Chemical apparatus and process disinfecting – deodorizing – preser – Control element responsive to a sensed operating condition
Reexamination Certificate
2001-11-05
2004-07-06
Warden, Jill (Department: 1743)
Chemical apparatus and process disinfecting, deodorizing, preser
Control element responsive to a sensed operating condition
C422S091000, C422S105000, C436S180000, C436S174000, C101S093040, C101S093050, C211S060100, C211S069100, C400S124010
Reexamination Certificate
active
06759012
ABSTRACT:
BACKGROUND ART
The invention relates to an apparatus for and method of holding pins. More especially, but not exclusively, the invention relates to holding pins in a pin-head as widely used in the field of chemistry and biotechnology for microarraying and other applications.
Microarraying is a technique in widespread use. Conventional microarraying is based on standard multi-well plates having a 4.5 mm grid and 384 wells, although other sizes are available. Liquid samples are stored in the wells of a well plate. The liquid may be assays or any other biological or chemical sample of interest. Sub-samples of the liquid within the well plates are carried to and deposited on a spotting surface as required. Usually many such deposits are needed and microarraying is a process whereby multiple deposits can be made simultaneously and under machine automation.
FIG. 1A
of the accompanying drawings shows schematically a bed of an exemplary microarraying apparatus
100
. A number of well plates
110
are shown on the apparatus bed. The well plates
100
contain liquid to be spotted onto an array of microscope-type slides
120
. The apparatus has a translatable head mechanism
130
which carries and positions the pin holder
140
in three orthogonal axes x, y and z.
FIG. 1B
of the accompanying drawings shows schematically a more detailed view of a conventional pin holder
140
designed to carry a 6×4 rectangular array of pins
170
. Each of the pins
170
is guided by an upper hole
180
and a lower hole
190
within the pin holder
140
so as to remain nominally vertical. The separation of neighboring holes matches that of the well plate spacing. The pins
170
are free to slide vertically within the pin holder
140
and a collar
175
provides an abutment for the pins
170
to define the bottom point of the pins
170
.
In operation, the translatable head mechanism
130
is initially positioned so as to align the pins
170
with the required section of well plate
110
. The pin holder
140
is then driven by the head mechanism
130
so as to partially immerse the pins
170
in the liquid to be spotted. Surface tension ensures that samples of fluid remain on the pins
170
as they are lifted away from the well plate. The pin holder
140
is then carried by the head mechanism
130
to the required location for spotting where it is again driven downwards to deposit some or all of the carried fluid at the chosen location. This can be achieved by bringing the pins
170
into direct contact with the surface
120
. To avoid the necessity of precise vertical positioning of the pin holder
140
the pins
170
are free to slide vertically so as to limit the force applied to the spotting surface
120
as the pins
170
contact it. The head mechanism
130
may be lifted and re-positioned for further spotting with the fluid remaining on the pins
170
, or it may be lifted and returned to the well plates
110
for re-coating with different fluid samples before further spotting. Typically, an extended and pre-programmed series of spotting operations will be undertaken automatically by the microarraying apparatus.
FIG. 2A
of the accompanying drawings shows the resulting fluid deposition pattern that would occur from a single spotting operation with the pin holder
140
shown in FIG.
1
B. There are 24 spots in a regular rectangular array and with a pitch which matches the well plate spacing. It is conventional to deposit a higher density of spots on the spotting surface
120
by repositioning the head
130
to a position slightly displaced from the initial spotting position for further spotting.
FIG. 2B
of the accompanying drawings shows the resulting fluid deposition pattern that would occur from two further spotting operations, each slightly displaced from the previous.
FIG. 2C
of the accompanying drawings shows the resulting fluid deposition pattern that would arise from many closely spaced spottings. Each of the individual boxes schematically represents a dense grid of spottings generated by a single pin. In order to reliably reproduce these dense grids, which typically comprise an 11×11 square grid of spots within the 4.5 mm pin separation, the pins
170
must be fixed such that their tips maintain the standard 4.5 mm spacing to a certain degree of accuracy, typically about 30 &mgr;m or better. The characteristic effect of a single misaligned pin in the spot pattern of
FIG. 2C
is shown as the uniformly displaced group of spots
230
.
FIG.
3
A and
FIG. 3B
of the accompanying drawings show, in grossly exaggerated form, two possible sources of pin misalignment error.
FIG. 3A
shows an example where the upper hole
180
and the lower hole
190
are not axially aligned.
FIG. 3B
shows an example where the upper hole
180
and the lower hole
190
are not co-parallel. These alignment errors require the guiding holes
180
,
190
to be oversized to allow free movement of the pins. However, these oversized holes themselves can lead to spotting errors in cases where the holes
180
,
190
are relatively well aligned such that a pin becomes free to move away from the vertical and rattle within the pin holder. This results in scatter about the otherwise regular spot pattern associated with the rastering of the affected pin.
The high-tolerance machining required to minimize the problems associated with misalignment of the holes in the pin holder leads to high manufacturing costs. Conventional drilling techniques are unable to provide the required accuracy and jig grinding is necessary. The cost of jig grinding each hole in a pin holder of the type described above is significant. With a pin holder containing 48 holes the machining cost of the pin holder makes up a significant proportion of the overall cost of the complete microarraying apparatus. It is therefore desirable to provide a pin holder which provides a high degree of accuracy for the pin guidance and which can be fabricated more cheaply and easily than a conventional pin holder.
SUMMARY OF THE INVENTION
According to a first aspect of the invention there is provided a pin holder for a microarraying apparatus comprising: at least one group of bodies of circular cross-section packed together to form a network of pathways in gaps between the bodies; and an array of pins slidably arranged in at least a subset of the pathways.
With the invention, the pins are held parallel to each other automatically as a result of the self organized packing of the circular cross-section bodies. This is a great improvement over the prior art approach described above in which guide holes for the pins are bored or ground individually, and thus inherently will not be parallel to each other and will also suffer from eccentricity errors in the case that the pins are guided in two or more vertically displaced guide holes.
With the invention, any misalignment of the circular cross-section bodies will be collective, so that all the pins will be misaligned in the same way and thus remain parallel to each other. Such a misalignment will therefore cause no net effect on the spotting process.
In one embodiment, the at least one group of bodies comprises a group of spherical bodies arranged in a common plane, such as ball bearings. More specifically, first and second groups of spherical bodies are preferably arranged in first and second planes vertically displaced from one another.
In another embodiment, the at least one group of bodies comprises a group of cylindrical bodies, such as needle roller bearings.
With the invention, the principal contributory factor to irregularity in the pin alignment, and thus spot spacing, will be irregularity in the size of the circular cross-section bodies. However, ball bearings (i.e. spheres) or needle roller bearings (i.e. cylinders) are manufactured to a very high degree of dimensional uniformity and are mass produced items of low cost. They are also available in a variety of materials, such as stainless steel, tungsten carbide and ceramic. A pin holder with a 4×6 pin array can be manufactured using conventional machini
Andrews John Richard
Haslam James Keith
Foley & Lardner
Genetix Limited
Gordon Brian
Warden Jill
LandOfFree
Pin holder for a microarraying apparatus does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Pin holder for a microarraying apparatus, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Pin holder for a microarraying apparatus will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3198676