Optical flow sensor

Abstract

A method for determining a flow rate of a fluid is provided. The method includes heating an aliquot of the fluid at a first position of a fluid-delivery channel, illuminating fluid in the fluid-delivery channel at a second position downstream from the first position, measuring an amount of light reflected from the illuminated fluid to determine a change in the amount corresponding to the heated aliquot passing the second position, and calculating the flow rate of the fluid based upon a distance between the first position and the second position and a time between the heating the aliquot and the heated aliquot passing the second position.

What is claimed is: 
     
         1 . A method for determining a flow rate of a fluid, comprising:
 heating an aliquot of the fluid at a first position of a fluid-delivery channel;   illuminating fluid in the fluid-delivery channel at a second position downstream from the first position;   measuring an amount of light reflected from the illuminated fluid to determine a change in the amount corresponding to the heated aliquot passing the second position; and   calculating the flow rate of the fluid based upon a distance between the first position and the second position and a time between the heating the aliquot and the heated aliquot passing the second position.   
     
     
         2 . The method according to  claim 1 , wherein the heating the aliquot comprises heating the aliquot with a laser. 
     
     
         3 . The method according to  claim 1 , wherein illuminating the fluid in the fluid-delivery channel comprises illuminating the fluid with an LED optically coupled to the fluid-delivery channel. 
     
     
         4 . The method according to  claim 1 , wherein the measuring the amount of light reflected comprises measuring the amount of light reflected with a photodetector optically coupled to the fluid-delivery channel. 
     
     
         5 . The method according to  claim 1 , wherein the fluid is opaque. 
     
     
         6 . A medicinal fluid administering system, comprising:
 a fluid delivery system for administering a fluid to a patient; and   an optical flow sensor for measuring a rate of the fluid administered to the patient, the optical flow sensor comprising:
 a laser configured to heat an aliquot of the fluid in an adjacent fluid-delivery channel; and 
 a sensor disposed adjacent to the fluid-delivery channel downstream from the laser, the sensor configured to illuminate the fluid in the fluid-delivery channel, to collect reflected light from the illuminated fluid, and to determine when the heated aliquot passes the sensor based upon an amount of the reflected light. 
   
     
     
         7 . The medicinal fluid administering system according to  claim 6 , wherein the optical flow sensor further comprises a processor configured to calculate a flow rate of the fluid in the fluid-delivery channel based upon a time between the laser heating the aliquot and the sensor determining when the heated aliquot passes the sensor. 
     
     
         8 . The medicinal fluid administering system according to  claim 6 , wherein the fluid delivery system comprises a reservoir configured to store the fluid, a pump configured to pump the fluid from the reservoir, and delivery path configured to deliver the fluid to the patient. 
     
     
         9 . The medicinal fluid administering system according to  claim 8 , further comprising a controller operably coupled to the optical flow sensor and to the pump, wherein the controller is configured to adjust a pumping speed of the pump based upon a calculated flow rate of the fluid in the fluid-delivery channel. 
     
     
         10 . The medicinal fluid administering system according to  claim 6 , wherein the sensor comprises an LED optically coupled to the fluid-delivery channel by a first fiber and a photodetector optically coupled to the fluid-delivery channel by a second fiber. 
     
     
         11 . The medicinal fluid administering system according to  claim 10 , wherein the first fiber and the second fiber are disposed on a same side of the fluid-delivery channel. 
     
     
         12 . The medicinal fluid administering system according to  claim 6 , wherein the sensor comprises one or more lenses configured to optically couple an LED with the fluid-delivery channel and a photodetector with the fluid-delivery channel. 
     
     
         13 . The medicinal fluid administering system according to  claim 12 , wherein the LED and the photodetector are disposed on a same side of the fluid-delivery channel.