EP1476218A2

EP1476218A2 - Arrangement for receiving electrical signals from living cells and for the selective transmission of electrical stimulation to living cells

Info

Publication number: EP1476218A2
Application number: EP03706118A
Authority: EP
Inventors: Emmerich Bertagnolli
Original assignee: Innovationsagentur GmbH
Current assignee: Innovationsagentur GmbH
Priority date: 2002-02-19
Filing date: 2003-02-19
Publication date: 2004-11-17
Also published as: AU2003208165A1; WO2003070316A2; WO2003070316A3; AU2003208165A8

Abstract

The invention relates to an arrangement for coupling a living cell, especially a neurone, to an electronic circuit for receiving directly or indirectly electrically active cell signals and/or for electrically stimulating the cell. Said arrangement comprises a passive electronic element (C1, R1) which is connected to a reference potential (M) by means of a connection and is connected to a switched output of an electronic switch (T1) by means of another connection. The input of said switch can be connected to a signal source or a voltage source (point B). An electroconductive contact element (1) can be brought into contact with the cell (2) and is connected between the output of the electrical switch (point P) and the connection of the passive electronic component (C1, R1) which is connected to said output.

Description

Arrangement for receiving electrical signals from living cells and for selectively transmitting electrical stimuli to living cells

The invention relates to an arrangement for coupling a living cell, in particular a nerve cell, to an electronic circuit for receiving directly or indirectly electrically active cell signals and / or for electrically stimulating the cell.

In the following, an interaction of the coupling arrangement with a cell, in which very general, directly or indirectly electrically effective cell signals, but especially electrical signals from nerve cells, are recorded and processed, is referred to as passive mode. An interaction of the coupling arrangement with a cell, which causes electrical stimulation of the cell, is referred to as an active mode.

Without restricting the generality of the inventive approach, the presented invention can also be implemented on an industrial scale, i. H. Can be realized on the basis of existing integration processes of micro and nanoelectronics, whereby initially only those processes and materials are used that are compatible on the one hand with a modern manufacturing environment for silicon chips and on the other hand are not biologically harmful. In a further embodiment, however, other data-processing-capable electronic structures, such as those represented by organic circuits, are also conceivable and possible.

Previous methods have used optical methods based on the voltage dependence of dyes (e.g. fluorescence) or extracellular metal electrodes. On the other hand, they use invasive methods, e.g. B. electrodes inserted directly into the cell for the detection of intracellular potentials. The class of invasive electrodes also includes the silicon needle, on which photolithographically produced conductor tracks with contact points at the tip are provided.

The reverse function, the electrical stimulation of a cell, has so far also been carried out by inserting electrodes.

In addition to the technical solutions mentioned for the detection and stimulation of singular cells, there are also so-called cuff electrodes. This is a cuff covered with a wire mesh, which is placed around a nerve fiber (including supply and support tissue). With cuff electrodes, however, potentials can only be summed up or impressed.

Since invasive access to the cell is always synonymous with an injury or direct or indirect destruction of the cell, there is a demand for higher

REPLACEMENT BLAπ (RULE 26) spatial and temporal resolution and electrical sensitivity with non-invasive (or non-penetrating) access to the cell. However, none of the existing devices or methods meet this requirement.

Previously, non-invasive solutions based on MOS transistors were essentially based on influencing the inversion layer in the channel of a MOSFET either directly by the nerve cell or an axon being placed on the gate dielectric, or indirectly by placing this electro-active cell part on the gate.

In one case, the contact between the cell and the transistor takes place in such a way that part of the cell membrane rests on the transistor in the channel region or is brought into contact. This area is separated from the substrate by the gate dielectric, usually a natural oxide or an artificially grown oxide. Charges or changes in charge of the overlying cell or overlying cell membrane influence the channel conductivity of the transistor. The coupling strengths achieved so far with these methods are in the range of 10% change in gate-to-cell membrane potential. The MOS transistor, covered by oxide, is completely immersed in electrolyte liquid, enriched with nutrient solution, except for the laterally extended connections, which is extremely detrimental to its service life (metal ions, but especially Na and K ions migrate into the gate dielectric and lead to progressive degradation). In addition, partially formed channels with a correspondingly variable or weak coupling result solely from incomplete coverage of the channel area.

Therefore, this approach provides only a limited solution for a few singular interfaces between tissue and electronics. Due to the lack of regular wiring options for the transistor, this solution allows only a limited number of sampling cycles and amplification and processing of the signals at the point of origin only under difficult conditions.

