Abstract:
The present device is directed to a reagent transfer device for transferring a plurality of reagent samples from one location to another. A transfer plate has a top surface with reservoirs, a bottom surface with orifices, and channels connecting the reservoirs and orifices. Fluid is moved from the reservoirs, through the channels and out of the orifices to form samples on the bottom surface about the orifices. A movement apparatus is provided for bringing the samples into contact with deposit surfaces at various deposition positions. Arrays of at least 100 orifices per square centimeter are provided.

Description:
This is a divisional of U.S. application Ser. No. 08/966,893, filed Nov. 10, 1997 now U.S. Pat. No. 5,882,930. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to transferring fluid samples and, more particularly, to a reagent transfer device for transferring a large number of fluid samples onto a very small surface area. 
     2. Description of the Related Art 
     Automated systems are used to transfer fluid samples from repositories, such as test tubes, vials or wells, to receptacles or surfaces. One such automated system is disclosed in U.S. Pat. No. 5,055,263, issued to Meltzer, entitled “Automated Pipetting System.” This reference discloses a system wherein a plurality of hollow probes are used to transfer a plurality of fluid samples. A probe is dipped into the fluid repository and a volume of fluid is drawn into the probe using aspiration. The probe is retracted from the repository and repositioned above the receptacle or surface that will receive the fluid sample. The probe is lowered towards the surface and pressure is exerted against the fluid to force the fluid sample out of the probe. A plurality of probes are mounted on a carriage that is in turn mounted to an overhead frame assembly which moves the carriage independently in the X-direction and Y-direction. The carriage includes a drive mechanism that moves each probe independently in the Z-direction. 
     The system described above is effective for transferring fluid samples from test tubes and vials. However, the use of hollow probes to transfer fluid samples from a plurality of repositories does not provide the precision necessary to transfer a plurality of fluid samples that are in the range of about 100 microns in diameter and spaced apart by a distance of less than about 500 microns. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to a reagent transfer device for transferring a plurality of reagent samples onto a deposit surface. In one embodiment of the present invention, the reagent transfer device includes a reagent tray having a top surface with a top surface area and a plurality of wells arranged in a two-dimensional array of at least 30 wells by at least 30 wells. The wells have a diameter of no greater than about 300 microns and are spaced apart by a center-to-center distance measured from the center of one well to the center of an adjacent well of less than about 500 microns. The reagent tray may further include a bottom surface having a bottom surface area larger than the top surface area, a plurality of coupling cavities, and a plurality of channels. Each of the channels connects one of the wells to a corresponding one of the coupling cavities so at the one well and the one corresponding coupling cavity are in fluid communication so as to allow replenishment of the one well by providing reagent to the one well through the one corresponding coupling cavity and the channel. 
     The reagent transfer device further includes a transfer member having a transfer surface with a two-dimensional array of pins extending therefrom. Each of the pins is positioned to correspond to one of the wells so that when the transfer member is moved in the Z-direction the pins are simultaneously dipped into the corresponding wells. The reagent transfer device also includes a means for moving the transfer member between a first position in which reagent from the wells is deposited on the pins and a second position in which reagent on the pins is deposited on the deposit surface. The moving means may be adapted for independent movement of the transfer member in the X-direction, the Y-direction, and the Z-direction. Alternatively, the moving means may be adapted to move the transfer member in the Z-direction, and to move the deposit surface in the X-direction and the Y-direction. 
     According to one aspect of the present invention, each of the pins has a diameter in the range of between about 30 microns and about 100 microns, and has an outer shape adapted to retain a sample of one of the reagents when the pin is dipped into the corresponding one of the wells. In another aspect of the present invention, at least about 100 wells are disposed on the top surface of the reagent tray in the ratio of at least 100 wells per square centimeter of top surface area. 
     In another aspect of the present invention, a method for transferring a plurality of reagent samples from a reagent tray via a transfer member to a deposit surface is provided. The reagent tray has a top surface with a top surface area and at least about 100 wells in the ratio of at least 100 wells per square centimeter of top surface area. The transfer member has a transfer surface with a plurality of pins extending therefrom. Each of the pins is positioned to correspond to one of the wells so that when the transfer member is moved in the Z-direction, the pins are simultaneously dipped into the corresponding wells. 
     The method according to the present invention includes the steps of dipping the pins into the corresponding wells so that a reagent sample is deposited on each of the pins by adhesion to the outer surfaces of the pins, moving the transfer member to a position proximate the deposit surface, and contacting the deposit surface with the reagent samples, whereby the reagent samples are deposited on the deposit surface by adhesion to the deposit surface. In one aspect, the method according to the present invention further includes the step of replenishing the reagent in the wells by providing reagent to the wells through corresponding coupling cavities and channels in the reagent tray. 
