WO2003079003A2

WO2003079003A2 - Method for capturing macromolecular biopolymers by means of a field effect transistor, biosensor and circuit arrangement comprising a biosensor and an evaluation circuit coupled thereto

Info

Publication number: WO2003079003A2
Application number: PCT/DE2003/000888
Authority: WO
Inventors: Thomas Haneder; Hagen Klauk; Günter Schmid; Roland Thewes
Original assignee: Infineon Technologies Ag
Priority date: 2002-03-18
Filing date: 2003-03-18
Publication date: 2003-09-25
Also published as: WO2003079003A3; DE10211901A1

Abstract

The invention relates to a biosensor comprising: a support; a gate region situated on said support; a first and a second source/drain region situated in said gate region and a body region positioned between the first and the second source/drain region, whereby the body region comprises an organic material; and a body connection located on the body region, which is configured in such a way that macromolecular biopolymers can be immobilised on said connection.

Description

Method for detecting macromolecular biopolymers by means of a field effect transistor, biosensor and circuit arrangement with biosensor and evaluation circuit coupled to it

The invention relates to a method for detecting macromolecular biopolymers by means of a field effect transistor, a biosensor and a circuit arrangement with a biosensor and an evaluation circuit coupled therewith.

Knowledge of the molecular and biochemical basics e.g. decoding of human genes in the context of the human genome has increased dramatically in recent years. Of particular interest are currently methods associated with the terms "functional genomics" or "proteomics", in which either e.g. the genes present in a cell or expressed at a specific time or the corresponding proteins are examined and detected.

Optical methods are mostly used today for examining, for example, the expression pattern of a cell using nucleic acids or generally for detecting nucleic acids. For this purpose, small amounts of different single-stranded nucleic acid molecules serving as capture molecules are preferably immobilized in a punctiform manner in an ordered grid (array) of, for example, some 10, 100 or 1000 points (dots) on a surface, for example made of glass, plastic, gold or other materials (see for example [1], [2]). An analyte (ie a liquid to be examined) which contains nucleic acids labeled with a fluorescent dye is then transferred pumped this surface. In this case, nucleic acids with capture molecules complementary to them can form double-stranded hybrid molecules on the surface of the support. After excitation of the fluorescence marking by means of a laser and subsequent measurement of the optical fluorescence signal, it is determined on the basis of the detected, emitted light beams whether or not a DNA strand to be detected with the correspondingly predetermined sequence is contained in the analyte.

Proteins can also be detected using optical detection methods which are based on the immobilization of a capture molecule on a surface of a support made of glass, plastic, silicon dioxide or metal. Here too, markings that emit an optical signal such as a fluorescence signal are detected with the aid of an excitation unit such as a laser and an external detection unit for the emitted radiation (cf. e.g. [3], [4]).

These optical processes are usually very complex, because e.g. a very precise adjustment of the detection means for detecting the emitted light beams is required so that these light beams can be correctly detected in a position-specific manner. These methods are also disadvantageous because the fluorescence radiation is detected by external spectrometers or CCD cameras. These are expensive and complex to operate.

Other proposals are to electronically detect macromolecular biopolymers on surfaces by measuring currents caused by redox-active markings or by measuring impedance. This eliminates the complex optical arrangement (laser, scanner, Adjustment devices) for reading out the carrier surfaces and reworking the resulting fluorescence images of the reactive surfaces. Instead, an electronic signal is obtained directly, which can be graphically displayed and further processed.

For example, from [5] a method for the detection of or DNA molecules is known, in which biosensors are used for the detection, which are based on electrode arrangements.

2a and 2b show such a sensor as described in [5]. The sensor 200 has two electrodes 201, 202 made of gold, which are embedded in an insulator layer 203 made of insulator material. Electrode connections 204, 205 are connected to the electrodes 201, 202, to which the electrical potential applied to the electrode 201, 202 can be supplied. The electrodes 201, 202 are arranged as planar electrodes. DNA probe molecules 206 are immobilized on each electrode 201, 202 (cf. FIG. 2a). The immobilization takes place according to the so-called gold-sulfur coupling. The analyte 207 to be examined is applied to the electrodes 201, 202. The analyte can be, for example, an electrolytic solution of different DNA molecules.

If the analyte 207 contains DNA strands 208 with a sequence that is complementary to the sequence of the DNA probe molecules 206, these DNA strands 208 hybridize with the DNA probe molecules 206 (cf. FIG. 2b).

Hybridization of a DNA probe molecule 206 and a DNA strand 208 takes place only if the sequences of the respective DNA probe molecule 206 and the corresponding DNA Strands 208 are complementary to each other. If this is not the case, no hybridization takes place. Thus, a DNA probe molecule of a given sequence is only able to bind to a specific one, namely the DNA strand with a complementary sequence, ie to hybridize with it.

If hybridization takes place, the capacitance between the electrodes also changes, as can be seen from FIG. 2b, in addition to other electrical parameters. This change in capacity can be used as a measurement variable for the detection of DNA molecules.

Furthermore, sensors are known in which a reduction / oxidation-recycling method is used to record macromolecular biopolymers (cf., for example, [6, 7]. In this method, there is, for example, a redox-active label on the proteins to be recorded. After binding of the proteins to be detected on capture molecules, this marking triggers a cycle of oxidation and reduction of suitable molecules, which leads to an electrical circuit current used for the detection of the proteins. In this method, electrode arrangements are used to detect this circuit current.

The biosensors used for the above electronic methods are also based on substrates / chips which are made from inorganic semiconducting materials such as silicon. The semiconducting material can either be used as a pure carrier material for the sensors, or it can be integrated circuits in addition to detection units such as electrodes as part of the semiconductor manufacturing process eg manufactured using CMOS technology. The latter type of sensor can also be called active sensors due to the integrated circuits. Compared to passive sensors, these sensors have the advantage of being able to amplify, process and process even weak sensor signals directly on-chip. This makes it possible, for example, to manufacture active sensors with a significantly smaller sensor area and / or significantly higher sensitivity and immunity to interference than passive variants.

However, expensive CMOS processes are required to manufacture such active semiconductor sensors. This makes them seem unsuitable for certain biotechnological and biochemical applications, because these applications usually require a sensor that is used only once and should therefore be inexpensive. One reason for the only one-time use of sensors is that one wants to rule out possible chemical / biological cross-contamination of the used areas from trial to trial and the resulting incorrect results.

Biosensors based on passive semiconductor chips, i.e. Sensors that do not have integrated circuit elements require large-area detection elements in order to be able to guarantee a certain degree of sensitivity and dynamics. The omission of on-chip signal preprocessing with the help of integrated circuits e.g. based on a CMOS process reduces the manufacturing costs of such biosensors compared to active semiconductor chips. In principle, however, such sensors cannot

Achieve the performance of sensors with active chips. Furthermore, the requirements for the external devices required for operation and reading are greater, and the The susceptibility to interference from radiated electromagnetic radiation, for example from nearby power supplies of commercially available electronic devices, is greater.

Another possibility, e.g. the so-called eSENSÖR from Motorola uses gold electrodes on printed circuit boards. A microfluidic chamber that is open to the surface and into which the analyte can be pumped is attached above the circuit board. Electrical connections go from the individual electrodes to the edge of the insulation

PCB where contacts are. The connection to a separate electronic reading device can be established [cf. 8,9]. Through elaborate processes in the preparation of the surface and the biochemical labeling of the analyte, it can be achieved that

Reader can detect a difference in the reading current between electrodes on which a reaction has taken place and those on the surface of which no reaction has taken place.

The principle of the eSENSOR is due to the external arrangement of the measuring electronics, however, firstly much less sensitive and secondly less robust to electromagnetic interference than a sensor that processes signals in close proximity to the

Sensor takes place. In addition, the

Electrode areas should be relatively large in order to obtain a measurable signal that can be derived from the sensor.

Another disadvantage of passive semiconductor sensors and sensors based on the eSENSOR principle is that the sample volume required for measurement and successful detection also increases with the required area. With only small ones available sample volumes, such sensors are therefore poor, if at all suitable.

