WO2009068749A2

WO2009068749A2 - Apparatus and method for preparing sample analysis

Info

Publication number: WO2009068749A2
Application number: PCT/FI2008/050691
Authority: WO
Inventors: Vesa Erkkilä; Ari-Pekka Kitinoja; Jesse Mattila; Heimo Soitamo
Original assignee: Wallac Oy
Current assignee: Wallac Oy
Priority date: 2007-11-30
Filing date: 2008-11-27
Publication date: 2009-06-04
Anticipated expiration: 2010-05-30
Also published as: WO2009068749A3; FI20075863A0

Abstract

The invention relates to an apparatus for handling sample carriers containing one or more biological samples impregnated therein. The apparatus comprises a holder adapted to receive a sample carrier, and cutting tool for cutting a sample-containing portion of the sample carrier supported by the holder. According to the invention, the cutting tool is adapted to direct to the sample carrier a localized cutting impact, such as laser beam or a water jet, which is moved on the surface of the sample carrier for detaching from the sample carrier said sample-containing portion. The invention offers a flexible, noiseless and dustless way of cutting samples for example for neonatal screening.

Description

Apparatus and Method for Preparing Sample Analysis

Background of the Invention

Field of the Invention

The invention relates to handling of sample carriers containing biological samples. In particular, the invention pertains to an apparatus for cutting fractions of sheets carrying biological materials. The fractions can thereafter be conveyed to further processing, such as analysis of the biological samples. Furthermore, the invention concerns a method for cutting sample-containing fractions from sample carriers.

Description of Related Art

Punching tools are used in analytical sciences and industry, for example, for carrying out neonatal screening. Such screening can be carried out, for example, using DELFIA system by PerkinElmer.

Conventional punching tools for taking biological samples comprise a punch and a die provided with a punching channel for conveying the sample from the upper surface of the die towards the lower end of the die. Such an instrument can be used to punch blood samples, saliva samples, tissue fluid samples and other body fluid samples. The samples are containedin a planar sheet made of fibrous material, from which several samples with a small diameter can be taken. The diameter of the sample typically ranges from 0.8 to 6.0 mm. The shape of the samples is generally circular. The sample is transferred from the instrument to a small vessel placed beneath it, when the sample has successfully been punched from the sheet. The vessel is a small cup that can easily be delivered to the laboratory where the sample will be analysed. WO 2006/0056658 describes an example of known punching tools.

Known mechanical punching tools have disadvantages. First, the size and shape of the cut portions are dictated by the punch and the die, whose cross-section profile is chosen to accommodate a predetermined amount of substance upon inspection. However, this causes waste since the cutting geometry cannot be freely adjusted to match the shape of the original (or remaining) sample area. Second, conventional technology causes operation failures because mechanical punching causes static electricity to be accumulated to the sample fractions, which impedes the descent of cut portions into receptive wells. Indeed, the forces caused by the static electricity are of the same order of magnitude than gravity. Third, the considerable size required by the mechanics of the punching tool incurs design limitations for the punching apparatus and additional expenses due to space consumed as well as manufacturing and shipping costs. Fourth, conventional punching produces excess operating noise, which may peak up to 75 dB as well as excess dust and residual fibre particles resulting in additional maintenance needs and failures in operation.

WO 01/31317 discloses a punching apparatus including a mechanical punching assembly or a non-mechanical CCh-laser-based punching assembly for samples which are deposited on a substrate. No further details of non-mechanical punching assembly or the punching process are given. US 2004/0077032 discloses a contactless cutting apparatus for biological tissue.

Summary of the Invention

The aim of the present invention is to achieve an improved apparatus and method for effectively extracting portions of absorbent sheets including biological samples, in particular blood. In particular, it is an aim of the invention to achieve an apparatus and method by means of which at least some of the negative side effects of conventional punching technology are avoided.

The invention is based on the concept of applying a localized cutting impact to the sample- containing sheet as opposed to one-shot punching. The localized impact is moved with respect to the sheet along its surface such that the desired fraction is detached or easily detachable from the remaining sheet. That is, the outline of the fraction is "drawn" to the sheet, for example, using a spatially controllable radiation or material stream having the ability to mechanically separate elementary parts of the sheet from each other in order to form said fraction.

