Implantable pump with infinitely variable resistor

Abstract

A variable hydraulic resistor for use with implantable pumps is disclosed. The variable hydraulic resistor according to the present invention is particularly useful in varying the flow rate of a medication fluid from an otherwise constant flow implantable pump. An implantable pump is also disclosed, which does not require a complicated clinching system or the like, and which may include an undulating membrane and chamber design to reduce the height of the pump.

1 . An implantable device for dispensing an active substance to a patient comprising: 
 a housing defining a chamber, said housing having an outlet for delivering said active substance to a target site within said patient, said outlet in fluid communication with the chamber; and    EAP means for varying a flow rate of said active substance between said chamber and said outlet.    
     
     
         2 . The implantable device according to  claim 1 , wherein said EAP means includes an insert.  
     
     
         3 . The implantable device according to  claim 2 , wherein said insert is constructed from polyanilin.  
     
     
         4 . The implantable device according to  claim 2 , wherein said insert is constructed from polypyrrol.  
     
     
         5 . The implantable device according to  claim 2 , wherein said EAP means further includes a power source.  
     
     
         6 . The implantable device according to  claim 5 , further comprising means for controlling said EAP means for varying the flow rate of said active substance between said chamber and said outlet.  
     
     
         7 . The implantable device according to  claim 6 , wherein said means for controlling said EAP means are capable of selectively applying between zero (0) and two (2) volts.  
     
     
         8 . An implantable device for dispensing an active substance to a patient comprising: 
 a housing defining a chamber, said housing having an outlet for delivering said active substance to a target site within said patient, said outlet in fluid communication with the chamber;    a capillary in fluid communication between said chamber and said outlet, said capillary having an inner surface; and    a flow control element received within said capillary, said element having an outer surface opposing said inner surface of said capillary defining therebetween a passageway for the flow of said active substance therethrough, said outer surface of said element moveable relative to said inner surface of said capillary to alter the flow of said active substance therethrough, wherein said flow control element is constructed of EAP.    
     
     
         9 . The implantable device according to  claim 8 , wherein said flow control element is an elongated filament constructed from an EAP having a cross sectional dimension, the filament capable of being elongated to reduce the cross sectional dimension.  
     
     
         10 . The implantable device according to  claim 9 , wherein said elongated filament is constructed from polyanilin.  
     
     
         11 . The implantable device according to  claim 9 , wherein said elongated filament is constructed from polypyrrol.  
     
     
         12 . The implantable device according to  claim 9 , further comprising means for elongating the filament.  
     
     
         13 . The implantable device according to  claim 12 , wherein said means for elongating the filament includes a power source.  
     
     
         14 . The implantable device according to  claim 13 , wherein said means for elongating the filament is capable of selectively applying between zero (0) and two (2) volts to the filament.