Furthermore, a self-conducting (depletion mode) FET is known from [10], in which the gate electrode has been removed and which can be used for the detection of macromolecular biopolymers such as nucleic acids and proteins. A disadvantage of the FET used as a sensor is that a complex process is required for its production and that, owing to the lack of the gate electrode, it is not possible to produce layers above it (metallization). In order to be able to wire such transistors, the level of the gate dielectric must be exposed either after metallization has taken place. This possibility means high technical effort and thus increased costs.

Finally, [11] also discloses a FET with a removed gate electrode, in which nanoparticles are used to form the FETs.

[23] discloses a measuring circuit with a biosensor using an ion-sensitive field effect transistor.

[24] discloses a method for improving the

Performance of organic thin film transistors.

[25] discloses a method for producing a biosensor with a planarized surface, which prevents the risk of tearing of biological or biochemical membranes. [26] discloses a chloride-free process for the production of alkylsilanes, suitable for microelectronic applications.

[27] discloses an ion sensor with a

Field effect transistor, which ion sensor is designed to determine an ion concentration of a sample liquid to be examined.

[28] discloses an object with an organic thin film transistor.

[29] discloses a method for producing an integrated CMOS circuit with an ISFET and with an evaluation MISFET in polysilicon technology.

The invention is based on the problem of providing an alternative method and an alternative sensor for the detection of macromolecular biopolymers.

The problem is solved by the methods, the biosensor for detecting macromolecular biopolymers and the circuit arrangement with the features according to the independent claims.

In the first of the methods for detecting macromolecular biopolymers, a field effect transistor is used which has a gate region, a first source / drain region, a second source / drain region, a body region and a detection region. Here, a) the body region of the transistor has an organic material, b) the detection region is a unit for immobilizing macromolecular biopolymers configured, and c) the detection area forms an interface to the body area, this interface lying opposite the interface that the body area forms with the gate dielectric (see FIG. 1 to FIG. 1c; FIG. 3).

With this method, first molecules are immobilized on the detection area. The first molecules to be detected are macromolecular biopolymers or binding molecules to which the macromolecular biopolymers to be detected can bind.

In the second method for detecting macromolecular biopolymers, a field effect transistor is also used which has a gate region, a first source / drain region, a second source / drain region, a body region and a detection region. Furthermore, a) the body area has an organic material and b) the detection area is also designed as a unit for immobilizing macromolecular biopolymers. However, this method uses a different transistor geometry, because in contrast to the first method, the detection area forms an interface to the gate area, this interface lying opposite the interface that the gate area forms with the gate dielectric (cf. .ld to Fig.lf).

As in the first method, the second method also immobilizes first molecules in the detection area, the macromolecular biopolymers or

Binding molecules are to which the macromolecular biopolymers to be detected can bind. In both methods (at least) a first electrical measurement is carried out with the transistor, specifically after the immobilization of the first molecules on the

Detection range. The detection area is then brought into contact with a sample which can contain second molecules, the second molecules being macromolecular biopolymers or binding molecules which can bind to the macromolecular biopolymers to be detected. This allows complexes to be formed from first and second molecules. The method then (at least) carries out a second electrical measurement with the transistor, and the macromolecular biopolymers are recorded by comparing the result of the first electrical measurement with that of the second electrical measurement by their effect on the transistor characteristic.

The biosensor for detecting macromolecular biopolymers has a carrier, a gate region applied to the carrier, first and second source / drain regions applied to the gate region and a body region located between the first and second source / drain regions and one on the Body area arranged body connection. The body area has an organic material. The body connector is set up in such a way that macromolecular biopolymers can be immobilized on it.

The circuit arrangement has a biosensor and an evaluation circuit which is coupled to the biosensor.

The biosensor in turn has a carrier, a gate region applied to the carrier, a first and second source / drain applied to the gate region. Area, a body area located between the first and second source / drain area, the body area having an organic material, and a body connection arranged on the body area, which is set up in such a way that macromolecular biopolymers can be immobilized thereon.

To put it clearly, the present method and the biosensor of the invention are largely based on two findings. The first finding is that the changes that a complex formation between a macromolecular biopolymer and a binding molecule that has a (specific) affinity for the macromolecular biopolymer have a great influence on the characteristics of a field-effect transistor such as the transfer characteristic (drain current versus

Gate voltage). The second finding is that a "four-terminal sensor" can be formed with a field-effect transistor which has a gate region / a gate electrode, in which a fourth connection, for example the upper side of the body region opposite the gate , can be used directly for detection (see Fig. 3) This connection can be referred to as a body or substrate connection.

The use of a gate electrode has the advantage that any drift of the component in the environment of biological media can subsequently be compensated for in a simple manner, or the sensor transistor can be brought to an operating point that is optimally sensitive for signal detection by simple means. This is not possible with transistors without a gate electrode, since these cannot be controlled due to the missing gate electrode. The use of a gate electrode which can be controlled separately by means of a freely selectable voltage also has the advantage that the transistor can be brought to an operating point in which changes in the control variables which determine the transistor current or other electrical transistor parameters have a strong or less pronounced effect. By choosing a suitable operating point, the sensitivity of the transistor can be maximized, which is helpful if very small changes are to be detected. On the other hand, a lower sensitivity may be desired if sensor signals within a very large dynamic range, for example changes over several orders of magnitude, are to be considered. The control variable is preferably the change in the transistor parameters due to the biochemical processes on the body area.

In principle, any field-effect transistor in which the body region has an organic material can be used in the present method and the biosensor. In the context of the invention, the body region is understood to mean that region in which the channel of the transistor can form.

In a preferred embodiment of those disclosed here

A method or the biosensor uses a transistor in which the body region of the transistor is formed by a layer with an organic semiconducting material. Such a transistor is preferably a so-called organic thin-film transistor.

These transistors, which are preferably used here, are known in principle, for example, from [12] to [14]. You can go to can be a transistor in which there is only one layer with semiconducting organic material, such as that described, for example, in [12] and [13]. In the case of these transistors, a metallic gate region or a gate electrode (for example made of nickel) is first applied to a suitable carrier (see FIG. 1), over which there is a layer made of a dielectric and the regions for source and drain. The dielectric can consist of an inorganic insulator material such as silicon dioxide or silicon nitride. However, it is also possible to form the layer of the dielectric from or with a dielectric plastic material such as polyvinyl alcohol, poly-4-hydroxystyrene or polyvinylidene fluoride. The areas • (electrodes) for source and drain can be made of palladium or platinum, for example. Between source and

Drain is (as the only organic electrically active layer) a layer made of the organic semiconductor pentazen, which consequently forms the body region of the transistor. If necessary, a passivation layer made of an electrically insulating inorganic material such as silicon dioxide or an insulating polymer material such as again e.g. Polyvinyl alcohol, poly-4-hydroxystyrene or polyvinylidene fluoride.

In principle, any organic material that shows the electrical properties and behavior of a semiconductor material can be used as the organic semiconducting material in the transistor and biosensor described here.

The semiconducting organic material is preferably selected from the group consisting of pentazene, anthracene, tetrazene, oligothiophene, polythiophene, polyaniline, poly-p-phenylene, Poly-p-phenylvinylene, polypyrrole, phthalocyanine, porphyrin and derivatives thereof. It can be seen from this that the semiconducting material can be a “molecular system” such as pentazene, anthracene, tetracene, phthalocyanine, porphyrin or oligothiophene or a “polymer system” (one or more polymer compounds) such as polythiophene, polyaniline, poly-p-phenylene , Poly-p-phenylvinylene, polypyrrole.

Another example of a material in monomer form are the fullerenes such as C ₆₀ C ₇₀ , C _7S - (Buckminster) fullerenes. An example of suitable derivatives of one of the above materials are the aforementioned poly (9, 9-dioctylfluorene-co-bithiophene), poly (3-alkyl tiophene) such as poly (3-hexylthiophene) or poly (3-octylthiophene). On

Examples of oligothiophenes are compounds with 1 to 10 thiophene units, preferably 6 thiophene units. Examples of semiconducting phthalocyanines or porphyrins are the corresponding (organometallic) complexes of copper such as copper phthalocyanine or

Perfluorokupferphthalocyanin. For the purposes of the invention, it is possible to use the semiconducting organic materials on their own or, if desired, as mixtures of at least two such materials.