Furthermore, a direct actuator irritation is fundamentally excluded with this system.

A second known approach is based on the coupling of a neuron to the gate of a MOS on the basis of a direct, metallic galvanic contact between the cell membrane and the gate of the transistor. In this case too, the measuring principle is based on the influence on the channel region of the MOSFET by the charging of the gate. As an advantage it must be assessed that the sensitive gate oxide does not have to be directly exposed to the nutrient solution and therefore a longer service life of this system can be expected.

In both cases, the readout principle is based on the use of differential amplifiers - generally of the CMOS type - for detecting the change in the conductivity of the contact transistor compared to a non-contacted, regular transistor.

In both cases, stimulation of the cell requires separate stimulation lines and corresponding connection configurations, e.g. B. by producing ring contacts around the contact transistor.

The present invention has for its object to provide a solution to the disadvantages of the prior art described above.

In order to achieve this object, an arrangement for coupling a living cell, in particular a nerve cell, to an electronic circuit for receiving directly or indirectly electrically active cell signals and / or for electrically stimulating the cell is provided in accordance with the characterizing features of claim 1. Advantageous embodiments of the invention are set out in the subclaims.

In contrast to all previously known approaches, the purely passive recording of directly or indirectly electrically active cell signals is possible in the coupling arrangement according to the invention, as is direct active electrical stimulation and influencing (activation) of the cell. The optional setting of the passive or the active operating mode is carried out by the external wiring and the choice of the applied voltages and currents.

The invention can be used in particular in the following subject areas:

> Investigations of directly or indirectly electrically active activities of cells and mechanisms of pulse transmission of action potentials along axons (nerve fibers).

Signal processing in networks of living neurons. > Local and temporally resolved, simultaneous detection of the signal / stimulus reactions of a large number of cells or neurons and the associated investigation of the electrical connection of cells or neurons.

Construction or assembly of biosensors, in particular of neuronal biosensors or sensor / actuator systems and arrays.

Realization of neuron-electronic circuits.

Further possible applications of the invention relate to the construction of sensory and sensomo toric actuators and receptors for prostheses and the implementation of electronic substitutes for nerve fibers, in particular for damaged or severed nerve fibers.

In addition, the invention also offers the possibility of examining the effect of chemical or physical stimuli, but in particular of medication and bioactive media, on the functioning and functionality of cells or tissues and tissue parts.

The basic idea of the invention is based on the fact that a living cell is brought into contact with passive electrical components in such a way that a change in the electrical properties of the cell itself, or of a part of the cell, can be electrically detected via a selection circuit and that this circuit can makes it possible to optionally also bring electrical signals or stimuli to this cell or to this part of the cell.

In a preferred embodiment of the coupling arrangement according to the invention, the electronic switch is designed as a switching transistor, preferably a field-effect transistor. This guarantees excellent switching behavior with the lowest electrical power consumption.

Biological cells are only viable in the long term if they are kept in a liquid environment, generally in a nutrient solution. Accordingly, the construction of the switching arrangement according to the invention should allow liquid storage of the biological cell. This is ensured according to the invention by the provision of a nutrient solution container, in the interior of which at least one contact element projects or at least partially forms it. Taking into account the importance of this configuration Exemplary embodiments of the invention are explained below, in which the cell is shown schematically in a liquid container. However, the invention is not limited to this embodiment.

In order to ensure a defined measurement potential, in a further development of the invention an electrically conductive reference electrode connected to a reference voltage is provided, which projects into the interior of the nutrient solution container.

A long service life of the coupling arrangement according to the invention and minimal influence on the cells coupled therewith can be achieved if the electrically conductive contact element comprises a material with a low biological activity, preferably selected from high-melting metals, such as platinum, iridium, osmium, tungsten or gold, or alloys thereof; or from semiconductor silicides, such as platinum silicide, tungsten silicide, titanium silicide; or from a doped monocrystalline or polycrystalline semiconductor, such as conductive polysilicon; or made of conductive plastics.

Notwithstanding the simplicity of the schematically illustrated exemplary embodiments, the coupling arrangement according to the invention is neither restricted to single cells, nor to cells stored in liquid.

Rather, the arrangement is excellently suited for electrically coupling entire cell clusters, cell assemblies, or even entire functional cell units or combinations thereof. In this case, contact fields are arranged in the liquid container instead of individual contacts, each of which is connected and connected electrically in the manner according to the invention.

