Dampers and Methods for Performing Measurements in an Autoinjector

Abstract

Systems and methods for measuring and damping forces within autoinjectors in accordance with embodiments of the invention are disclosed. In one embodiment of the invention, an injection system comprises a syringe disposed within a housing, the syringe having a first end and a second end; a needle disposed at the second end of the syringe; a plunger disposed at the first end of the syringe and configured to move toward the second end of the syringe; a stopper disposed between the plunger and the second end of the syringe; a first damper disposed between the plunger and the stopper, such that the first damper is capable of damping a first event occurring between the plunger and the stopper; and a second damper disposed at the second end of the syringe, such that the second damper is capable of damping a second event occurring at the second end of the syringe.

What is claimed is: 
     
         1 . An injection system, comprising:
 a syringe disposed within a housing, the syringe having a first end and a second end, wherein the second end comprises an exit opening;   a needle disposed at the second end of the syringe;   a plunger disposed at the first end of the syringe and configured to move along an interior cavity of the syringe toward the second end of the syringe;   a stopper disposed between the plunger and the second end of the syringe, within the interior cavity of the syringe;   a first damper disposed between the plunger and the stopper, such that the first damper is capable of damping a first event occurring between the plunger and the stopper; and   a second damper disposed at the second end of the syringe, such that the second damper is capable of damping a second event occurring at the second end of the syringe.   
     
     
         2 . The injection system of  claim 1 , wherein movement of the plunger is spring-actuated. 
     
     
         3 . The injection system of  claim 1 , wherein at least one of the first damper or the second damper is formed with viscoelastic foam. 
     
     
         4 . The injection system of  claim 1 , wherein the first damper is disk shaped. 
     
     
         5 . The injection system of  claim 1 , wherein the second damper is cylinder shaped. 
     
     
         6 . The injection system of  claim 1 , wherein the first damper is capable of limiting a strain in the syringe during the first event, and the second damper is capable of limiting a strain in the syringe during the second event, such that fracture is prevented in the syringe. 
     
     
         7 . The injection system of  claim 1 , wherein the syringe is formed of glass. 
     
     
         8 . The injection system of  claim 1 , wherein the needle receives sufficient force from activation of the plunger to penetrate human skin. 
     
     
         9 . The injection system of  claim 1 , wherein the needle is fixed to the syringe, and fluid within the interior cavity of the syringe is capable of exiting through the exit opening and a hollow cavity of the needle. 
     
     
         10 . The injection system of  claim 1 , wherein the needle is capable of moving from a retracted position to an advanced position, and fluid within the interior cavity of the syringe is capable of exiting through the exit opening and a hollow cavity of the needle while the needle is in the advanced position. 
     
     
         11 . A method for measuring forces in an injection system, comprising:
 creating a clear shell with dimensions of an original autoinjector, the clear shell being elongated and hollow for housing components of the original autoinjector, including a syringe and a syringe carrier;   installing a pressure transducer inside the syringe;   filling the syringe with fluid;   installing at least one strain gauge on an outer surface of the syringe; and   assembling an instrumented autoinjector by:
 mounting the syringe with the pressure transducer, the fluid, and the at least one strain gauge into the syringe carrier; and 
 mounting the syringe carrier into the clear shell. 
   
     
     
         12 . The method of  claim 11 , further comprising:
 removing a needle from the syringe;   
       wherein installing the pressure transducer includes:
 inserting at least one magnet wire into the syringe; and 
 connecting a first end of the at least one magnet wire to at least one leadwire of the pressure transducer, wherein a second end of the at least one magnet wire extends out of the syringe through a needle opening of the syringe. 
 
     
     
         13 . The method of  claim 11 , wherein the fluid includes deionized water. 
     
     
         14 . The method of  claim 11 , wherein installing the at least one strain gauge includes:
 bonding a portion of at least one leadwire of the at least one strain gauge to the outer surface of the syringe.   
     
     
         15 . The method of  claim 11 , further comprising:
 forming an opening in a syringe carrier of the original autoinjector;   
       wherein:
 the at least one strain gauge includes at least one leadwire; 
 mounting the syringe into the syringe carrier includes:
 directing the at least one leadwire of the at least one strain gauge through the opening formed in the syringe carrier; and 
 
 mounting the syringe carrier into the clear shell includes:
 directing the at least one leadwire of the at least one strain gauge through an opening of the clear shell. 
 
 
     
     
         16 . The method of  claim 11 , wherein assembling the instrumented autoinjector is further performed by:
 mounting a power pack of the original autoinjector to the clear shell.   
     
     
         17 . The method of  claim 11 , further comprising:
 connecting the at least one leadwire of the pressure transducer and the at least one leadwire of the at least one strain gauge to signal conditioners.   
     
     
         18 . The method of  claim 11 , further comprising:
 mounting the instrumented autoinjector onto a fixture.   
     
     
         19 . The method of  claim 11 , further comprising:
 positioning a high-speed camera to capture movement of components within the instrumented autoinjector upon activation of the instrumented autoinjector.   
     
     
         20 . The method of  claim 11 , further comprising:
 activating the instrumented autoinjector; and   recording data transmitted from the pressure transducer and the at least one strain gauge.