Furthermore, field-effect transistors can also be used in the methods of the invention, in which the body region has an organic inert polymer material as (electrically inert) matrix material, in which inorganic semiconducting particles are embedded. These transistors are therefore also polymer transistors in the sense of the invention. In the layer forming the body region, the semiconductor properties are consequently fulfilled by inorganic semiconducting materials. Any known inorganic semiconducting material can be used. However, for reasons of cost, among others, common semiconductor materials such as silicon, silicon carbide, germanium, gallium arsenide, gallium nitride, indium phosphide, cadmium selenide or mixtures thereof are preferably used in the present invention. A particularly preferred material is polycrystalline silicon, which is generated, among other things, as waste in the production of silicon single crystals during zone melting and which only has to be comminuted here for use as an inorganic semiconductor material. The semiconductor material can be doped or undoped.

The particle size of the inorganic semiconducting material used here is generally between 100 μm and 1 nm, preferably between 50 μm and 0.1 μm or 0.05 μm. For example, n- and p-conductive nanoparticles, as described in [15], which are embedded in an organic matrix, are also used.

In principle, any of the polymer materials which are mentioned below as polymer materials for forming the gate dielectric in transistors or as a carrier material of the biosensor can be used as the electrically inert organic matrix material.

In a further embodiment of the transistor, the body region of which is formed by a layer in which inorganic semiconducting particles are embedded in an organic matrix material, this layer can supporting semiconducting organic material (as matrix material). This material can be one or more of the above-mentioned organic semiconducting polymers such as polythiophene, polyaniline, poly-p-phenylene and the like. his. Likewise, monomeric or low molecular weight, supporting (semiconducting) organic additives such as pentazene or oligothiophenes (for example with 1 to 10 thiophene units, preferably 6 thiophene units) can also be present as such organic material. The proportion of such supporting polymers and additives in the semiconducting layer is generally about 0.5 to 25% by volume, preferably at most 10% by volume.

The transistors preferably used here can also be formed entirely from organic materials, preferably organic polymer and oligomer materials.

For example, As described in [14], the source, gate and drain region made of an electrically conductive polymer material such as poly (3, 4-ethylenedioxythiophene, which is doped with polystyrene sulfonic acid (PEDOT / PSS), can be applied to a carrier. The body region can again, for example, from pentazene or an oligomer material such as poly (9, 9-dioctylfluorene-co-bithiophene) (F8T2).

The layer of the gate dielectric of both such transistors and that of the transistors described above, in which organic and inorganic materials are combined, can consist of a dielectric organic polymer material. Examples of polymer materials that can be used here are common dielectric plastics such as epoxy resins, polyalkylenes such as polyethylene or polypropylene resins, polyvinyl alcohols, polystyrenes, polyurethanes, polyimides, polybenzoxazoles, polythiazoles, polyethers, polyether ketones, polyacrylates, polyterephthalates, polyethylene naphthalate, polycarbonates of all kinds and other known plastics of this type, as described, for example, in [16]. The organic polymers used can preferably be dryable and curable materials, preferably IR and / or UV-curable polymers such as polystyrenes, epoxy resins, polyalkylenes, polyimides, polybenzoxazoles, polyacrylates, since these are used in the

Manufacturing the transistors are easy to process.

The use of transistors, which consist partly or completely of organic materials and are also referred to hereinafter simply as polymer transistors, offers several advantages.

First, they allow the use of numerous materials that are compatible with biological reactions, such as silver, which can also be chlorinated (Ag / AgCl electrode) to form a reference electrode, or titanium, TiN (which is also metallic and a relatively important material), gold, Platinum or iridium or also conductive oxidic materials, such as indium tin oxide (ITO), which are partly or hardly compatible with the usual processes used in traditional semiconductor manufacturing, such as the manufacturing process for active CMOS sensors (chips). Thus, the use of the present polymer transistors enables the use of silver as an electrode material, for example in the form of a silver wire or a silver electrode (see above). On the one hand, this can be applied directly to the carrier material or integrated into it. Such an electrode can also be used, for example Reference electrode, in a housing of the sensor or in a separate chamber, which separates the reaction chamber from the evaluation circuit, for example. This material must be subjected to a chlorination step to form a reference electrode.

Secondly, such polymer transistors and thus also the sensors disclosed here based on them can be produced by means of printing techniques such as inkjet printing, which results in a considerable simplification of the production process and a reduction in costs.

Thirdly, the body region of the transistor can be formed as a very thin layer with the aid of the organic semiconducting materials. Studies carried out within the scope of the invention have shown that a layer thickness in the range from 10 to 50 nm is sufficient for the body region in order to ensure that the transistor functions. The actual electricity transport takes place only within a few monolayers of the organic semiconductor on the border to

Gate dielectric instead. In principle, however, the body area can be made as thick as desired (a few 100 μm), provided that leakage currents do not increase the off-current of the transistor by a tolerable amount. However, the body area can also have a greater thickness, as long as a satisfactory detection sensitivity, as will be explained below, can be achieved.

In one embodiment of the method or the biosensor, as already mentioned, the detection area forms an interface to the body area, this interface lying opposite the interface that the body area forms with the gate dielectric. This is one Given transistor geometry, in which the detection area is arranged on the body area of the transistor, and the body area is in turn above the gate area (see Fig.la to Fig.lc). In the case of the second transistor geometry, in which the detection area is one

Forms interface to the gate area and this interface is opposite to the interface that the gate area forms with the gate dielectric (see Fig.ld to Fig.lf), body area is located below the gate area, but the detection area is arranged above the gate area is (see Fig. 1). With this construction, the detection area (the "sensor area") can also be located, for example, to the side of the imaginary connecting line between the source and drain area. For example, the detection area can then be in an area near the

Located transistor channel in which the body material is not covered by the gate electrode, or figuratively speaking, look out of the transistor or form an "island".

In the method, a change in the impedance or capacitance at the surface of the detection area is preferably measured in the electrical measurement, which is caused by the formation of complexes from macromolecular biopolymers and binding molecules to be detected.

In one embodiment of the method, the conductivity (of the channel) of the transistor is determined for the predetermined measurement of the gate, drain and source voltage or the threshold voltage of the transistor during the electrical measurement. The electrical parameters for this can be a) the current flowing through the transistor, b) the effective control voltage which is necessary for the transistor to carry a specific current, or c) the voltage at one of the Control electrodes, which is necessary for the transistor to carry a certain current, are determined.

In a preferred embodiment of the method, the gate electrode is controlled by the freely selectable voltage, whereby the setting of a suitable operating point can maximize the sensitivity of the transistor.

For the purposes of the invention, detection is understood to mean both the qualitative and quantitative detection of macromolecular biopolymers in an analyte (to be examined). This means that the term "capture" also includes determining the absence of macromolecular biopolymers in the analyte.

In the present method, a biopolymer to be detected can on the one hand be a molecule that by means of a first molecule, i.e. of a capture molecule located on the detection area (a unit for immobilization) of macromolecular biopolymers.

On the other hand, a molecule to be detected can also be applied from a sample / analyte to the detection area (a unit for immobilization) and then with the second molecule which has (specific) binding affinity for the molecule to be detected

Process and / or using the biosensor disclosed here.

For the purposes of the invention, “unit for immobilization” is understood to mean an arrangement which has a surface on which first molecules can be immobilized, which can either be capture molecules or macromolecular biopolymers to be detected; ie an arrangement which has a surface to which the first molecules can bind through physical or chemical interactions. These interactions include hydrophobic or ionic (electrostatic) interactions and covalent bonds. The detection area or the body connection of the biosensor used in the present method is designed as such a unit which enables immobilization of binding molecules (capture molecules) or macromolecular biopolymers.

Examples of suitable surface materials which can generally be used for the design of the detection area or of the body connection are metals such as gold, plastics such as polyethylene, polypropylene or polystyrene or inorganic substances such as silicon dioxide.

