U.S. patent application number 15/467584 was filed with the patent office on 2017-08-03 for cuvette.
This patent application is currently assigned to Eppendorf AG. The applicant listed for this patent is Eppendorf AG. Invention is credited to Sven EIKELMANN, Wolfgang GOEMANN-THOSS, Kurt HARNACK, Christoph JOLIE, Helmut KNOFE, Peter SCHEFFLER.
Application Number | 20170216836 15/467584 |
Document ID | / |
Family ID | 40983733 |
Filed Date | 2017-08-03 |
United States Patent
Application |
20170216836 |
Kind Code |
A1 |
HARNACK; Kurt ; et
al. |
August 3, 2017 |
CUVETTE
Abstract
Cuvette, comprising at least one measuring area on each one of
two arms that are pivotally connected to each other such that from
a swung-apart condition, they can be swung together into a
measuring position in which the two measuring areas have a distance
for positioning a sample between the measuring areas, and means for
positioning the two arms in a measuring position in a cuvette shaft
of an optical measuring device with a sample between the two
measuring areas in a beam path of the optical measuring device that
crosses the cuvette shaft.
Inventors: |
HARNACK; Kurt; (Tangstedt,
DE) ; KNOFE; Helmut; (Norderstedt, DE) ;
SCHEFFLER; Peter; (Hamburg, DE) ; GOEMANN-THOSS;
Wolfgang; (Hamburg, DE) ; EIKELMANN; Sven;
(Hamburg, DE) ; JOLIE; Christoph; (Hamburg,
DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Eppendorf AG |
Hamburg |
|
DE |
|
|
Assignee: |
Eppendorf AG
Hamburg
DE
|
Family ID: |
40983733 |
Appl. No.: |
15/467584 |
Filed: |
March 23, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
14450946 |
Aug 4, 2014 |
9677994 |
|
|
15467584 |
|
|
|
|
12933789 |
Mar 21, 2011 |
8842274 |
|
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PCT/EP09/02121 |
Mar 23, 2009 |
|
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|
14450946 |
|
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61038596 |
Mar 21, 2008 |
|
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B01L 3/508 20130101;
B01L 2200/141 20130101; B01L 2300/043 20130101; B01L 9/52 20130101;
B01L 2200/021 20130101; G01N 2021/035 20130101; G01N 21/15
20130101; B01L 2300/168 20130101; B01L 3/18 20130101; G01N 21/03
20130101; B01L 2200/025 20130101; B01L 2300/0809 20130101; B01L
3/5088 20130101; G01J 3/0267 20130101; B01L 2300/161 20130101; G01N
2021/0307 20130101; G01N 21/0303 20130101 |
International
Class: |
B01L 3/00 20060101
B01L003/00; G01N 21/15 20060101 G01N021/15; G01J 3/02 20060101
G01J003/02; G01N 21/03 20060101 G01N021/03 |
Claims
1. A cuvette, comprising insert parts with two measuring areas and
an adapter for insertion into a cuvette shaft of an optical
measuring device, wherein the insert parts have two measuring
areas, and means for detachably holding the insert parts on the
adapter, the measuring areas being in a distance from each other,
for positioning a sample between the measuring areas in a beam path
of the optical measuring device that crosses the cuvette shaft, and
wherein the insert parts and adapter are fixedly connected to each
other.
2. A cuvette according to claim 1, wherein the adapter has a shape
matched to the cuvette shaft.
3. A cuvette according to claim 1, wherein the cross section of the
cuvette is matched to the cross section of a standard cuvette
shaft.
4. The cuvette according to claim 3, wherein the cross section of
the cuvette is matched to the cross section of a standard cuvette
shaft, which has a square cross section with a bottom area of
12.5.times.12.5 mm.
5. A cuvette according to claim 1, wherein the insert and/or the
adapter is made of metal and/or of one or plural plastics.
6. A cuvette according to claim 1, wherein the measuring areas or
insert parts are made of transparent plastics, quartz glass or
another optically transparent glass.
7. A cuvette according to claim 1, wherein the distances between
the two measuring areas are dimensioned such that samples with
volumes in the range of 0.2 to 5 microliters, can be held there
between.
8. A cuvette according to claim 1, wherein the measuring areas are
present on said insert parts made of quartz glass or plastics that
are replaceably or not detachably connected to said adapter.
9. A cuvette according to claim 1, which has means for detachably
locking said adapter in the measuring position.
10. The cuvette according to claim 1, wherein the adapter is made
of metal and comprise incorporated magnets for locking the adapter
in the measuring position, or wherein said adapter is made of
plastics and comprise elastic catching hooks that co-operate with
catching edges for locking the adapter in the measuring
position.
11. A cuvette according to claim 1, wherein the at least one insert
part is a platelet.
12. A cuvette according to claim 1, wherein the measuring areas are
present on plane-parallel platelets in an arrangement so as to
cover up each other.
13. A cuvette according to claim 1, wherein the distance of the
measuring areas from each other is 5 mm or less in the measuring
position.
14. A cuvette according to claim 1, wherein the optically
transparent measuring areas are realized so as to have a central
liquid-wetting surface portion in their center, around which there
is a liquid-repellent surface portion.
15. The cuvette according to claim 14, wherein a light-permeable
surface portion corresponds to the liquid-wetting surface portion,
and a light-impermeable surface portion on the outer side of the
insert part corresponds to the liquid-repellent surface
portion.
16. A cuvette according to claim 1, wherein deepenings are arranged
in the measuring areas.
17. A cuvette according to claim 1, wherein a planar pedestal is
arranged on each measuring area.
18. A cuvette according to claim 1, wherein the thickness of a
layer between the two measuring areas is defined by a spacer
ring.
19. The cuvette according to claim 18, wherein spacer rings are
assigned to both measuring areas, which come into contact with each
other when the device is closed.
20. A cuvette according to claim 1, wherein the layer thickness is
ensured by magnetic forces from magnets, whose unlike poles are
arranged in a short distance from each other when the device is
closed.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a Continuation from U.S. Ser. No.
14/450,946 filed on Aug. 4, 2014 which was a Continuation from U.S.
Ser. No. 12/933,789 filed on Mar. 21, 2011, now U.S. Pat. No.
8,842,274 issued on Sep. 23, 2014; which was a utility application
from U.S. Provisional patent application 61/038,596 filed on Mar.
21, 2008, the priorities of which are all claimed and the
disclosures of which are all incorporated herein by reference. U.S.
Ser. No. 12/933,789 also claimed priority from PCT/EP09/002114
filed on Mar. 23, 2009.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH
[0002] Not applicable.
BACKGROUND OF THE INVENTION
[0003] The present invention is related to the analysis of liquid
samples with a spectrometer or photometer or other optical
measuring devices. Such analyses are made typically, but not
exclusively, in the molecular-biological, biochemical,
inorganic-chemical, and organic-chemical and foodstuff chemical
laboratory. Samples are optically analysed for instance in
research, in diagnostics and in quality control.
[0004] They are analysed for instance by way of absorption-,
reflection-, emission-, fluorescence-, Raman- or luminescence
spectroscopy in the UV-VIS or IR wavelength range. Examples for
analytes to be measured are biomolecules like nucleic acids,
proteins, lipids as well as inorganic or organic materials and
compounds. These analytes can be measured directly or after a
chemical reaction that serves for facilitating the spectrometric or
photometric analysis.
