WO2008096318A2

WO2008096318A2 - Identification system

Info

Publication number: WO2008096318A2
Application number: PCT/IB2008/050424
Authority: WO
Inventors: Willem M. J. M. Coene; Anke Pierik
Original assignee: Koninklijke Philips Electronics N.V.
Priority date: 2007-02-09
Filing date: 2008-02-06
Publication date: 2008-08-14
Also published as: WO2008096318A3

Abstract

A two-dimensional sensor array or sensor carrier (110), comprising a substrate (111) and a plurality of spots (113, 114) formed on the substrate (111), wherein the plurality of spots (113, 114) comprise at least one reference spot (113) arranged for encoding identification information for identification of said two- dimensional sensor-array.

Description

Identification system

FIELD OF THE INVENTION

The invention relates to a sensor carrier.

Further, the invention relates to a set of sensor carriers.

Beyond this, the invention relates to a method of manufacturing a sensor carrier. Moreover, the invention relates to an apparatus for determining identification information for identification of the sensor carrier. Further, the invention relates to a method of determining identification information. Moreover, the invention relates to a method of use.

BACKGROUND OF THE INVENTION

A biosensor assembly may comprise a membrane having a plurality of detection spots printed on the membrane in accordance with a specific two-dimensional lattice. The biosensor assembly may further comprise a light source for illuminating the membrane with light, wherein a fluorescence pattern originating from the spots may then be detected by a multi-pixel detector such as a CCD. On the CCD image, positions corresponding to the spots of the membrane have to be reconstructed during image processing.

For verifying that spots of such a biosensor assembly have been printed on the membrane with a correct intensity, so called intensity calibration spots may be printed on the biosensor assembly.

WO 2004/017374 A2 discloses an array reader suitable for clinical purposes for reading a two-dimensional array of features on a planar substrate, in which the features carry photo -responsive markers, the markers capable of emitting light upon excitation, the array reader comprising an illumination system for simultaneously exciting multiple photo -responsive markers distributed in a two-dimensional array over the substrate, and an image collection and recording system having a field of view for emissions from the features on the substrate, wherein the illumination system comprises a light source arranged to flood the two-dimensional array with light at an excitation wavelength, along an illumination path disposed at an angle to the plane of the substrate, the image collection and recording system having an image-acquiring axis substantially normal to the plane of the substrate carrying the array, employing a two-dimensional sensor comprising a solid-state array of photosensitive elements, for instance a charge- coupled device (CCD) or a CMOS array, and the image collection and recording system constructed and arranged to apply an image of the array of features upon the solid-state array of size of the same order of magnitude as the size of the array, for instance within a range of magnification of up to about 25% or reduction down to 75%, the image collection and recording system having an intermediate numerical aperture to enable recording the image of fluorescence from the excited two-dimensional array with clinical accuracy and without translation of the array. However, it may be difficult or cumbersome to reliably identify the information carrier or sensor carrier of a biosensor assembly, which is for instance a two- dimensional substrate or a two-dimensional membrane on which capture-probes are attached.

OBJECT AND SUMMARY OF THE INVENTION

It is an object of the invention to provide a sensor system with a sensor carrier being identifiable with reasonable effort.

In order to achieve the object defined above, a sensor carrier, a set of sensor carriers, a method of manufacturing a sensor carrier, an apparatus for determining identification information, a method of determining identification information, and a method of use according to the independent claims are provided.

According to an exemplary embodiment of the invention, a two- dimensional sensor carrier is provided comprising a substrate and a plurality of spots formed on the substrate, wherein each spot (or a part thereof) may contain capture probes that are able to bind to analyte molecules, and wherein the plurality of spots comprise at least one reference spot arranged for encoding identification information for identification of said two-dimensional sensor-array or sensor-carrier.

According to another exemplary embodiment of the invention, a set of sensor carriers is provided, the set comprising a plurality of sensor carriers having the above mentioned features, wherein the plurality of sensor carriers differ regarding the arrangement of the at least one reference spot for encoding individual (for instance unique) identification information in each of the plurality of sensor carriers (so that each of the plurality of sensor carriers is distinguishable from the other sensor carriers merely on the basis of the identification code which unambiguously identifies this specific sensor carrier).

According to still another exemplary embodiment of the invention, a method of manufacturing a sensor carrier is provided, the method comprising forming a plurality of spots on a substrate, and arranging/configuring at least one of the plurality of spots as at least one reference spot for encoding identification information. According to still another exemplary embodiment of the invention, an apparatus for determining identification information is provided, the apparatus comprising a decoding unit adapted for decoding identification information of a sensor carrier having the above mentioned features by analyzing the arrangement (for instance by considering a printing position and/or a surface property) of the at least one reference spot. According to yet another exemplary embodiment of the invention, a method of determining identification information is provided, the method comprising decoding identification information of a sensor carrier having the above mentioned features by analyzing the arrangement of the at least one reference spot.

According to a further exemplary embodiment of the invention, at least one reference spot of a sensor carrier having the above mentioned features is used for encoding identification information.