     In another alternative embodiment of the present invention, the reagent transfer device includes a transfer member having a bottom surface with a bottom surface area and at least about 100 orifices in the ratio of at least 100 orifices per square centimeter of bottom surface area. The transfer member further includes a top surface having a plurality of reservoirs and a plurality of channels. Each of the channels connects one of the orifices to a corresponding one of the reservoirs so that the one orifice and the one corresponding reservoir are in fluid communication. A reagent sample is formed on the bottom surface about the orifice by providing reagent to the orifice through the corresponding one reservoir and the channel. The reagent transfer device further includes a means for moving the transfer member between a first position in which reagent samples are deposited onto a first deposit surface and a second position in which reagent samples are deposited on a second deposit surface. The means for moving the transfer member may be adapted to move the transfer member in the X-direction, the Y-direction and the Z-direction. Alternatively, the means for moving may be adapted to move the transfer member in the Z-direction, and to move the first and the second deposit surfaces in the X-direction and the Y-direction. 
     In yet another embodiment of the present invention, a method for depositing a plurality of reagent samples via a transfer member onto a deposit surface is provided. The transfer member includes a bottom surface with a bottom surface area and at least about 100 orifices in the ratio of at least 100 orifices per square centimeter of bottom surface area. The transfer member further includes a top surface having a plurality of reservoirs and a plurality of channels. Each of the channels connects one of the orifices to a corresponding one of the reservoirs so that the one orifice and the one corresponding reservoir are in fluid communication. The method includes the steps of forming a reagent sample on the bottom surface of the orifice by providing reagent to the orifice through the one corresponding reservoir and the channel, moving the transfer member to a position proximate the deposit surface, and contacting the deposit surface with the reagent samples whereby the reagent samples are deposited on the deposit surface by adhesion to the deposit surface. 
     The features and advantages of the invention will be apparent to those of ordinary skill in art in view of the detailed description of the preferred embodiment, which is made with reference to the drawings, a brief description of which is provided below. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a partial side view of a transfer member and reagent tray in accordance with the present invention; 
     FIG. 2 is a partial top view of the reagent tray of FIG. 1; 
     FIG. 3 is a partial side view of a pin according to the present invention with a reagent sample in the form of a fluid drop deposited thereon; 
     FIG. 4 is a schematic view of a system for moving a transfer member between a reagent tray and a deposit surface; 
     FIG. 5 is a partial side sectional view of an alternative embodiment of the reagent tray according to the present invention; 
     FIG. 6 is a partial side sectional view of an alternative embodiment of the transfer member according to the present invention; 
     FIG. 7 is a partial bottom view of the transfer member of FIG. 6; 
     FIG. 8 is an enlarged partial sectional view of the transfer member of FIG. 6; and 
     FIG. 9 is a schematic view of a system for transferring reagent samples from the transfer member of FIG. 6 to a plurality of deposit surfaces. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The first embodiment of a reagent transfer device in accordance with the present invention is shown in FIGS. 1-4. Referring to FIG. 1, the transfer device includes a transfer member  10  having an array of reagent sampling pins  12 . The transfer device further includes a reagent tray  14  having an array of reagent wells  16 , as shown in FIG.  2 . The array of pins  12  corresponds to the array of wells  16  so that the pins  12  can be simultaneously dipped into the corresponding wells  16  when the transfer member  10  is moved downward to a position proximate the reagent tray  14 . The array of wells  16  contains at least about 100 wells with a density of at least about 100 wells per square centimeter. In a preferred embodiment, the wells  16  are arranged in a two-dimensional array of 32 wells by 32 wells for a total of 1,024 reagent wells  16 . Each of the wells  16  has a very small width a which is no greater than about 300 microns. Alternatively, the wells  16  can be cylindrical with a diameter no greater than about 300 microns. Adjacent wells  16  in the array are spaced apart by a center-to-center distance b which is less than about 500 microns, and preferably about 350 microns. In this way, the array of wells  16  has a density of approximately 1,000 wells per square centimeter on the surface of the reagent tray  14 . Similarly, the pins  12  on the surface of the transfer member  10  are arranged in a two-dimensional array of 32 pins by 32 pins for a total of 1,024 pins  12 . Each of the pins  12  in the array has a diameter in the range of between about 30 microns and about 100 microns. 