With regard to the storage of cells, cell clusters, cell function groups or combinations thereof in a liquid or a nutrient solution, it is also true that any aqueous environment, in particular also body or tissue fluids, is sufficient to achieve an electrolytic coupling.

In an expedient embodiment of the invention, a multiplicity of coupling arrangements is arranged in the form of a matrix with rows and columns, the input of a respective electronic switch being connected to a column address line and a control connection of the electronic switch being connected to a row address line. Furthermore, an addressing circuit can be provided for individually or group-wise supplying column address lines with supply or signal voltages and row address lines with control voltages. If the matrix has a structure in the form of i rows and j columns, the function of the ijth element enables a unique spatial assignment on the cell field that is assigned to the matrix. If a number of cells, for example nerve cells, are brought into contact with such a matrix, one can contact the cells individually and exchange signals in the passive mode or in the active mode. Because of the peculiarity of the receiving circuit, namely the form of the matrix, the electrical signals - as described above - can be assigned locally. It is thus possible to determine the individual active cells from a more or less large number of cells, which for example represent a functional combination, and to come into contact with them. This contact can either take place only in passive mode, or in active mode, or alternatively alternately in both modes.

If there is now a larger cell ensemble on one or more such matrix-shaped cell fields of electronic single cells, then by activating the electronic query (passive / active mode) it can be determined at which point which type of contact is present, which spatial configuration these contacts are taking, and in which way a signal sequence corresponding to the respective application purposes or which algorithm is to be used.

Inactive, or insufficiently active, or non-contacted cells can also be determined and z. B. from a further interactive processing (passive and / or active mode) can be excluded by the addressing circuit addressing evaluation means for the detection of dysfunctional cells and faulty contacts between the contact element and cell, with such detection possibly the further interaction of these cells or contact elements is selectively interruptible. Interrupting means, such as electronic switches or fuses, can be provided to selectively interrupt the interaction of cells.

The coupling arrangement according to the invention allows a multiplicity of coupling arrangements to be arranged on a chip, the chip preferably being manufactured in Si-planar technology and possibly with other technologies, such as circuits for local amplification, “on-chip logic” or “systems on chips (SoC ) "is integrated. The packing densities which can already be achieved according to the prior art allow the design of very large arrays of cell sensors and actuators, with local electronic circuits optionally being able to be accommodated at any nodes in the array. This may be necessary with low signal strengths (e.g. a stroke of the cell membrane voltage when a nerve cell is activated is typically <60 mV) and with the noise sources and interference levels that occur.

With the help of these sensor arrays and suitable addressing circuits, the signal propagation and signal processing in biological cells, cell clusters and functional cell systems, in particular in nerve cell tissues, can be observed or measured and, if necessary, the data obtained in this way can also be processed further.

In a further embodiment of the invention, the nutrient solution container is arranged on the chip. This allows the liquid storage of entire cell clusters, cell assemblies or even whole functional cell units or combinations thereof in the contact area of the contact elements and enables the chip to be used in an aqueous environment, in particular also body or tissue fluids that enable electrolytic coupling. In this embodiment, the top layer of the chip, the so-called passivation, should be designed such that the contact points or surfaces of the contact elements are attached to special penetration points and these are then brought into contact with the cells.

The coupling arrangement according to the invention can be introduced directly into living tissue or into openings in the same. According to the invention, a suitable, optionally also integrated contact is to be provided for contact with the tissue fluid, the electrolyte.

In one embodiment of the coupling arrangement according to the invention, a capacitor is provided as a passive electronic component. The optional setting of the passive or the active operating mode is carried out by the external wiring and the choice of the applied voltages and currents.

In an alternative embodiment of the coupling arrangement according to the invention, an electrical resistor is provided as the passive electronic component. In this case, the cell-resistance system represents a voltage divider, and the cell potential can be tapped via the contact element. Read, write and refresh the Potential is possible through suitable external wiring and the application of suitable voltages and currents.

Exemplary embodiments of the invention are explained below with reference to the drawings. However, the invention is not limited to these examples.

