Patent Publication Number: US-2022225968-A1

Title: A laboratory sample carrier

Description:
The present invention relates to a laboratory sample cassette having a marking or writing surface. 
     A tissue processing laboratory sample cassette may have a writing surface disposed generally at an angle of 45° to the main body of the cassette. The main body has a recess for holding a tissue sample so that the main body forms a tray, and the tray is covered by a removable lid. 
     The writing surface is marked by a printer, such as a thermal printer, with details of a tissue sample to be put in the tray. After the tissue sample is put in the tray, the lid is placed over the tray and the laboratory sample cassette is processed. This includes an embedding process wherein the writing surface and other surfaces of the cassette may be at least partially covered by wax. The wax on the writing surface needs to be removed so that details of the sample printed on the writing surface are not obscured. This may be done by rubbing or holding the writing surface against a surface of a heated metal block to melt the wax from the writing surface. A problem with this is that the surface of the metal block can be abrasive which may damage the sample details printed on the writing surface making the sample details unreadable. 
     It is an object of the present invention to provide a laboratory sample cassette that alleviates the above-mentioned problem. 
     According to one aspect of the present invention there is provided a laboratory sample cassette comprising a main body having a writing surface, and at least two protrusions extending from the writing surface, each said protrusion having the same height or substantially the same height from the writing surface. 
     The laboratory sample cassette may be of unitary or monolithic construction. 
     The at least two protrusions may be configured to hold the writing surface parallel or substantially parallel to a flat surface when the laboratory sample cassette is placed against the flat surface with the writing surface facing the flat surface. Thus, the protrusions of the laboratory sample cassette enable the writing surface to be held away from the flat surface of a heated metal block so that it cannot be abraded by the metal block whilst at the same time enabling any wax on the writing surface to be melted from it. The molten wax may run off the writing surface between the protrusions. The at least two protrusions may be configured to engage the flat surface. 
     Each said protrusion may be adjacent at least one edge of the writing surface. Each said protrusion may have a rounded profile. This provides the advantage that tape used in the printing process, such as thermal tape, will not be damaged by the protrusions as it passes over the writing surface. The height of each said protrusion from the writing surface may be in the range of 0.05 mm to 3 mm. Such a range of heights provides an appropriate stand-off from a heated block to prevent damage to printing on the writing surface while allowing the writing surface to be close enough to the heated block to allow wax on the writing surface to be melted by radiant heat from the heated block and therefore be able to run away from the writing surface. 
     The writing surface may be rectangular. 
     There may be four said protrusions, each said protrusion being adjacent a respective corner of the writing surface and having substantially the same height from the writing surface. A print area on the writing surface for a print head of a thermal printer to print on may be defined between two said protrusions adjacent a first shorter edge of the rectangular writing surface and two said protrusions adjacent an opposite second shorter edge of the rectangular writing surface. 
     There may be two said protrusions, each said protrusion comprising a rib extending parallel or substantially parallel to and adjacent a respective opposite edge of the writing surface and having the same height or substantially the same height from the writing surface. The ribs may be spaced apart to define a print area on the writing surface for a print head of a thermal printer to print on. Each said rib may extend parallel or substantially parallel to and adjacent a respective shorter edge of the writing surface. Each said rib may extend parallel or substantially parallel to and adjacent a respective longer edge of the writing surface. 
     The protrusions may be sized and positioned to provide the maximum suitable print area. 
     The laboratory sample cassette including the at least two protrusions may be formed by injection moulding or may be an injection moulded cassette. 
     Each said protrusion may have a width at its base on the writing surface in the range of 0.1 mm to 3 mm. 
     The writing surface may be disposed at an inclined angle to the main body of the cassette or may be disposed at an acute angle to a bottom of the main body of the cassette. 
     There may be a combination of the laboratory sample cassette and the flat surface which may be heated. 
     According to another aspect of the present invention there is provided a method for removing wax from a writing surface of a laboratory sample cassette, comprising the steps of: (a) providing at least two protrusions which extend from the writing surface of a main body of the laboratory sample cassette, each said protrusion having the same height or substantially the same height from the writing surface; and (b) holding the laboratory sample cassette so that the protrusions engage a flat heated surface causing the writing surface to be parallel or substantially parallel to the flat surface, and enabling wax on the writing surface to be melted from the writing surface. 
     Step (a) may include providing the laboratory sample cassette which is of unitary or monolithic construction and includes the at least two protrusions which extend from the writing surface of the main body. 
     The method may include the step of marking the writing surface after step (a) and before step (b). 
    
