Actuators and fluid delivery systems using such actuators

Abstract

An actuator includes a non-magnetic, electroactive material that is suitable to impart force upon application of an electric current, a power supply to provide an electric current to the electroactive material and a controller in operative connection with the power supply to control application of electric current to the electroactive material. In one embodiment, the controller is adapted to limit rates at which electric current is applied to or removed from the electroactive material to predefined rates, thereby reducing the potential for high frequency harmonic emissions.

1 . A fluid delivery system comprising a syringe having a reciprocating plunger disposed therein, the plunger being in operative connection with a piston member, the piston member being in operative connection with an actuator including a nonmagnetic, electroactive spring adapted to apply force to the piston member to pressurize the fluid within the syringe.  
   
   
       2 . The fluid delivery system of  claim 1  wherein the electroactive material is a shape memory alloy.  
   
   
       3 . A fluid delivery system comprising a syringe having a reciprocating plunger disposed therein, the syringe including an inlet and a outlet, the plunger being in operative connection with a piston member, the piston member being in operative connection with an actuator including a nonmagnetic, electroactive material adapted to apply force to the piston member to pressurize the fluid within the syringe.  
   
   
       4 . The fluid delivery system of  claim 3  wherein the electroactive material is adapted to apply force in one direction to pressurize fluid within the syringe and in another direction to draw fluid into the syringe.  
   
   
       5 . The fluid delivery system of  claim 3  wherein the electroactive material is adapted to apply force in one direction to pressurize fluid within the syringe and a biasing element is used to apply force in another direction to draw fluid into the syringe.  
   
   
       6 . A fluid delivery system comprising a collapsible enclosure having an inlet valve an outlet valve therein, and an actuator including a nonmagnetic electroactive material that is adapted to change the volume of the collapsible enclosure.  
   
   
       7 . A fluid delivery system comprising a fluid chamber in fluid connection with a diaphragm and an actuator including a nonmagnetic, electroactive material that is operable to compress the diaphragm.  
   
   
       8 . A fluid delivery system comprising a length of elastic tubing and an actuator including at least one pressure member that is operable to compress a section of the elastic tubing when a force is applied thereto by a nonmagnetic, electroactive material.  
   
   
       9 . The fluid delivery system of  claim 8  wherein the actuator includes a plurality of pressure members, each of the pressure members being operable to compress a section of the elastic tubing when a force is applied thereto by electroactive material in operative connection with the pressure member.