1 shows a schematic illustration of a coupling arrangement according to the invention with a capacitance as a passive electrical coupling element. FIGS. 2 and 3 show the embodiment of FIG. 1 together with various electrical equivalent circuit diagrams of the cells to be coupled. FIGS. 4 to 7 show matrix arrangements of the coupling arrangement according to the invention with a capacitance as a passive electrical coupling element. 8 shows a schematic illustration of a coupling arrangement according to the invention with a resistor as a passive electrical coupling element. FIGS. 9 and 10 show the embodiment of FIG. 8 together with various electrical equivalent circuit diagrams of the cells to be coupled. FIGS. 11 and 12 show matrix arrangements of the coupling arrangement according to the invention with a resistor as a passive electrical coupling element. FIGS. 13 and 14 show the coupling of several cells, which are in a container with nutrient solution, to coupling arrangements according to the invention. FIGS. 15 to 50 show a method according to the invention for producing a coupling arrangement according to the invention with a capacitance as a passive electrical coupling element. FIGS. 51 to 62 show exemplary embodiments with different capacities.

In the following explanations, the same or similar elements are designated with the same reference symbols, so that a repeated description of these elements can be omitted.

1 shows a schematic representation of an arrangement according to the invention for the electrical coupling of a biological cell 2 to this arrangement.

The living cell 2 is in a nutrient solution 5, which is an electrolyte. The nutrient solution 5 is arranged in a nutrient solution container 3. The potential of the nutrient solution 5 is via a reference electrode 4, for. B. a platinum electrode or a hydrogen electrode, held at a defined potential, for example ground potential or potential Uq with respect to ground. The electrical coupling of the cell 2 to an electronic circuit takes place through a direct galvanic contact with a contact element 1 made of a conductive material, e.g. B. a metal that has little or negligible biological effect, such as. B. platinum, iridium, osmium or gold, or a doped mono- or polycrystalline semiconductor, such as conductive polysilicon, or a conductive plastic.

The contact element 1 is connected at point P to a connection of a capacitor C1 and an electronic switching element T1, hereinafter also referred to as a selection transistor. The second connection of the capacitor C1 is at a reference potential, more precisely the ground potential M. The selection transistor T1 can be connected to an input connection at point B with a signal or voltage source. Its switching state (on / off) is controlled via the gate G.

Without this being interpreted as a restriction of the general approach, the reference potential is shown as ground potential M in the figures. Of course, however, any other potential or a reference voltage such as VDD / 2 can also be used for this without the function of the arrangement being impaired.

The operating principle of the arrangement according to the invention is described below.

Any change in the membrane potential of the cell 2 or of the cell part lying on the contact area of the contact element 1 is transmitted via the contact element 1 to the capacitor C1 and charged accordingly. The branching point P in FIG. 1 changes its potential in accordance with the changes in the cell 2. This blocked change in transistor T1 cannot compensate for this change in potential, and no charge (apart from the inevitable leakage currents) can flow off. If the blocked selection transistor is brought into the conductive state by applying a suitable control voltage to the gate G (gate voltage), then the charge can flow away via point B and the potential or the charge is reduced.

Conversely, a potential present at point B can be applied to point P when selection transistor T1 is made conductive (switched through). This potential is then passed on to the cell 2 via the contact element 1. The cell 2 can thus be electrically stimulated. Generally speaking, the electronic arrangement represents a type of memory cell which is charged, ie "written", by the action potentials of the cell. In this context, the derivation of the charge represents the "reading" of the previously impressed charges, that is to say the action potentials. If a potential is applied to the cell from the outside, this process represents a cell irritation.

If you only want to read the cell signal without changing it over time, you have to ensure that the information read out, i.e. the charge that has flowed out as part of the detection is immediately returned to the capacitor C1, i.e. the cell information has to be written back or restored.

Depending on the leak rate of the system, this process may also be necessary in order to maintain the cell potentials for a sufficiently long time.

1 shows a basic structure of the coupling arrangement according to the invention. The living cell is located in the container 3 with nutrient solution 5, on the bottom of which the contact point of the contact element 1 is shown schematically. This contact point is connected at point P to the selection transistor T1 and the capacitor C1. The voltage source Uq is optional and is intended to show that the electrolyte potential of the nutrient solution 5 can also deviate from the ground potential or from the reference potential.

Depending on the effectiveness of the contacts or the signal / stimulus response of the cell, the cell can be viewed in the equivalent circuit diagram EZ as a generator Sz, which emits signal pulses, as shown in FIG. 2, the cell having a cell resistance Rz, as well as a signal - / stimulus-dependent variable resistance Rx, which acts in series with the cell resistance Rz (see FIG. 3). 3 there is essentially a resistive interaction between the electronic circuit T1, Cl and the biological part, namely the cell. In this case, the electrically effective change in the cell is essentially a change in resistance.