    
     
       Embodiments of the present invention will now be described, by way of example, with reference to the accompanying schematic drawings, in which: 
         FIGS. 1 and 2  are perspective views of a laboratory sample cassette according to one embodiment of the invention, the cassette having an associated lid; 
         FIG. 3  is a plan view of a writing surface of the laboratory sample cassette with a thermal tape over it and a thermal print head on the tape; 
         FIG. 4  is a longitudinal sectional view of the laboratory sample cassette containing a tissue sample; 
         FIG. 5  is a longitudinal sectional view of the laboratory sample cassette on a mould; 
         FIG. 6  is a side elevational view of the laboratory sample cassette with a block of wax on its underside; 
         FIG. 7  is a longitudinal sectional view of a portion of the laboratory sample cassette against a flat surface of a heated metal block; 
         FIG. 8  is a perspective view of a modified laboratory sample cassette; and 
         FIG. 9  is a longitudinal sectional view of a portion of the modified laboratory sample cassette against the flat surface of the heated metal block. 
     
    
    
     Referring to  FIGS. 1 and 2  of the accompanying drawings, a laboratory sample cassette  1  has a main body  2 . A rectangular writing or marking surface  3  is disposed at an inclined or acute angle to a bottom of the main body  2  of the cassette  1 . The cassette  1  has a hollow space or recess  4  behind the writing surface  3  for holding a tissue sample so that the main body  2  forms a tray  5 . The tray  5  has a first shorter wall surface  6  adjacent the writing surface  3  and an opposite second shorter wall surface  7 , and has first and second longer wall surfaces  8 ,  9  facing each other. A pair of tabs  10  extends into the tray recess  4  at the top of the first wall surface  6  and the top of the second wall surface  7  has a bevel  11 . A ledge  29  at the top of a rear of the main body  2  of the cassette  1  extends away from the rear. A base  12  of the tray  5  has a plurality of rows of through holes  13 . The holes  13  are substantially oblong in shape along the row and the rows extend across the width of the tray  5 . 
     There are four protrusions  14  or standoff features extending from the writing surface  3  of the main body  2  of the cassette  1  wherein each protrusion  14  is adjacent a respective corner of the writing surface  3 . Thus, there is a first pair  15  of protrusions  14  adjacent a first shorter edge of the rectangular writing surface  3  and there is a second pair  16  of protrusions  14  adjacent an opposite second shorter edge of the rectangular writing surface  3 . The two pairs  15 ,  16  of protrusions  14  are spaced apart to define a print area  30  (shown in chain dot) on the writing surface  3  for a print head of a thermal printer to print on. Each protrusion  14  has substantially the same height from the writing surface  3  and has a rounded profile (see also  FIG. 7 ) wherein the protrusion  14  may be in the form of a dome. 
     The tray  5  is covered by a removable rectangular lid  17  which has a perimeter edge surface formed from first and second opposed shorter edge surfaces  18 ,  19  interconnected by first and second opposed longer edge surfaces  20 ,  21 . A pair of recesses  22  extends into a lower part of the first shorter edge surface  18  and are spaced and shaped to receive the respective tabs  10  of the laboratory sample cassette  1  when the lid  17  is placed on the cassette  1 . The second shorter edge surface  19  is inclined to correspond with the bevel  11  of the second wall surface  7  of the tray  5  of the cassette  1  when the lid  17  is placed on the cassette  1 . The lid  17  has a plurality of rows of through holes  23 . The holes  23  are substantially oblong in shape along the row and the rows extend across the width of the lid  17 . The lid holes  23  substantially align with the tray base holes  13  when the lid  17  is placed on the cassette  1 . 
     The laboratory sample cassette  1  including the protrusions  14  is formed by injection moulding as is the lid  17 . 
     An example of use of the laboratory sample cassette  1  will now be described. 
     Referring to  FIG. 3 , the laboratory sample cassette  1  is placed against a thermal printer so that thermal tape  24  of the printer runs across the length of the writing surface  3  and over the first and second pairs  15 ,  16  of protrusions  14 . The rounded profile of the protrusions  14  prevents them from damaging the thermal tape  24  placed over them. A thermal print head  25  of the printer pushes the tape  24  against the writing surface  3  just in from the first pair  15  of protrusions  14  and moves towards the second pair  16  of protrusions  14  to mark the writing surface  3  before the thermal print head  25  moves away from the writing surface  3 . The cassette  1  is then ejected from the printer. 
