Systems and methods for infusion of fluids using stored potential energy and a variable flow resistor

1. An infusion device comprising:

a plunger situated within a vessel so as to define a chamber within which a volume of fluid can be accommodated between a downstream surface of the plunger and the vessel;

an outflow path through which the fluid in the chamber is dispensed upon displacement of the plunger and

a variable flow resistor in fluid communication with the outflow path and being configured to increase exposure of a permeable area through which the fluid from the outflow path is dispensed as a force acting on the plunger decreases to maintain a substantially constant fluid flow rate from the vessel.

2. The infusion device of claim 1 , wherein the force acting on the plunger is a stored potential energy that has been released.

3. The infusion device of claim 1 , wherein the variable flow resistor acts to lower the resistance to fluid flow as the force acting on the plunger decreases.

4. The infusion device of claim 1 , wherein the variable flow resistor includes a solid member and a permeable member designed to move relative to one another so as to increase an area across the permeable member through which fluid within the outflow path can flow as the force acting on the plunger decreases.

5. The infusion device of claim 4 , wherein the solid member is attached to the plunger so that as the displacement of the plunger acts to move the solid member relative to the permeable member so as to increase the area across the permeable member through which fluid within the outflow path can flow as the force acting on the plunger decreases.

6. The infusion device of claim 1 further comprising an electronic control module to pre-set the flow rate of the fluid from the vessel.

7. The infusion device of claim 1 further comprising an electronic control module configured to dispense a pre-set flow rate of the fluid from the vessel based on information about a patient.

8. An infusion system comprising an array of infusion devices of claim 1 , wherein each device in the array of infusion devices is controlled by an electronic control module and is in fluid communication with a lumen of a multi-lumen tubing.

9. A method for delivering fluid comprising:

providing within a chamber, defined between downstream surface of a plunger and a vessel within which the plunger is situated, a volume of fluid to be delivered;

causing a force to act on the plunger to displace the plunger within the vessel, such that the fluid is dispensed from the chamber; and

varying the resistance to flow within a path through which the fluid is being dispensed from the chamber by increasing exposure of a permeable area through which the flow is being dispensed as the force acting on the plunger decreases, to maintain a substantially constant rate of dispensing.

10. The method of claim 9 , wherein, in the step of causing, the force acting on the plunger is a stored potential energy that has been released.

11. The method of claim 9 , wherein, in step of varying, the variable flow resistor acts to lower the resistance to fluid flow as the force acting on the plunger decreases.

12. The method of claim 9 , wherein the step of varying includes providing a variable flow resistor comprising a solid member and a permeable member designed to move relative to one another so as to increase an area across the permeable member through which fluid within the outflow path can flow as the force acting on the plunger decreases.

13. An infusion device comprising:

a plunger situated within a vessel so as to define a chamber within which a volume of fluid can be accommodated between a downstream surface of the plunger and the vessel;

an outflow path through which the fluid in the chamber can be dispensed upon displacement of the plunger by a force acting thereon; and

a variable flow resistor in fluid communication with the outflow, the resistor having an inlet cavity into which the fluid from the outflow path is received and an outflow cavity from which the fluid is dispensed out of the variable flow resistor, the resistor configured to vary a flow rate of the fluid between the inlet cavity and the outflow cavity to maintain a substantially constant pressure therein as the force acting on the plunger decreases, so that such pressure can act to deliver the fluid from the resistor at a substantially constant rate.

14. The infusion device of claim 13 , wherein the variable flow resistor is in fluid communication with a valve having a pre-determined aperture through which the fluid may be dispensed from the variable flow resistor.

15. The infusion device of claim 13 further comprising an electronic control module configured to dispense a pre-set flow rate of the fluid from the vessel based on information about a patient.

16. A method for delivering fluid comprising:

providing within a chamber, defined by a downstream surface of a plunger and a vessel in which the plunger is situated, a volume of fluid to be dispensed;

causing a force to act on the plunger to displace the plunger within the vessel, such that the fluid is dispensed from the chamber;

receiving the fluid dispensed from the chamber in an environment comprising an inlet cavity into which the fluid from the chamber is received and outflow cavity from which the fluid is dispensed, designed to maintain a substantially constant pressure therein that can act to dispense the fluid from the environment; and

dispensing the fluid from the outflow cavity while maintaining a substantially constant pressure in the outflow cavity by varying the flow rate of the fluid between the inlet cavity and the outlet cavity by increasing the exposure of a permeable area through which the fluid from the outflow path is dispensed, the pressure acting to dispense the fluid from the outflow chamber at a constant flow rate to a patient as the force on the plunger declines.

17. An infusion device comprising:

a plunger situated within a vessel so as to define a chamber within which a volume of fluid can be accommodated between a downstream surface of the plunger and the vessel;

an outflow path through which the fluid in the chamber can be dispensed upon displacement of the plunger by a force acting thereon; and

a variable flow resistor in fluid communication with the outflow path and having an inlet cavity into which the fluid from the outflow path is received, an outflow cavity from which the fluid is dispensed out of the variable flow resistor, the resistor being configured to increase exposure of a permeable area through which the fluid from the inlet cavity is transferred into the outflow cavity as the force acting on the plunger decreases to deliver the fluid from the resistor at a substantially constant rate.