     Reagent samples are deposited on the pins  12  when the pins  12  are dipped into the corresponding wells  16 . Each of the wells  16  contains a supply of reagent, a portion of which is transferred by the pins  12  to a deposit surface  20  (see FIG.  2 ). FIG. 3 illustrates the end portion of a pin  12  with a reagent sample in the form of a fluid drop  18 . Each of the pins  12  has an outer shape adapted to retain a reagent sample when the pin  12  is dipped into one of the wells  16 . In a preferred embodiment, the outer shape of each of the pins  12  is cylindrical. The reagent in the wells  16  adheres to the outer surface of the pin  12 , and the fluid drop  18  remains adhered to the pin  12  when the pin  12  is retracted from the well  16 . When the transfer member  10  is moved into position proximate the deposit surface  20 , the fluid drop  18  contacts and adheres to the deposit surface, thereby leaving the reagent sample on the deposit surface  20  when the pin  12  is retracted from the deposit surface. 
     One arrangement of an automated system for moving the transfer member  10  between the reagent tray  14  and the deposit surface  20  is illustrated schematically in FIG.  4 . The transfer member  10  is mounted to a carriage  22  which is positioned above the transfer member  10 . The carriage  22  in turn is mounted between a first positioning member  24  and a second positioning member  26 . The positioning members  24 ,  26  are mounted on opposite sides of a frame  28 . The carriage  22  contains a drive mechanism which provides independent movement in the Z-direction of the transfer member  10 . Additionally, the drive mechanism of the carriage  22  moves the carriage  22  and the transfer member  10  laterally between the positioning members  24 ,  26  in the X-direction. Finally, the positioning members  24 ,  26  and, correspondingly the transfer member  10  and the carriage  22 , move back and forth in the Y-direction along the frame  28  under the influence of a drive mechanism in either or both of the positioning members  24 ,  26 . In this way, the transfer member  10  is moved independently in the X-direction, the Y-direction and the Z-direction between the reagent tray  14  and the deposit surface  20 . 
     To begin the process of transferring a plurality of reagent samples from the reagent tray  14  to the deposit surface  20 , the transfer member  10  is positioned above the reagent tray  14 . The drive mechanisms in the carriage  22  and the positioning members  24 ,  26  move the transfer member  10  in the X-direction and Y-direction, respectively, until the transfer member  10  is aligned above the reagent tray  14 . Once positioned, the drive mechanism in the carriage  22  moves the transfer member  10  downwardly in the Z-direction to dip the pins  12  into the corresponding wells  16 . The drive mechanism of the carriage  22  reverses to withdraw the transfer member  10  from the regent tray  14  with the reagent samples adhering to the pins  12 . The drive mechanism in the carriage  22  and the positioning members  24 ,  26  reposition the transfer member  10  in the X-direction and Y-direction, respectively, until the transfer member  10  is positioned above the deposit surface  20 . The drive mechanism in the carriage  22  moves the transfer member  10  downwardly until the reagent samples contact the deposit surface  20 . The reagent samples adhere to the deposit surface  20  and remain on the deposit surface  20  when the drive mechanism of the carriage  22  is reversed, thereby moving the transfer member  10  upwardly in the Z-direction away from the deposit surface  20 . 
     The particular arrangement for positioning the transfer member  10  described herein is illustrative only. Additionally, the arrangement may include mechanisms for moving the deposit surfaces  20  in the X-direction and the Y-direction into position to receive the reagent samples. Other automated mechanisms for moving the transfer member  10  and the deposit surface  20  will be obvious to those of ordinary skill in the art and are contemplated by the inventor having use in connection with the present invention. 
     FIG. 5 is a partial side sectional view of an alternative embodiment of a reagent tray  30  in accordance with the present invention. The reagent tray  30  is formed generally in the shape of a pyramid with a top surface  32  having a smaller surface area than a bottom surface  34 . In a preferred embodiment, the top surface  32  is about 1 centimeter by 1 centimeter and the bottom surface  34  is about 30 centimeters by 30 centimeters. The top surface  32  of the reagent tray  30  has an array of wells  36  formed thereon similar to the array of wells  16  previously illustrated and discussed in relation to FIG.  2 . The bottom surface  34  has an array of coupling cavities  38  corresponding to the array of wells  36  on the top surface  32 . The coupling cavities  38  have a larger diameter than the wells  36  to facilitate attachment of reagent supply lines (not shown) to the bottom surface  34 . The larger diameter of the coupling cavities  38  necessitates the increased surface area of the bottom surface  34 . Each well  36  is placed in fluid communication with the corresponding coupling cavity  38  by a channel  40  which connects the bottom of the well  36  to the top of the coupling cavity  38 . Reagent from the reagent supply lines passes through the coupling cavities  38  and the channels  40  to the wells  36  to replenish the supply of reagent in the wells  36 . 
