also has inlet and outlet ports in communication with the cavity and a magnetic piston disposed within the cavity. In preferred embodiments the electromagnets are capable of operating at different strengths and different polarities.
In some other embodiments, the piston is movable between a first open position and a second closed position. Also, the inlet and outlet ports may be part of the removable cassette. The inlet and outlet ports can take any form known in the art but it is preferred that the ports are one-way flapper valves.
In another embodiment the magnetic piston includes a piston body and a Neodymium magnet. Furthermore, the cavity may be on a first side of the piston and the piston includes an extension defining a passage on a second side of the piston. In such an embodiment the cassette would further include a sterile vent in communication with the passage. In further embodiments the cassette further includes a flexible barrier disposed within the cavity.
In yet other embodiments the electromagnetic pump further includes a first sensing device capable of detecting when the piston is in the closed position. It is preferred that the pump also include a second sensing device capable of detecting when the piston is in the open position. It is highly preferred that the first and second sensing devices are LED sensors and the cassette is capable of reflecting light from the LED sensors back to the LED sensors.
In highly preferred embodiments the default position of the piston is in the closed position.
In other embodiments a method of dispensing a liquid is disclosed. The method includes the step of providing an electromagnetic pump. The pump includes a housing including first and second spaced apart electromagnets, a controller for controlling the magnets within the housing, a power source for powering the electromagnets within the housing, a cassette in engagement with the housing between the first and second electromagnets and including a cavity, inlet and outlet ports in communication with the cavity and a magnetic piston disposed within the cavity. Next a liquid to be dispensed is supplied to the inlet port and the first electromagnet is powered to draw the piston into an open position thereby drawing the liquid through the inlet port and into the cavity. The first electromagnet is depowered and the second electromagnet is powered to draw the piston into a closed position thereby pushing the liquid out of the cavity and through the outlet port. In the current invention the concept of depowering the magnet includes, but is not limited to, two different operations. The first operation of depowering is removing the charge from the electromagnet in question thus allowing the pull from the opposite electromagnet to work on piston independently. Alternatively, the operation described as depowering is to reverse the polarity of the electromagnet thus pushing the piston if the electromagnet had been pulling it.
In another embodiment of the method, the method further includes the step of providing free-flow protection against liquid flowing back through the inlet port. It is preferred that the free-flow protection is provided via a one-way flapper valve. In addition, or separately free-flow protection can also be provided by the controller controlling the piston to default to the closed position.
In still further embodiments, the method also includes the step of sensing the position of the piston within the cavity. It is preferred that this step is accomplished by the housing including a sensor for reading the location of the piston. It is highly preferred that the sensor is an LED.
In other embodiments, the method further includes the step of calculating the volume of liquid delivered via movement of the piston. Preferably, after the step of powering the second electromagnet to draw the piston into a second position thereby pushing the liquid out of the cavity and through the outlet port, the second electromagnet is depowered, thereby allowing a cycle of powering the first electromagnet, depowering the first electromagnet, and powering the second electromagnet is capable of being repeated plurality of times. In such an embodiment the method further includes the step of calculating the total volume of liquid delivered via the plurality of cycles. It is highly preferred that the steps of calculating are performed by the controller.
In other preferred embodiments the cassette is removable. In such an embodiment, it is highly preferred that the method further include the step of sensing for the presence of the removable cassette in the pump.
Also, wherein the movement of the piston between the open and closed positions is at a velocity, it is preferred that the method further include the step of varying the velocity of the piston to control a rate of deliver. The method further includes varying the dwell time between depowering the first electromagnet and powering the second electromagnet to control the rate of delivery.
Referring now to
The front 24 of the housing 12 includes an LCD display 32 for display of information related to dosage to the user. The housing 12 shown varies between open and closed positions by the upper housing 16 and lower housing 18 being pivotally joined at the magnet sections 26. However, in other embodiments the upper and lower housings 16, 18 could be joined at the side or any other known manner. In yet other embodiments the housings could be separate but lock together to from a housing.
Referring now to
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Referring specifically to
Referring again to
The barrier 64, magnet 66 and piston 68 are positioned within the cavity 46. Referring now to
Referring now to
In operation, a cassette 14 is inserted into the pump 10. The LEDs 38 then detect the presence of the cassette 14 because of the reflection of light from the reflectors 41, 43 back to the LEDs 38. The inlet connection 52 is connected to a source of fluid/medicine to be delivered and the outlet connection 54 is connected to the patient for delivery. The controller 34 sends a first control signal to the electromagnets 36 which in turn are powered to move the magnet 66 from the default closed position to the open position. When the magnet 66 is moved fluid is drawn from the inlet port 56 through the valve 76 and into the inner cavity 88. The magnets 36 are powered until the LED 38b recognizes that the magnet has moved as far to the bottom of the cavity 46 as it can by the reflection from the reflector 43 being cut off. When the magnet 66 has moved as far as possible (into the open position), the inner cavity 88 then contains a known amount of fluid since the volume of the inner cavity 88 is known.
The controller then sends a second control signal to the electromagnets 36, which powers the electromagnets 36 to reverse the polarity thus pushing the magnet 66 toward the closed position. As the magnet 66 moves toward the closed position fluid is pushed out of the inner cavity 88 and through the outlet port 58 and its corresponding valve 76. Once the magnet reaches the closed position and activates (i.e. cut off the reflection from the reflector 41) the corresponding LED 38a the controller 34 can calculate the amount of time it took to move the magnet 66 from the open position to the closed position. This amount of time can then be compared to an expected amount of time for such movement. The amount of time could vary based upon the viscosity of the fluid being delivered. If the time is longer than expected, the controller 34 can utilize more power in the next cycle (a cycle being from closed position to open position to closed position) to speed up delivery to reach a desired or preset delivery rate. This allows a high level of delivery accuracy. This pumps' delivery accuracy is also increased in that the pump can track the number of cycles and calculate the total delivery of fluid along with tracking the rate, this information can then be utilized to increase or decrease the pump rate accordingly.
While the principles of the invention have been shown and described in connection with specific embodiments, it is to be understood that such embodiments are by way of example and are not limiting.