The cell control in a cell matrix in the case of cells which represent the function of a generator Sz for electrical pulses is shown schematically in FIGS. 4 and 5. According to the above explanations, the processes “reading”, ie passive mode, “writing”, ie active mode and “refreshing” or “holding” the charge, are also possible, as is restoring the potential after the reading process. Cell activation in a cell matrix 10 in the case of cells whose signal / stimulus reaction is predominantly resistive is shown schematically in FIGS. 6 and 7. According to the above statements, the processes “reading”, ie passive mode, “writing”, ie active mode and “refreshing” or “holding” the charge, are also possible in this case, as is restoring the potential after the reading process.

FIGS. 8 to 10 show a further coupling arrangement according to the invention which, in contrast to the previous embodiments, contains a resistor R1 instead of a capacitor. In these cases, the cell-resistor system represents a voltage divider. The potential at point P can be tapped via the selection transistor T1. Reading, writing and refreshing the potential is possible as above by applying suitable voltages at point B. The corresponding matrix arrangements of such a coupling in a cell field are shown in FIGS. 11 and 12, FIG. 11 showing an example of a line control when a predominantly resistive coupling is present, and FIG. 12 an example of the cell control when an active / shows resistive coupling.

To illustrate the robustness and fault tolerance, FIGS. 13 and 14 show the very general case of the coupling arrangement according to the invention when there is a large number of cells with incorrect occupancy and cell failure.

In the case of an arrangement with a coupling capacitor C1 (FIG. 13), it can easily be seen that the absence of a cell (see A) on a contact element 1 can be easily recognized via the selection transistor T1 (potential at point P always equals the potential of the nutrient solution 5, ie the electrolyte). As long as the selection transistor T1 is switched off, this contact element at point A is ineffective.

A dysfunctional cell (2C) can also be recognized by showing no or an insufficient type of stimulus / response pattern. This cell 2C can also be switched off easily using the associated selection transistor T1. Cells 2B, 2D and 2E show a satisfactory stimulus / response pattern, i.e. the cells react actively / passively and thus have fully functioning cell contact.

In summary, it can be stated that the arrangement via a corresponding addressing circuit and addressing processes, ie algorithms, allows faulty contacts (A) and dysfunctional cells (2C) to be prevented from further interaction without impairing the interaction of the remaining cells (2B, 2D, 2E) is coming. The coupling arrangement shown in FIG. 14 with the resistance element R1 as the coupling element is also able to detect missing cell assignments (at A) and cell dysfunction (2C). However, if the cell only reacts resistively, a leakage current is to be expected, which can only be prevented if the supply line can be destroyed in the sense of a fuse.

This can be done, for example, in that point B together with point P, i.e. together with the nutrient solution 5 (the electrolyte), the potential is shifted relative to the potential point M to such an extent that in the area of the line branch between P and M the line is destroyed by the current flowing through, like a fuse. Since there is no potential difference between points B and P in this procedure, the cells in the nutrient solution are not impaired.

In the sense of the arrangement according to the invention, the container 3 with the nutrient solution 5 and the cells 2B-2E can also be applied directly to a semiconductor chip without any restrictions. In this case, the top layer of the chip, the so-called passivation, can be designed in such a way that the contact elements 1 are applied at special penetration points and these are then brought into contact with the cells.

Components with these contacts can also be inserted directly into a living tissue on the surface. A suitable, possibly also integrated contact must then be provided for contact with the tissue fluid, the electrolyte.

An exemplary embodiment for producing a coupling arrangement according to the invention with a capacitive neuron coupling is described below.

The individual method steps can be seen in cross-section in FIGS. 15A to 50A and in FIG. 15B to 50B as a so-called layout, in the text below figure numbers without the indices A or B being common references to cross-section and layout.

On a substrate (layer 10) (FIG. 15), which will generally be p-doped silicon, three layers are deposited or produced one after the other, namely: layer 11 (eg silicon dioxide), layer 12 (eg poly Silicon), layer 13 (eg silicon nitride), as can be seen in FIG. 16. The transistor region TO is then defined with the aid of a photo technique 1 via a resist mask (layer 14) (FIG. 17) and the region defined in this way is etched generated by layer 13 (Fig. 18). The next step is to remove the coating material (FIG. 19) and, as shown in FIG. 20, to oxidize the area outside of TO (LOCOS, local oxidation of silicon) in order to remove the so-called field oxide area (layer 15) outside the transistor area TO. to create. The field oxide area (layer 15) can, however, also be generated by any other technique, for example shallow trench isolation.