According to still another exemplary embodiment of the invention, a program element (for instance a software routine, in source code or in executable code) is provided, which, when being executed by a processor, is adapted to control or carry out a method of manufacturing a sensor carrier or a method of determining identification information having the above mentioned features. According to yet another exemplary embodiment of the invention, a computer-readable medium (for instance a CD, a DVD, a USB stick, a floppy disk or a harddisk) is provided, in which a computer program is stored which, when being executed by a processor, is adapted to control or carry out a method of manufacturing a sensor carrier or a method of determining identification information having the above mentioned features.

The information encoding and decoding scheme according to embodiments of the invention can be realized using a computer program, that is by software, or by using one or more special electronic optimization circuits, that is in hardware, or in hybrid form, that is by means of software components and hardware components.

In the context of this application, the term "identification information" may particularly denote one or more data bits of information which are provided in the form of a specific arrangement of distinguishable reference spots. The presence or absence of a reference spot at a particular position, a property of a spot at a particular position, etc., and such a characteristic for several positions, may encode information in a similar manner as letters of a word or a sentence.

The term "plurality of spots" may particularly denote an array of several, for instance some hundred or some thousand, pixels or spots. Each of these spots may form a sensor portion of a sensor array. The spots may be arranged, for instance in a matrix- like manner. Each of the plurality of spots may comprise capture molecules or other probes which may be used during the actual sensor performance for identifying particles of a sample, for instance by hybridization events. The plurality of spots may comprise a plurality of sensor or detection spots which are (only) intended for use as probes during the sensor procedure. Additionally, the plurality of spots may comprise a plurality of reference spots.

The term "plurality of reference spots" may particularly denote several spots formed at specifically selected positions on the array of spots and dedicated to serve as markers which allow to identify the sensor carrier. Simultaneously, such reference spots may serve for one or more additional purposes such as intensity calibration, gridding (i.e. retrieving information indicative of a lattice type according to which the spots are arranged in a spot-depositing step or spot-printing step), etc.

In the context of this application, the "substrate" may be made of any suitable material such as glass, plastics, or a semiconductor. The term "substrate" may be thus used to define generally the elements for layers that underlie a spot comprising layer or portions of interest. Also, the "substrate" may be any other base on which a structure is formed, for example a glass or metal layer.

The term "electromagnetic radiation" may particularly denote a beam of photons of any appropriate wavelength or any appropriate range of wavelengths. This may include the optical spectrum (for instance the range between 400 nm and 800 nm), but may also include electromagnetic radiation of other wavelengths such as UV, infrared, or even X-rays.

The term "sample" may particularly denote any solid, liquid or gaseous substance to be analysed, or a combination thereof. For instance, the substance may be a liquid or suspension, furthermore particularly a biological substance. Such a substance may comprise proteins, polypeptides, nucleic acids, lipids, carbohydrates or full cells, etc.

The term "dispenser device" may particularly denote any device for emitting or applying any substance to a specific region in space, particularly onto a defined surface portion of a substrate. According to an exemplary embodiment of the invention, a sensor carrier may be provided on which a plurality of spots are printed/deposited, wherein an arrangement of one or more reference spots on the sensor carrier is indicative of an identification number or any other identification code which is provided on the level of the substrate of the sensor carrier. Therefore, in a single procedure with the printing of (sensor) spots such as capture molecules immobilized on the substrate, an identification code for the sensor carrier may be printed/deposited directly onto the sensor carrier without the need of an additional manufacture procedure. According to an exemplary embodiment, the information may be printed on the surface level of the substrate in the same manufacturing procedure during which also the sensor spots are deposited, and one and the same spot may serve for a double function, namely for encoding the identification information and for performing an additional function (for instance to serve as an intensity calibration marker, a corner marker, a PCR control marker, etc.).

In the context of a (bio-)sensor assembly with a sensor-carrier, which may be a two-dimensional substrate or a two-dimensional membrane on which capture probes are attached, it may be of interest to identify the substrate that carries the spots with specific capture probes.

According to an exemplary embodiment of the invention, it is possible to identify an information carrier or sensor-carrier (for instance a 2D-substrate). A possible application scenario is a sensor device comprising a liquid processing unit (producing the analyte molecules in one way or the other), a spotted array with capture probes (such as a sensor carrier), a reaction unit (for the reaction between spotted array and analyte molecules), and a detection unit for detection of the binding via binding specific signals. The sensor carrier which is the spotted array with capture probes may be a disposable. The detection device can be used many times, each time for a different spotted array. So, the identification of the spotted array may be an issue according to an exemplary embodiment of the invention. Thus, a sensor carrier may denote a substrate used for sensing purposes or may denote a (spotted) array or an assay.

In accordance with this, a readout system may be provided for automatically reading out identification information encoded in the arrangement of the reference spot(s) on the substrate level. According to an exemplary embodiment, such reference spots are provided at a specific position on the substrate so as to allow the readout system to determine which sub-arrangement of reference spots is indicative of the identification information. Furthermore, it is possible that spots which are used for other purposes, for instance as intensity calibration spots, corner marker spots, PCR control spots, etc. (see Fig. 2) are simultaneously or synergetically used to encode identification information.

According to an exemplary embodiment of the invention, permutation coding and/or decoding of one or more subsets of intensity calibration spots may be used in an assay to code for a unique identification number for each printed assay or each family of printed assays. This may include position coding of the set of intensity calibration markers and the combination of permutation and position coding. Particularly, this may allow for providing an array identification code via a double use of intensity calibration markers for the purpose of intensity calibration and for encoding identification information.

