DEPOSITION APPARATUS

Abstract: Apparatus for making discrete closely-spaced deposits on a microscope slide comprises a support (9) for holding several slides and a vertically reciprocable carrier (3) for holding several applicators, e.g. mapping pen nibs, which can be touched onto the slides by lowering the carrier. In order to allow the deposists to be made at a closer spacing than the spacing of the applicators the support (9) is moved laterally under the carrier between several indexed positions along a path with the carrier being lowered to make deposits when the support (9) is at each of the indexed positions. The applicators in the carrier (3) are positionally offset by differing amounts relative to the indexed position so that the deposits are made at different positions on the slide.

Description: DEPOSITION APPARATUS This invention relates generally to apparatus for depositing a substance on a substrate and more particularly to apparatus for making a number of closely spaced discrete deposits on a substrate. The need for making closely spaced discrete deposit of substance on a substrate occurs in many branches of science and industry but has become particularly important recently in medical applications where various assay techniques such as fluorescent or luminescent assays use microscope slides on which a large number of closely spaced deposits of a test substance need to be made. For example in a direct immunoassay for the detection of antigens (substances which stimulate production of an antibody) in tissues or cells, a sample containing the suspected antigen is immobilised by depositing it on a microscope slide and is then contacted with a corresponding antibody which has been conjugated with a fluorochrome. The slide is then washed to remove unreacted materials and illuminated under ultra-violet light for inspection. Areas of enhanced fluorescence indicate where the antigen-antibody reaction has taken place and thus the presence of the suspected antigen or antibodies. In this technique and other similar techniques it is often necessary to make a number of tests with different antigens or antibodies. This can conveniently be done by making several deposits on one slide and recently a new technique has become known where the deposits are made in the form of "micro-dots" which are very small, discrete deposits. This technique uses slides which have a number of circular wells - typically 18- formed on one surface by apertures in a Teflon coating. Each well is typically a few millimetres in diameter. In the micro-dot technique a number of small deposits, e.g. 4 or 9, are made in each well and each of the deposits in each well may be a different substance. The slide is then used in the same way as in previous techniques - i.e. a test substance is applied to the slide to react with the deposits, the slide is washed and inspected. At present the deposits in the wells are made individually by hand using a mapping pen. This is clearly a painstaking and time consuming process and thus tends to reduce the advantage gained by having more deposits on one slide. According to the present invention there is provided apparatus for applying one or more substances to a substrate in a plurality oξ spaced discrete deposits, characterized by means for guiding relative movement of the substrate and a plurality of applicators of such a substance to follow a predetermined path and means for defining a plurality of indexed relative positions of the substrate and applicators along that path and at which at least one applicator is operated to apply the substance to the substrate, individual applicators being disposed relative to the respective indexed positions such that the spacing between adjacent deposits can be less than the spacing between adjacent applicators, longitudinally and/or transversely of the path. A second aspect of the invention provides apparatus for applying one or more substances to a substrate comprising a plurality of applicators for applying a substance to the substrate, characterized by means for guiding the ' substrate and applicators to follow a predetermined path of relative movement, which may be linear or circular, means defining a series of indexed positions of the substrate relative to the applicators, at each of which at least one applicator is used to apply substance to the substrate, the applicators each being positioned to make a deposit at a different points on the substrate. Preferably, the positions are disposed along the path in an arrangement such that deposits made by the applicator(ε) at successive positions are interleaved with one another lengthwise and/or transversely of the path. The substrate may be moved around the path by hand e.g. by being a suitable mechanical linkage or by a motor. The applicator(s) at each indexed position may be positionally offset within its respective indexed position by differing amounts in a manner such that the interleaving is achieved. At each indexed position, there may be a number of applicators arranged in a one or two dimensional- array. The inter-applicator εpacings in each array may be the same for each array, with the offset of each array relative to its respective 'indexed position being such as to interleave deposits made by applicators at the respective indexed position. Preferably the apparatus is adapted for making the deposits in a plurality of spaced groups, each group comprising a plurality of discrete deposits and a plurality of applicators are used to make the deposits in a group, the applicators being divided between the respective