After the oxidation, the remaining parts of the layer 13, 12, 11 are removed (FIG. 21). If necessary, after a suitable overetching step to remove the residual oxide (eg native oxide), the transistor region is exposed and the gate stack is built up. For this purpose, after the gate oxide (layer 16) (FIG. 22) or another suitable dielectric has been grown, a poly Silicon layer (layer 17) (FIG. 23) either deposited doped or deposited undoped and subsequently doped (for example n-doped). According to the prior art, this layer can also be another conductive material, for example a metal (metal gate technology)

A thin silicon dioxide layer or another suitable dielectric is then grown (layer 18) (FIG. 24) or deposited on this poly-silicon layer.

In the next step, the gate G0 or the gate plane is defined photolithographically (layer 19) and then generated by structuring the layers 18, 17 and 16. In this process, the gate G0 (layer 17) is generated (see FIGS. 25 and 26).

The photoresist (layer 19) is then removed (FIG. 27) and the so-called lightly doped drain (layer 20) zone is self-aligned via an implantation process or another suitable doping process (FIG. 28).

In the next step, a so-called side wall spacer (layer 22) (FIG. 30) is generated by conformal deposition of a dielectric (layer 21) (FIG. 29) and subsequent anisotropic etching back. After the spacer has been created, the so-called Heavily Doped Drain (HDD) implantation is carried out (layer 23) (FIG. 31) and the source / drain connection region is defined. In the exemplary embodiment, a dielectric layer, for. B. silicon dioxide (layer 24) (Fig. 32) and planarized or planarized deposited.

Subsequently, the contact windows K1 and K2 are defined (layer 25) by means of a photo technique 3 (FIG. 33) and produced by etching the layers 24, 18 and possibly 16 (FIG. 34). These contact holes are filled with a conductive material (for example tungsten / titanium nitride) (layer 27) (FIG. 35), if necessary with the aid of a barrier layer (layer 26).

In the next step, a metallic layer (layer 28) is applied (FIG. 36) and structured using a photo technique 4 (FIG. 37 and FIG. 38).

After completion of the metallization level M1 (layer 28), a dielectric layer is applied in the exemplary embodiment, which is either planarized or deposited in a planarizing manner (layer 30 in the picture) (FIG. 39).

The contact hole KC is then defined using a photo technique 5 (layer 28) (FIG. 40) and openings are produced by etching the corresponding layers (layer 30 and layer 24, possibly layer 16), which extend to the connection region of the transistor (FIG. 41 ).

This contact hole KC is filled - if necessary with the aid of a barrier layer - with a conductive material (e.g. doped polysilicon, or a metal such as e.g. tungsten / titanium nitride) (layer 32) (Fig. 42).

In the next step, a conductive layer (layer 33) is applied and structured using a photo technique 6 (production of the capacitance electrode) (FIG. 43).

A thin dielectric is then deposited (layer 35) and then a conductive layer (layer 36). z. B. doped polysilicon, deposited (Fig. 44), which serves as a second electrode (counter electrode) of the capacitance structure.

The layout of this second electrode of the capacitance structure is defined using a photo technique 7 and is produced by etching the layer (FIG. 45).

After removal of the lacquer (layer 37), a thick dielectric single or multiple layer is deposited and optionally planarized or planarized (layer 38 and layer 39) (FIG. 46).

The contact hole K0 is then defined using a photo technique 8 (layer 40) and by etching the corresponding layers (layer 39 and layer 38, and layer 36 and Layer 35) creates an opening that extends to the first electrode of the capacitance structure (FIG. 47). After the etching, the photoresist is removed. -

By depositing a conformal dielectric (layer 41) (Fig. 48) and by anisotropic etching back in the sense of a spacer technique (Fig. 49), this contact hole is lined with an insulator on the inside of the side wall, while contact with the first electrode of the capacitance structure is maintained.