If the surface of the detection area or the body connector is not suitable per se for immobilizing the first molecules, it can be modified for the immobilization by suitable functionalization. Such functionalization can e.g. by forming and derivatizing a monolayer as described in [3] on page 25, line 2 to page 31, line 5 or [17], FIG. 4. Before this, the surface of the immobilization unit can still be activated by methods such as plasma etching, gas phase deposition of suitable materials (e.g. chemical or physical deposition, (CVD; PVD) (cf. [3], page 19)) If the detection range is used, the immobilization can also be carried out as described in [18].

An example of a physical interaction that involves the immobilization of the first, for example, serving as capture molecules Molecules causes adsorption on the surface. This type of immobilization can take place, for example, if the immobilization agent is a plastic material that is used for the production of microtiter plates (for example polypropylene or

Polystyrene). However, a covalent linkage of the first molecules to the immobilization unit is preferred because the orientation of the molecules can thereby be controlled. The covalent linkage can take place via any suitable linker chemistry ("linker chemistry") (cf. e.g. [17, Fig. 7].

The following options are available for the design (the surface) of the detection area or the body connection.

A) The surface can be modified so that it becomes compatible with the biomolecules to be detected and is suitable for immobilization. If, for example, the body area is formed by an organic semiconducting material such as pentazene, its surface can be modified after activation. To produce functional groups, the finished pentacene layer is subjected to a short acid plasma flash in the range of seconds. The surface is thereby provided with functional groups containing oxygen (hydroyl, carbonyl and carboxyl). This can be treated (silanized) with reagents such as silanes, in particular trichlorosilanes and trialkoxysilanes, which have previously been functionalized, for example in the alkyl radical, with other groups which are suitable for immobilizing the first molecules (cf. here, for example, [19]). and [3], page 27, lines 1-5). Amino acids can also be attached to the carboxy groups directly via an amide bond tie. A monolayer of the reagent binds to the functional groups. The surface can also be oxidized / functionalized by wet-chemical processes such as Caro's acid (H ₂ 0 ₂ / H ₂ S0) or KMn0 / H ₂ S0 ₄ etc. The functionalization itself can also be carried out in a variety of ways. In particular, plasmas which contain reactive species with halogens, in particular Cl, ammonia or sulfur, are suitable for subsequent binding of nucleic acids such as DNA by means of amide, ester, glycoside, phosphate or also sulfide formations. These can also be used to complex metal-containing enzymatically active species. However, the plasmas should act as gently as possible on the organic semiconductor surface in order not to unnecessarily dope the semiconductor.

Since the formation of a complex of the binding molecule and the macromolecular biopolymer to be detected takes place directly on this surface, this complex formation has a direct influence on the state of the body / channel region and thus on the characteristics of the transistor, which is advantageous in terms of detection sensitivity.

B) On the other hand, the organic semiconductor materials can be chemically modified before the manufacturing process of the transistor or biosensor, ie before the detection area is applied, such that they carry the molecules suitable for immobilization as substituents. This is explained using the example of regional polythiophenes. In order to ensure the charge carrier mobility sufficient for the transistor function through increased π-π overlap, the thiophene monomer units are substituted in the 3-position, for example by hexyl or octyl groups, and then polymerized in a regioregular manner. This Substituents can now also carry functional groups on those termini to which, as shown in case A, can be attached or can themselves have or represent such a group with an amino acid sequence at which the hybridization can take place. The imide unit in naphthalene bisimides is suitable for this purpose [19].

C) It is also possible that the organic semiconductor layer is made up of several individual layers. For example, a non-biologically active layer can be deposited to stabilize the transistor channel. A semiconductor layer is deposited over it, which carries biologically active substituents. This possibility takes into account the fact that the actual current flow takes place only in the range of a few nanometers (<10 μm) above the boundary layer between the semiconductor and the dielectric. For example, an inert organic semiconductor is applied directly to the gate dielectric (e.g. pentazene is vapor-deposited). A further layer e.g. from 6.13-

Evaporated pentacenequinone. Bioactive molecules are now attached to the extremely reactive carbonyl bonds. Alternatively, the functionalization of the 6,13-pentacenequinone can take place before the application, which in particular facilitates the introduction of sensitive polypeptides, proteins or amino acid sequences. Accordingly, the layer facing the channel made of an N-

Fluoroalkylnaphthalinbis id (n-semiconductors, [19]), while the side facing the sensor consists of an N-amino acid-substituted naphthalene bisimide. Through the use of different species, a "stabilization" of the entire structure against external Influences reached so that the redox potentials can be adjusted accordingly.

In the case of the biosensor disclosed here, this semiconductor layer can be the body connection, the “fourth” connection.

D) It is also possible not to modify the layer of the organic semiconductor material in order to form the biocompatible surface, but rather a metal that can be easily integrated using biochemical detection methods, e.g. Au to use. It is possible e.g. apply a layer of gold on the semiconducting material as long as there is no short circuit between source and drain (see Fig. lg)

On this layer, e.g. from [17] it is known that the capture molecules necessary for the biochemical reaction can be safely and easily immobilized on the gold surface by means of the gold-sulfur coupling.

E) Another alternative is the integration of other conductive inorganic non-metallic materials such as (poly) silicon, which e.g. can be deposited on the semiconducting layer above a material used for the wiring process. Catcher molecules for macromolecular biopolymers or the biopolymers themselves can be immobilized on silicon surfaces.

F) It is also possible to apply a dielectric above the organic semiconductor layer, onto which capture molecules or macromolecular biopolymers to be detected can be immobilized. The dielectric can be inorganic in nature, such as silicon dioxide, silicon nitride, or an organic dielectric, such as Polyvinyl alcohol, which can be used as passivation of the transistor as described above. In principle, all connections that can be deposited or processed above the channel region material can be used for the modification. It goes without saying that neither the deposition nor the structuring of this material may damage the underlying layers and materials of the transistor.

Such materials can be used if that

Detection signal not on a current measurement or the like rests, i.e. no electrically conductive connection between the detection unit and analyte (electrolyte), in particular the capture molecules, their reaction partners or possibly additional markers, is necessary. An example of this is the impedance method.

G) Finally, it is also possible to additionally apply a further organic or inorganic layer on the dielectric which is suitable for immobilization. In an embodiment, this further layer is a metal such as gold. This embodiment is advantageous if, on the one hand, a galvanic separation between the analyte (a sample to be examined) is desired, the biochemical reaction to be examined on another

Surface to be performed as the dielectric itself. This can be advantageous if, for example, the potentials present in the analyte would trigger a side reaction that could lead to the measurement result being falsified (for example, reduction or oxidation of water leads to a pH change in the vicinity of the electrode). The length and thickness of the layer which forms the body region of the transistor of the biosensor disclosed here can be varied within a wide range. Both length and width can be selected from a few μm (the width even smaller, from approx. 5 to 10 nm upwards, the width is only limited by the tolerable leakage current) to a few 100 μm. This is advantageous because consequently the size of the area of the detection area on which the complex formation takes place can be selected depending on the available volume and / or the required sensitivity. The reaction area, ie the area of the detection area, can extend both over the entire area of the active transistor area or only over part of this area.

In a preferred embodiment, the transistor of the biosensor is a folded (polymer) transistor shown in FIG. 8, which provides an order of magnitude of the electrical parameters to be evaluated that is optimal for measurement and circuit technology. In this context, folding is understood to mean that several individual transistors are connected in parallel, so that their electrical modeling can be considered as a single overall transistor with a very large width. The drain and source areas are used on both sides of their longitudinal edges, which leads to an area-efficient implementation of such components.