indexed position. Conveniently each deposit in a group is made by a different applicator and at a different indexed position, there being at least one applicator at each indexed position. Preferably a plurality of applicators is disposed at each indexed position each for making a deposit of a different group and a sufficient number of applicators are provided at each indexed position so that one deposit in every group may be made at each indexed position. Preferably the indexed positions are spaced apart by a distance substantially equal to the dimensions of the substrate, e.g. wherein the substrate is a microscope slide - the width of the slide, in the direction of relative movement of the substrate and applicators although where the deposits are grouped and a deposit is not made in every group at each of the indexed position, the indexed position can be spaced apart by distance substantially equal to the spacing between the groups. In an alternative embodiment a plurality of applicators is disposed at each indexed position so that a plurality of deposits in at least one of the groups are made at each indexed position and preferably a plurality of deposits are made in every group. Preferably the apparatus is adapted to hold a plurality of microscope slides as said substrate and the slides are held with their longest edges parallel to each other and transverse to the direction of relative motion of the slides and applicators. The relative movement of the support and applicators may then be achieved by moving the support parallel to the width of the slides. The applicators may be held in a mounting mounted for reciprocal movement towards and away from the substrate and the reciprocal motion of the mounting used to effect the relative movement of the support and substrate - conveniently by means of a mechanical linkage. The linkage may be adapted so that the movement of the substrate between the respect indexed position is complete before the applicators closely approach the substrate so that the substrate is still as the applicators touch the substrate. The applicators may be nibs, eg. mapping pen nibs, and are conveniently loosely held in a mounting plate so that they are permitted at least limited motion or "give" when the nib touches the substrate, in the direction away from the substrate. This "give" means that satisfactory deposits can be made despite differences in the length of the nibs. — o — The apparatus may be adapted so that it can continuously and automatically make deposits on substrates and this can conveniently be achieved by providing a continuous supply of substrate to the applicators and effecting the movement of the applicators and relative motion of the applicators and substrate between the work indexed position by means of a motor or motors under the control of a computer. Where the substrate consists of microscope slides a slide feeder and stacking apparatus may be used in conjunction with the invention and the slides may also be packaged and labelled automatically. Thus completely automated production is possible. With the present invention a plurality of closely spaced discrete disposits may be made on a substrate relatively quickly and easily. The close spacing of the deposits is achieved by making the deposits at a number of different work indexed position spaced apart by distances greater than the distance between the deposits. At each of the different indexed position the applicators are disposed at slightly different positions e.g. different off-set positions with respect to the slide so that a number of closely spaced deposits may be made. The invention will be further described by way of non-limitative example with reference to the accompanying drawings in which: Figure 1 is a front view of part of an embodiment of the present invention; Figure 2 is a side view of the embodiment of figure 1 ; Figure 3 is a top view corresponding to figure 1; Figure 4 is a cut-away rear view of the embodiment of figure 1; Figure 5 is a bottom view of the embodiment of figure 1; Figure 6 is a top view of a slide magazine used in the embodiment of figure 1; Figure 7 is a side view of an applicator used in the figure 1 embodiment; Figure 8 is a cross-section corresponding to figure 7; Figure 9 is a top view of a component of the slide magazine of figure 6; • Figure 10 is a front view corresponding to figure 9. As shown in figures 1 and 2 the apparatus 1 comprises a base part 2 on which a pen carrier 3 is mounted for reciprocal movement on collars 6 running on two guide columns 5 and 7. The pen carrier 3 consists of a plate having a plurality of groups of bores therein for receiving the applicators - in this embodiment, mapping pen nibs. The pen carrier 3 may be moved towards and away from the base unit 2 by means of a handle 15 hinged to an upstanding column 2a at the rear of the base unit at 16 and connected to the pen carrier by a shaft 17 connected to the handle and pen carrier by a respective ball-and-socket joint 19, 21 at each end. The pen carrier 3 is urged away from the base unit by springs 23 and 24 surrounding two further columns 22 disposed parallel to and close to the guide column 5 or 7 and is retained on the column by removable retainers 25. The base unit has an extension unit 11 fitted to each side (only one is shown complete but they are identical to each other) whose top surfaces together with the top surface 13 of base unit 2 forms a track or path 9 for magazines which carry the slides on which substance is to be deposited. The extensions 11 are connected to the base unit 2 by