Disposable syringe and cartridge with pneumatic chamber

Abstract

A syringe or cartridge having a hollow barrel with an open end and a second end suitable for attaching a needle assembly. A master plunger assembly that includes a master plunger and a plunger member is mounted in the barrel for longitudinal movement therein. A slave plunger is mounted in the barrel for longitudinal movement therein, and is located between the master plunger assembly and the second barrel end so as to define two chambers. The first chamber a liquid chamber and is between the slave plunger and the second barrel end, and the second chamber is a pneumatic chamber and is between the slave plunger and the master plunger assembly. The liquid-containing chamber is suitable for containing a liquid to be dispensed from the syringe, and the pneumatic chamber contains a gas such as air. When the liquid-containing chamber contains a liquid to be dispensed, a user applying selective pressure to the plunger member will cause the master plunger assembly to slide towards the slave plunger and compress the gas against the slave plunger. The slave plunger will as a result of this pressure slide towards the second barrel end as the gas decompresses and apply pressure against the liquid as a result thereof. The liquid will then be dispensed out of the syringe or cartridge via a needle attached to the barrel end.

What is claimed is:  
     
         1 . A syringe comprising: 
 a) a hollow barrel comprising a first barrel end and a second barrel end, said first barrel end being open and said second barrel end comprising means for allowing attachment of a needle assembly;    b) a master plunger assembly mounted in said barrel for longitudinal movement therein, said master plunger assembly comprising a master plunger and a plunger member extending through said first barrel end for allowing a user to apply pressure thereto;    c) a slave plunger mounted in said barrel for longitudinal movement therein, said slave plunger located between said master plunger assembly and said second barrel end so as to define a liquid chamber between said slave plunger and said second barrel end, and to define a pneumatic chamber containing a gas between said slave plunger and said master plunger assembly;    whereby, when said liquid chamber contains a liquid to be dispensed from said syringe, a user applying selective pressure to said plunger member will cause said master plunger assembly to slide towards said slave plunger and compress said gas against said slave plunger, said slave plunger will as a result of said pressure slide towards said second barrel end as said gas decompresses and apply pressure against said liquid as a result thereof, and said liquid will be dispensed out of the syringe via the means for allowing attachment of a needle assembly.    
     
     
         2 . The syringe of  claim 1  in which the gas substantially comprises air.  
     
     
         3 . The syringe of  claim 1  in which the means for allowing attachment of a needle assembly comprises an opening in said second barrel end for coupling with a needle assembly.  
     
     
         4 . The syringe of  claim 1  in which the slave plunger and the master plunger each are comprised of a rubber disc having at least one ridge for making substantial contact with the barrel, said ridge being suitable for sliding engagement with said barrel when pressure is applied thereto.  
     
     
         5 . The syringe of  claim 1  wherein said plunger member comprises a thumb engagement means at an end opposite the master plunger, said thumb engagement means allowing a user to pull said plunger member away from said syringe and cause a negative pressure on said master plunger.  
     
     
         6 . The syringe of  claim 1  further comprising a flexible tether connected between the master plunger and the slave plunger.  
     
     
         7 . A cartridge comprising: 
 a) a hollow barrel comprising a first barrel end and a second barrel end, said first barrel end being open and said second barrel end comprising means for allowing penetration of a needle assembly;    b) a master plunger mounted in said barrel near said first barrel end for longitudinal movement therein;    c) a slave plunger mounted in said barrel for longitudinal movement therein, said slave plunger located between said master plunger and said second barrel end so as to define a liquid chamber between said slave plunger and said second barrel end and a pneumatic chamber between said slave plunger and said master plunger;    wherein said liquid chamber is filled with a liquid to be dispensed from the cartridge via said second barrel end and said pneumatic chamber is filled with a gas.    
     
     
         8 . The cartridge of  claim 7  in which the gas substantially comprises air.  
     