In a hexagonal lay-out of an assay, a number of intensity calibration spots may be included. These can be positioned in the center of the array, at pre-defined locations on the two-dimensional grid. Below, it will be described how permutation coding of one or more subsets of these calibration spots can be used to code for a unique identification number or ID-number for each printed assay or family of printed assays. Further, some extra measures may be taken to increase the robustness of proper detection and decoding of this ID information. Finally, position coding of the overall set of intensity-calibration markers can be used to provide extra capacity for ID- numbers, for instance in order to identify generations of batches of assays. Position coding and permutation coding may also be combined so that an indexing system with the following hierarchy may be provided: generation-ID - batch-ID - membrane-ID. For instance, intensity calibration spots which are usually but not exclusively provided in a middle of the spot array can be used according to exemplary embodiments for two purposes, namely to check whether the printing process was acceptable, based on checking different spots with different intensities. A second purpose of these intensity calibration spots may be that different intensities /wavelengths of electromagnetic radiation emitted by such intensity calibration spots after excitation with electromagnetic radiation may serve to encode identification information. The identification calibration spots may be capture molecules labelled with a fluorophore, which are shortly referred to as pre-labelled molecules, and printed with different concentrations and amounts of pre-labelled molecules thicknesses/areas/characteristic wavelengths of the fluorophore on specific portions of the sensor array. In the context of the verification of the quality of the printing process, the intensity calibration spots may also be used for a (semi-)quantitative data evaluation.

Therefore, it is possible to print intensity calibration spots or other reference spots in a free (not fixed) pattern, wherein the permutation of the reference spots may be indicative of the identification information to be encoded. Such identification information may include the unique identifier for the assay, for a batch of assays, etc. In other words, it may be possible to identify a specific membrane or assay or sensor carrier based on the batch number of the batch of assays and the individual assay number. Also an identification code indicative of the generation of a product of assays may be used in this context.

According to an exemplary embodiment of the invention, an identification of a spotted array may be performed on the level of the printed spots. Specifically dedicated spots, for instance already present spots or additional spots of a sensor array, may be used for identification. This may save cost and space on the sensor active area. For example, at each position of an identification portion of the surface, a binary coding may be performed including an information whether a specific spot is present (logical information "1") or is not present (logical information "0").

By providing different signal levels per spot, two or more bits may be stored in one reference spot. It is also possible to provide one or more of the dedicated reference spots/identification spots with an intensity of "0", i.e. to provide capture molecules without fluorophore or to provide no capture molecules at all at a spot position. When capture molecules are provided, these may also be used in the context of the actual sensing so that essentially no loss of capacity occurs.

Next, further exemplary embodiments of the sensor carrier (or assay) will be explained. However, these embodiments also apply to the manufacturing method, to the set, to the apparatus, to the identification information determining method, and to the method of use.

The plurality of spots may comprise a plurality of detection spots adapted for detecting the presence of analyte molecules to be detected. Such spots or sensor cells or pixels may include capture molecules, electric sensor pixels, magnetic sensor pixels, electrochemical sensor pixels, etc. The plurality of spots may be arranged in accordance with a specific grid pattern (for instance in a hexagonal manner with specific angular and distance parameters) which may be re-calculated on the basis of an image captured from the plurality of pre-labelled spots before an analyte-probe reaction sensor event (which may denote the interaction of analyte molecules with specific types of capture probe molecules) has taken place. The at least one reference spot may comprise a fluorescent material. Then, in the absence of an analyte-probe reaction sensor event, illumination of the sensor carrier with electromagnetic radiation may cause only the pre-labelled reference spots to emit light which can be detected by a detector such as a CCD array. Alternatively, the reference spots may comprise a highly reflective material so that electromagnetic radiation impinging on the reference spots will be reflected and directed to the detector. The material of the reference spots may be adapted to cause an image (only) of the reference spots.

The sensor carrier may comprise a plurality of reference spots, for instance at least ten reference spots. By permuting a plurality of reference spots having different spot-characteristic physical modulation like characteristic emission wavelengths of fluorophores, different characteristic concentrations of fluorophores, different characteristic emission areas (i.e. different sizes of spots provided with fluorophores), etc., it may be possible to encode a large amount of information in the identification portion of the sensor carrier that contains the reference spots.

In a particular embodiment, all reference spots do carry fluorophore- labels. In another embodiment, at least one of the plurality of reference spots may be free of a fluorophore. The reference spots of a given subset may have different intensities due to e.g. different capture probe concentrations. It is not absolutely necessary that one reference spot is completely empty, it might in some cases be preferred to have signal from all reference spots, for instance when combining corner-marker spots with identification spots, since it may be desirable that all corner-marker spots give rise to a detectable signal. In other words, such a reference spot may only contain capture molecules or may be simply an empty portion on the substrate surface. Also the number and positions of empty spots on the sensor carrier may include identification information.