In particular, the invention can be realized by exposing the absorbent sheet carrying the sample of biological matter to a cutting material jet or radiation beam. While cutting, it is assured that the sheet remains correctly positioned during the cutting process by keeping the sheet in a suitable holder. The cutting can be achieved using a high-pressure material jet, such as a liquid stream, or a radiation beam, such as a laser beam. The apparatus according to the invention comprises means for cutting away a sample- containing portion from a sample carrier containing a biological sample impregnated therein, so that a localized cutting impact is directed to the sample resulting in a detached or easily detachable sample portion. According to one embodiment of the invention, the localised cutting impact is produced by using a radiation source, such as a laser source. In particular, the laser source can be a diode laser, CCh-laser or a fibre laser. According to another embodiment, the localised cutting impact is achieved using a nozzle capable of spouting a high-pressure fluid jet, typically a liquid jet, in particular a water jet. The device may further comprise means for taking the detached sample portion into a receiving recess, typically a sample well of a microtiter plate or the like, for analysis of the biological sample.

In the method according to the invention, a sample-containing portion is cut from a sample carrier containing a biological sample impregnated therein by directing a localised cutting impact to the sample carrier resulting in a detached sample portion. According to one embodiment of the invention, a radiation beam is used for achieving the localised cutting impact. According to another embodiment, the localised cutting impact is achieved by subjecting the sample carrier to a high-pressure fluid jet, the fluid being typically liquid, water in particular. The term "water" is described to include all aqueous solutions such as assay buffers.

The present invention provides substantial advantages compared to conventional ways of cutting sample sheets. One of the main advantages of applying the present cutting method and apparatus to cutting absorbent sheets is that the form of the sample fraction to be cut can be freely chosen, even during the cutting process, for example, to match the geometry of the sample area on the sample carrier. Secondly, cutting jet and beam devices can be manufactured to be relatively small in size and thus take up less valuable space in operational areas and are less expensive to transport. Thirdly, they present functional advantages by not exposing the sheet to a conventional cutting blade, which produces less disruptive static electricity, dust and fibre particles that would otherwise compromise product quality. Avoided quality issues include impaired integrity of executed analyses due to dust and fibre particles as well as the cut samples not landing successfully into corresponding receptive wells because of static electricity accumulated on the fraction cut. Also because the sheet needs not be subjected to a typically vociferous punch-like tool, the noise level is reduced. At least laser and liquid jet "punchers" produce virtually no noise, which has an improving effect on the working environment of operators. Fourthly, the present invention is advantageous in terms of costs, since it can be manufactured using relatively inexpensive components and with its ability to produce samples of optimal shape and size, it produces little waste (this is illustrated later with reference to Fig. 4 and Fig. 5). Because of the disk shape optimization, also the sample donor comfort can be increased, as fewer or smaller samples need to be collected.

According to one embodiment, the laser source is a diode laser. It is generally known that diode lasers can not be used for cutting paper because of paper does not absorb diode laser wavelengths (900 - 1500 nm). However, the inventors have found that such wavelength are well absorbed by blood-impregnated paper, for example, and thus diode lasers and other lasers operating at the window of low absorbance of paper (about 700 - 2500 nm) are suitable to be used within the present invention.

By "sample carriers" we mean mainly planar substrates, which have substantial porosity so as to be able to be impregnated by a wet sample, in particular blood. In particular, the sample carrier can be a sheet comprising or consisting essentially of fibres that are bound together so as to form a thin substrate. Sample sheets used also in conventional punching for the purposes of, for example, neonatal screening (that is, so called Guthrie cards and the like, e.g., a guanidine thiocyanate-impregnated filter paper (GT-903)) are found to be suitable to be used in connection with the present method and apparatus. Such sample sheets are typically in the form of cards, which contain a plurality of sample-receiving zones in the form of pre-printed regions in the cards. The sample carrier lies typically during cutting in a plane, but it may be bent and/or folded as well.