[0005] The present invention is related in particular to all the
applications that were mentioned by way of example above. An
essential field of its application is the measurement of valuable
samples in small amounts in molecular biology. Often only small
amounts of sample are at hand (for instance, from less than 1 up to
5 micro-litres), because nor more material can be obtained. When
diluting the samples, the measurement results would become too
inaccurate due to decreased absorption. A typical application is
the photometric or fluorometric measurement of nucleic acid
concentrations before a PCR or real-time PCR, in order to be able
to use that starting amount of the nucleic acid which is optimum
for PCR. Another example is the measurement of the concentration of
nucleic acids and marker substances incorporated into the nucleic
acid, as well as of the marking density of marked nucleic acids
derived from this, in order to be able to use the optimum amount of
marked nucleic acid before beginning a micro array experiment, and
to be sure that the marking density of the nucleic acid is in the
optimum range.
[0006] For spectrometric or photometric analysis, liquid samples
are filled into cuvettes. Standard cuvettes are suited for the
insertion into the cuvette shafts of most of the current
spectrometers and photometers. These cuvette shafts are also called
"standard cuvette shafts" in the following. Standard cuvette shafts
of usual commercial optical measuring instruments having a cross
section of 12.5 mm.times.12.5 mm have become wide-spread. The
heights of the light beam above the bottom of the cuvette shaft
vary from 8.5 mm to 20 mm, depending on the type of the device.
Standard cuvettes have a box-like outline, wherein the cross
section and the height are matched to the dimensions of the
standard cuvette shafts.
[0007] Re-usable standard cuvettes of quartz glass for small
amounts of sample are marketed by the companies Hellma and Starna
in particular. These ultra micro cuvettes have a layer thickness of
1 mm or more. It is very difficult to fill them without bubbles,
and very sumptuous to empty and to clean them. Because the main
application of the optical measurements is the measurement of very
small volumes when measuring nucleic acids in the UV region, they
are made of quartz glass and are particularly expensive. They must
be treated with much care, because they are very expensive to buy.
For the ultra micro cuvettes of quartz glass that are obtainable on
the market, a minimum volume of 5 micro-litres must be used, which
is too much for many applications.
[0008] Other cuvettes are marketed with the designation
"Mikroliter-Messzelle" (micro-litre measuring cell). Under the
product name "Tray Cell.RTM.", the company Hellma, and under the
product name "Label Guard" the company Implen markets a micro-litre
measuring cell which corresponds to a standard cuvette in its
dimensions, and may therefore be used in many of the today's
spectrometers. The micro-litre measuring cell of the company Hellma
is described in WO 2005/114146 A1. In order to make an analysis,
one drop of about 1 to 2 micro-litres of the liquid to be analysed
must be applied to the topside of a measuring window at a layer
thickness of 0.2 mm, or at a layer thickness of 1 mm when the drop
is 3 to 5 micro-litres. The measuring chamber is closed by a lid.
The light beam of the measuring optics is guided from the radiation
source through the sample to the sensor via beam deflections and
fibre-optic light guides and via a mirror in the lid.
[0009] The micro-litre measuring cell is very sumptuous in its
construction and it has a high price, and therefore it cannot
always be used in an economically reasonable fashion. Moreover, it
has a high apparatus-dependent intrinsic absorption of 1.3 E at 230
to 650 nm, about which the measurement range of the measuring
instrument is reduced. Further, it is not possible to visually
check the measuring solution in the measurement chamber after
filling in the sample and putting up the lid, in order to detect
disturbing bubbles, particles and erroneous pipettings that might
lead to erroneous measurements. In addition it is disadvantageous
that the user must clean the measuring window after use in a
time-consuming way.
[0010] Under the product name "Nano Quant Plate", the company Tecan
offers a kind of collapsible micro-plate for a micro-plate
reader.
[0011] Under the product name "NanoDrop.RTM.", the company NanoDrop
Technologies markets a photometer, which permits to analyse samples
that have a volume of one micro-litre only. This spectrometer is
described in WO 2006/086459 A2. The system envisions the direct
optical measurement in a drop of liquid which is located between
two horizontally aligned, planar surfaces. A light source
illuminates the sample of liquid from the side through the gap
between the two surfaces. A fibre light guide runs out into the
lower surface, which leads the light further to a fibre optics
spectrophotometer after it has passed through the liquid sample.
Thus, the sample liquid is in direct contact with the glass
fibre.
[0012] In the spectrophotometer, it is disadvantageous that the
optical surface can be negatively affected by certain samples.
According to the operation manual of the spectrophotometer of the
type NanoDrop-1000, such samples are for instance protein
containing solutions. In this case, the user must manually
condition anew the optical surface after repeated usage by intense,
time-consuming strong rubbing. Also, strongly acidic or alkaline
solutions cannot be used.
[0013] Further, the sample is in direct, open contact with the
solution. Thus, dangerous substances cannot be examined with this
system. However, dangerous materials, like possibly infective
substances, are often used in the molecular-biological,
cell-biological, biochemical and chemical laboratory. The system is
not suited for these samples. Due to the open contact of the sample
with the surroundings, samples may become contaminated. This may
disturb the measurement. Moreover, it is not possible to re-obtain
valuable samples after the measurement without the risk of
contamination.
[0014] The spectrophotometer is a very expensive measuring system.
It comprises a measuring unit and a PC and consumes much space. The
sample may quickly evaporate and easily become contaminated,
because the surface area of the open drop of liquid has direct
contact to the surroundings.
BRIEF SUMMARY OF THE INVENTION
[0015] Starting from this, the present invention is based on the
objective to provide a device that is suited for the optical
examination of small amounts of sample with high precision, using
conventional optical measuring devices.
[0016] Further, a method is to be provided which permits the
optical examination of particularly small amounts of sample.
[0017] The cuvette of the present invention comprises at least one
measuring area on each one of two arms that are pivotally connected
to each other, such that from a swung-apart condition, they can be
swung together into a measuring position in which the two measuring
areas have a distance from each other for positioning a sample
between the measuring areas, and means for positioning the two arms
in the measuring position in a cuvette shaft of an optical
measuring device with a sample between the two measuring areas in a
beam path of the optical measuring device that crosses the cuvette
shaft.
[0018] According to one embodiment, a cuvette of the present
invention comprises at least one measuring area on each one of two
arms that are pivotally connected to each other, preferably by way
of an articulation, such that from a swung-apart condition, they
can be swung together into a measuring position in which the arms
can be positioned in a cuvette shaft, and the two measuring areas
face each other and have a distance from each other. As means for
positioning, this embodiment has a form of the arms swung together
in the measuring position that matches the cuvette shaft. This
cuvette is adapted to the cuvette shaft by the form of the arms
swung together, so that a sample held between the measuring areas
is disposed in the beam path when the cuvette is put into the
cuvette shaft. As a consequence, the arms of this cuvette are also
designated as "adapter parts," or both arms together as "adapter"
in the following.
[0019] According to another embodiment, a cuvette of the present
invention comprises at least one insert with two measuring areas
and an adapter for insertion into a cuvette shaft of an optical
measuring device, and means of insert and adapter for detachably
holding the at least one insert on the adapter, the measuring areas
being in a distance from each other, for positioning a sample
between the measuring areas in a beam path of the optical measuring
device that crosses the cuvette shaft.
