Field effect transistor for measuring biocomponents
The invention relates to a device for measuring living cells or similar biocomponents comprising a field effect transistor which is provided with a source, a drain and a channel area placed on a substrate. Said channel area connects said source and drain and is provided with a gate-electrode mounted thereon. The gate electrode has at least two laterally disposed parallel electrode areas which are perpendicular to a direction in which the channel area connects the source to the drain in such a way that they are distant and electrically insulated from each other.
1. A device for conducting measurements on biological components in a nutrient solution, especially on live cells, containing at least one field effect transistor that has on a substrate a source, a drain, and a channel area connecting said source and drain on which a gate electrode that is insulated from the channel area by a thin insulation layer is arranged, whereby the gate electrode has at least two electrode regions arranged laterally next to each other, which are separated from each other perpendicular to the direction in which the channel area connects the source electrode to the drain and are electrically insulated from each other, and whereby the electrode regions have at least partial contact to the nutrient solution that lies on an electric reference potential over a reference electrode.
2. The device as defined in claim 1 , characterized in that at least three, principally at least five, and preferably at least seven of the electrode regions are arranged in a row next to each other.
3. The device as defined in claim 1 , characterized in that the edges of the drain and the source bordering the channel area run approximately parallel to each other and that facing electrode edges of neighboring electrode regions each run at approximately right angles to the edges of the drain and/or the source bordering the channel area, respectively.
4. The device as defined in claim 1 , characterized in that an electrical insulation layer is arranged on the drain and the source, respectively, which is preferably an oxide layer whose thickness is thicker by a factor of at least 10, if applicable 30, and preferably 50 than the insulation layer, and that the electrode region and, if applicable, the insulation layer border laterally directly on the edges of the insulation layer facing the channel area.
5. The device as defined in claim 1 , characterized in that the area that is covered by the individual electrode regions at each channel area respectively, is smaller or equal to the area that covers a focal contact of a biological cell that can be immobilized on the gate electrode, and is preferably between 0.5 and 5 μm 2 .
6. The device as defined in claim 1 , characterized in that the insulation layer is designed as a silicon-oxide layer, in particular as a silicon-dioxide layer, and the gate electrode as a precious metal layer, in particular as a palladium layer, that between the insulation layer and the gate electrode a poly-silicon layer is arranged, which is interrupted in the spaces between the neighboring electrode regions, and that there is a precious metal silicide layer between the poly-silicon layer and the precious metal layer, which connects the two.
7. The device as defined in claim 1 , characterized in that the gate electrode borders directly onto a measurement chamber or a trough for the reception of the biological component(s) and, if necessary, a nutrient solution containing said biological component(s).
8. The device as defined in claim 1 , characterized in that the individual electrode regions are each connected by a circuit path with the electrical contact elements, which—for contact with the biological component—is arranged in a biological component contact area separate from the gate electrode.
9. The device as defined in claim 1 , characterized in that it has several field effect transistors, and that these field effect transistors are preferably arranged in a matrix-form on top of a common semiconductor substrate.
10. The device as defined in claim 1 , characterized in that at least one electrode region gate electrode and/or one existing and neighboring stimulating electrode in addition to the electrode regions is connected to electric stimulation equipment for the biological component.
11. Use of a device designed to measure a signal on a biological cell extracellularly, whereby the device has at least one field effect transistor, which has on a substrate a source, a drain, and a channel area connecting the said source and drain on which a gate electrode is arranged that is electrically insulated from the channel area by a thin insulation layer, whereby the gate electrode has at least two electrode regions arranged laterally next to each other, which are separated from each other perpendicular to the direction in which the channel area connects the source to the drain and are electrically insulated from each other.