The term "biological sample" is used to describe all kinds of biological fluids, including bodily fluids such as blood and DNA samples in particular. The term "impregnated" in this context means that the sample in question has been introduced to the receptive sample carrier in such a way that the sample has partially or entirely adhered to pores of the sample carrier. Typically, the sample is impregnated entirely into a fibrous sheet. "Localized cutting impact" means any kind of relatively small-sized physical interaction capable of breaking the structure of the sample carrier at local level, such that a fraction of desired shape can be separated from the remaining sample carrier. In particular, the width of the kerf resulting from the cutting is less than 0.5 mm, in particular less than 0.3 mm. According to one embodiment, the cutting impact is based on the local increase in temperature (that is, the "burning" effect) achieved by a laser beam directed to a fibrous sample carrier. According to another embodiment, the cutting impact is based on the capability of high-speed fluid particles to break bonds in a fibrous sample carrier at a micro-level because of collisions taking place in the sample carrier. According to a further embodiment, the instantaneous area of influence of the cutting impact is point-like, that is, substantially circular in cross section. The diameter of the circle is typically less than 0.5 mm, in particular less than 0.3 mm.

The terms "sample-containing portion" and "sample fraction" are used to describe a part of the sample carrier whose shape and size are determined by the trajectory of the moving cutting impact. In detail, the above mentioned terms refer to those particular parts of the sample desired to be detached or samples that have been or are being detached from the sample carrier for being later introduced into a microplates or the like. In particular, the present invention relates to sample fractions, which can be fitted into a 96- or 384-well SBS standard microtiter plates.

The term "sample carrier holder" is used to describe any means capable of holding the sample carrier at a cutting zone in a desired position with respect to the cutting means during the cutting process. The sample holder can be, for example, simply a frame or plate on which the sample carrier rests or it may comprise grabbing means for providing a firm hold of the carrier. The sample holder may also serve so as to transport the sample carrier in and out of the cutting zone before and after cutting, respectively.

Next, the embodiments of the present invention are described more closely with reference to the attached drawings.

Brief Description of the Drawings

Fig. 1 shows a schematic view of an apparatus according to one embodiment of the invention.

Fig. 2 shows a schematic view of an apparatus according to one embodiment of the invention.

Fig. 3 shows a schematic view of an apparatus according to one embodiment of the invention.

Fig. 4 shows a conventional punching geometry. Fig. 5 shows an optimized punching geometry achievable by the present invention.

Fig. 6 shows in a schematic view a cutting arrangement comprising an underpressure grabber according to one embodiment of the invention.

Detailed Description of the Invention

As illustrated by Fig. 1, according to one embodiment of the invention, a sample sheetlβ impregnated with a biological sample 11 is fixed to a supporting holder 17 during a cutting process carried out with a cutting laser beam 15 produced by a laser source 14. During said cutting process the cutting means produces a kerf 12 of a desired shape into sample carrier.

The shape of the kerf 12 can be selected to be optimal in terms of wasted sample material, which in one embodiment of the invention is a pentagonal, hexagonal, or octagonal shape (or a shape of higher order), in particular a hexagonal shape. This is particularly advantageous in the usual case of substantially circular sample regions (the natural form of impregnated blood drop samples). Other possible shapes include, for example, circular, elliptical, triangular and rectangular shapes. According to one embodiment, the apparatus includes means, such as a camera or scanner and a computing unit connected thereto, for detecting the shape of the usable sample area and means for calculating the optimal shape of the kerf 12 such that sample waste is minimized. The shape can vary from one "punch" to another.

The desired shape of the kerf 12 is accomplished by temporally changing the optical pathway of the laser beam 15 while the beam is switched on. Thus, the trajectory of the laser beam 15 in the lateral plane of the sample sheet 16 forms the kerf 12. The aiming of the laser beam 15 can carried out by moving or tilting the laser source 14 to point to the desired direction.