The plurality of reference spots may be grouped to form at least two groups of reference spots. For example, 16 reference spots may be divided into two groupsof 5reference spots and one group of 6 reference spots. In a particular embodiment, each individual one of the groups may include specific identification information. For example, a first group may be indicative of an identification number of a specific assay/sensor carrier, a second group may be indicative of a specific batch of sensor arrays, and a third group may be indicative of a product generation of sensor arrays.

The at least one reference spot may comprise an intensity calibration spot, or a corner marker spot (such that the at least one spot has at least a double functionality, being for identification and for intensity calibration, or, being for identification and as a corner-marker spot). It is also possible that other specific and usually used spot types such as a PCR control spot are used additionally to encode identification information. Alternatively, it is also possible to dedicate a specific portion of the sensor surface exclusively for the identification purpose. An intensity calibration spot may be used for verifying the quality of the printing procedure. Corner marker spots may be used for gridding purposes, that is to say to correlate an image on a CCD device to a sensor array on the sensor carrier (assay) and to determine information indicative of a lattice order according to which the spots are arranged during spot-deposition. A PCR control spot may be used to verify the quality of a polymerase chain reaction (PCR) which may be performed to dramatically increase the concentration of a sample on the sensor surface.

The identification information may be indicative of the assay/sensor carrier (that is to say may be a unique identifier for the assay/sensor carrier), a batch of sensor arrays to which the particular sensor assay at hand device relates (that is to say a product charge or the like), a generation of batches to which the sensor assay relates, and/or a product generation to which the sensor assay relates (that is to say a version or product number of a specific company). However, other identification information may also be stored in the sensor carrier such as a date of expiry of the sensor carrier, a resolution of the sensor, information characterizing the capture molecules, etc.

At least a part of the plurality of spots may comprise capture molecules adapted for hybridizing with complementary analyte molecules to be detected. For example, the capture molecules may be DNA molecules which are immobilized on the sensor surface. When a sample to be analyzed is brought in contact with the surface of the sensor carrier, possibly present particles in the sample which have a complementary sequence to the sequence of the capture molecules may selectively hybridize with the capture molecules, thereby forming double-stranded molecule complexes. The presence of such a detection event may be read out electrically, optically, etc. The sensor carrier may be a biosensor or a molecular diagnostics sensor carrier. A biosensor may be a molecular probe, or particularly an array of a plurality of molecular probes, measuring the presence or concentration of biological molecules, biological structures, etc., by translating a biochemical interaction at the probe surface into a quantifiable physical signal such as light or an electric pulse. However, embodiments of the invention may be applied to any array- like sensor structure, for instance a gas sensor, a temperature sensor, or any molecular sensor.

In the following, further exemplary embodiments of the identification information determining apparatus will be explained. However, these embodiments also apply to the sensor carrier, to the manufacturing method, to the set, to the identification information determining method, and to the method of use.

The apparatus may comprise an imaging device adapted for capturing the image of the plurality of reference spots. Such an imaging device may be a multiple pixel detector, such as a CCD (charge coupled device) or a CMOS detector. In an information readout phase, the reference spots may be imaged on the surface of the detector. Based on this image, it is possible to determine the identification information encoded in the reference spots of the sensor carrier.

The apparatus may further comprise an electromagnetic radiation source adapted for illuminating the plurality of reference spots. Such an electromagnetic radiation source may be an LED, a laser, or any other lamp. However, it is also possible to use electromagnetic radiation sources of other wavelengths such as infrared radiation, UV radiation or even X-rays.

The aspects defined above and further aspects of the invention are apparent from the examples of embodiment to be described hereinafter and are explained with reference to these examples of embodiment.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described in more detail hereinafter with reference to examples of embodiment but to which the invention is not limited.

Fig. 1 illustrates a sensor device, that is a complete sensor assembly or sensor arrangement, according to an exemplary embodiment of the invention. Fig. 2 illustrates a two-dimensional assay/sensor carrier according to an exemplary embodiment of the invention. Fig. 3 illustrates an enumerative coding for N=5 probes in a probe set.

Fig. 4 showsanexampleofpermutationcodingwith5 spots forindexi=46. Fig. 5 shows a hexagonal layout for a sensor carrier according to an exemplary embodiment of the invention with 16 intensity calibration spots allocated in a center area. Fig. 6 shows a distribution of intensity levels over three disjoint sets.

Fig. 7 illustrates a hexagonal layout for a sensor carrier according to an exemplary embodiment of the invention with 16 intensity calibration spots allocated within a selection of 20 spot locations. Fig. 8 illustrates a sensor carrier according to an exemplary embodiment of the invention having four sets of ID coding.

Fig. 9 to Fig. 12 illustrate the four sets of identification coding of the sensor carrier of Fig. 8. Fig. 13 illustrates an apparatus for manufacturing a sensor carrier according to an exemplary embodiment of the invention.

DESCRIPTION OF EMBODIMENTS

The illustration in the drawing is schematically. In different drawings, similar or identical elements are provided with the same reference signs. In the following, referring to Fig. 1, a sensor arrangement 100 according to an exemplary embodiment of the invention will be explained.

The sensor arrangement 100 comprises a sensor carrier 110 and a readout apparatus 190.

The sensor carrier 110 comprises a substrate 111 which may be a membrane. On the substrate 111, a plurality of spots 113, 114 are formed in accordance with a predefined grid pattern. These spots 113, 114 comprise pre-labelled reference spots 113 and un-labelled detection spots 114.