locking mechanisms 27 (see figure 5) . The locking mechanism consists of a finger 12 on each of the extensions which engage with a bore 47 in a sleeve 44 and shaft 45. The sleeve and shaft arranged so as the locking lever 27 is turned the shaft 45 moves axially of the sleeve 44 and the finger 12 of the extension unit 11 is trapped as the hole in the sleeve moves off-centre from the bore in the shaft. This locking mechanism has been found to be reliable and simple but, of course, other locking mechanisms may also be used. As can be seen from figure 3 the pen carrier 3 consists of a support part 3b which runs on the columns 22, 5 and 7 and to which the handle 15 is connected, and a drilled plate 3a. The pen plate 3a fits into an aperture in the support part 3b and is held there by its weight - the aperture either being countersunk or having stepped edges to support the plate. Semicircular cut-outs 6 are provided at each end of the aperture so that the plate can be easily lifted out. This arrangement allows plates with a different pattern of drilled holes to be substituted quickly and easily so that different patterns of deposits may be made with the same apparatus. The holes 4 in the pen carrier 3 are dimensioned and shaped according to the type of applicator which is used. In this embodiment the applicators are mapping pen nibs, as shown in figure 7 and 8, which have a thin tube 60 supported in a barrel 62 and in fluid communication with a reservoir 63 in which the substance to be deposited is contained. The diameter of the barrel 62 is 0.25mm and thus in this embodiment the holes for in the pen plate 3a are simply cylindrical holes having a diameter slightly greater than 0.25mm so that the pens are free to slide in the holes but are supported by the shoulder between barrel 62 and the reservoir 63. The fact that the pens are free to move in the pen plate means that the pen plate can, in use, be lowered towards the substrate slightly further than the distance where the pens first touch the substrate. This means that all of the pens in the pen plate touch the substrate and operate reliably despite any differences which exists in the length of the pen nib and also that the pens are touched on to the substrate with only a light pressure caused by their own weight and the weight of the substance in the reservoir. In this embodiment the pens are simply filled at the beginning of a depositing operation and refilled if necessary when they are empty. However in an alternative embodiment the pens are connected to a continuous supply of substance and, of course, each pen or any of the pens can be connected to a different substance. The pen plate 3 shown in figure 3 is provided with four arrays of eighteen holes each. Assuming pens are placed in all of the holes, this plate will make a deposit consisting of eighteen groups each of four discrete disposits 16 as shown in figure 3a. Each of the arrays of eighteen bores in the pen plate is a indexed position at which one deposit in each group of deposits is made. The indexed position are spaced by a distance w corresponding to the width of one slide and between each depression of the handle 15 the slides are moved along by that distance to the next indexed position. The four arrays are each offset differently with respect to a slide placed between them so that when a slide has passed beneath and had a deposit made at each indexed position eighteen groups of deposits each containing four discrete deposits have been made. In more detail; the centres of the holes in the second indexed position are spaced at a distance w + d, where d is the desired spacing between deposits in a group, from the corresponding hole in the first indexed position thus (referring to figure 3A) at the first indexed position the upper left deposit (i) is made and at the second indexed position the upper right hand deposit (ii) is made in each group. Ξach bore in the third indexed position is displaced a distance w in the direction of motion of the slides from the corresponding bore in the second indexed position and a distance d transversely of the direction of the motion so that the bottom left hand deposit (iii) is made in each group. Each bore in the fourth indexed position is displaced at a distance w - d from the corresponding bore at the third indexed position and is not displaced transversely to the direction of the motion of the slide so that the bottom right hand deposit (iv) is made in each group. Clearly, different pen carriers can be used to produce different patterns and numbers of groups and to make different numbers of deposits. However the principle of making deposits at different indexed position and having the applicators positioned slightly differently at each indexed position allows very closely spaced deposits to be made despite the large physical size of the applicators themselves. As mentioned above, the slides on which the deposits are being made are supported in a magazine shown in figure 6. The slides are held with their long edges transverse to the direction of motion of the magazine along the track 9 and are held firmly in place on the magazine by a movable strip 57 which can be displaced to narrow the track and squeeze the slides. The slides are also prevented from slipping longitudinally along the magazine by being pressed against a stop 58 by a plate 59 urged towards the other end of the slide magazine by a spring 51 (see figures 9 and 10) . It is envisaged that the slide magazine may, if desired, be made of plastic so that it. is disposable. " Figure 2 shows more clearly the