Diagnostic instrument and flow process

Abstract

A diagnostic instrument is disclosed. The diagnostic instrument may have a highly efficient probe washer station and/or may be able to sense whether there is a tube septum on a specimen tube to be sampled. The instrument may also be able to determine where the bottom of the tube is located. The probe washer station may have a flow of saline that is used to wash both the internal cavity and the external circumference of the probe.

1 .- 20 . (canceled) 
     
     
         21 . A flow cytometer comprising:
 a laser beam positioned to excite sample particles in a sensing zone;   an aperture that directs a flow of the sample particles through the sensing zone where the sample particles are interrogated by the laser beam, the aperture having a cross-sectional size; and   a flow cytometer filtration system including a filter having multiple holes with cross sectional sizes that are less than or equal to the cross-sectional size of the aperture, wherein the filter is located in an area of the flow cytometer having a fluid velocity of less than 200 microliters per minute.   
     
     
         22 . The flow cytometer of  claim 21 , further comprising a sample injector located in the area of the flow cytometer having a fluid velocity of less than 200 microliters per minute. 
     
     
         23 . The flow cytometer of  claim 22 , further comprising a backflushing system, wherein the filter is positioned in the flow cytometer at a location where the filter can be back flushed at a high fluid velocity of greater than 200 microliters per minute. 
     
     
         24 . The flow cytometer of  claim 23 , wherein the backflushing system further comprises an automatic clog detecting system. 
     
     
         25 . The flow cytometer of  claim 21 , wherein the aperture has a cross sectional shape selected from: a square, a rectangle, and an equilateral triangle. 
     
     
         26 . The flow cytometer of  claim 25 , wherein the cross-sectional size of the aperture is from 100 to 300 microns per side. 
     
     
         27 . The flow cytometer of  claim 26 , wherein the aperture has a length greater than 1000 microns long. 
     
     
         28 . The flow cytometer of  claim 21 , wherein the cross-sectional size allows hydro-dynamic focusing of the particles to a center of the aperture where the particles are interrogated by the laser beam. 
     
     
         29 . The flow cytometer of  claim 21 , wherein the filter prevents the aperture from clogging. 
     
     
         30 . A flow cytometer filtration system for filtering sample particles in a flow cytometer, the flow cytometer filtration system comprising:
 a filter configured to prevent clogging of a flow cytometer aperture; and   multiple holes formed in the filter, wherein the multiple holes provide multiple pathways for particles in the instance where one or more of the holes is partially blocked.   
     
     
         31 . The flow cytometer filtration system of  claim 30 , wherein the multiple holes formed in the filter reduce overall fluid resistance, reduce fluid velocity through any single one of the holes, and provide multiple pathways in the instance where one or more of the holes is partially blocked. 
     
     
         32 . The flow cytometer filtration system of  claim 31 , wherein the multiple holes have cross-sectional areas that are less than or equal to the cross sectional area of a flow cytometer aperture. 
     
     
         33 . The flow cytometer filtration system of  claim 32 , wherein the multiple holes include nine holes. 
     
     
         34 . The flow cytometer filtration system of  claim 32 , wherein the multiple holes have lengths less than 300 microns. 
     
     
         35 . The flow cytometer filtration system of  claim 30 , wherein the filter further comprises:
 an elongate tube; and   a filter plate coupled across an end of the tube, wherein the multiple holes are formed in the filter plate of the filter.   
     
     
         36 . The flow cytometer filtration system of  claim 35 , wherein the filter tube further comprises a fitting portion. 
     
     
         37 . The flow cytometer filtration system of  claim 36 , wherein the fitting portion has a series of alternating tapered portions and stepped portions. 
     
     
         38 . The flow cytometer filtration system of  claim 35 , wherein the filter plate is formed of a circular plate. 
     
     
         39 . A method of preventing clogging of a flow cytometer aperture, the method comprising:
 locating a filter in an area of the flow cytometer having a fluid velocity of less than 200 microliters per minute, the filter including multiple holes providing multiple pathways for sample particles to pass therethrough;   passing the sample particles through the filter, wherein particles having a cross-sectional size greater than a cross-sectional size of the holes are blocked by the filter to prevent clogging of the flow cytometer aperture; and   passing the sample particles having a cross-sectional size less than the cross-sectional size of the holes through an aperture that directs the sample particles through a sensing zone where the sample particles are interrogated by the laser beam.   
     
     
         40 . The method of  claim 39 , wherein the flow cytometer further comprises a sample injector located in the area of the flow cytometer having a fluid velocity of less than 200 microliters per minute.