The reference spots 113 which may also be denoted as "intensity calibrating and identification spots" comprise a fluorescent material and are adapted and arranged for verifying the printing procedure according to which the spots 113, 114 are printed on the substrate 111. Simultaneously, the reference spots 113 are arranged and configured for encoding identification information uniquely identifying the sensor carrier 110.

For deriving this identification (ID) information, the image containing signal from the reference spots 113 only may be captured by a CCD camera 150 of the information/data readout device 190. According to an exemplary embodiment of the invention, the plurality of reference spots 113 are arranged at such positions and with such fluorescence properties that the fingerprint of the reference spots 113 on the CCD array 150 is unambiguously indicative of an identification code identifier identifying the sensor carrier 110. For detecting this identification information (before or after an actual sensor event has occurred), a light source 180 such as an LED emits a beam of light 181 which is impinged on the surface of the substrate 111. In the absence of any sensor event (analyte-probe reaction) which will be described below in more detail, only the pre- labelled reference spots 113 having fluorescence labels generate light spots on the surface of the CCD detector 150.

A CPU 160 of the readout apparatus 190 is capable of deriving the identification information encoded in the arrangement of the reference spots 113, i.e. is adapted as an ID data decoder.

For detecting a sensor event between capture molecules of the detection spots 114 and analyte molecules particles of a sample/an analyt, the detection spots 114 (which may comprise different kinds of capture molecules) may be brought in functional contact or in fluidic communication with the fluidic sample so that hybridization events may occur between the molecules to be detected and the capturing molecules assigned to the spots 114. The particles to be detected may be labelled with fluorescence labels. When the particles to be detected comprise fluorescence labels, this may result, after illumination of the sensor surface 111 by the light source 180, in a spot pattern on the CCD camera 150. To determine which spot on the image detector 150 is assigned to which detection spot 114, the information encoded in the arrangement of the reference spots 113 may be used as well.

An analysis unit 170 may be dedicated for performing the analysis, that is to say for determining the presence and/or quantity of particles to be detected by the sensor carrier 110.

The decoding performance of the unit 160 and the detection analysis performance of the unit 170 may be carried out by a single CPU (central processing unit) 175 or by a microprocessor. Furthermore, as can be taken from Fig. 1, the sensor arrangement 100 comprises a user interface 185 which allows a user to bidirectionally communicate with the apparatus 190, or more particularly may perform a bidirectional communication with the CPU 175. The user interface or input/output unit 185 may comprise input elements such as a keypad, a joystick, a trackball or even a microphone of a voice recognition system. Furthermore, the input/output unit 185 may comprise a display device such as a cathode ray tube, an LCD device, a monitor, a TFT device, a plasma device, etc.

Fig. 2 illustrates the sensor carrier 110 in more detail. Particularly, specific different types of spots are indicated in Fig. 2.

PCR control spots are denoted with reference numeral 200 and are adapted for controlling a polymerase chain reaction (PCR) which may be initiated in the liquid pre-processing module of the sensor arrangement on a sensor surface of the sensor carrier 110. Corner marker spots 201 may be used for identifying a gridding scheme, i.e. a scheme according to which the spots of the sensor carrier 110 are arranged.

Furthermore, an identification portion 204 located in a centre of the array of the spots is provided and is used for two purposes. The first purpose is the encoding of an identifier information identifying the sensor carrier 110. The second purpose is the use of the spots of the portion 204 as intensity calibration spots, that is to say for controlling or monitoring the deposition procedure which can be a printing procedure by which the capture molecules of the spots of Fig. 2 are formed are printed on the substrate 111.

Moreover, background spots 202 and detection spots 114 are shown as well. Coming back to the identification portion 204, the capture molecules bound to the individual spots 113 are labelled with fluorophores. Furthermore, the intensity of the fluorescence characteristic of the spots 113 may differ in accordance with differences in the as-deposited concentrations and amounts of pre-labelled probe- molecules. Therefore, the specific permutation of the individual spots 113 to the 16 positions of the identification portion 204 may include the identification information.

In the following, aspects regarding a permutation code will be explained in more detail.

In a subset of N reference spots, each spot having a different intensity, there are N possible locations on the array 110 to distribute these N spots 113, 114 that will yield different intensities with values Io, Ii, ..., I_N-_I - Without loss of generality, these intensity values are assumed to belong to a set of ordered intensity values (for instance in the order of increasing intensity). Obviously, there are N! possibilities to allocate these N different spots (with different intensities) over the N possible locations (for instance over the 16 positions of region 204 of Fig. 2). Via enumerative coding techniques, it is possible to devise simple encoding and decoding procedures as is outlined below.

In the following, aspects regarding encoding will be explained in more detail.

Given is an index i that needs to be encoded in the actual positions of the N consecutive probe intensities Io, Ii, ..., I_N-_I - These (yet unknown) probe positions will be denoted by X_k. Note that X_k indicates the probe position that has intensity I_k.

A schematic picture is shown in Fig. 4.