     Referring to  FIG. 4 , a tissue sample  26  is placed in the tray  5  and the lid  17  is placed over the tray  5  to hold and protect the tissue sample  26  in the laboratory sample cassette  1 . The cassette  1  is passed through a series of solvents and solutions which ensures that the tissue sample  26  is dehydrated and cleaned so that it is ready for the process of paraffin wax embedding. 
     This process involves placing the laboratory sample cassette  1  in a wax bath. The cassette  1  is then taken out of the wax bath, the lid  17  is removed and the tissue sample  26  is taken out of the tray  5 . 
     Referring to  FIG. 5 , the tissue sample  26  is placed in a recess  33  in a base of a mould  27 , and the cassette  1  is placed in the mould  27  above the recess  33 . Molten wax is poured into the mould  27  and passes through the holes  13  in the base  12  of the tray  5  and into the recess  33 . The wax is left to cool in the mould  27  and the mould  27  is then removed from the underside of the cassette  1 . 
     Referring to  FIG. 6 , when the mould  27  has been removed, a solid block of wax  28 , which has been formed by the mould recess  33 , is left on the underside of the laboratory sample cassette  1  wherein the wax block  28  contains the tissue sample  26 . 
     As a result of the wax bath and the pouring of molten wax into the mould  27 , the writing surface  3  and other surfaces of the cassette may be at least partially covered by wax. Referring to  FIG. 7 , to remove any wax on the writing surface  3 , the laboratory sample cassette  1  is placed against a flat surface  31  of a heated metal block  32  so that the four protrusions  14  of the writing surface  3  hold the writing surface  3  parallel to the flat surface  31 . Wax on the writing surface  3  melts and runs off the writing surface  3  between the protrusions  14 . 
     Other surfaces of the laboratory sample cassette  1  may also be placed against the heated metal block  32  to remove any wax from those surfaces which could otherwise make it difficult to fit the cassette  1  later into a microtome chuck. Once the cassette  1  with the block of wax  28  containing the tissue sample  27  on its underside is placed in the microtome chuck, a blade of the microtome is then used to cut the wax block  28  containing the tissue sample  27  into thin slices. These thin slices are mounted on laboratory slides so that sections of the tissue sample  27  can be analyzed. 
     The height of the protrusions  14  from the writing surface  3  is sufficiently low so that the protrusions  14  do not cause the thermal tape  25  to be held away from the writing surface  3  during the printing process whilst also being sufficiently high to provide a gap between the writing surface  3  and the flat surface  31  of the heated metal block  32  to enable wax to melt and run off the writing surface  3 . In a specific example of a preferred embodiment, the height of each protrusion  14  from the writing surface  3  is in the range of 0.05 mm to 1.5 mm. However, the protrusion  14  may be up to 3 mm high. Also, each protrusion  14  has a width at its base on the writing surface  3  in the range of 0.1 mm to 1 mm. However, the protrusion  14  may be up to 3 mm wide. 
     A modified laboratory sample cassette  40  is illustrated in  FIG. 8 , wherein the rectangular writing surface  41  has two ribs  42  instead of four protrusions, and the lid has been omitted. Each rib  42  extends substantially parallel to and adjacent a respective opposite shorter edge of the writing surface  41  and has substantially the same height from the writing surface  41 . Each rib  42  also has a rounded profile. 
     Similar to the pairs of protrusion of the laboratory sample cassette  1 , the ribs  42  of the modified laboratory sample cassette  40  are spaced apart to define a print area on the writing surface  41  for the print head  25  of a thermal printer to print on. 
     During processing, any wax on the writing surface  41  is removed by placing the laboratory sample cassette  40  against the flat surface  31  of the heated metal block  32  so that the two ribs  42  of the writing surface hold the writing surface  41  parallel to the flat surface (see  FIG. 9 ). Wax on the writing surface  41  melts and runs off the writing surface  41  between the ribs  42 . 
     Whilst embodiments have been described, it will be understood that various modifications may be made without departing from the scope of the claimed invention. The laboratory sample cassettes  1 ,  40  and lid  17  described are examples and there can be other designs of the cassette and lid which fall within the scope of the claimed invention.