Sample tube and rack to reduce ice formation on barcode
The 2D barcode at the base of a sample tube is protected from frosting by an air pocket within a wall of high thermal conductivity material that surrounds the barcode. The wall is of thermal conductivity greater than 14W/m K and preferably greater than 200W/m K. The wall may be formed as a skirt extending from the base of the sample tube or as a part of a supporting rack. The wall, cooled by the sample tube and the frozen sample within the tube, collects frost that would otherwise collect on the 2D barcode and deflects the flow of moist air that would otherwise flow against the barcode.
1 . A sample tube comprising:
a sidewall open at one end and closed with a bottom at an opposite end;
an optically readable code on the bottom that is readable from below the sample tube; and
a skirt that extends axially from and beyond the bottom of the sidewall and about the optically readable code, thereby forming a recessed air pocket and diverting convective flow from across the optically readable code, wherein the skirt:
has a thermal conductivity greater than 14 W/m K and greater than a thermal conductivity of the sidewall;
is a) over-molded, b) press fit, or c) deposited on a surface of the sample tube; and
is non-separable from the sample tube.
2 . The sample tube as claimed in claim 1 wherein the skirt extends from the bottom of the sidewall by an amount in a range of 15-30% of an external diameter of the sample tube.
3 . The sample tube as claimed in claim 1 wherein the skirt extends at least 2 mm from the bottom of the sidewall.
4 . The sample tube as claimed in claim 1 wherein the skirt extends 2-4 mm from the bottom of the sidewall.
5 . The sample tube as claimed in claim 1 wherein an inner surface of the skirt has a thermal conductivity of at least 100 W/m K.
6 . The sample tube as claimed in claim 1 wherein an inner surface of the skirt has a thermal conductivity of at least 200 W/m K.
7 . The sample tube as claimed in claim 1 wherein the skirt includes a metal.
8 . The sample tube as claimed in claim 1 wherein the skirt is a metal skirt that extends from the bottom of the sidewall by 15-30% of an external diameter of the sample tube.
9 . The sample tube as claimed in claim 1 wherein the skirt is a metal skirt that extends 2-4 mm from the bottom of the sidewall.
10 . The sample tube as claimed in claim 1 wherein the optically readable code is a two-dimensional barcode.
11 . The sample tube as claimed in claim 1 , wherein:
the sidewall transitions to a reduced diameter bottom through a frustoconical section;
vanes extend radially from the frustoconical section; and
the skirt forms air pockets between the vanes and below the bottom of the sidewall.
12 . The sample tube as claimed in claim 1 , wherein the skirt is molded directly into the bottom, and wherein the skirt is thicker than the sidewall.
13 . The sample tube as claimed in claim 1 , wherein the skirt is cylindrical.
14 . A method of inhibiting icing on an optically readable code on a sample tube, the method comprising:
removing the sample tube from below the freezing temperature of water; and
exposing the sample tube to warmer air, wherein the sample tube comprises:
a sidewall open at one end and closed with a bottom at an opposite end;
the optically readable code on the bottom that is readable from below the sample tube; and
a skirt that extends axially from and beyond the bottom of the sidewall and about the optically readable code, thereby forming a recessed air pocket and diverting convective flow from across the optically readable code, wherein the skirt:
has a thermal conductivity greater than 14 W/m K and greater than a thermal conductivity of the sidewall;
is a) over-molded, b) press fit, or c) deposited on a surface of the sample tube; and
is non-separable from the sample tube.
15 . The method as claimed in claim 14 wherein the skirt extends from the bottom of the sidewall by an amount in a range of 15-30% of an external diameter of the sample tube.
16 . The method as claimed in claim 14 wherein the skirt extends at least 2 mm from the bottom of the sidewall.
17 . The method as claimed in claim 14 wherein the skirt extends 2-4 mm from the bottom of the sidewall.
18 . The method as claimed in claim 14 wherein an inner surface of the skirt has a thermal conductivity of at least 100 W/m K.
19 . The method as claimed in claim 14 wherein an inner surface of the skirt has a thermal conductivity of at least 200 W/m K.
20 . The method as claimed in claim 14 wherein the skirt includes a metal.
21 . The method as claimed in claim 14 wherein the skirt is a metal skirt that extends from the bottom of the sidewall by 15-30% of an external diameter of the sample tube.
22 . The method as claimed in claim 14 wherein the skirt is a metal skirt that extends 2-4 mm from the bottom of the sidewall.
23 . The method as claimed in claim 14 wherein the optically readable code is a two-dimensional barcode.
24 . The method as claimed in claim 14 , wherein:
the sidewall transitions to a reduced diameter bottom through a frustoconical section;
vanes extend radially from the frustoconical section; and
the skirt forms air pockets between the vanes and below the bottom of the sidewall.
25 . The method as claimed in claim 24 , further comprising positioning the sample tube in a holder of a rack, the holder comprising:
a cylindrical port that receives the sample tube;
an annulus that receives the skirt; and
holder vanes that support the frustoconical section and interact with the vanes that extend radially from the frustoconical section to prevent rotation of the sample tube.
26 . The method as claimed in claim 14 , wherein the skirt is molded directly into the bottom, and wherein the skirt is thicker than the sidewall.
27 . The method as claimed in claim 14 , wherein the skirt is cylindrical.