In a preferred embodiment, the biosensor has a plurality of transistors, which are preferably arranged in a regular arrangement, an array, on the (common) carrier or embedded therein. In principle, any material on which the various units of the sensor can be permanently applied can be used as the carrier material for the biosensor. Examples of suitable carrier materials are insulators such as paper, plastic films, ceramics or glass, and also metal coated with an insulator or metal coated with plastic. Examples of carrier materials made from suitable organic polymer materials are common dielectric synthetic plastics such as epoxy resins, polyalkylenes such as polyethylene or polypropylene resins,

Polyesters, polystyrenes, substituted polystyrenes such as poly-o-hydroxystyrene, polyvinyl compounds such as polyvinyl alcohols or polyvinyl carbazoles, polyurethanes, polyimides, polybenzoxazoles, polythiazoles, polyethers, polyether ketones, polyacrylates, polyterephthalates, polyethylene naphthalates or polycarbonates of all types. In particular, biodegradable polymers are also suitable, such as poly-degradable polymers , The surface properties of such a polymer material or glass support can easily be changed, so that hydrophilic or hydrophobic surfaces are created. This is desirable for many biochemical sensors.

In one configuration of the sensor, the detection area, which is located above the gate area, has a compartment in which it is preferably designed in the form of a pan or a pot. This makes it easier to take up small sample volumes, e.g. be applied by means of a pipetting robot. This configuration of the sensor is therefore particularly suitable for use with high-throughput devices such as those in the

Genome and proteome research can be used. In particular, nucleic acids, oligonucleotides, proteins or complexes of nucleic acids and proteins can be detected with the present sensor as macromolecular biopolymers.

Macromolecular biopolymers include, for example, (longer chain) nucleic acids such as DNA molecules, RNA molecules, PNA molecules or cDNA molecules or shorter oligonucleotides with e.g. 10 to 50 bases, in particular 20 to 40 bases understood. The nucleic acids can be double-stranded, but also have at least single-stranded regions or, for example by preceding thermal denaturation (strand separation) for their detection, can be present as single strands. The sequence of the nucleic acids to be detected can be at least partially or completely predetermined, i.e. be known. Other macromolecular biopolymers are proteins or peptides. These can be made up of the 20 amino acids usually found in proteins, but can also contain naturally occurring amino acids or e.g. be modified by sugar residues (oligosaccharides) or contain post-translational modifications. Furthermore, complexes from several different macromolecular biopolymers can also be detected, for example complexes from nucleic acids and proteins.

If proteins or peptides are to be detected as macromolecular biopolymers with the biosensor, ligands which can specifically bind the proteins or peptides to be detected are preferably used as capture molecules. The capture molecules / ligands are preferably linked to the detection area by covalent bonds. Low-molecular enzyme agonists or enzyme antagonists, pharmaceuticals, sugars or antibodies or other suitable molecules which have the ability to specifically bind proteins or peptides are suitable as ligands for proteins and peptides.

If DNA molecules (nucleic acids or oligonucleotides) of a given nucleotide sequence are detected with the biosensor described here, they are preferably detected in single-stranded form, i.e. if necessary, they are converted into single strands before the detection by denaturing as explained above. In this case, DNA probe molecules with a sequence complementary to the single-stranded region are then preferably used as capture molecules. The DNA probe molecules can in turn

Have oligonucleotides or longer nucleotide sequences as long as they do not form any of the intermolecular structures that prevent hybridization of the probe molecule with the nucleic acid to be detected. However, it is also possible to use DNA-binding proteins or agents as the capture molecule.

It should be noted that it is of course possible to use the sensor at hand to not only detect a single type of biopolymer in a single series of measurements. Rather, several macromolecular biopolymers can be recorded simultaneously or one after the other. For this purpose, for example, several types of first molecules (capture molecules), each of which has a (specific) binding affinity for a specific biopolymer to be detected, can be bound on the detection area of a transistor, and / or several transistors can be used are, whereby only one type of capture molecule is bound on the detection surface of each transistor.

In principle, any evaluation circuit that can be coupled to the sensor or a transistor of the sensor and that can further process a signal received by the sensor, e.g. compares the result of the first electrical measurement with that of the second electrical measurement and thus records macromolecular biopolymers.

In a preferred embodiment, the evaluation circuit has at least one component with a semiconducting layer with an organic material.

The layer with the organic material (the component of the evaluation circuit) can have an organic semiconducting material. On the other hand, this layer with the organic material can also have an organic inert polymer material as the matrix material, in which inorganic semiconducting particles are embedded. This means that the same possibilities exist for the configuration of the semiconducting layer as for the transistors used for detection.

The component of the evaluation circuit with such a semiconducting layer can be, for example, a diode, a resistor, capacitor or transistor.

Such a diode can have, for example, a layer with an n- or p-semiconducting organic material or both a layer made of an n-conducting and a layer of a p-conducting organic semiconductor material (see [20, 21]). For example, the polymer polyvinyl carbazole [cf. 20] or p-semiconductors based on condensed aromatic ring systems such as pentazene, anthracene or tetracene. Suitable n-semiconducting organic materials are based, for example, on electron-poor aromatic compounds. Examples are the fluorinated or non-fluorinated amido derivatives of naphthalene tetracarboxylic acid dianhydride or fluorinated derivatives of phthalocyanine or thiophene, such as, for example, perfluorocupferphthalocyanine or bis (Nl, 1-dihydropentadecafluorooctyl) naphthalene bisimide or bis (N-1,1-difluorophenyl) bisimide ], Hexadecaflurokupferphthalocyanine [22]. The usability of the inorganic semiconducting particles mentioned above and described in [15] is also within the meaning of the invention.

Such a diode can also be designed as a Schottky diode. For example, a layer sequence of aluminum-pentazene-palladium shows a pronounced diode character.

Resistors or capacitors with organic semiconducting materials can e.g. be constructed analogously to the resistors or capacitors described in FIG. 4 or FIG. 6 of [21]. In [21] these passive components are manufactured using inkjet techniques. In general, however, these can also be produced by standard lithography and metallization.

In a preferred development of the circuit arrangement, the at least one component of the evaluation circuit is a transistor. A transistor in which the layer with the (organic) semiconducting material is the preferred Body area of the transistor forms. This transistor is preferably a "polymer transistor" as described above and can be used in the biosensor and method of the invention.

In an advantageous development of the circuit arrangement, there is the entire _. Evaluation circuit from transistors with a layer made of an organic semiconducting material, ie from the "polymer transistors" mentioned here.

In a further embodiment, the circuit arrangement has a multiplicity of biosensors. A circuit arrangement is particularly preferred in which one or more of the biosensors with the associated coupled evaluation circuit are applied to a common carrier.

This embodiment is particularly advantageous if all biosensors and components of the evaluation circuit are based on polymer materials. In this case, the entire circuit arrangement can be produced by printing techniques such as inkjet printing, which means both a significant reduction in the necessary process steps compared to the conventional technology based on inorganic semiconductors (for the evaluation circuit alone, the number of process steps can be approximately 300 CMOS processes can be reduced to approx. 50) as well as a cost saving.

Embodiments of the invention are shown in the figures and are explained in more detail below.

Show it Figures la to li field effect transistors that can be used in the method and the biosensor of the invention;

Figures 2a and a sketch of two planar, ^'by means of which the existence of DNA strands to be detected in an electrolyte (Figure 2a) or the non-existence (Figure 2b) can be detected 2b;

Figures 3a to 3f a biosensor to different

Process states on the basis of which the method is explained according to an embodiment of the invention;

Figures 4a to 4c a symbolic representation of the field effect transistor according to the invention (Fig.4a) and two different electrical equivalent circuit diagrams (Fig.4b, Fig.4c);

Figure 5 shows an evaluation circuit of the invention

Biosensor based on a polymer transistor according to a first embodiment of the invention;

Figure 6 shows an evaluation circuit of the biosensor of the invention according to a second embodiment of the

Invention;

Figure 7 shows an evaluation circuit according to a third embodiment of the invention;

Figure 8 shows an embodiment of the biosensor, which is based on a folded polymer transistor. Fig.l shows various configurations of a field effect transistor 100 which can be used in the invention.