This contact hole is filled - if necessary with the aid of a barrier or adhesive layer - with a conductive material (eg doped polysilicon, or a metal such as tungsten / titanium nitride) (layer 42 and layer 43) (Fig. 50) that the surface remains essentially flat. This contact area establishes the coupling to the biological cell according to the invention. As can be seen from FIGS. 51A (cross section) and 51B (layout) and in an enlarged representation in FIG. 53, the cell contact can be established directly via this docking point. The illustration described here is called variant A.

In a variant B (FIGS. 52A (cross section) and 52B (layout)), without restricting the generality of the invention, the first electrode of the capacitance structure cannot extend directly to the connection region of the transistor, but only to a metal contact, which in turn has a normal contact is connected to the transistor.

In a variant C (FIG. 54) of the invention, the cell contact to the capacitance can also take place without using a metallic intermediate piece. In this exemplary embodiment, the dielectric layer to which the cell rests has a conical shape.

In a variant D (FIG. 55), instead of a cylindrical capacity, a hollow-cylindrical capacity is formed.

In a variant E, capacitance structures are also conceivable that have a calyx-like structure to enlarge the surface (FIGS. 56 to 58).

Furthermore, in a variant F capacities are also conceivable which are designed as trench cells (FIGS. 59 to 62). In this case, the cells can be connected directly to the inner electrode or to the connection areas. A regular metal contact can of course also be carried out and the cells connected to it.

Claims

claims:

1. Arrangement for coupling a living cell, in particular a nerve cell, to an electronic circuit for receiving directly or indirectly electrically active cell signals and / or for electrically stimulating the cell, characterized by a passive electronic element (Cl, Rl), which has a connection is connected to a reference potential (M) and is connected to another connection to a switched output of an electronic switch (Tl), the input of which can be connected to a signal or voltage source (point B), an electrically conductive contact element (1) having the cell (2) can be brought into contact and is connected between the output of the electrical switch (point P) and the associated connection of the passive electronic component (Cl, Rl).

2. Coupling arrangement according to claim 1, characterized in that the electronic switch (Tl) is a switching transistor, preferably a field effect transistor.

3. Coupling arrangement according to claim 1 or 2, characterized in that a nutrient solution container (3) is provided, in the interior of which at least one contact element (1) protrudes or at least partially forms it.

4. Coupling arrangement according to claim 3, characterized in that an electrically conductive reference electrode (4) connected to a reference potential or a reference voltage (Uq) is provided, which projects into the interior of the nutrient solution container (3).

5. Coupling arrangement according to one of claims 1 to 4, characterized in that the electrically conductive contact element (1) comprises a material with low biological activity, preferably selected from refractory metals, such as platinum, iridium, osmium, tungsten or gold, or alloys thereof ; or from semiconductor silicides, such as platinum silicide, tungsten silicide, titanium silicide; or from a doped monocrystalline or polycrystalline semiconductor, such as conductive polysilicon; or made of conductive plastics.

6. Coupling arrangement according to one of the preceding claims, wherein a plurality of coupling arrangements in the form of a matrix (10) with rows (i, i + 1) and columns (j, j + 1) is arranged, characterized in that the input of a respective electronic switch (Tl) is connected to a column address line (j, j + 1) and a Control connection (G) of the electronic switch (Tl) with a row address line (i, i + 1) is connected.

7. Coupling arrangement according to claim 6, characterized by an addressing circuit for individual or group loading of column address lines (j, j + 1) with supply or signal voltages and row address lines (i, i + 1) with control voltages.

8. Coupling arrangement according to claim 7, characterized in that the addressing circuit has addressing evaluation means for the detection of dysfunctional cells (2C) and faulty contacts (A) between the contact element and the cell, with such detection possibly further interrupting the interaction of these cells or contact elements selectively is.

9. Coupling arrangement according to claim 8, characterized in that interrupting means, such as electronic switches or fuses, are provided for selectively interrupting the interaction of cells.

10. Coupling arrangement according to one of the preceding claims, characterized in that a multiplicity of coupling arrangements is arranged on a chip, the chip preferably being produced in Si planar technology and optionally with other technologies, such as circuits for local amplification, “on-chip logic ", or" Systems on chips (SoC) "is integrated.

11. Coupling arrangement according to claim 10 in conjunction with claim 3, characterized in that the nutrient solution container is arranged on the chip.

12. Coupling arrangement according to one of claims 1 to 1 1, characterized in that the passive electronic component is a capacitor (Cl).

13. Coupling arrangement according to one of claims 1 to 1 1, characterized in that the passive electronic component is an electrical resistor (Rl).