[0020] In this embodiment, the adapter has a shape matched to the
cuvette shaft, so that a sample held between the measuring areas of
the insert is disposed in the beam path when the insert is put into
the adapter and the adapter is set into the cuvette shaft. A
preferred embodiment features means for positioning the two arms
disposed in the measuring position in a standard cuvette shaft. A
standard cuvette shaft in the spirit of the present invention has a
rectangular, in particular square cross section. According to one
embodiment, it has a bottom area of 12.5 a 12.5 mm. According to a
further embodiment, the beam path runs in a distance of 8.5 mm to
20 mm above the bottom of the cuvette shaft. According to a further
embodiment, the beam path runs in a distance of 8.5 mm or 15 mm
above the bottom of the cuvette shaft. The cross section of the
cuvette, for instance the cross section of the swung together arms
or the cross section of the adapter for receiving the insert, is
matched to the cross section of the standard cuvette shaft.
According to one embodiment, the measuring areas are positioned
such in the cuvette that their centre has the above-mentioned
distance of the beam path from the bottom of the cuvette shaft.
[0021] According to one embodiment, the cuvette has means for
positioning the two arms disposed in the measuring position in
different positions in a cuvette shaft. According to further
embodiments, these are means for positioning in different heights
and/or different horizontal positions in the cuvette shaft. The
means may for instance be feet of the cuvette that can be drawn or
screwed outward, or they may be realised by an asymmetrical
arrangement of the measuring areas in connection with an
arrangement of the cuvette in different rotational positions in the
cuvette shaft. For instance, they serve for the adaptation to the
height of the beam path of the measuring device, or for measuring
different samples on the measuring areas of one cuvette in the same
measuring device.
[0022] In the spirit of the present invention, a cuvette is a
device which is destined to position samples for optical
examinations. Thus, a cuvette of the present invention has not to
be realised in a conventional manner as a vessel with an
accommodation for liquids that is enclosed by bottom- and side
walls, such a realisation being not excluded at all, however.
[0023] In the cuvettes of the present invention, a small volume of
a liquid sample is positioned between the two measuring areas. A
column between the two measuring areas is formed by the surface
tension of the liquid, through which an optical measurement can be
performed. The adapter serves to position the measuring areas in a
preferably vertical alignment such in the cuvette shaft, that it
can be measured in a conventional photometer or spectrometer
without further alterations of the light path. For this purpose,
the adapter is preferably matched to the dimensions of a standard
cuvette shaft, so that it can be inserted like a standard cuvette.
But however, the adapter can also be matched to a cuvette shaft
with other dimensions than a standard cuvette shaft.
[0024] The insert and/or adapter may be realised for multiple use
or as a consumable or disposable item for single use. The insert
and/or the adapter may be made of one or plural plastics and/or of
one or different materials. Insert and adapter can alternatively be
fixedly connected, or consist of one single device,
respectively.
[0025] The insert and/or the adapter is for instance made of metal
(like aluminium or stainless steel, e.g.), and/or of one or plural
plastics or hard plastics or soft plastics, respectively (for
instance polystyrene, PVC, polypropylene, polyethylene). The
measuring areas or insert parts that have the measuring areas are
for instance made of transparent plastics (for instance Topas or
polystyrene), quartz glass or another optically transparent glass
(for instance BK 7). For measuring nucleic acids, a combination of
an adapter of aluminium with measuring areas or insert parts,
respectively, of quartz glass is well suited in particular.
[0026] Alternatively, the measuring areas may also be realised such
that several samples can be arranged on them, for instance by
corresponding surface shaping. The samples may be different or be
applied on the measuring area as identical samples.
[0027] According to possible embodiments, the two measuring areas
are arranged on two arms of an insert, of a pincette in particular,
or on two adapter parts of an adapter realised as a collapsible
device, by the aid of which a sample arranged between the two
measuring areas can be aligned in the measuring direction. In this,
the two measuring areas can be connected in one piece with the two
arms or adapter parts, which on their turn can be connected with
each other by being one piece. When the arms or adapter parts are
swung apart, the measuring areas stand one towards the other such
that a sufficiently great free space is provided for applying the
liquid sample, for instance in the form of a drop. The sample can
be applied to only one or to both measuring areas. By swinging the
two arms or adapter parts together, it is achieved that the medium
wets both measuring areas and a column of liquid is formed there
between. Alternatively, the liquid may also be applied directly
into a gap between the two measuring areas, so that a relative
movement of the measuring areas towards each other can be omitted.
For this purpose, the liquid can be put in between measuring areas
that are movable with respect to each other and which were set to a
suitable distance from each other. Further, for this purpose the
liquid can be put between two measuring areas which have a
stationary, fixed distance from each other.
[0028] Measurements with volumes from less than one micro-litre up
to several micro-litres can be realised in one cuvette by distances
of different magnitude between the two measuring areas. According
to a preferred embodiment, the distances between the two measuring
areas are dimensioned such that samples with volumes in the range
of 0.2 to 5 micro-litres can be held there between. Further
preferred, the distances between the measuring areas are
dimensioned such that the volumes of the samples that can be held
between them amount to about 1 to 3 micro-litres. Thus, the cuvette
can be dimensioned for a certain volume, wherein the measuring
areas can be held in the beam path only in a certain distance from
each other.
[0029] Positioning a liquid sample on one of the two measuring
areas, for instance of an insert or a collapsible device, can take
place with the aid of a pipette. In this, the pipette can be set
onto the measuring area with or without a guide device. After
delivery of the necessary amount of sample, the arms of the
pincette or collapsible device are swung together.
[0030] After application of the sample, an insert can be set into
an adapter and it can be positioned in a vertical alignment in a
cuvette shaft.
[0031] An insert of the present invention for an adapter that is
insertable into a cuvette shaft of an optical measuring device has
two measuring areas and means for holding on the adapter, the
measuring areas being in a distance from each other, in order to
position a sample between the measuring areas in a beam path of the
optical measuring device that crosses the cuvette shaft.
[0032] The means for detachably holding the insert can be in
particular contours or an outer geometry of the insert,
respectively, which is matched to a contour or respectively
geometry of the adapter, so that the insert can be joined to the
adapter.
[0033] The insert of the present invention may advantageously have
one or plural features of the insert of the cuvette of the present
invention explained above, which comprises at least one insert and
an adapter.
[0034] An adapter of the present invention for at least one insert
having two measuring areas can be put into the cuvette shaft of an
optical measuring device and has means for detachably holding the
at least one insert, the measuring areas being in a distance from
each other, in order to position a sample between the measuring
areas in a beam path of the optical measuring device that crosses
the cuvette shaft.
[0035] The adapter of the present invention may advantageously have
one or plural features of the adapter of the cuvette of the present
invention explained above, which comprises at least one insert and
an adapter.
[0036] The means for detachably holding the adapter can be in
particular a contour or respectively geometry of the adapter, which
is matched to a contour or respectively geometry of an insert, so
that the adapter can be joined to the insert.
[0037] A collapsible device of two arms or respectively adapter
parts that are connected by an articulation has the shape of a
common commercial cuvette when the two adapter parts are swung
together. The measuring areas can be present in particular on
replaceably installed insert parts of quartz glass or plastics.
Further, they may be connected to the arms or respectively adapter
parts as being one piece and/or in a not detachable fashion. For
instance, the arms with the measuring areas are made as one piece
of plastics. In this, the arms are connected to each other
preferably as being one piece, for instance via a film hinge.
Insert parts of quartz glass or replaceable insert parts of
plastics can in particular be present in cuvettes for multiple use.