In the field effect transistor 100 according to Fig.la to Fig.lc is on a carrier 101, e.g. consists of polyethylene naphthalate, applied a gate region 102, which consists of nickel. On the gate region 102 there is in turn a layer 103 made of a dielectric material such as silicon dioxide, which separates the gate region 102 from the first source / drain region 104 and the second source / drain region 105, which are made of palladium. Between the source / drain regions 104, 105 there is a layer 106 made of pentacene as a semiconducting organic material. The layer 106 forms the body region of the transistor 100. Alternatively, the body region 106 can also be formed from a layer of inert polymeric matrix material in which inorganic semiconducting particles are embedded.

For the immobilization of capture molecules or the biopolymers to be detected and thus for the formation of the region of decompression, a functional layer 107, e.g. consists of octadecyltrichlorosilane molecules can be generated as follows.

The pentacene layer is then functionalized with a short oxygen plasma treatment (1 to 2 seconds). The functionalization is preferably completed by a rinsing step with deionized water, but the normal air humidity is also sufficient for the functionalization). The reaction is then carried out with silane-functionalized oligonucleotides to remove the capture molecules (see, for example, FIG. 2, for example 206). to dock. In addition to the chlorinated silanes (mono-, di- and trichloro-), less reactive alkoxysilanes (mono-, di- and trialkoxy, eg methoxy) are also suitable. In addition to silane coupling, other coupling methods such as amide, ester or glycosidic bonds, ionic or complexing bonds can also be used.

As previously discussed, layer 107 can also consist of a gold layer which enables coupling via the gold-sulfur bond. 107 may also include a dielectric.

The field effect transistor 100 according to Fig.ld to Fig.lf initially has a layer 106 of semiconducting organic material on the carrier 101. This layer 106 forming the body region of transistor 100 has e.g. Tetracene on. The transistor 100 also has a first and a second source / drain region 104, 105 made of platinum. A layer 103 is located above the source / drain regions 104, 105 or the body region 106

Silicon dioxide as a dielectric on which the gate region 102 made of nickel is applied. The gate area 102 also has a layer 108 of gold, which forms the detection area, on which either macromolecular biopolymers to be detected or capture molecules are immobilized. Alternatively, the gate area can be formed directly and completely from gold. The gate area then also directly represents the detection area.

The field effect transistor 100 according to FIG. 1g to Fig.li basically has the same structure as the transistor according to Fig.la to Fig.lc. However, there is an additional layer 108 in the transistor 100 according to FIGS. which can be used as an additional electrode for immobilizing biopolymers if, for example, the body area is not to be functionalized directly to form an immobilization unit.

The field effect transistors according to Fig.l with the layer with semiconducting organic material or the layer with the polymeric matrix material, in which inorganic semiconducting particles are embedded, can be produced with the method described in [12]. The deposition of the source / drain regions 104, 105 takes place before the deposition of the semiconducting layer 106 in the embodiments according to FIGS. 1c, 1c and Fig. Le, while in the embodiments according to FIGS. 1b, 1d and 1d If the semiconducting layer 106 is applied in front of the source / drain regions 104, 105.

3a shows a field effect transistor 300 with which a detection method described here can be carried out. The transistor 300 has a carrier 301, which consists of polyethylene naphthalate, a gate region 302 made of nickel, and a dielectric layer 303 made of silicon dioxide arranged thereover. Furthermore, the transistor 300 has a first source / drain region 304 and a second source / drain region 305 made of platinum as well as a layer 306 made of pentazen between the source / drain regions 304, 305 as a semiconducting organic material. Layer 306 forms the body region of transistor 300 and is at the same time modified by, as described above with reference to FIG

Form detection area for immobilization of macromolecular biopolymers. Layer 306 has one Pot or tub shape to facilitate the absorption of liquid analytes.

On the layer 306 of the transistor 300 there are first oligonucleotide molecules 307 (FIG. 3a) and second ones

Oligonucleotides 308 (FIG. 3b) applied as capture molecules. The oligonucleotide molecules 307 and 308 have different base sequences.

To the purine bases adenine (A) and guanine (G) and the

Pyrimidine bases thymine (T) or cytosine (C) can in each case complement sequences of the DNA strands complementary to the sequences of the probe molecules in the usual manner, i.e. hybridize by base pairing via hydrogen bonds between A and T or between C and G. When using others

Correspondingly, other bases, in the case of an RNA molecule, for example uridine (U), are used for nucleic acid molecules.

Fig.3c and Fig.3d show the transistor at the time when an analyte (not shown) with the detection area, i.e. here layer 306, the transistor, is brought into contact. The case is shown that the analyte contains DNA molecules 309 which have a predetermined first nucleotide sequence which is complementary to the sequence of the first DNA capture molecules

(Probe molecules) 307. In this case, the DNA molecules 309 complementary to the first DNA probe molecules 307 hybridize with the first DNA probe molecules 306, which are applied to the detection region of the semiconducting layer (the body region) 306.

The conditions under which the hybridization is carried out are (stringent) selected so that only the Hybridize sequences of DNA strands with the specific (perfectly) complementary sequence. Therefore, the DNA molecules 309 complementary to the first DNA probe molecules do not hybridize with the second DNA probe molecules 308.

The result after contacting the analyte and an optional washing step is therefore that double-stranded hybrid molecules are located on the semiconducting layer 306 according to FIG. double-stranded DNA molecules have formed. 3f, only the second DNA probe molecules 308 are present as further single-stranded molecules on the detection area 306 of the transistor according to FIG. 3f.

Before the analyte has been brought into contact with the detection area, a first electrical measurement is carried out with the transistor 300. In this embodiment of the method, the current flowing through the transistor is measured.

In transistor 300, the molecules immobilized during hybrid formation modulate an electric field which acts on the body region of the transistor and which thus influences the channel current of the field-effect transistor. Thus, the current through the transistor is a direct measure of the amount of charge immobilized on the detection area 306. A second electrical measurement is therefore carried out after contacting the analyte, in which the transistor current is determined. The comparison of the two electrical measurements is used to detect the nucleic acid molecules. If the difference determined in the comparison exceeds a (predetermined) threshold value, it is concluded from this that DNA molecules 309 were present in the sample that are (perfectly) complementary to the capture molecules 307, and possibly in what concentration (cf. .3e). If there is a difference below the threshold value, it is concluded that no DNA molecules were present. This is the case with the example here in that the statement can be made that there were no DNA molecules that were among the given ones

Hybridization conditions (perfect) are complementary to the capture molecules 308. This classification according to the threshold value can also be carried out in the other methods disclosed here.

In this context, the following should be noted again regarding the detection method disclosed here. Even if in the case of nucleic acids as biopolymers to be detected during hybridization or e.g. in the complex formation between an immobilized antigen and a specific one

If no charges are bound to the antibody, the reaction can be detected. For example, the hybridization or, in general, the complex formation between the two binding partners changes the gate capacitance or - as described here primarily by way of example - the substrate steepness (this term is borrowed from the MOS transistor) or the substrate penetration and thus the transfer characteristic of the transistor. This change in the transfer characteristic is used here to detect complex formation and biopolymers.

Another way to operate the sensor of the invention is continuously, for example during contacting the analyte with the sensor surface or also during an optional washing step after the measurement. Changes to the sensor surface can then be tracked transiently.

At this point it should also be noted that it is also possible with the present method, e.g. a so-called mismatch, i.e. to determine a hybridization between not perfectly complementary nucleic acids, since the complementarity influences the properties of the field effect transistor, and thus e.g. influences the current flow through the transistor (cf. [10]).

FIGS. 4 a to 4 c show a symbol 400 for the field effect transistor 100 according to the invention with the following four connections (see FIG. 4 a):

A first source / drain region 401,

A second source / drain region 402,

• a gate connection 403, and • a body connection 404, which connects with the analyte in

Is brought into contact.

4b and 4c show two different electrical equivalent circuit diagrams for the field effect transistor 100 according to the invention shown in FIG.

In the first electrical equivalent circuit diagram 410 according to FIG. 4b, it is assumed that the behavior of the field effect transistor 100 according to the invention is achieved by connecting two field effect transistors in parallel, a first one

Field effect transistor 411 and a second field effect transistor 412, which have different properties in their electrical parameters, such as for example, their threshold voltage, their steepness, etc., can be approximated sufficiently well and can thus be replaced in the equivalent circuit.