Fig. 2 shows a modified embodiment in which a laser beam 23 is guided to a sample sheet 27 by means of an optical fibre 26 comprising an input end attached to the laser source 25 and an output end in the vicinity of the sample sheet 27. The desired shape of the kerf 22 is accomplished by moving the output end of the optical fibre 26 in such a way that the aimed positions of the laser beam 23 result in a path producing the desired cutting profile, that is, the trajectory of the laser beam 23 is changed. The movement may comprise translation of the output end of the fibre 26 such that the angle of the beam 23 is not changed or by tilting the output end of the fibre 26. This way the laser apparatus 25 would not be repositioned at all, but instead the adjustable fibre 26, being more easily manoeuvrable, is aimed according to the above-mentioned scheme.

As illustrated by Fig. 3, according to a further modified embodiment of the invention, the desired kerf shape is accomplished by using other types of adjustable optics, such as a lens 35 or a plurality of lenses. Instead of or in addition to a lens or lenses, also a mirror, a prism or the like passive optical components may be utilized. The light-guiding arrangements shortly discussed above and shown in Figs. 1 - 3 can also be combined.

As also illustrated by Fig. 3, the desired kerf shape can be accomplished by moving the sample sheet in the plane of the sheet with respect to the radiation source. That is, the holder of the sample sheet is movable. Effectively the same result is achieved by moving the laser source parallel to the plane of the sample sheet.

The mechanics relating to the abovementioned optical arrangements can be implemented by means known in the art per se.

The laser source can be a semiconductor laser, such as a diode laser, because of their inherently small size, although fiber or gas lasers, for example, can be also used. In this application, the main criteria for the optical arrangement are the cutting speed and kerf width. The cutting speed is typically higher than 2, normally higher than 5, in particular higher than 10 sample fractions / second. The kerf width is typically less than 500 μm, in particular less than 200 μm, even less than 100 μm. We have discovered that speed of moving the laser beam on the sample affects the kerf width to some extent. That is, higher cutting speeds generally lead to narrower kerf widths and thus have an improving effect on cut quality, too. Typically, the laser beam is moved on the surface of the sample sheet at a velocity of 10 - 100 mm/s, depending mainly on the laser power, and desired kerf width.

Also, we have surprisingly discovered that sample sheets having a body fluid, in particular blood, absorbed therein can be more easily cut using laser radiation than clean sample sheets. A clean sheet has a window of very low absorption factor at wavelengths of about 700 - 2500 nm. This is, low-speed cutting or substantially no cutting takes place at this wavelength range using conceivable laser powers. Unfortunately, diode lasers, which otherwise are very suitable for cutting sample sheets, generally emit radiation at a wavelength range of 900 - 1500 nm. However, according to our discovery, body fluids impregnated into the sheet can significantly increase the absorption factor of the sheet. In particular, a bloodstained paper exhibits very good properties in this respect. Consequently, considerably greater cutting speeds and narrower kerf widths are achieved with bloodstained paper than with clean sample sheets.

According to one embodiment of the invention, a laser wavelength of 700 - 2500 nm, in particular 900 - 1500 nm is used.

There is typically provided a focusing lens having its focal point approximately at the plane of the sample sheet for maximizing the local radiation exposure of the sheet. Normally the laser beam is directed to the sheet essentially perpendicular to the sheet, but also tilted configurations can be used.

The power and beam width of the laser are chosen so as to promote cutting quality. The required power of the laser depends on the wavelength and desired cutting speed. Typically the laser power is more than 300 W/mm², in particular more than 600 W/mm². There is no fundamental upper limit for the power.

For maximum performance, the sheet should be positioned with respect to laser optics at a suitable distance. The alteration in the suitable distance is called the positioning tolerance (dtoi). The positioning tolerance depends mainly on the focusing optics of the laser beam and on the sheet thickness (dsheet). The most typical working area is 0.5 dsheet ≤ dtoi ≤ 4 d_sheet, in particular 2 d_sheet ≤ d_toi ≤ 4 d_sheet- The positioning tolerance is typically lower than the kerf width.