track 9 in which the slide magazines run. The track is formed by a flat floor part 10 and two parallel ribs or walls 12. In this embodiment the vertical movement of the handle 15 to lower -the pen plate towards the substrate is also used to move the slide magazines along the track 9. This is achieved by a mechanism shown in figures 2, 4 and 5. The vertical motion of the pen carrier 3 is converted into horizontal motion by a plate 35 in one face of which is formed a generally diagonal groove 37 which is engaged by a stud 34 mounted on a plate 32 connected to the collar 6 which supports the pen carrier. The plate 35 is mounted by runners 39 which are free to run in a horizontal groove 41 in the rear of the base unit 2. Thus as the handle 15 is moved vertically the plate 35 is urged horizontally by the stud 34. The movement of the plate 35 is transmitted to the slide magazine by a ratchet mechanism consisting of two sprung levers 40 which engage with triangular cutouts 54 on the edge of the slide magazine 56. The ends of the levers 40 are cut at an angle so that when the plate 35 moves in one direction they urge the slide magazine along the track and when the plate moves in the other direction they disengage from the cutouts on the slide magazine and run back along the edge of the slide magazine until they reach the next cutout, An adjustable rubber stop 10 is provided at the bottom of the guide columns 5 and 7 to allow the extent of downward movements of the pen carrier to be adjusted. As can be seen from figure 4 the groove 37 in the plate 35 consists of a diagonal part 37a and straight part 37b. The length and angle of the diagonal part 37a are set so that the plate moves horizontally exactly by one slide width for each depression of the handle 15 and so that that movement is achieved before the pens in the pen carrier touch the slide. The straight part 37b allows the slide magazine to remain stationary for the last part of the depression of the handle as the pens approach closely and touch the slide. This means that the slide is not moving as the pens touch it and the deposits can be well defined. Clearly, if slides of different dimensions are used then correspondingly different plates 35 can be fitted to the apparatus. In this embodiment the slides are loaded in the slide magazine edge-to-edge and the slide magazine is moved by exactly one slide width each time the handle is depressed. It will be appreciated that if there are large variation in the width of the slides then the placing of the deposits will become inaccurate. It has been found that the glass slides presently produced by manufacturers are accurate enough for present purposes, however if the dimensional tolerance does cause a problem, for instance because a very close spacing of deposits wer e required , then it would be possible to space the slides by a set distance by having suitable stops or marks on the magazine . The apparatus is provided with illumination for the sl ides by bulbs (not shown) which shine through translucent windows 31 and are powered by mains electr icity and controlled by a switch 30. An ind icator light 32 is also provided . The l ighting is provided so that the generator can watch the deposition process to check that the deposits are being well made i .e . correct shape and spacing etc . In automatic embodiments of the machine it is possible for the deposits to be checked by means of an electronic sensor . A micro- switch (not shown) is disposed in the channel 9 to detect the trailing edge of a slide magazine and to activate a buzzer to indicate when a new magazine needs to be loaded in to the apparatus . The appar atus is used as follows . An operator first selects a suitable pen plate for the required number and disposition of depos its , places it in the pen carrier 3 and loads it with pens containing the desired substance or substances to be deposited . He then loads a des ired number of slides into one or more slide magazines and places the f irst sl ide magazine in position on the extension part 11 of the track in such a position that it is engaged by the first of the levers 40 . Then by successively depressing the handle 15 the slide magazine containing the slides is moved along the track 9 beneath the pen carr ier 3 and successive deposits in each group are made. When the buzzer sounds indicating that the training edge of the slide magazine has passed the micro switch, a second slide magazine (if desired) is loaded and slid up the track to abut the trailing edge of the first. Continued depressions of the handle then bring the second magazine beneath the pen carrier, the first magazine moving out on to the second extension part 11 (only partly shown in figures 1 and 3) from where it can be unloaded and the slides removed. The above embodiment has been described for essentially manual operation. However, clearly the movement of the pen carrier and of the slide magazine could be achieved by using a motor under automatic control, for instance under the control of a computer. While, in this embodiment, it would be convenient for the motion of the pen carrier to be carried to the motion of the slide magazine so that only one motor is needed, clearly two motors could be used, controlled separately by the controller. It is also envisaged that this embodiment should be provided with a continuous supply of the substance(s) to be deposited connected to each applicator and with automatic slide supplying and stacking apparatus so that a very large number of slides with a desired pattern of deposits can be produced automatically.