This equivalent circuit assumes that the gate connection and the body connection each control a transistor independently of one another.

In the case of a very thin body material, the second electrical equivalent circuit diagram 420 shown in FIG. 4c is more suitable for describing the electrical behavior, since in this case it is assumed that the control effect of the control electrodes, i.e. of the gate connection 403 and the body connection 404 extends to the entire volume of the body material. In this equivalent circuit diagram, a MOS voltage acts on a MOS field-effect transistor 421, which results from the weighted sum of the electrical voltages present at the gate connection 403 and at the body connection 404, these voltages possibly also adding an additive surcharge are provided in order to be able to take into account different work functions and similar effects, as is described, for example, for deriving the threshold voltage in conventional MOS field-effect transistors in [10]. For this reason, the second electrical

Equivalent circuit 420 has an adder 422 coupled with its output to the gate connection of the MOS field-effect transistor 421, the first input of which is coupled to the body connection 404 via a first amplifier element 423 and a first voltage source 424 and the second

Connection is coupled via a second amplifier element 425 and a second voltage source 426 to the gate terminal 403. Evaluation circuits for evaluating the signal provided by the biosensor are described below.

5 shows an evaluation circuit 500 of the biosensor according to the invention based on a polymer transistor according to a first exemplary embodiment of the invention.

According to this exemplary embodiment, the transistor 400 according to the invention is

/ Drain area to the second source / drain area electric current flowing measured.

In this context, FIG. 5 shows the electrical occurring in the analyte at the body connection 404

Voltage VE, symbolized in FIG. 5, as analyte voltage source 501 connected to body connection 404.

The first source / drain connection 401 is coupled to the ground potential 502.

The gate voltage VG present at the gate connection 403 is provided via the symbolically represented gate voltage source 503.

The second source / drain region 402 is via a current measuring device 504 with which the current flowing through the transistor 400 is measured, i.e. the electrical flowing through the body region of transistor 400 from first source / drain region 401 to second source / drain region 402

Current is measured, coupled to a symbolically represented drain voltage source 505, which provides the drain voltage. 6 shows an evaluation circuit 600 according to a second exemplary embodiment of the invention.

According to this exemplary embodiment, the change in the effective control voltage which is required for the transistor 400 to carry an electrical current of a predetermined current strength is measured.

In operation of transistor 400, this change may preferably occur at first source / drain region 401, i.e. can be tapped from the source node of transistor 400.

In this case, transistor 400 is operated as a source follower. The voltage at the first source / drain region 401 is measured by means of a voltage measuring device 601 connected to the first source / drain region, a current source 603 being coupled to the first source / drain region 401.

When operating as a source follower, an advantageous transmission characteristic is obtained in particular. In this case, the drain-to-source potential affects the current only slightly, or the influence of the gate-to-source potential is significantly greater than the influence of the drain-to-source potential for maintaining a constant current , if the transistor operating point is placed in the saturation range or the sub-threshold range.

In the same manner as in the first embodiment 501 is coupled via the body terminal 404 to the transistor 400, a ^{'analyte-voltage} source and a gate voltage source 503 to the gate terminal 403 and a Drain voltage source 505 with the second source / drain region 402.

7 shows an evaluation circuit 700 according to a third exemplary embodiment of the invention.

According to this exemplary embodiment, the voltage at one of the control electrodes is measured, which is required for the transistor to carry an electrical current of a predetermined current.

According to this exemplary embodiment, a control circuit 701 is provided, which controls the gate voltage source 503 in such a way that the current measured by the current measuring device 504 and flowing through the transistor 400 is kept constant.

Thus, according to this embodiment, the electrical potential applied to the body connection 404, i.e. the electrical voltage VE provided by the analyte voltage source 501 is kept constant and the gate voltage is regulated accordingly.

Thus, the evaluation circuit according to the third exemplary embodiment has an electrical voltage acting on the transistor via the analyte, which is symbolized by the analyte voltage source 501 and which is coupled on the one hand to the ground potential 702 and on the other hand to the body connection 404.

The first source / drain region 401 is directly coupled to the ground potential. Furthermore, the gate connection 403 is coupled to the gate voltage source 503 and the gate voltage source 503 to the ground potential 702 via the control circuit.

The second source / drain region 402 is coupled via the current measuring device 504 to the drain voltage source 505, which in turn is coupled to the ground potential 702. In the event that the transistor 400 according to the invention is modeled by the first electrical equivalent circuit diagram 410 shown in FIG. 4b, the transistor 412 controlled by the gate connection 403 is preferably “disconnected” by applying a suitable control voltage to the gate connection 403, ie switched into a state in which the second transistor 412 delivers such a small electric current that it does not make a significant contribution and thus has to be taken into account in the signal processing.

As part of the evaluation according to the evaluation circuit according to the second exemplary embodiment or according to the third exemplary embodiment, the electrical voltage at the gate connection 403 should be applied to the same electrical potential before and after the biochemical reaction that has taken place.

If the procedure according to the third exemplary embodiment is used for the evaluation, the electrical

Potential of one of the control electrodes kept constant and the change in potential at the other electrode, which is regulated, for example, by means of the control circuit, measured.

Polymer transistors can be easily manufactured with very different channel lengths and channel widths from a few μm and below to a few 100 μm. For this reason, the size of the reaction area can be chosen, for example, depending on the available sample volume or the required sensitivity. The reaction area can consist of the entire active area of the transistor area or only part of this area.

In particular, a folded polymer transistor 800 (see FIG. 8) can also be used in order to provide an order of magnitude of the electrical parameters to be evaluated that is optimal for measurement technology and circuit technology. The folding of the polymer transistor 800 leads to an overall transistor with a very large electrical width, it being noted that the relative change in the measured parameters, i. the relative sensitivity of the biosensor does not change.

Due to process engineering, it can be easily achieved that the sensor surface has a pot-like or pan-like shape, i.e. has a compartment. This makes it easier to take up small sample volumes.

By arranging several of the transistors shown in FIG. 3 with bio-compatible sensor areas on the same carrier next to one another, a matrix-like arrangement of sensor surfaces can thus be achieved very easily according to the invention.

It should be noted that the possibilities described above can of course also be combined, in particular also for the production of arrays from such biosensors, which additionally contain circuits for processing the sensor signals, which are also carried out with the aid of Polymer transistors can be realized.

The following publications are cited in this document:

[1] http: // ww. affymetrix. com / technology / tech_j? robe_content. html

[2] http: // www. affymetrix.com/technology/ tech_spotted_content .html

[3] WO 00/04382

[4] N.L. Thompson, B.C. Lagerholm, Total Internal Reflection Fluorescence: Applications in Cellular Biophysics, Current Opinion in Biotechnology, Vol. 8, pp. 58-64, 1997

[5] P. van Gerwen, Nanoscaled Interdigitated Electrode Arrays for Biochemical Sensors, IEEE, International Conference on Solid-State Sensors and Actuators, Chicago, pp. 907-910, June 16-19, 1997

[6] R. Hintsche et al. , Microelectrode arrays and application to biosensing devices, Biosensors & Bioelectronics, Vol. 9, pp. 697-705, 1994

[7] R. Hintsche et al. , Microbiosensors Using Electrodes Made in Si-Technology, Frontiers in Biosensorics, Fundamental Aspects, edited by F. W. Scheller et al. , Dirk Hauser Verlag, Basel, pp. 267-283, 1997

[8] http: //www.motorola.com/lifesciences/morloc00.htm

[9] http: // ww .microsensor. com [10] FK Perkins et al. , An Active Microelectronic

Transducer for Enabling Label-Free Miniaturized Chemical Sensors, Tech. Dig. IEDM, 2000, pp. 407-410 (publication 17.3)

[11] WO 00/20916

[12] M.G. Kane et al, Analog and Digital Circuits using Organic Thin-Fil Transistors on Polyester Substrate, IEEE Electron Device Letters, Vol. 21, No. 11, pp. 534-536, 2000