Collapsible cuvettes for multiple use may in particular feature
arms or respectively adapter parts of metal. An arm or respectively
an adapter part of metal or of another material that is not
optically transparent (for instance of an opaque plastics) can be
realised as a stop for limiting the light passage through the
measurement volume.
[0038] A collapsible cuvette can be made of plastics or another
material for multi-use or as a disposable item for single use. The
two adapter parts can be connected articulately with each other via
a film hinge, or each may have articulation parts which are
mutually connected to a joint. The adapter parts can serve as stops
for shielding the measurement volume against excess light. For this
purpose, the adapter parts may consist entirely or partly of
coloured plastics, or they may wear light-impermeable coatings. For
instance, the collapsible cuvette has adapter parts of
UV-impermeable plastics and inserts of UV-transparent plastics.
[0039] According to one embodiment, there are means for detachably
locking the two adapter parts in the measuring position. These may
be incorporated magnets, in adapter parts of metal in particular.
Elastic catching hooks that co-operate with catching edges may
exist in adapter parts of plastics in particular. The catching
hooks and catching edges can be made in one piece with the adapter
parts of plastics.
[0040] In all the variants of the present invention mentioned
above, the beam path of the optical measuring device may run
crosswise through the measuring areas, for which purpose the
measuring areas or respectively the insert having the measuring
areas are realised as being transparent or clear or optically
diaphanous, respectively. According to another embodiment, the beam
path of the optical measuring device runs in parallel to the
measuring areas through open sides of the distance region between
the measuring areas. In this case, the measuring areas may also be
made light-impermeable. Even though the beam path does not run
across the measuring areas in this embodiment, they are designated
as "measuring areas", because they position the drop for the
measurement in the beam path.
[0041] In principle, measuring areas may have a curved one or
another shape. According to a preferred embodiment, the measuring
areas are planar. When the measuring areas are disposed on the side
of an insert part (for instance, of a platelet) or respectively of
a wall, both sides of the platelet or respectively the wall are
preferably planar.
[0042] In principle, the planar measuring areas may have any
arbitrary alignment to each other. For instance, they may be
aligned at an angle to each other. According to a preferred
embodiment, the measuring areas are disposed with surfaces parallel
to each other. This plane-parallel arrangement of planar measuring
areas serves in particular for the passage of the beam path through
the measuring areas without disturbing deflection of the light
beam.
[0043] In principle, the measuring areas may have different
alignments with respect to each other, for instance such that the
measuring areas occupy angles against each other in all the three
spatial axes. According to a preferred embodiment, the measuring
areas are disposed such that they cover up each other. Preferably,
the measuring areas are present on plane-parallel platelets in an
arrangement so as to cover up each other.
[0044] According to one embodiment, the distance of the measuring
areas from each other is 5 mm or less in the measuring position. At
the mentioned distance, many of the liquid samples to be examined
are held between the measuring areas due to capillary forces. The
distance is preferably 0.1 to 2 mm. Particularly preferred is a
distance of about 1 millimetre.
[0045] According to a method of the present invention for optically
examining small amounts of liquid, two drops of liquid are applied
to two preferably planar measuring areas, the drops are brought
into contact with each other by drawing the two measuring areas
near to each other, so that the drops coalesce into one single
drop, and this drop is subjected to an optical measurement.
[0046] By applying a reduced measurement volume to both measuring
areas, and the subsequent positioning or drawing together of the
areas, a volume reduction may be achieved. Namely, the added height
of two drops with half the volume is greater than the height of one
single drop with the whole volume. Thus, wetting both measuring
areas can be achieved with a smaller volume also.
[0047] According to a further variant, in a method of the present
invention for optically examining small amounts of liquid, two
measuring areas arranged in a distance from each other are
simultaneously wetted with a liquid sample, so that the drop is
spanned out between the measuring areas through its surface
tension, and this drop is subjected to an optical measurement.
[0048] This method of positioning the sample amount upon
simultaneous wetting of both measuring areas directly when the
sample is applied results also in a reduction of the necessary
amount of sample. A pipette may be used in order to position the
sample. Guiding the pipette point before and after the pipetting
process may favour this effect.
[0049] In all the variants of the present invention, safe and
handling-friendly positioning of drops can be facilitated by
guiding the pipette point when picking up and/or delivering the
liquid.
[0050] The cuvette of the present invention is preferably
dimensioned such that it fits into a standard cuvette shaft as a
standard cuvette. But it may also be made such that it fits into a
cuvette shaft of other conventional or future optical measuring
devices.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0051] In the drawings shows:
[0052] FIG. 1 a pincette with planar measuring areas at the free
ends and opened arms, in a perspective view slantwise from the
side;
[0053] FIG. 2 the same pincette with arms swung together, in the
same perspective view;
[0054] FIG. 3 an adapter with an accommodation for the pincette, in
a perspective view slantwise from the topside and from the
side;
[0055] FIG. 4 the same adapter with inserted pincette, in a
perspective X-ray image;
[0056] FIG. 5 a pipette point with planar measuring areas on the
lower end, in a perspective view slantwise from the downside and
from the side;
[0057] FIG. 6 an adapter with an accommodation and the pipette
point inserted therein, in a perspective view slantwise from the
topside and from the side;
[0058] FIG. 7 the pipette point being inserted into the adapter, in
a top view;
[0059] FIG. 8 the pipette point being inserted into the adapter, in
a side view;
[0060] FIG. 9 a slide with a planar measuring area, in a
perspective view slantwise from the topside and from the side;
[0061] FIG. 10 an adapter for accommodating two slides in the
opened condition, in a perspective view slantwise from the topside
and from the side;
[0062] FIG. 11 the adapter equipped with two slides in an unfolded
condition, in a perspective view slantwise from the downside and
from the side;
[0063] FIG. 12 the adapter equipped with the slides in the
collapsed condition, in a perspective view on two sides;
[0064] FIG. 13 an adapter equipped with insert parts having planar
measuring areas, the adapter parts being swung apart, in a
perspective view slantwise from the downside and from one side;
[0065] FIG. 13.1 a variant of the adapter with a recess for
inserting a pipette point with arms swung apart, in a perspective
view;
[0066] FIG. 14 the same adapter with adapter parts swung together
in the same perspective view;
[0067] FIG. 14.1 the same adapter with arms swung together in a
perspective view;
[0068] FIG. 14.2 the same adapter with arms swung together in a
side view;
[0069] FIG. 15 insert part with planar measuring area having
liquid-wetting and liquid-repellent zones, in a view slantwise
towards the planar measuring area and towards the side;
[0070] FIG. 16 the same insert part in a perspective view towards
the opposing planar outer side;
[0071] FIG. 17 planar measuring area with recess, in a longitudinal
section;
[0072] FIG. 18 planar measuring area with several overflow chambers
in a top view;
[0073] FIG. 19 planar measuring area with one overflow chamber in
the top view;
[0074] FIG. 20 planar measuring area with liquid-wetting centre
region and liquid-repellent border surfaces in a longitudinal
section;
[0075] FIG. 21 planar measuring areas with one drop put up there
before drawing the measuring areas together, in a longitudinal
section;
[0076] FIG. 22 the same measuring areas after drawing together, in
a longitudinal section;
[0077] FIG. 23 two planar measuring areas with two drops put up
there before drawing the measuring areas together, in a
longitudinal section;
[0078] FIG. 24 the same measuring area after drawing together, in a
longitudinal section;
[0079] FIG. 25 magnetic locking of two measuring areas in the
measuring position in a longitudinal section;
[0080] FIG. 26 cuvette with a capillary channel that is open
towards two sides, in a side view;
[0081] FIG. 27 the same cuvette in another side view;
[0082] FIG. 28 the same cuvette, in a perspective view slantwise
from two sides;
[0083] FIG. 29 an insert having plural measuring areas, the arms
being swung apart, in a perspective view;
[0084] FIG. 30 the same insert, put into an adapter, in a
perspective view.