Claims: CIsAXHS 1. Apparatus for applying one or more substances to a substrate (8) in a plurality of spaced discrete deposits (16) , characterized by means (11,12) for guiding relative movement of the substrate and a plurality of applicators (60,61,62,63) of such a substance to follow a predetermined path_.and means (35,40) for defining a plurality of indexed relative positions of the substrate (8) and applicators (60,61,62,63) along that path and at which at least one applicator (60,61,62,63) is operated to apply the substance to the substrate (8) , individual applicators (60,61,62,63) being disposed relative to the respective indexed positions such that the spacing between adjacent deposits (16) can be less than the spacing between adjacent applicators (60,61,62,63) , longitudinally and/or transversely of the path. 2. Apparatus for applying one or more substances to a substrate (8) comprising a plurality of applicators (60,61,62,63) for applying a substance to the substrate (8), characterized by means for guiding the substrate (8) and applicators (60,61,62,63) to follow a predetermined path of relative movement, which may be linear or circular, means defining a series of indexed positions of the substrate (8) relative to the applicators (60,61,62,63) , at each of which at least one applicator (60,61,62,63) is used to apply substance to the substrate (8) , the applicators (60,61,62,63) each being positioned to make a deposit at a different point on the substrate (8) . 3. Apparatus according to claim 1 or 2 wherein the positions are disposed along the path in an arrangement such that deposits made by the at least one applicator (60,61,62,63) at successive positions are interleaved with one another lengthwise and/or transversely of the path. 4. Apparatus according to claim 1, 2 or 3 wherein the applicators (60,61,62,63) are poεitionally offset with respect to their respective indexed positions by differing amounts. 5. Apparatus according to any one of the preceding claims wherein there are a plurality of applicators (60,61,62,63) at each indexed position. 6. Apparatus according to any one of the preceding claims adapted for making the deposits (16) in a plurality of spaced groups (14) , each group (14) comprising a plurality of discrete deposits (16) , wherein a plurality of applicators (60,61,62,63) each at a different indexed position are used to make the deposits (16) in a group. 7. Apparatus according to any one of claims 1 to 5 adapted to make the deposits (16) in a plurality of spaced groups (14) wherein a plurality of applicators (60,61,62,63) is disposed at each station such that a plurality of deposits (16) of each of at least one of the groups (14) are made at each station. 8. Apparatus according to any one of the preceding claims wherein the relative movement of the substrate (8) and applicators (60,61,62,63) between the stations is achieved by sliding the substrate (8) . 9. Apparatus according to any one of the preceding claims wherein a support (11) is provided to hold a plurality of microscope slides (8) as said substrate. 10. Apparatus according to any one of the preceding claims wherein the applicators (60,61,62,63) are held in a mounting (3) mounted for reciprocal movement towards and away from the substrate (8) and the reciprocal movement of the mounting (3) causes the substrate (8) to move in a direction perpendicular to the direction of reciprocal movement.

Inventors: DAROUGAR SOHRAB, DAROUGAR, SOHRAB
Applicants: DAROUGAR SOHRAB, DAROUGAR, SOHRAB
Application year: 1989
Main classification: B01L3
IPC codes: B01L3, B01L9, B01L11, G01N1