Fig. 4 illustrates a practical example of permutation coding with 5 Spots (for index i = 46). The algorithm that is outlined below makes use of a set of ordered probe positions. The initial set of ordered probe positions comprises all positions, and can be denoted by

S₀ = {0, 1, ..., N-I } . The encoding procedure proceeds along the following four steps, that are to be repeated starting from k = 0 up to and including k = N-I : STEP- 1 : find the integer 1 such that I [X - * - I V _..-, ( < ι i : I v W ~ k ~ I ..?

STEP-2: determine probe position Xk as the 1-th element out of the ordered set Sk, that is:

JTk S_k \l\ .

STEP-3 : update the current remainder of the index i by:

Ϊ i - h N - k ~- I ) !

STEP-4: update the current ordered set of remaining probe positions, hereby eliminating the probe position that has just been selected, by:

The adapted set Sk contains N-k remaining probe positions that are available for the next step in the algorithm. If k < N-I then the procedure goes for the next index k -> k+1 following the same sequence of four steps, otherwise when k = N-I the encoding operation is finished.

In the following, aspects regarding decoding will be explained in more detail.

This time, the N locations Xk are given with k = 0, 1, ..., N-I of the consecutive intensities of the set So. The corresponding index (or identification number) can be computed as:

:v 2 i \ ^'t'k' ^'k ' ' -V ^■- k ^■- ϊ V

£^• - 0 where the rank rk of the set Xk is defined as the order of element Xk in the subsequence of remaining x-parameters, that is, Xk, Xk+i,. • • ^XN I- By definition, for k = N- 1, there is only a single element in said sub-sequence, and then the rank is equal to 0. In the following, some practical examples will be given. As examples, two cases will be considered, one with N = 13 intensity calibration probes, the other with N = 16 intensity calibration probes.

First, the case with N= 13 intensity calibration probes will be discussed. In this context, a case will be explained with N= 13 intensity calibration probes treated as a single set in the ID-coding (Δ = 1)

There are 13! = 6,227,020,800 cases, which implies 32 bits of information that can be stored in the position information of the 13 intensity calibration probes II, 12, ..., 113. Consecutive intensity values differ by only one step in intensity (Δ = 1). This information might be subject to errors in case two neighboring intensity values are detected in the wrong order (the one detected lower than the other, whereas it should be otherwise). Even substantially less error-prone coding (at lower information density) may be realized through the choices made in the subsequent discussion.

Next, a case with N= 13 intensity calibration probes treated as two sets in the ID-coding will be discussed (Δ = 2).

In each of both sets, consecutive intensity values within a set differ by two steps in intensity. Therefore, detection of the proper spot-locations dependent on the respective intensities may be even substantially less error-prone than in the previous case. One set reads as:

1 1 - Vi - n - 17 - Vi - i l l - Ϊ I Λ

whereas the other set is derived as:

\2 - I i - \b - I- - \ U⁾ - I U

The total number of possible combinations by using these two sets equals 7! x 6! = 3,628,800, which implies that 21 bits of information can be stored. In the following, a case with N= 13 intensity calibration probes treated as three sets in the ID-coding will be explained (Δ = 3).

Similarly, it is possible to consider the case where consecutive intensity values within a set differ by three steps in intensity. So misdetection of the respective intensity levels is most unlikely. The three sets (Set-O, Set-1, Set-2) read as: E i - 1 1 - 17 - W V - I I . ϊ

[j - r \ -

U - h > - V- - \ \ 2

The total number of possible combinations by using these three sets equals 5! x 4!² = 69120, which implies that 16 bits of information can be stored. This seems to be an interesting number of combinations that will be explored in more detail. One of the possible configurations of the three sub-sets may be plotted as follows: i t i I

[ I O tl U ! '

The combination of the three sets into one ID-number i (0 < i < 69120) is obtained by:

where io, ii and 12 are the indices corresponding to the permutation codes for the respective sub-sets Set-O, Set-1 and Set-2. Therefore, the ranges of these indices are given by: 0 < io < 5! = 120, 0 < ii < 4! = 24, 0 < i₂ < 4! = 24.

Given an index i, it is possible to derive the sub-indices for each of the sub-sets, io, ii and i₂. Then, for each of these sub-indices, it is possible to apply the permutation coding via the enumerative encoding procedure as outlined above. So, it is not necessary to allocate to each subset of spots a different type of identification number, all sets can be used jointly together to generate one single identification number (with a larger range than in the case when more than one identification number is being used). Next, the case with N= 16 intensity calibration probes (with three probe sets, Δ = 3) will be discussed.

The case of three probe-sets will be considered, with 6, 5 and 5 probes respectively.

For a hexagonal lay-out of a 2D-array 500, a possible location of these 16 probes is shown in Fig. 5.

Fig. 5 shows a hexagonal lay-out for the assay 500 with 16 intensity calibration spots 113 allocated in the center area 204. A division of these 16 spots 113 into three disjoint sets, Set-O, Set-1 and Set-2, is also shown by proper color-coding ("R", "G", "B") of the respective spots 113, which reflect the different sub-sets.

Regarding the color-code of these 16 spots 113, referring to the three probe-sets, the intensity values that are selected for each probe-set are shown in Fig. 6. In Fig. 6, the sub-sets are really indicated to be disjoint. In another embodiment, it may be chosen to have intensity values for different sub-sets to be partly overlapping, or even to be identical (if the size of the subsets is the same). For instance, with 16 spots and 4 sets, having only 4 really different intensity levels is also an implementation of this basic principle.