As shortly mentioned above, instead of using a laser beam, the localized cutting impact may be produced by using a nozzle capable of spouting a high-pressure water jet, for example, to the sample sheet. The jet is very thin in cross section and moved along a suitable path by steering the nozzle or by moving the sample carrier along a corresponding path. Thus, the basic principle is the same as described above with reference to the laser-based cutting while the mechanism of cutting is different. By using a water jet, the quality of the kerf is comparable to that of achievable by laser. Because the flow-through of water can be kept extremely low and its impact time very short, no adverse wetting of the sample fraction takes place. The rest of the apparatus is designed water jet -compliant, for example, by means of appropriate shieldings in the vicinity of the cutting zone and a waste water collector.

After cutting, the sample fraction is conveyed to a cavity, in which sample analysis can be carried out. The cavity typically is contained in a sample-receiving plate comprising several such cavities and thus being suitable for multi-sample analysis. Typically the sample- receiving plate is a microtiter plate. The apparatus typically has a space for accommodating one or more such plates and has necessary equipment for the detached sample-containing portions to be conveyed one after another to the cavities of the sample-receiving plate. Alternatively, the sample can be conveyed directly into a suitable sample analyser for immediate sample analysis.

According to one embodiment, the conveying of the sample portions to the analysis cavities is a purely gravitational process. That is, during the cutting, the cavity is aligned with the sample fraction, which, after being cut, simply falls into the cavity. Conventional punchers exhibit problems at this stage because of the static electricity caused by conventional punching and the resulting sticking of the sample fraction to walls of the cavity. The "punching" schemes discussed herein, are, however, free of accumulation of static electricity, whereby the sample fraction falls more reliably to the bottom of the cavity.

According to another embodiment, there is provided a positioning device (denoted with reference numerals 10, 20, 30 in Figs. 1 - 3, respectively) for handling the sample fraction during or after the cutting process. The positioning device may comprise suction means which, by means of underpressure, grabs to the surface of the sample fraction and has the capability of holding and moving the sample fraction in grabbed state. The sample fraction can be released by interrupting the suction or by mechanically shoving the sample fraction.

As illustrated in Fig. 4, the shape of the detached portion has previously been dictated by the shape of the puncher, which has resulted in circular portions and thus wasted sample material. Since the cutting method of the present invention allows practically all cutting profiles, the cut portion may have a hexagonal shape, as illustrated in Fig. 5. One should note that when favouring near optimal shapes as the so-called honeycomb shape, less material is wasted compared to, say, a circular shape (Fig. 4). The shape and/or size of the cut portions can also be determined individually for each sample area and/or sample sheet and/or assay, whereby the apparatus comprises suitable means, such as a controller of the cutting tool, adapted to allow modifying the shape and/or size of the sample-containing portion to be detached from the sample carrier. These means may be functionally connected with the sample shape detection means in order to allow efficient on-line determination of the size and/or shape.

With reference to Fig. 6 the suction means may comprise an elongated suction head 66, which has a small-area suction tip. Naturally the footprint of tip must be smaller than that of the sample portion to allow the laser to have undisturbed access to perform the desired cutting process. The suction head is movable in one, two or three dimensions and is controllable so as to transport the sample fraction to the sample cavity after being detached from the sample sheet. In Fig. 6, the sample sheet is denoted with reference numeral 60, the sample fraction to be cut with reference numeral 62 and the laser beam with reference numeral 64.

The suction means typically comprises a control unit and a controllable pump capable of causing the underpressure at a tip of the suction head. According to one embodiment, the suction means comprises also pressure sensor coupled to the control unit of the suction means. The pressure sensor can be used for detecting when the suction head in close to or at the surface of the sample sheet, which shows as a pressure change. That is, both the grabbing and conveying stages can be carried out reliably. There may be a feedback connection in the system causing the amount and timing of applied pressure to be altered based on the pressure detected, if necessary.

The underpressure grabber described above has many advantages. It assists in taking the sample fraction to its destination, whether a well of a microplate or an analysis spot of a sample analyser, reliably, without any uncertainties related to purely gravitational mechanism traditionally used. In addition, it offers for more flexible analysis schemes, as there are no strict restrictions as to the placement of the sample fraction. Moreover, the sample sheet can be kept even in non-horizontal positions, unlike when using traditional sample sheet handlers and punchers.