DETAILED DESCRIPTION OF THE INVENTION
[0085] While this invention may be embodied in many different
forms, there are described in detail herein a specific preferred
embodiment of the invention. This description is an exemplification
of the principles of the invention and is not intended to limit the
invention to the particular embodiment illustrated
[0086] In the following, the designations "upside" and "downside"
refer to that orientation which the corresponding parts of the
device have when they are arranged in a cuvette shaft of a
photometer or spectrometer.
[0087] The cuvette shown in FIGS. 1 to 4 consists of at least two
parts.
[0088] A device 1 consists of two platelets 2, 3 with planar
measuring areas 4, 5 on the inner sides, and an adapter 6 for
positioning the device 1 in a conventional photometer, spectrometer
or the like.
[0089] In the example, the platelets 2, 3 of the device 1 are
arranged on the free arms 7, 8 of a pincette 9. In their lower
region, the arms 7, 8 are bevelled towards the platelets 2, 3. The
arms 7, 8 are preferably fixedly connected to each other on the
upper ends at 10. The arms 7, 8 can be elastically swung together.
Swinging the arms 7, 8 together is limited by the spacer parts 11,
12 arranged on the inner sides of the arms 7, 8 in the form of two
ribs running crosswise to the arms, preferably near to the
measuring areas.
[0090] The adapter 6 itself has the cuboid-shaped outline of a
standard cuvette. In its upper region, it is closed all around, and
at the bottom side it has four feet 14 to 17.
[0091] The adapter 6 has a cavity 18 in its interior, two parallel
guide rails 19, 20, 21, 22 for the pincette 9 being arranged in the
interior on each of two opposing side walls. The pincette 9 can be
inserted into the guiding mechanism formed by the guide rails 19 to
22 when the arms are swung together according to FIG. 2.
[0092] At the downside, the guide rails 19 to 22 are limited by
limitation walls 23, 24 inclined towards the inside, whose
inclination corresponds to the inclination of the bevels of the
arms 7, 8 of the pincette 9. At the inside, the limitation walls
23, 24 project from the side walls which bear the guide rails 19 to
22.
[0093] A box-like bottom part 25 is inserted onto the lower borders
of the limitation walls 23, 24. This part has passage openings 26,
27 on opposing front surfaces.
[0094] Thus, the construction of the adapter 6 corresponds
essentially to the cuvette according to the German patent DE 198 26
470 C1, U.S. Pat. No. 6,249,345, the disclosure of which is
incorporated herein by reference. The deviations from the known
constructions are that the inner sides of the side walls are
provided with the guide rails 19 to 22, and that the box-like
bottom part 25 has passage openings 26, 27.
[0095] The pincette 9 may be realised as a disposable item. The
adapter 6 may also be a disposable item or it may be re-usable.
Pincette 9 and adapter 6 are preferably made of plastics.
[0096] A small volume of the liquid to be analysed is positioned
between the optically transparent measuring areas 4, 5 of the
device 1. The adapter 6 serves to position subsequently the device
1 having the planar measuring areas 4, 5 in a vertical alignment
such in a cuvette shaft that it can be measured in a conventional
photometer or respectively spectrometer without further change of
the light path.
[0097] The pincette 9 may feature an introducing aid, which permits
a simple "filling" of the measuring areas 4, 5. In the opened
condition, the arms 7, 8 of the pincette stand towards other such,
that a sufficiently large space is provided for applying the
sample, for instance in the form of a drop, onto one of the planar
measuring areas 4, 5. By pushing together the two arms 7, 8, the
planar measuring areas 4, 5 on the ends of the arms 7, 8 are moved
towards each other, so that the drop wets both measuring areas 4,
5. In this, the planar measuring areas 4, 5 can be shaped and/or
coated such that the direction of spreading of the medium towards
the measurement direction is favoured, and that when it is
overdosed, it can escape only in one direction, for instance
towards the topside. By the two spacer parts 11, 12, preferably
situated near to the planar measuring areas 4, 5, the arms 7, 8 are
positioned such that a defined optical layer thickness between the
measuring areas 4, 5 is generated. Measurements with volumes from
one micro-litre up to several micro-litres can be realised in one
adapter 6 by means of different pincettes 9 having different layer
thicknesses.
[0098] In addition, the pincette 9 may contain a locking function
which permits the user to leave the pincette from his/her hand in
the closed state, in which the spacer parts 11, 12 sit close to
each other.
[0099] Furthermore, the pincette may contain alignment devices in
addition, which align the measuring areas 4, 5 in parallel.
[0100] In its closed condition, the pincette 9 is inserted into the
guide rails 19 to 22 of the adapter 6, until the bevels of the arms
7, 8 abut against the inclined limitation walls 23, 24 of the
adapter. In this position, the platelets 2, 3 are arranged
vertically in the adapter 6, and are directed towards the passage
openings 26, 27 with their outer sides. The pincette 9 can be kept
in the closed condition by the guide rails 19 to 22.
[0101] When the adapter 6 is arranged in the cuvette shaft of a
photometer or spectrometer, the passage openings 26, 27 are
arranged in the beam path of the measuring optics, so that the same
can be used for the optical measurement of the sample between the
measuring areas 4, 5.
[0102] The adapter 6 can be realised such that any leakage of the
liquid sample upon mistreatment, at shocks for instance, is
prevented. Moreover, it can have the features of a stop, by which
an universal utilisation not depending on the type of the
spectrometer is possible. The adapter 6 can be realised as a
disposable item like a cuvette, but replacement is necessary only
in the case of mistreatment.
[0103] The cuvette of FIGS. 5 to 8 is not subject matter of the
present invention, it is described only for illustrating the
claimed invention.
[0104] The cuvette according to FIGS. 5 to 8 consists of at least
two components, namely of a measurement point 28 and an adapter 29.
The measurement point 28 has an upper end with an upper opening 30,
by which it can be clamped onto a fastening neck of for instance a
currently marketed pipette. Further, it has a bottom end with a
bottom opening 31. This bottom opening 31 is limited by a device 1,
comprising two transparent platelets 2, 3 having planar and
preferably plane-parallel measuring areas 4, 5 at the inner sides.
The distance region between the platelets 2, 3 is laterally closed,
so that the distance region is open only on the bottom side at
31.
[0105] A continuous channel is formed in the measuring point 28
between the upper opening 30 and the lower opening 31. At the
outside, the measuring point 28 has a form that tapers from the
topside to the bottom side.
[0106] The adapter 29 is also box-like and matched to a standard
cuvette shaft. In the upper region 32, it is closed on the
circumference, and on the downside it has four feet 33 to 36. In
the interior, the adapter 29 has a cavity 37, in which an
accommodation 38 is arranged. The accommodation 38 is matched to
the outer contour of the measurement tip 28. At the inside, the
accommodation 38 is supported on the walls of the adapter 29 via
radially running ribs 39, 40, 41, 42.