Fig. 6 shows a distribution of intensity levels (I₀, Ii, ..., I15) over the three - in this particular case - disjoint sets. Note the separation of two consecutive intensity levels within one set by three steps in intensity.

In each of these three sets, consecutive intensity values within a set differ by three steps in intensity. Therefore, detection of the proper spot locations dependent on the respective intensities is more robust than in case there would only be two or even only one step difference in intensity. Next, batch-index and membrane-index will be explained in more detail.

With this allocation of intensity calibration spots to sets, it is possible to use the largest set, Set-O, for the generation of a membrane index (between 0 and 719), for a given batch. The two other sets can be combined to generate a batch-index, ranging from 0 to 14399. In the following, error detection will be explained in more detail.

Some extra error detection (or reliability) measure can be devised as follows: in case the (absolute value of the) distance between two consecutive intensity levels within a probe-set is getting above a certain pre-set threshold value, then the 2D- assay can be declared to be unreliable because of this obvious error in the respective values of the intensity-calibration markers. The threshold can be set equal to a fraction (for instance f x 1/15) of the total signal range Ii₅-I₀.

In Fig. 3, the enumerative coding for N = 5 probes in a probe-set is written out (with the index ranging from 0 up to 119).

Next, position coding (for extra ID-information) will be explained. An additional way of coding ID information is via the position of intensity calibration spots. In the above description, a fixed location (in the center of the 2D assay) of these (N_1C = 16 or N_1C = 13) special intensity calibration spots has been considered. It is possible to generate an extra degree of freedom via some variation in the possible positions of these spots. Suppose available N_pos > N_1C positions are available to allocate these N_1C spots, then there are C^°^s possible allocations, which carry the

(extra) ID-information. The remaining "free" locations are not left unused, but may be printed with capture-probe molecules (otherwise, this remaining area would be wasted).

In the following, it will be discussed where the information resides.

The information resides in the precise location of these intensity- calibration spots.

However, these spots are (or may be) interleaved with other spots carrying the specific capture probes that are spotted for detection of the pathogens, see the open circles 701 in Fig. 7.

Fig. 7 shows a hexagonal lay-out for an assay 700 with 16 intensity calibration spots allocated within a selection of 20 spot locations. A division of these 16 spots 113 into three disjoint sets, Set-0, Set-1 and Set-2, is also shown (by proper color- coding of the respective spots 113). This division should be set (or agreed upon) for each position allocation. The remaining four spots 701 (indicated with open circles) are available as spots with capture-probe molecules. The difference between an intensity calibration spot 113 and a capture probe spot 114 is that the former has attached to each spotted molecule, one fluorophore for (optical) detection, whereas the latter does not since hybridization to a fluorophore- labelled molecule from the patients (blood) cells is needed to generate the optical signal from such a capture probe spot 114. Next, it will be explained how to detect this information.

A way to detect the position of the intensity calibration spots 113 is to detect which spots are "on" (that is, produce a fluorescence yield) or "off prior to the hybridization step. In this way, it is possible to avoid also that capture probe spots 114 may be confused with potential intensity calibration spots 113 (which would make detection difficult or impossible). Some practical numbers will be given next.

With N_1C = 16 and N_pos = 20, precisely 4845 possible allocations are obtained. This number multiplies with the permutation coding devised in the previous description.

One of these allocations is shown in Fig. 7. This numbering can be used to identify a class (or generation) of batches of membranes. The hierarchical indexing can then be: generation-ID -> batch-ID -> membrane-ID.

For each generation, it is advantageous to define the pattern of different sets for permutation coding.

Fig. 8 illustrates another sensor carrier 800 according to an exemplary embo diment o f the invention.

Fig. 8 is similar to Fig. 2. However, in the identification portion 204 in the centre of the sensor carrier 800, green-coded ("G"), orange-coded ("O"), red-coded ("R") and blue-coded ("B") color-coded reference spots 113 are provided. Therefore, Fig. 8 illustrates four sets of ID coding via permutation coding. 16 membrane ID spots 113 are provided in an asymmetric design. Each of the groups G, O, R, B includes four spots 113 so that four sets of each four spots 113 are provided.

Within each group, four different intensities 10, II, 12 and 13 are characteristic for the individual spots 113. The green and the red spots 113 are indicative of a membrane ID, so that codes for 24² = 576 membranes per batch are possible. The red and blue spots 113 are indicative of a batch ID and are capable of encoding 24²=576 batches. Therefore, the combination of the 16 spots 113 of Fig. 8 allows an identification of 331776 membranes.

Fig. 9 illustrates the set of the green-color-coded reference spots 113.

Fig. 10 illustrates the set of the orange-color-coded reference spots 113. Fig. 11 illustrates the set of the red-color-coded reference spots 113.

Fig. 12 illustrates the set of the blue-color-coded reference spots 113. Referring to the legend in Fig. 9 to Fig. 12, "11" denotes a very low, "1" a low, "h" a high and "hh" a very high intensity.

In the following, referring to Fig. 13, a dispenser device or deposition device 1300 which could be an inkjet printer, according to an exemplary embodiment of the invention will be explained.