Although disclosed herein in connection with the localized-impact cutting, the underpressure grabber described above can be used also in connection with traditional mechanical punchers. According to one embodiment, the apparatus comprises further comprises automated sample sheet handling equipment. Such equipment comprises a container capable of accommodating a plurality of sample sheets. The sample sheets may be arranged in a stack in the container. Further, the device comprises means for feeding the sample carriers successively, that is, one by one, to said sample carrier holder. That is, the "punching" of several sample sheets may be fully automated. The automated sample sheet handling equipment is typically may be used in combination with automated microplate handling equipment, too.

Experimental section

In order to study if the disclosed method is suitable for practical use, a measurement was set up. More specifically, it was an aim to find out whether analytes contained in the samples to be analysed (in this case, the thyroid stimulating hormone (TSH) analyte) withstand the thermal strain caused by laser-aided punching. In the experiment, samples were cut from sample cards and subjected to DELFIA Neonatal hTSH assay.

In the experiment, control samples whose analyte concentration was known, were used. Therefore, the signal level of the analysis device with respect to analyte concentration was known. Same measurements were made for conventionally punched and laser-punched sample discs.

Below, the reagents, instruments and protocol used in the experiment are listed:

Reagents:

1) Neo-hTSH Assay Buffer, 13801043, lot 283736, Exp. date 2007-04

2) Bloodspot std: A,B,C,D,E ja F, lot 336345 , Exp.date 2007-10, referennce, Laser-punched small (received 2007-09-03) 3) Bloodspot controls: Cl ja C2 , lot 333448 , Exp.date 2007-09, reference, Laser-punched small (received 2007-09-03)

4) Anti-hTSH Microtitration Strips, 8x12 wells 13804640, lot 412833, Exp. date 2008-07

5) Anti-hTSH Eu, 13801085, (ca. 20 μg/ml) lot 380725 , Exp. date 2008-01

6) Delfϊa Wash Solution, lot 398953, Exp.date 2009-06 7) Enhancement Solution, ES, lot 385082, Exp. Date 2009-03 Instruments:

1) Blood spot puncher PUN34, DBS puncher, 1296-071 Delfϊa dried blood spot puncher

2) 1296-061 Delfϊa Diskremove + 1296-062 Delfϊa Vacuum Unit, LPO2

3) 1296-026 Delfϊa Platewash, PLA 243 4) 1296-041 , Delfϊa dispense, DSP 23

5) Victor2 D, Danny, Multicalc ( 12 NTSH )

Protocol:

1) Puncing (conventionally) of bloodspots to wells, three in parallel to two rows and moving laser-punched bloodspots with tweezers three in parallel to two rows

2) Anti-hTSH Eu dilution 200 μl / well

3) 10 minutes fast shake

4) Incubation O/N +4°C, wells sealed

5) Incubation for 1 hour (slow shake RT) 6) Removal of bloodspots using a Disk Remove -device

7) Washing 6x , (program TSH)

8) ES 200 μl / well

9) 5 minutes slow shaking

10) Measuring or evaluating of the results using Multicalc-program and Victor 2D:lla (Danny)

Dilutions:

According to Anti-hTSH Eu dilution kit: 70 μl Eu to four strips + 11.5 ml Assay Buffer

The results are shown in Table 1. As can be seen, the resulting measurement values for laser- punched samples are slightly smaller than in the reference measurement. However, laser- punched bloodspots can very well be used in real analyses, because the signal level falls into practical limit range. There are several factors, which may explain the differences between the measurements. One of the most remarkable factors is the size of the punched discs, which was not exactly the same. Table 1 : Results of the experiment

Claims

1. An apparatus for handling sample carriers containing one or more biological samples impregnated therein, comprising: a holder adapted to receive a sample carrier, and - a cutting tool for cutting a sample-containing portion of the sample carrier supported by the holder, characterized in that the cutting tool is adapted to direct to the sample carrier a localized cutting impact which is moved on the surface of sample carrier for detaching from the sample carrier said sample-containing portion.

2. An apparatus according to claim 1, characterized in that the cutting tool comprises a laser source adapted to emit a laser beam directed to the sample carrier.