[0107] The measuring point 28 can be put up onto a fastening neck
of e.g. an usual commercial pipette, like a conventional pipette
point, by way of which the medium to be measured can be sucked in
between the platelets 2, 3. In doing so, the medium wets the planar
measuring areas 4, 5. Measuring reservoirs of different magnitude
for measurements having volumes of less than one micro-litre up to
several micro-litres or different layer thicknesses, respectively,
can be realised in one cuvette by way of different measuring points
28 with different distances between the measuring areas 4, 5. In
embodiments for the measurement of very small volumes in
particular, the sample to be measured can be drawn between the
plates 2, 3 by the capillary forces already. Picking up the sample
with the aid of for instance a commercially available pipette is
then no more necessary.
[0108] The filled measuring point 28 is put into the adapter 29
with the aid of a pipette. The shape of the accommodation 38 is
matched to the shape of the measuring point 28, such that the
inserted measuring point is arranged with the platelets 2, 3 in the
free spaces between the feet 33 to 36. The cuvette 29 can then be
put into a cuvette shaft with the measuring point 28 being put in,
so that the light path of the optical measurement device runs
between opposing free spaces between the pairs of feet 33, 34 and
35, 36 and crosswise through the two platelets 2, 3 and the sample
situated therein. Picking up the sample is favoured by hydrophilic
surfaces.
[0109] The adapter 29 can be realised such that leakage of the
liquid to be measured upon wrong handling--at too strong a shock
for instance--is prevented. Furthermore, it can serve as a guiding
mechanism for the correct alignment of the planar measuring areas
4, 5 with respect to the measurement direction of the photometer.
Further, it may have the nature of a stop, by which a universal
utilization independent of the spectrometer's type is possible.
[0110] Measuring point 28 and adapter 29 can each be realised as
consumables. The measuring point 28 can be replaced after each
measurement. Replacement of the adapter 29 can be limited to cases
of wrong treatment.
[0111] The following two realisation examples comprise two
collapsible adapter parts, which are preferably captively connected
to each other via an articulation. In a collapsed condition, the
adapter parts form an adapter, with the dimensions of e.g. a
standard cuvette. The articulation may be attached on the short or
on the long side of the device. Swung apart, the sample to be
measured is applied to only one or to both measuring areas.
[0112] The cuvette according to FIGS. 9 to 12 comprises two
plate-shaped sample carriers ("slides") 43, 44 and an adapter 45.
The sample carriers 43, 44 are identical. The have an enlarged grip
and path stop 47 on the upper end of a strip-shaped centre part 46.
At the downside, the strip-shaped centre part 46 tapers conically
at 48. On the lower end, each of the slides 43, 44 has a platelet
2, 3 with the planar measuring area 4 respectively 5, preferably on
one side.
[0113] The adapter 45 comprises two adapter parts 49, 50, which are
articulatedly connected to each other via a film hinge 51. In a
collapsed condition, the adapter parts 49, 50 according to FIG. 12
form an adapter 45, whose form corresponds essentially to that of
the adapter 6 according to FIGS. 3 and 4. However, in difference to
the adapter 6, the adapter 45 has a complete guiding mechanism
consisting of four guide rails 52 to 55 and 56 to 59 in each one of
both adapter parts 49, 50.
[0114] The adapter 45 and the slides 43, 45 are preferably made of
plastics.
[0115] According to FIG. 11, two slides 43, 44 are inserted into
the guiding mechanisms 52 to 55 and 56 to 59, until the grip and
path stop 47 finds rest on the upper border of the two adapter
parts 49, 50. In this position, the platelets 2, 3 are disposed in
recesses between feet 60, 61 of the adapter part 49, and 62, 63 of
the adapter part 50. Further, a catch lock of the slides 43, 44
with the guiding mechanisms 52 to 55 and 56 to 59 can be
provided.
[0116] Then, one drop of the liquid to be measured is applied to
the planar measuring area 4. Thereafter, the two adapter parts 49,
50 are swung together, whereby the liquid comes into contact with
the measuring area 5.
[0117] The collapsed adapter parts 49, 50 are locked with each
other by way of a catching hook 64 having a catching recess 65 on
the adapter part 50, and a catching projection 66 on the adapter
part 49. In this, the catching hook 64 is pushed onto the catching
projection 66 with its catching recess 65. By actuating the
catching hook 64 in the opposite direction, the locking can be
released.
[0118] According to FIG. 12, the closed adapter 45 can be put into
a standard cuvette shaft, wherein the beam path of the optical
measuring device crosses the two platelets 2, 3 through the
recesses between the feet 60, 61 and 62, 63.
[0119] In the cuvette according to FIGS. 9 to 12, the arms or
respectively adapter parts 49, 50 are articulated to each other
along a long side. In the cuvette according to FIGS. 13 and 14, the
arms or respectively adapter parts 67, 68 have an articulated joint
69 along a transversal axis.
[0120] For this purpose, the adapter part 67 has a plate-shaped
base part 70, which has two bridges 71, 72 at its upper region on
one side at the outside. Bearing eyes 73, 74 of the revolution
joint 69 are arranged in the bridges 71, 72.
[0121] In principle, the adapter part 68 consists of a plate-shaped
carrier part 75, which is connected to one end of a connection arm
76, which carries a bearing block 77 at its other end. The bearing
block 77 is arranged between the legs 71, 72, an axis or shaft 78
being guided through a central passage bore of the bearing block 77
and being held in the bearing eyes 73, 74 on both ends.
[0122] The base part 70 and the carrier part 75 have passage
openings 79, 80, which are in true alignment with each other in the
collapsed condition of the adapter parts 67, 68. On the inner sides
of the passage openings 79, 80 sit plate-shaped insert parts 81, 82
with planar measuring areas 83, 84 on their inner sides.
[0123] Preferably, the base part 70 and the carrier part 75 each
have magnets 85, 86, 87 and 88 and 89, 90, 91 and 92, each inserted
in the inside, which sit pairwise close to each other in the
collapsed condition. Further, a centring pin 93 projects from the
base part 70, to which is associated a centring accommodation 94 of
the carrier part 75.
[0124] It is advantageous to adjust the distance between the
measuring areas 83, 84 via the magnet pairs in the manufacture of
the cuvette. This may for instance be achieved by setting the
magnets 85 to 92 into adhesive beds. These are allowed to harden
when the cuvette is in a closed condition, the correct alignment of
the magnets 85 to 92 being made sure by a locating piece that is
inserted between the measuring areas 83, 84. At option, the
adhesive bed of one magnet 85 to 92 at a time of each pair can be
hardened already before closing. In order to design the system
without remaining degrees of freedom, but not in an overdetermined
fashion, it is advantageous to use three pairs of magnets. In
addition, for the same reason it is advantageous to design the
revolution joint 69 of the cuvette floatingly, i.e. with clearance,
with respect to the axis vertical to the measuring areas 83,
94.
[0125] A sample can be applied to one or both planar border
surfaces 81, 82 in the opened condition of the adapter. After
collapsing the adapter parts 67, 68, the adapter is insertable into
a standard cuvette shaft. The light path of the optical measuring
device passes through the passage openings 79, 80, the transparent
platelets 81, 82 arranged behind them and the sample situated there
between.
[0126] The insert parts 81, 82 are for instance made of
UV-permeable quartz glass or UV-permeable plastics. As the case may
be, they are provided with a special surface structure.