     
         9 . The cartridge of  claim 7  in which the means for allowing penetration of a needle assembly comprises a membrane disposed across an opening in the second barrel end.  
     
     
         10 . The cartridge of  claim 7  in which the slave plunger and the master plunger each are comprised of a rubber disc having at least one ridge for making substantial contact with the barrel, said ridge being suitable for sliding engagement with said barrel when pressure is applied thereto.  
     
     
         11 . The cartridge of  claim 8  further comprising an aperture in said barrel, said aperture disposed along said barrel so as to allow air to flow to or from said pneumatic chamber.  
     
     
         12 . The syringe of  claim 7  further comprising a flexible tether connected between the master plunger and the slave plunger.  
     
     
         13 . A packaged cartridge combination comprising: 
 i) a cartridge comprising 
 a) a hollow barrel comprising a first barrel end and a second barrel end, said first barrel end being open and said second barrel end comprising means for allowing penetration of a needle assembly;  
 b) a master plunger mounted in said barrel near said first barrel end for longitudinal movement therein;  
 c) a slave plunger mounted in said barrel for longitudinal movement therein, said slave plunger located between said master plunger and said second barrel end so as to define a liquid chamber between said slave plunger and said second barrel end and a pneumatic chamber between said slave plunger and said master plunger;  
 d) an aperture in said barrel, said aperture disposed along said barrel so as to allow air to flow to or from said pneumatic chamber;  
 wherein said liquid chamber is filled with a liquid to be dispensed from the cartridge via said second barrel end; and  
   ii) a cartridge packaging hermetically sealed around said cartridge in which said cartridge is vacuum sealed within said packaging; 
 whereby as a result of said vacuum sealing, the volume of space interior to said cartridge packaging and said pneumatic chamber are substantially void of air.  
   
     
     
         14 . The packaged cartridge of  claim 13  in which the means for allowing penetration of a needle assembly comprises a membrane disposed across an opening in the second barrel end.  
     
     
         15 . The packaged cartridge of  claim 13  in which the slave plunger and the master plunger each are comprised of a rubber disc having at least one ridge for making substantial contact with the barrel, said ridge being suitable for sliding engagement with said barrel when pressure is applied thereto.  
     
     
         16 . A pipette comprising: 
 a) a hollow barrel having a first diameter and comprising a first barrel end and a second barrel end, said first barrel end being open and said second barrel end tapering from the first diameter to a second diameter, said second diameter being substantially smaller than said first diameter, said second barrel end being open at said second diameter;    b) a master plunger mounted in said barrel for longitudinal movement therein;    c) a slave plunger mounted in said barrel for longitudinal movement therein, said slave plunger located between said master plunger assembly and said second barrel end so as to define a liquid chamber between said slave plunger and said second barrel end, and to define a pneumatic chamber containing a gas between said slave plunger and said master plunger assembly;    d) a squeeze bulb mounted on the first barrel end; and    e) a flexible tether connected between the master plunger and the slave plunger;    whereby, when said liquid chamber contains a liquid to be dispensed from said pipette, a user applying selective pressure to said squeeze bulb will cause said master plunger assembly to slide towards said slave plunger and compress said gas against said slave plunger, said slave plunger will as a result of said pressure slide towards said second barrel end as said gas decompresses and apply pressure against said liquid as a result thereof, and said liquid will be dispensed out of the pipette via the second barrel end.    
     
     
         17 . The pipette of  claim 16  in which the slave plunger and the master plunger each are comprised of a rubber disc having at least one ridge for making substantial contact with the barrel, said ridge being suitable for sliding engagement with said barrel when pressure is applied thereto.  
     
     
         18 . The pipette of  claim 16  wherein the squeeze bulb further comprises a release valve.  
     
     
         19 . The pipette of  claim 16  wherein the master plunger comprises a threaded aperture suitable for receiving a mating threaded rod, wherein when a mating threaded rod is engaged with said threaded aperture, said mating threaded rod may be utilized to move the master plunger along the pipette.