Dilution system

Abstract

A dilutor has a control interface to receive control signals and a block having an orifice. The dilutor has a single piston at least partially within the block, and there is not another piston within the block. The dilutor has a motor and drive configured, in response to the control signals, to automatically move the single piston away from the orifice to aspirate fluid and to move the single piston toward the orifice to dispense the aspirated fluid. The dilutor has a first valve coupled to the orifice and configured, in response to the control signals, to automatically couple the orifice either to a sample line or to a diluent line.

1 . A diluter, comprising: 
 a body having an outside surface, the body forming a cavity having an inside surface and a top end;    an orifice positioned to connect the inside surface of the cavity with the outside surface of the body;    a single piston configured to fit inside the cavity;    a motor and drive configured to move the single piston away from the orifice to aspirate fluid and to move the single piston toward the orifice to dispense the aspirated fluid.    
   
   
       2 . The dilutor of  claim 1  wherein the drive comprises a nut and a screw, wherein the nut is directly coupled to the single piston, and wherein the motor is configured to directly turn the screw within the nut.  
   
   
       3 . The dilutor of  claim 2  wherein the nut comprises plastic.  
   
   
       4 . The dilutor of  claim 1  wherein the cavity and the single piston are cylindrical in shape.  
   
   
       5 . The diluter of  claim 1  where the orifice is positioned at the top end of the cavity.  
   
   
       6 . The diluter of  claim 5  where the block is configured such that the orifice connects the highest point of the cavity with the outside surface of the block.  
   
   
       7 . The diluter of  claim 1  where the single piston essentially fills the cavity when the single piston is in a position closest to the top end of the cavity.  
   
   
       8 . The dilutor of  claim 1  where the motor is a stepper motor having at least 29,000 half-steps corresponding to a full range of the piston movement.  
   
   
       9 . The dilutor of  claim 1  wherein the cavity is configured to hold approximately 9.2 milliliters.  
   
   
       10 . The dilutor of  claim 1  wherein the diluter can aspirate and dispense two fluids having a combined total volume of 8 milliliters and a dilution range between 1:1.6 and 1:4000.  
   
   
       11 . The diluter of  claim 1  where the single piston forms a seal with respect to the inside surface of the cavity.  
   
   
       12 . The diluter of  claim 1  further comprising: 
 a gasket attached to the single piston and forming a seal between the single piston and the inside surface of the cavity.    
   
   
       13 . The diluter of  claim 1  further comprising: 
 a valve connected to the orifice, the valve connecting the orifice to a first fluid source when the valve is in a first position;    a controller configured to switch the valve to a second position, where the valve connects the orifice to a probe when the valve is in the second position.    
   
   
       14 . The diluter of  claim 13  where the probe is a dual probe.  
   
   
       15 . A method for diluting a fluid, comprising: 
 drawing a first fluid into a conduit by moving a single piston inside a cavity, away from an orifice, where the orifice connects the cavity to the conduit;    drawing the second fluid into the conduit by moving the single piston away from the orifice;    pushing the two fluid out of the conduit into a dilution receptacle by moving the single piston towards the orifice.    
   
   
       16 . The method of  claim 15  where the single piston and the cavity are cylindrical in shape.  
   
   
       17 . The method of  claim 15  further comprising: 
 drawing air into the conduit by moving the single piston away from the orifice;    mixing the two fluids in the dilution receptacle by blowing the air out of the conduit into the two fluids by moving the single piston towards the orifice.    
   
   
       18 . The method of  claim 15  further comprising: 
 drawing air into the conduit between the first fluid and the second fluid by moving the single piston away from the orifice.    
   
   
       19 . The method  claim 15  where the orifice is positioned at a top end of the cavity and the single piston essentially fills the cavity when the single piston is in a position closest to the orifice.  
   
   
       20 . A diluter, comprising: 
 a fluid holding means;    a means for drawing a first fluid into the fluid holding means using a single piston;    a means for drawing a second fluid into the fluid holding means using the single piston    a means for dispensing the two fluids from the fluid holding means using the single piston.