[0127] The borders of the passage openings 80, 81 form stops, which
effect that the measuring light of the photometer or spectrometer
irradiates only through the sample. The adapter parts 67, 68 are
preferably made of plastics.
[0128] The adapter parts 67, 68 may be made of another material, of
metal for instance, in particular when they are destined for
re-use. In a further variant, the adapter parts 67, 68 may consist
of the same plastics like the insert parts 81, 92, and as the case
may be, they may be produced inseparably as one single injection
moulded object.
[0129] In particular, the cuvette can be made such that a gap
remains after collapsing it, via which the region between the
measuring areas 83, 84 can be inspected. This can be used in order
to fill the cuvette in its closed condition. In order to facilitate
filling, the gap can be enlarged with a recess in the direction
towards the measuring areas.
[0130] Another variant, which permits to fill the cuvette in the
closed condition, is shown in FIGS. 13.1, 14.1 and 14.2. When
filling the cuvette in the closed condition, both measuring areas
83, 84 are wetted at the same time. This has the advantage that a
smaller volume is needed in order to produce a liquid bridge
between the measuring areas 83, 84. Besides to this, the
evaporation of the sample during the handling can be prevented by
doing so.
[0131] In FIGS. 13.1, 14.1 and 14.2, those elements that correspond
to elements of the embodiment of FIGS. 13 and 14 are designated
with the same reference signs, but which are indicated by a
superscripted dash (').
[0132] In order to fill it in the closed condition with the aid of
a pipette, the embodiment of FIGS. 13.1, 14.1 and 14.2 has a recess
125 in the arm 67 which extends on the free end of the arm 67' from
out its outer side 126 up to the measuring area 83'. The slot-like
recess 125 is shaped and dimensioned such that the lower end of the
pipette point 127 fits into it and is laterally guided therein.
Further, the insert part 81' is arranged somewhat nearer to the
revolution joint 69' than the insert part 82', so that the sample
can be metered directly onto the measuring area 84' and into the
interstice between the measuring areas 83', 84' by way of the
pipette point 127.
[0133] In this embodiment, the insert parts 81, 82' are made
strip-shaped and detachably or fixedly connected to the arms 67',
68'. The revolution joint 69' is made as a floating hinge, for
instance by arranging the axle or shaft 78' either in a passage
opening with oversize of the bearing block 77' and pressing it into
the bearing eyes 73', 74', or by pressing it into the passage bore
and arranging it in the bearing eyes 73', 74' that have oversize.
Further, this embodiment has three pairs of magnets 85', 86' and
87' and 89', 90' and 91' for locking the arms 67', 68' in the
measuring position.
[0134] According to FIGS. 15 and 16, the optically transparent
measuring areas 83, 84 are realised so as to have a central
liquid-wetting surface portion 95, around which there is a
liquid-repellent surface portion 96. The liquid-wetting and
liquid-repellent properties of the regions 95, 96 can be produced
by coatings. Between the two surface portions 95, 96 there is no
mechanical edge which would disturb when the measuring areas 83, 84
are being cleaned. The measuring areas 83, 84 are cleaned starting
from the surface portion 95 and towards the surface portion 96, so
that no residual contaminations remain in the central surface
portion 95.
[0135] A light-permeable surface portion 97 corresponds to the
liquid-wetting surface portion 95, and a light-impermeable surface
portion 98 on the outer side of the insert part 83, 84 corresponds
to the liquid-repellent surface portion.
[0136] The surface portions 95, 96 limit the spreading of the
liquid sample on the measuring areas 83, 84. On the
liquid-repellent respectively hydrophobic surface portion, the drop
of liquid has a great contact angle point. Due to this, it projects
far above the measuring areas 83, 84. However, in the
liquid-wetting respectively hydrophilic surface portion 95, the
drop is retained or anchored, respectively. Due to this, there
arise no flat, but approximately semi-globular drops of liquid, so
that when collapsing the adapter parts 67, 68, a drop that is
applied to a measuring area 83 or 84 securely wets the other
measuring area 84, 83, or other drops applied to both measuring
areas 83, 84 securely unite with each other. As a consequence,
there arises a defined column of liquid, and through this a defined
measurement path or layer thickness, respectively.
[0137] The platelets 2, 3 of the remaining realisation examples can
be realised correspondingly on the measuring areas 4, 5 and the
outer sides.
[0138] In the realisation example according to FIGS. 17 to 20,
differently shaped deepenings 99, 100, 101, 102 are arranged in the
measuring areas 83, 84. The deepenings 99 to 102 accommodate
samples and limit the spreading thereof on the measuring areas 83,
84. According to FIGS. 18 and 19, excess amount of sample can
escape into reservoirs 104 via radial channels 103, or into an
overflow chamber 106 via an overflow edge 105. In the realisation
example of FIG. 20, the deepening 102 is conically enlarged towards
the outside. In addition, the border surface 107 that limits the
extension can be liquid-repellent, and the base surface 108
liquid-wetting, so that the drop projects from the measuring area
83, 84 as far as possible.
[0139] In order to limit the drop spreading, a planar pedestal
having a small surface area can also be arranged on the measuring
area 83, 84. The planar pedestal prevents the spreading of the drop
due to its surface tension. This results in an increase of the drop
height, and a reduction of the necessary amount of sample can be
achieved.
[0140] The form of the measuring areas according to FIGS. 17 to 20
or with a pedestal can be realised in all embodiments.
[0141] According to FIGS. 21 and 22, the thickness of the layer
between the two measuring areas 4, 5 can be defined by a spacer
ring 109. A stop 110 is applied as a coating on the outer side of
the platelet 3.
[0142] In this example, a drop is applied only to measuring area 5,
which wets the measuring area 4 upon close contact with the spacer
ring 9.
[0143] In the realisation example according to FIGS. 23 and 24,
spacer rings 111, 112 are assigned to both measuring areas 4, 5,
which come into contact with each other when the device is closed.
In this example, the layer thickness is defined by both spacer
rings 111, 112. Further shown is the application of drops onto both
measuring areas 4, 5, which coalesce when the device 1 is
closed.
[0144] The realisation example of FIG. 25 differs from that
according to FIGS. 21 and 22 in that the defined layer thickness is
preferably ensured by magnetic forces from magnets 113, 114, 115,
116, whose unlike poles are arranged in a short distance from each
other when the device 1 is closed. The magnets 113 to 116 are
integrated into device components (for instance adapter parts 67,
68) of the cuvette, which accommodate the inserts 2, 3.
[0145] In order to ensure the plane-parallel alignment of the
measuring areas 4, 5, a hinge 69 that is formed between the device
components 67, 68 can be made to float, so that the system is not
geometrically overdetermined. In the closed condition, the sample
to be measured is positioned definedly, safely and stably in the
collapsible cuvette which has two adapter parts 67, 68.
[0146] A further embodiment of the present invention represents
magazining of the single-use items and is not shown in detail. From
an easy to handle magazine, preferably in the form of a cartridge,
the inserts 2, 3 for single-use can be inserted easily into the
openings of a re-usable collapsible cuvette which are provided for
this purpose. After use, the single-use inserts 2, 3 are pushed out
of the collapsible adapter by hand or by way of a device or by way
of a lug on the cartridge, and then thrown away. New inserts 2, 3
may then be inserted again.