[13] CD. Sheraw et al, Fast Organic Circuits on flexible Polymeric Substrates. IEEE, 2000

[14] R. Sirringhaus et al, High-Resolution InkJet Printing of All-Polymer Transistor Circuits, Science, Vol. 290, pp. 2123-2126

[15] M. Shim, N-Type colloidal Semiconductor Nanocrystals, Nature Vol. 407, pp. 981-983, 2000

[16] Plastic Compendium, 2nd edition 1988, Franck / Biederbick, Vogel-Buchverlag Würzburg, ISBN 3-

8023-0135-8, pp. 8-10, 110-163

[17] Mirsky et al. , Capacitive monitoring of protein immobilization and antigen-antibody reactions on monomolecular alkylthiol fil s on gold electrons,

Biosensors & Bioelectronics Vol. 12, No. 9-10, pp. 977 - 989, 1997 [18] T. Cass, FS Ligler, Immobilized Biomolecules in

Analysis, pp. 195ff, Oxford University Press, 1998, ISBN 0-19-963636-2

[19] H. Katz et. al. , A soluble and air-stable organic semiconductor with high electron mobility, Nature Vol. 404, pp. 478-481, 2000

[20] WO 99/39373

[21] WO 99/19900

[22] B. Crone et. al. Large Scale complementary integrated circuits based on organic transistors, Nature Vol., 403, pp. 521-523, 2000

[23] US 5,309,085 A

[24] US 6,335,539 sheets

[25] DE 41 15 398 AI

[26] US 2002 002299 AI

[27] DE 38 76 602 T2

[28] US 5,596,208 A

[29] DE 41 15 397 AI LIST OF REFERENCE NUMBERS

100 field effect transistor

101 carriers

102 gate area

103 layer of dielectric material

104 Source / drain area

105 Source / drain area

106 layer with semiconducting material (body area)

107 monomolecular layer of molecules

108 additional shift

200 sensor

201 gold electrode

202 gold electrode

203 insulator layer

204 electrode connection

205 electrode connection

206 DNA probe molecules

207 analyte

208 strand of DNA

300 field effect transistor

301 carriers

302 gate area

303 dielectric layer

304 first source / drain region

305 second source / drain region

306 layer of the body area

307 first oligonucleotide molecules (probe molecules) 308 second oligonucleotide molecules (probe molecules) 309 DNA molecules

400 symbol for field effect transistor

401 first source / drain region

402 second source / drain region 403 gate connector

404 body connector

410 equivalent circuit diagram

411 first field effect transistor

412 second field effect transistor

420 equivalent circuit diagram

421 MOS field effect transistor

422 adders

423 first amplifier element

424 first voltage source

425 second reinforcement element

426 second voltage source

500 evaluation circuit

501 analyte voltage source

502 ground potential

503 gate voltage source

504 current measuring device

505 drain voltage source

600 evaluation circuit

601 voltage measuring device

602 ground potential

603 power source

700 evaluation circuit

701 control circuit

702 ground potential

800 polymer transistor

Claims

claims

1. A method for detecting macromolecular biopolymers by means of a field effect transistor which has a gate region, a first source / drain region, a second source / drain region, a body region and a detection region, with a) the body region comprises an organic material, and b) the detection area is designed as a unit for immobilizing macromolecular biopolymers, and c) in which the detection area forms an interface to the body area, this interface lying opposite the interface that the body area with the gate Dielectric forms, • where first molecules are immobilized on the detection area, the first molecules being macromolecular biopolymers or binding molecules to which binding molecules the macromolecular biopolymers to be detected can bind

In which at least one first electrical measurement is carried out with the transistor,

• the detection area is brought into contact with a sample that can contain second molecules, the second molecules being macromolecular

Are biopolymers or binding molecules to which the macromolecular biopolymers to be detected can bind, as a result of which complexes of first and second molecules can form, • in which subsequently at least a second electrical one

Measurement is carried out with the transistor, and

• in which macromolecular biopolymers are detected by comparing the result of the first electrical measurement with that of the second electrical measurement.

2. Method for detecting macromolecular biopolymers by means of a field effect transistor which has a gate region, a first source / drain region, a second source / drain region, a body region and a detection region, with a) the body region comprises an organic material, and b) the detection area is designed as a unit for immobilizing macromolecular biopolymers, and c) in which the detection area forms an interface to the gate area, this interface being that of

Opposite surface that the gate region forms with the gate dielectric,

• First molecules are immobilized on the detection area, the first molecules to be detected macromolecular biopolymers or

Binding molecules are to which binding molecules the macromolecular biopolymers to be detected can bind

• The detection area is brought into contact with a sample which can contain second molecules, the second molecules to be detected being macromolecular biopolymers or binding molecules to which the macromolecular biopolymers to be detected can bind, as a result of which complexes of first and second molecules can form .

• in which at least one second electrical measurement is then carried out with the transistor, and • in which macromolecular biopolymers are recorded by comparing the result of the first electrical measurement with that of the second electrical measurement.

3. The method according to claim 1 or 2, wherein the body region of the transistor comprises an organic semiconducting material.

4. The method according to claim 1 or 2, wherein the body region comprises an organic inert polymer material as the matrix material, in which inorganic semiconducting particles are embedded.

5. The method according to any one of claims 1 to 4, wherein in the electrical measurement, a change in the impedance or capacitance is measured at the surface of the detection area, which is caused by the formation of complexes of macromolecular biopolymers and binding molecules to be detected.

6. The method according to any one of claims 1 to 5, in which the conductivity of the electrical measurement

Body region of the transistor or the threshold voltage of the transistor is determined.

7. The method according to claim 6, wherein a suitable operating point is selected to the

Maximize transistor sensitivity.

8. biosensor with a support,

With a gate region applied to the carrier, with a first and second source / drain region applied to the gate region, and

With a body area located between the first and second source / drain areas, the body area having an organic material, and with a body area arranged on the body area.

Connection that is set up in such a way that macromolecular biopolymers can be immobilized on it.

9. Biosensor according to claim 8, in which a transistor is used, in which the body region has an organic inert polymer material as the matrix material, in which inorganic semiconducting particles are embedded.

10. Biosensor according to claim 8, in which a transistor is used in which the body region has an organic semiconducting material.

11. The biosensor of claim 9 or 10, wherein the transistor is an organic thin film transistor.

12. Biosensor according to one of claims 10 or 11, wherein the organic semiconducting material is selected from the group consisting of pentazene, antrazene, tetrazene, oligothiophene, polythiophene, polyaniline, poly-p-phenylene, poly-p-phenylvinylene, polypyrrole , Phthalocyanine, porpyhrin and derivatives thereof.

13. Biosensor according to one of claims 9 to 12, wherein the transistor is a folded polymer transistor.

14. Biosensor according to one of claims 8 to 13, which has a plurality of transistors.

15. Circuit arrangement with a biosensor, which has a carrier, • with a gate region applied to the carrier,

With a first and second source / drain region applied to the gate region and With a body area located between the first and second source / drain areas, the body area having an organic material,

And a body connection arranged on the body area, which is set up in such a way that macromolecular biopolymers can be immobilized thereon, and

• an evaluation circuit that is coupled to the biosensor.

16. Circuit arrangement according to claim 15, wherein the evaluation circuit has at least one component with a layer with an organic material.

17. The circuit arrangement according to claim 16, wherein the layer with the organic material comprises an organic semiconducting material.

18. Circuit arrangement according to claim 16, in which the layer with the organic material has an organic inert polymer material as the matrix material, in which inorganic semiconducting particles are embedded.

19. Circuit arrangement according to claim 17 or 18, wherein the at least one component of the evaluation circuit is a transistor.

20. Circuit arrangement according to claim 19, wherein the layer with the organic material forms the body region of the transistor.

21. Circuit arrangement according to one of claims 17 to 20, in which the entire evaluation circuit consists of transistors with a layer of an organic semiconducting material.

22. Circuit arrangement according to one of claims 15 to 21, which has a plurality of biosensors.

23. Circuit arrangement according to one of claims 15 to 22, in which the biosensor and the evaluation circuit are applied to a common carrier.