     Another alternative embodiment for a reagent transfer device according to the present invention is shown in FIGS. 6-9. In this embodiment, a transfer member  42  performs both functions of supplying the reagent for the reagent samples and transferring the reagent samples to a deposit surface. Referring to FIG. 6, the transfer member  42  has a bottom surface  44  with an array of orifices  46 . The array of orifices  46  contains at least 100 orifices with a density of at least about 100 orifices per square centimeter of bottom surface area. A top surface  48  of the transfer member  42  has an array of reservoirs  50  which corresponds to the array of orifices in the bottom surface  44 . Each reservoir  50  is placed in fluid communication with the corresponding orifice  46  by a channel  52  which connects the bottom of the reservoir  50  to the orifice  46 . The transfer member  42  is mounted on a mechanism (not shown) for positioning the transfer member  42  proximate a deposit surface (not shown) to deposit a plurality of reagent samples thereon. 
     FIG. 7 is a bottom view of the transfer member  42  which shows the orifices  46  on its bottom surface  44 . The orifices  46  are arranged in a two dimensional array of 32 orifices by 32 orifices for a total of 1,024 orifices  46 . Each of the orifices  46  has a very small diameter c which is no greater than about 100 microns. Adjacent orifices  46  in the array are spaced apart by a center-to-center distance d which is less than about 500 microns, and preferably about 350 microns. In this way, the array of orifices  46  has a density of approximately 1,000 orifices  46  per square centimeter on the bottom surface  44  of the transfer member  42 . 
     Referring to FIG. 8, which is an enlarged view of a portion of the transfer member  42 , reagent samples are formed on the bottom surface  44  of the transfer member  42  about each of the orifices  46 . Reagent from the reservoir  50  passes through the channel  48  to the orifice  46 . As reagent passes through the orifice  46  and adheres to the bottom surface  44  of the transfer member  42 , a reagent sample is created in the form of a fluid drop  54 . When the transfer member  42  is moved into position proximate the deposit surface (not shown), the fluid drop  54  contacts and adheres to the deposit surface, leaving the reagent sample on the deposit surface when the transfer member  42  is retracted from the deposit surface. 
     One arrangement for moving the transfer member  42  into contact with a plurality of deposit surfaces  56 - 68  is illustrated schematically in FIG.  9 . The transfer member  42  is mounted to a carriage  70  above a rotating shelf  72 . The carriage  70  includes a drive mechanism which moves the transfer member  42  upwardly and downwardly in the Z-direction. The deposit surfaces  56 - 68  are arranged on the shelf  72  so that the deposit surfaces  56 - 68  pass under the transfer member  42  as the shelf  72  rotates in the direction indicated by the arrows. The rotation of the shelf  72  is precisely controlled to stop when one of the deposit surfaces  56 - 68  is positioned beneath the transfer member  42 . 
     The drive mechanism of the carriage  70  moves the transfer member  42  downwardly until the transfer member  42  is close enough to the deposit surface  56  for the fluid drops  54  to contact the deposit surface  56 . After the fluid drops  54  contact the deposit surface  56 , the transfer member  42  is retracted from the deposit surface  56 , leaving the reagent samples deposited thereon. A new set of fluid drops  54  is formed on the bottom surface  44  of the transfer member  42  by passing additional reagent from the reservoirs  50  through the channels  48  to the orifices  46 . In preparation for depositing reagent samples on the next deposit surface  58 , the shelf  72  is rotated to position the deposit surface  58  under the transfer member  42 . Once positioned, the transfer member  42  is lowered toward the deposit surface  58 . 
     This arrangement for transferring a plurality of reagent samples from the transfer member  42  to the deposit surfaces  56 - 68  is illustrative only. Alternatively, an arrangement similar to that illustrated schematically in FIG. 4 may be used to move the transfer member in the X-direction, the Y-direction and the Z-direction in order to deposit reagent samples on the deposit surfaces  56 - 68 . Additional mechanisms for positioning the transfer member  42  and the deposit surfaces  56 - 68  will be obvious to those of ordinary skill in the art and are contemplated by the inventor as having use in connection with the present invention. 
     While the present invention has been described with reference to the specific examples, which are intended to be illustrative only and not to be limiting of the invention, it will be apparent to those of ordinary skill in the art that changes, additions, and/or deletions may be made to the disclosed embodiment without departing from the spirit and scope of the invention.