3. An apparatus according to claim 2, characterized in that the laser source is a diode laser source.

4. An apparatus according to claim 2, characterized in that said laser source is a fibre laser source or a CCh-laser.

5. An apparatus according to any of claims 2 - 4, characterized in that the wavelength of radiation emitted by the laser source is such that the absorption factor of a fibrous sample carrier, in particular a Guthrie card or the like, which has been impregnated with blood is at that wavelength higher than the absorption factor of the sample carrier without impregnation.

6. An apparatus according to any of claims 2 - 5, characterized in that the wavelength of radiation emitted by the laser source is 700 - 2500 nm, in particular 900 - 1500 nm.

7. An apparatus according to any of claims 2 - 6, characterized in that the laser beam is guided to the sample carrier through an optical fibre.

8. An apparatus according to any of claims 2 - 7, characterized in that the laser beam is focused to the sample carrier through a lens or multi-lens objective, having its focal point essentially at the plane of the sample carrier.

9. An apparatus according to claim 1, characterized in that the cutting tool comprises a fluid nozzle and a channel for feeding through the nozzle fluid, such as water, at high pressure so as to form a fluid jet directed to the sample carrier.

10. An apparatus according to any of the preceding claims, characterized in that it comprises a controller adapted to allow modifying the shape and/or size of the sample-containing portion to be detached from the sample carrier.

11. An apparatus according to any of the preceding claims, characterized in that it comprises a space for holding a multi-cavity sample -receiving plate, such as a microtiter plate, in a position allowing the detached sample-containing portions to be conveyed to the cavities of the sample-receiving plate.

12. An apparatus according to claim 11, characterized in that it comprises suction head for holding sample-containing portions by means of underpressure and for conveying the sample-containing portions to the wells of the sample-receiving plate.

13. An apparatus according to any of the preceding claims, characterized in that the sample holder is adapted to hold sample carriers comprising planar sheets of fibrous material, in particular Guthrie cards and the like.

14. An apparatus according to any of the preceding claims, characterized in that it is adapted to cut non-circular, such as honeycomb-shaped sample-containing portions from the sample carrier.

15. An apparatus according to any of the preceding claims, characterized in that it further comprises - accommodation means for a plurality of sample carriers in a stack, - a feeder for moving the sample carriers successively to said sample carrier holder.

16. A method for cutting away a sample-containing portion from a sample carrier containing at least one biological sample impregnated therein, characterized by directing to the sample carrier a localized cutting impact, which is moved on the surface of the sample carrier for detaching from the sample carrier said sample- containing portion.

17. A method according to claim 16, characterized by using a laser beam for achieving said localized cutting impact.

18. A method according to claim 17, characterized by using a diode laser for producing said laser beam.

19. A method according to any of claims 16 - 18, characterized by using a laser wavelength whose absorption factor in a fibrous sample carrier, in particular in a Guthrie card or the like, which has been impregnated with blood is at that wavelength higher than the absorption factor in the sample carrier without impregnation, in particular a wavelength of 700 - 2500 nm, typically 900 - 1500 nm.

20. A method according to any of claims 16 - 19, characterized by guiding the laser beam to the sample carrier through an optical fibre.

21. A method according to any of claims 16 - 20, characterized by focusing the laser beam to the sample carrier using a focusing lens or a multi-lens objective having its focal point essentially at the plane of the sample carrier.

22. A method according to claim 16, characterized in that said cutting impact is produced using a fluid jet, in particular a water jet.

23. A method according to claim 16, characterized in that said sample containing portion of the sample carrier is transported into a sample cavity of a sample-receiving plate after being detached from the sample carrier.

24. A method according to any of claims 16 - 23, characterized in that after being detached from the sample carrier, the sample-containing portion is conveyed to a sample-receiving cavity by using an underpressure-operated handler.

25. A method according to any of claims 16 - 24, characterized by using as said sample carrier a fibrous material sheet, in particular a Guthrie card.

26. Use of laser for cutting away sample-containing portions of sample carriers containing impregnated biological samples.

27. Use of a fluid jet for cutting away sample-containing portions of sample carriers containing impregnated biological samples.