[0147] The single-use items can also be combined with adapters that
are realised as single-use items. Further possible is a combined
single-use item with front and rear part from one tool, as the case
may be also as a so-called two component injection moulded
article.
[0148] The cuvette of FIGS. 26 to 28 is not subject matter of this
application. It is described only for the sake of illustration of
the claimed invention.
[0149] The cuvette according to FIGS. 26 to 28 corresponds to a
great extent to the cuvette according to the realisation example of
DE 198 26 470 C1, which is incorporated by reference. However, in
difference to the known cuvette, the box-like bottom part 121,
arranged between the four feet 117, 118, 119, 120, is not opened at
the inside towards a cavity of the cuvette, but is closed instead.
Further, a channel 122, open towards both sides, runs through this
bottom part 121, which has funnel-shaped expansions 123, 124
towards both outer sides.
[0150] The cuvette has the shape of a commercially available
cuvette, so that it can be put into a conventional commercial
photometer or spectrometer, respectively.
[0151] Crossing the channel 122 which is open on both sides,
optical measurements can be performed. Through this, no light is
guided through a plastics wall of the cuvette during the
measurement, and thus, the measurement is not influenced. It is not
necessary to measure a value for each empty cuvette.
[0152] The channel 122 tapers conically towards the outer sides of
the cuvette, so that an overdosage results only in a marginal
increase of the optical layer thickness. As a side effect, the
cuvette receives a filling aid through this. A pipette point can be
put on the expansions 123, 124 and the channel 122 be filled in
this way, until the liquid reaches from the boarder between the
conical and the cylindrical region of the channel 122. Now, the
liquid completely fills the channel 122 and is held therein by
adhesion or capillary action, respectively.
[0153] The conical expansions 123 can be made rough, on the one
hand for achieving the stop effect, and on the other hand in order
to avoid leaking of the liquid upon wrong handling. In addition to
this, a trough can then be provided below the channel 122, which
can receive the liquid that leaks out. As the channel 122 is
significantly shorter than the overall width of the cuvette, the
liquid can fall down only into this trough.
[0154] In the realisation example of FIGS. 29 and 30, elements that
correspond to elements of the realisation example of FIGS. 1 to 4
are provided with the same reference numerals, but in addition
marked by a superscripted dash (').
[0155] The insert 1' is also realised in the kind of a pincette,
wherein however, the arms 7', 8' are connected to each other on
their upper ends by a film hinge 128. Each strip-shaped arm 7', 8'
has a shoulder 129, 130 or respectively a flattening at one end, in
which the measuring areas 4', 5' are arranged. Each of these
measuring areas 4', 5' has a group (6 in the example) of circular
area portions 131, 132 for receiving sample liquid. One pair at a
time of the area portions 131, 132 faces each other, so that it
overlaps when the arms 7', 8' are swung together.
[0156] The area portions 131, 132 can be delimited from the rest of
the measuring areas 4', 5' in that they are arranged deeper in
little deepenings.
[0157] According to another embodiment, the area portions 131, 132
are arranged in deepenings and the area portions and the further
area portions 133, 134 of the measuring areas 4', 5' which surround
them have a hydrophobic coating. According to another embodiment,
in which the area portions 131, 132 are not arranged in deepenings,
the area portions 131, 132 have a hydrophilic coating, so that the
samples are held thereon. According to another embodiment, in which
the area portions are not arranged in deepenings, the further area
portions 133, 134 of the measuring areas 4', 5' that surround them
and which should not receive sample, have a hydrophobic coating.
According to another embodiment, in which the area portions are not
arranged in deepenings, the area portions 131, 132 have a
hydrophilic coating and the further area portions 133, 134 that
surround them have a hydrophobic coating.
[0158] When the arms 7', 8' are swung together, samples put on the
area portions 131, 132 of the measuring areas 4', 5' are spanned up
between the same.
[0159] Further, the arms 7', 8' each have a group of parallel
grooves 135, 136 at the outer sides, which extend crosswise to
their longitudinal axis. The grooves 135, 136 are disposed near to
the free ends of the arms 7', 8'. In the example, the grooves 135,
136 on the different arms 7', 8' are disposed at equal distances
from the free ends of the arms 7', 8'. In another embodiment, which
is not shown, the grooves 135, 136 on the different arms 7', 8' are
disposed at different heights. In still another embodiment, which
is not shown, only one of the arms 7', 8' has grooves 135 or 136,
respectively.
[0160] The insert 1' is made in one piece of plastics. Due to the
elasticity of the film hinge 128, it takes on the configuration of
FIG. 29 automatically.
[0161] The adapter 6' has the cuboid outline of a standard cuvette.
It is essentially cuboid. It has an accommodation 137 with
rectangular cross section, into which the insert 1' can be put in
from the topside when the arms 7', 8' are swung together. An
elastically acting projection 148 of the adapter 6' engages into
the accommodation 137, which engages into one of the grooves 135 or
136 of the inserted insert 1'. Through this, the insert 1' is
caught in the accommodation 137 in a height position.
[0162] The elastic catching projection 138 is realised as a small
wheel, which is rotatably mounted at the end of a spring tongue
139. The spring tongue 139 is disposed in a longitudinal slot 140
of a side wall 141 of the adapter 6; and fixed at the lower end by
way of a screw 142. As a consequence, the spring tongue 139 can be
deflected within the longitudinal slot 140. The spring tongue 139
is deflected when the catching projection 138, realised as a small
wheel, rolls over the outer side of an arm 7', 8'. Finally, the
catching projection 138 falls into one of the grooves 135, 136, and
through this, the insert 1' is fixed in the adapter 6' at a certain
height.
[0163] On opposing side walls 141, 142, the adapter 6' has passage
openings 26', 27' for the beam path of an optical measuring device.
The passage openings 26', 27' are arranged in the lower third of
the side walls 141, 142, approximately on the centre axis of the
same.
[0164] In the catching position shown in FIG. 30, the area portions
131, 132, which are situated in FIG. 29 at the right downside on
the measuring areas 4', 5' on the arms 7', 8', are arranged exactly
between the passage openings 26', 27'. When the adapter 6' with the
insert 1' is put into a cuvette shaft in this catching position, a
sample can be measured between these area portions 131, 132 of the
measuring areas 4', 5'. In the next deeper catching position, that
sample moves into the beam path which is situated between the
middle area portions 131, 132 of the right row, and so forth.
[0165] By pulling out the insert 1' from the accommodation 137,
turning it about 180.degree. around its longitudinal axis and
putting it into the accommodation 137 anew, the samples between the
area portions 131, 132, which are situated on the measuring areas
4', 5' on the arms 7', 8' in the left row at the downside in FIG.
29, can be brought into the beam path.
[0166] In another embodiment, filling the insert 1' when the arms
7', 8' are swung together is favoured in that the arms 7', 8' have
small openings or respectively guiding mechanisms for a pipette on
the two lateral borders of the measuring areas 4', 5', which extend
from the lateral borders to the area portions 131, 132. A pipette
point can be put into the openings or respectively guiding
mechanisms, so that samples can be applied to the area portions
131, 132 of the collapsed measuring areas 4', 5' by way of a
pipette.
[0167] The described realisation examples serve for illustrating
the invention. However, the present invention is not limited to the
realisation examples.
[0168] This completes the description of the preferred and
alternate embodiments of the invention. Those skilled in the art
may recognize other equivalents to the specific embodiment
described herein which equivalents are intended to be encompassed
by the claims attached hereto.
* * * * *