Injection System with Capacitive Sensing

Abstract

A powerhead ( 50 ) of a power injector is disclosed that includes a syringe housing ( 110 ) that contains a capacitive fluid detector ( 112 ). The capacitive fluid detector ( 112 ) may be operable to detect fluid within a syringe ( 116 ) installed on the syringe housing ( 110 ). The output of the capacitive fluid detector ( 112 ) may be used to estimate the volume of fluid within the syringe ( 116 ). The capacitive fluid detector ( 112 ) may include a plurality of discrete capacitors ( 118 a - 118 h ) arranged serially along a longitudinal axis ( 120 ) of the syringe ( 116 ). Each of the plurality of capacitors ( 118 a - 118 h ) may be operable to produce an electric field extending into the syringe ( 116 ). Each of the plurality of capacitors ( 118 a - 118 h ) may be formed on a printed circuit board ( 130 ).

What is claimed: 
     
         1 . An injection system comprising:
 an injection device operable to hold a syringe and discharge fluid from said syringe when engaged by said injection device; and   a syringe barrel zone, wherein said injection device is operable to hold said syringe such that a syringe barrel of said syringe is coextensive with said syringe barrel zone, wherein said syringe barrel zone comprises a syringe barrel zone length coinciding with a syringe barrel length of said syringe when said syringe is held by said injection device, and wherein said syringe barrel zone comprises a syringe barrel zone longitudinal axis coinciding with a syringe barrel longitudinal axis of said syringe when said syringe is held by said injection device;   said injection device comprising a capacitive fluid detector, wherein said capacitive fluid detector comprises a first capacitor, a separate second capacitor, and a separate third capacitor, wherein an electric field of said first capacitor penetrates said syringe barrel zone at a first position along said syringe barrel zone longitudinal axis, wherein an electric field of said second capacitor penetrates said syringe barrel zone at the same said first position along said syringe barrel zone longitudinal axis, and wherein an electric field of said third capacitor penetrates said syringe barrel zone at the same said first position along said syringe barrel zone longitudinal axis.   
     
     
         2 . The injection system of  claim 1 , wherein a length of each of said first capacitor, said second capacitor, and said third capacitors corresponds with said syringe barrel zone length. 
     
     
         3 . The injection system of  claim 2 , wherein said electric field of each of said first capacitor, said second capacitor, and said third capacitor penetrates said syringe barrel zone along an entirety of said syringe barrel zone length. 
     
     
         4 . The injection system of  claim 1 , wherein said injection system further comprises a plurality of capacitor groups that are arranged serially along said syringe barrel zone length and that are spaced from one another along said syringe barrel zone length such that each said capacitor group is disposed at a different position along said syringe barrel longitudinal axis, and wherein each said capacitor group comprises one said first capacitor, one said second capacitor, and one said third capacitor. 
     
     
         5 . The injection system of  claim 1 , wherein each of said first capacitor, said second capacitor, and said third capacitor independently measure a same fluid level of a syringe when installed on said injection device. 
     
     
         6 . The injection system of  claim 1 , wherein said injection system is configured to compare a capacitance from each of said first capacitor, said second capacitor, and said third capacitor. 
     
     
         7 . The injection system of  claim 1 , wherein if a signal from one of said first, second, and third capacitors is of a different value than a signal from the other two of said first, second, and third capacitors, said injection system is configured to ignore said signal from said one of said first, second, and third capacitors and to estimate a volume based on said signals from the other two of said first, second, and third capacitors. 
     
     
         8 . The injection system of  claim 1 , wherein said injection system is configured to compare readings from each of said first capacitor, said second capacitor, and said third capacitor and to determine a fluid volume when readings from at least two of said first capacitor, said second capacitor, and said third capacitor are in agreement. 
     
     
         9 . The injection system of  claim 1 , wherein each of said first capacitor, said second capacitor, and said third capacitor are mounted on a curved support. 
     
     
         10 . The injection system of  claim 9 , wherein said curved support follows a contour of said syringe when installed on said injection device. 
     
     
         11 . The injection system of  claim 1 , wherein said capacitive fluid detector comprises a fourth capacitor, and wherein an electric field of said fourth capacitor also penetrates said syringe barrel zone at the same said first position along said syringe barrel zone longitudinal axis as said first capacitor, said second capacitor, and said third capacitor. 
     
     
         12 . The injection system of  claim 11 , wherein said first capacitor and said second capacitor are mounted on a first support, wherein said third capacitor and said fourth capacitor are mounted on a second support that is spaced from said first support, and wherein said first support and said second support are disposed in different orientations. 
     
     
         13 . The injection system of  claim 12 , wherein said first support and said second support are oriented as the mirror image of one another. 
     
     
         14 . The injection system of  claim 12 , wherein said first support and said second support collectively define a V-shaped configuration. 
     
     
         15 . The injection system of  claim 12 , wherein a first surface of said first support on which said first capacitor and said second capacitor are mounted is flat, and wherein a second surface of said second support on which said third capacitor and said fourth capacitor are mounted is flat. 
     
     
         16 . A method of operating an injection system, said method comprising:
 installing a syringe onto an injection device;   sensing, with a first capacitive sensor, a second capacitive sensor, and a third capacitive sensor, fluid within a syringe barrel of said syringe after said installing step and at a common position along a length dimension of said syringe barrel; and   identifying erroneous readings based at least partly on comparing outputs from said first, second and third capacitive sensors acquired during said sensing step.   
     
     
         17 . The method of  claim 16 , further comprising estimating a total volume of fluid within said syringe based on said sensing and identifying steps.