Adapter for holding a sample container to facilitate sensing of liquid level in the sample container

Abstract

An adapter for holding a sample container includes a main body portion and a tapered body portion that forms a continuation of the main body portion. The tapered body portion includes a mouth opening that is of lesser diameter than the diameter of the main body portion. The mouth opening of the adapter is sized to provide direct support of a sample container which holds a liquid sample. During liquid level sensing ultrasonic waves from an ultrasound detector are reflected back to the sound detector as echoes from the lip flange of the sample container and from the liquid level within the sample container. The tapered surface of the adapter deflects sound echoes away from the sound detector. The adapter is thus invisible to the ultrasound detector. The echo from the liquid level is a variable duration echo and the echo from the lip flange of the sample container is a fixed duration echo that is always of lesser duration than the variable duration echo. Thus the sound detector can easily recognize the liquid level echo and convert the characteristics of the liquid level echo to a discernible liquid level.

What is claimed is:  
     
         1 . An adapter for holding a sample container to facilitate liquid level sensing in the sample container, said adapter comprising, 
 a) a generally tubular structure with a main body portion having a first outside diameter,    b) a tapered body portion extending from said main body portion and having a mouth opening for receiving and supporting a sample container, the mouth opening having a second outside diameter that is of lesser magnitude than the first outside diameter, and    c) said tapered body portion having an outer diameter that increases in magnitude in a direction from said mouth opening toward the main body portion.    
     
     
         2 . The adapter as claimed in  claim 1  wherein said tapered body portion includes an inner surface with spaced projections projecting radially inwardly from the inner surface to bear against a sample container of predetermined size received in said mouth opening of said adapter.  
     
     
         3 . The adapter as claimed in  claim 1  wherein the main body portion and the tapered body portion are formed as a one piece integral structure.  
     
     
         4 . The adapter as claimed in  claim 3  wherein said main body portion has bottom portion with a bottom opening.  
     
     
         5 . The adapter as claimed in  claim 4  wherein the body portion has a curved semi-spherical shape and said bottom opening is at the lowermost portion of said curved semi-spherical shape.  
     
     
         6 . The adapter as claimed in  claim 1  wherein said main body portion has a closed bottom portion.  
     
     
         7 . The adapter as claimed in  claim 6  wherein said bottom portion has a curved semi-spherical shape.  
     
     
         8 . The adapter as claimed in  claim 1  wherein said main body portion and said tapered body portion are separately formed and joined together such that said tapered body portion is a continuous extension of said main body portion.  
     
     
         9 . The adapter as claimed in  claim 8  wherein said main body portion and said tapered body portion are formed of plastic and are joined together by ultrasonic welding.  
     
     
         10 . The adapter as claimed in  claim 8  wherein said main body portion and said tapered body portion are formed of plastic and connected together at a joint, one of said main body portion and said tapered body portion including a first lip that projects radially outwardly and the other of said main body portion and said tapered body portion including a second lip that projects radially inwardly, said first and second lips being sized such that they can bypass each other with slight interference to permit one of said lips to bypass the other said lip to form an inseparable snap fit joint between the main body portion and the tapered body portion.  
     
     
         11 . The adapter as claimed in  claim 1  wherein the tapered body portion has two distinct tapered sections, one of the tapered sections having a lesser amount of slope than the other tapered section.  
     
     
         12 . The adapter as claimed in  claim 11  wherein the tapered section with the lesser amount of slope includes the mouth opening.  
     
     
         13 . An adapter for holding a sample container to facilitate liquid level sensing in the sample container, said adapter comprising, 
 a) a generally tubular structure having an open mouth portion at one end and a bottom portion at an opposite end, said tubular structure including a main body section and a tapered body section extending from said main body section.    b) said tapered body section having the open mouth portion of said tubular structure and a tapered wall portion that diverges from the open mouth portion to a maximum diameter where the tapered body section meets the main body section, and    c) said main body section having an outside diameter that does not exceed the maximum diameter of the tapered body section.    
     
     
         14 . The adapter as claimed in  claim 13  wherein the tapered body portion has two distinct tapered sections, one of the tapered sections having a lesser amount of slope than the other tapered section.  
     
     
         15 . The adapter as claimed in  claim 14  wherein the tapered section with the lesser amount of slope includes the mouth opening.  
     
     
         16 . The adapter as claimed in  claim 13  wherein the main body portion and the tapered body portion are formed as a one piece integral structure.  
     
     
         17 . The adapter as claimed in  claim 16  wherein said main body portion has bottom portion with a bottom opening.  
     
     
         18 . The adapter as claimed in  claim 13  wherein said main body portion and said tapered body portion are separately formed and joined together such that said tapered body portion is a continuous extension of said main body portion.  
     
     
         19 . The adapter as claimed in  claim 18  wherein said main body portion and said tapered body portion are formed of plastic and connected together at a joint, one of said main body portion and said tapered body portion including a first lip that projects radially outwardly and the other of said main body portion and said tapered body portion including a second lip that projects radially inwardly, said first and second lips being sized such that they can bypass each other with slight interference to permit one of said lips to bypass the other said lip to form an inseparable snap fit joint between the main body portion and the tapered body portion.  
     
     
         20 . A method of ultrasonically sensing liquid level in a sample container comprising, 
 a) forming an adapter with a mouth opening and a tapered body portion that extends below the mouth opening, the mouth opening being sized to hold an open-mouthed sample container,    b) forming a main body portion of the adapter to extend below the tapered body portion with a main body diameter that is larger than the mouth opening of the adapter to permit accommodation of the adapter in a sample tube rack,    c) placing the sample container in the mouth opening of the adapter such that a lip flange of the sample container rests on the mouth opening of the adapter,    d) placing the adapter with the sample container in a sample tube rack such that the elevation of the lip flange of the sample container in the adapter is at a known height from a reference level,    e) providing an ultrasound detector at a predetermined elevation above the lip flange of the sample container when the adapter and sample container are supported in the sample tube rack,    f) directing a first ultrasonic wave from the ultrasound detector at the sample container and identifying a first ultrasonic echo from the sample container lip flange based on a known distance between the ultrasound detector and the lip flange of the sample container,    g) directing a second ultrasonic wave from the ultrasound detector at liquid level in the sample container and identifying a second ultrasonic echo as corresponding to the liquid level in the sample container based on known characteristics of the first ultrasonic echo and on a difference between the second ultrasonic echo and the first ultrasonic echo because there is a greater distance between the ultrasound detector and the liquid level than between the ultrasound detector and the lip flange of the sample container, and    h) allowing the tapered surface of the adapter to deflect any ultrasonic echoes from the tapered surface away from the ultrasonic detector, whereby the adapter permits echo reflection back to the ultrasonic detector of only the first and second ultrasonic waves.