The dispenser device 1300 is capable of manufacturing a sensor carrier 110 according to an exemplary embodiment of the invention. The dispenser device 1300 generates the spots 113, 114 to generate a pattern of detection spots 114 and identification spots 113 on the surface of the membrane 111. For this purpose, the dispenser device 1300 comprises a tip 1301 having an internal cavity through which spot material from containers 1302 to 1304 may be printed on specific positions of the surface of the substrate 111. For instance, one of the containers 1302 may comprise a fluorescence material which is used by a control unit (such as a CPU) 1310 to detect reference spots 113. A two-dimensional motion mechanism 1315 allows to perform a relative motion in a two-dimensional manner between the substrate 110 and the tip 1301. By taking this measure, the surface of the substrate 111 may be scanned by the tip 1301 to deposit suitable material for forming the respective reference spots 113 or detection spots 114 on the surface of the substrate 111. In the CPU 1310, a predetermined pattern is stored at which positions of the two- dimensional array of reference spots 113 and in which positions detection spots 114 shall be spotted.

It should be noted that the term "comprising" does not exclude other elements or features and the "a" or "an" does not exclude a plurality. Also elements described in association with different embodiments may be combined. It should also be noted that reference signs in the claims shall not be construed as limiting the scope of the claims.

Claims

CLAIMS:

1. A sensor carrier (110), comprising a substrate (111); a plurality of spots (113, 114) formed on the substrate (111); wherein the plurality of spots (113, 114) comprise at least one reference spot (113) arranged for encoding identification information that is related to the sensor carrier (110).

2. The sensor carrier (110) of claim 1, wherein the plurality of spots (113, 114) comprise a plurality of detection spots (114) adapted for detecting the presence of molecules to be detected.

3. The sensor carrier (110) of claim 1 , wherein the at least one reference spot (113) comprises a fluorescent material.

4. The sensor carrier (110) of claim 1, wherein the plurality of spots (113, 114) comprise a plurality of reference spots (113).

5. The sensor carrier (110) of claim 4, wherein the plurality of reference spots (113) differ regarding at least one property of the group consisting of a fluorescence intensity, a fluorescence wavelength, a shape, a thickness, and an area.

6. The sensor carrier (110) of claim 4, wherein the encoding of the identification information of the sensor carrier (110) is realized via positional permutation coding of the plurality of reference spots (113).

7. The sensor carrier (110) of claim 4, wherein at least one of the plurality of reference spots (113) is free of a fluorophore.

8. The sensor carrier (110) of claim 4, wherein the plurality of reference spots (113) are grouped to form at least two separate groups of reference spots (113).

9. The sensor carrier (110) of claim 1, wherein the at least one reference spot (113) comprises at least one of the group consisting of an intensity calibration spot, a corner marker spot, and a polymerase chain reaction control spot.

10. The sensor carrier ( 110) of claim 1 , wherein the at least one reference spot (113) is arranged in a center (204) of an arrangement of the plurality of spots (113, 114).

11. The sensor carrier (110) of claim 1 , wherein the identification information is indicative of at least one of the group consisting of a two-dimensional assay (110), a batch to which a two-dimensional assay (110) relates, a generation of batches to which the sensor carrier (110) relates, and a product generation to which the sensor carrier (110) relates.

12. The sensor carrier (110) of claim 1, wherein at least a part of the plurality of spots (113, 114) comprises capture molecules adapted for hybridizing with complementary molecules to be detected.

13. The sensor carrier (110) of claim 1 , adapted as at least one of the group consisting of a biosensor carrier and a molecular diagnostics sensor carrier.

14. A set of sensor carriers (110), the set comprising a plurality of sensor carriers (110) of claim 1; wherein the plurality of sensor carriers (110) differ regarding the arrangement of the at least one reference spot (113) for encoding individual identification information in each of the plurality of sensor carriers (110).

15. A method of manufacturing a sensor carrier (110), the method comprising forming a plurality of spots (113, 114) on a substrate (111); arranging at least one of the plurality of spots (113, 114) as at least one reference spot (113) for encoding identification information.

16. The method of claim 15 , comprising manufacturing a plurality of sensor carriers (110) differing regarding the arrangement of the at least one reference spot (113) for encoding individual identification information in each of the plurality of sensor carriers (110).

17. The method of claim 15, comprising forming the at least one reference spot (113) and the at least one remaining of the plurality of spots (113, 114) in a common spotting procedure.

18. An apparatus (190) for determining identification information, the apparatus (190) comprising a decoding unit (160) adapted for decoding identification information of a sensor carrier (190) of claim 1 by analyzing the arrangement of the at least one reference spot (113).

19. The apparatus ( 190) of claim 18 , comprising an imaging device (150) adapted for capturing an image of the at least one reference spot (113).

20. The apparatus (190) of claim 19, comprising an electromagnetic radiation source (180) adapted for illuminating the at least one reference spot (113).

21. A method of determining identification information, the method comprising decoding identification information of a sensor carrier (110) of claim 1 by analyzing the arrangement of the at least one reference spot (113).

22. A method of using at least one reference spot (113) of a sensor carrier (110) of claim 1 for encoding identification information.