DD244818A1 - MEMBRANE ASSEMBLY FOR PRESSURE SENSORS - Google Patents

Abstract

The invention relates to a diaphragm assembly for a pressure sensor, which is used on the basis of acoustic surface waves for pressure measurement in gases, gas mixtures and fluids in all areas of technology application. The object and the object of the invention are to develop a membrane arrangement for pressure sensors which, by geometrically varying a membrane layer structure and by suitable positioning of the membrane layer structure over the surface of an SAW component, effects a preferably pressure-proportional mechanical deformation of the membrane and achieves an increase in sensitivity. According to the invention, this object is achieved in that a membrane layer structure consists of an electrically conductive base layer with an electrically nonconductive cover layer arranged thereon and in that the membrane layer structure with a Membranaufnahme- and tensioning device in a basic distance of 5 to 100 mm optionally via the interdigital transducer structures, on the Wandlermittenflaeche or is fixed over the entire surface of an AOW device.

Description

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The membrane layer structure can also be made of an electrically non-conductive base layer and an electrically conductive

Cover layer exist.

It is expedient that the membrane layer structure is arbitrarily formed in its geometric shape and thickness.

embodiment

The solution according to the invention will be explained in more detail using an exemplary embodiment.

The drawing shows a membrane arrangement for a pressure sensor with a membrane layer structure 1, which consists of an electrically conductive base layer 2 with an electrically non-conductive cover layer 3 arranged thereon. The membrane layer structure 1 is fixed with a membrane holding and tensioning device 4 at a basic distance of 5 to 100 / xm optionally via the interdigital transducer structures 5, over the transducer center surface 6 or over the entire surface of an SAW component 7. The membrane layer structure 1 can also consist of an electrically non-conductive base layer 2 and an electrically conductive cover layer 3. The membrane layer arrangement can also be formed arbitrarily in its geometric shape and thickness.

By utilizing the membrane arrangement according to the invention, by utilizing the effect of a cover-dependent field short circuit of the electric field associated with the SAW excitation and SAW propagation, the sensitivity of the action of pressure on the membrane component arrangement is influenced by the positioning and geometric shape of the membrane layer structure 1. The thickness of the membrane layer structure 1 is also crucial for this effect: The advantages of the invention are that a possibility of sensitivity increase over the measured pressure by spatial arrangement of the membrane assembly over the surface of the SAW device, by geometric shape of the membrane layer structure or through Membrane design was created without changing the requirements for the AOW device.

In addition, an extension of the possibility of designing the Druckmeßbereiches by the variation of the membrane assembly and the positioning of the membrane assembly is given.

Claims (3)

Invention claim: Membrane assembly for pressure sensors with a membrane which is fixed and tensioned with a clamping device and which consists of electrically conductive material or electrically non-conductive material, wherein the membrane underside is provided with a metallic coating, characterized in that a membrane layer structure (i) of a electrically conductive base layer (2) with an electrically nonconductive covering layer (3) arranged thereon, and in that the membrane layer structure (1) with a membrane receiving and tensioning device (4) at a basic distance of 5 to 100 μm optionally via the interdigital transducer structures (5), over the Wandlermittenfläche (6) or over the entire surface of an AOW device (7) is fixed. 2. Membrane arrangement for pressure sensors according to item 1, characterized in that the membrane layer structure (1) consists of an electrically non-conductive base layer (2) with an electrically conductive cover layer (3) arranged thereon. 3. membrane assembly for pressure sensors according to item 1 and 2, characterized in that the membrane layer structure (1) is arbitrarily formed in its geometric shape and ceiling. For this 1 page drawing Field of application of the invention The invention relates to a membrane assembly for pressure sensors with a membrane which is fixed and tensioned with a clamping device and which consists of electrically conductive material or electrically non-conductive material, wherein the underside is provided with a metallic coating.
The invention finds application in pressure measurement in gases, gas mixtures and liquids in all fields of technology. Characteristic of the known technical solutions Membrane solutions are known which are included in devices for measuring pressure on the basis of the AOW principle, in which the substrate of the surface acoustic wave device is designed as a membrane. A deformation of the geometry of the interdigital transducer structure of a designed as a matched filter SAW device causes a pressure-dependent change of the surface signal (DD-WP 218794). The disadvantage of this device is that the size to be measured pressure causes a mechanical deformation of the microacoustic device. In addition, sensor parameters, such. As sensitivity and reproducibility, highly linked to the mechanical properties of the substrate. Furthermore, it proves to be disadvantageous that the dimensions and tolerances of the substrate realized as a membrane define the technical-technological characteristics of the pressure sensor. Furthermore, a solution has already been proposed in which plane-parallel to the surface of a surface acoustic wave device, an electrically conductive membrane is fixed with a clamping device and tensioned. The membrane may also consist of electrically non-conductive material in this solution, wherein the Mem bra η bottom is provided with 3inem metallic coating. A disadvantage of this membrane arrangement is the influencing of the entire surface of the AOW component, so that the sensitivity of the membrane component arrangement can be Ariiert / only by the distance of the membrane to the AOW device surface /. Object of the invention It is an object of the invention to provide a membrane assembly for pressure sensors, which achieved by the use of any Wembranmaterialien or membrane layer structures, a significant increase in sensitivity to the measured variable - pressure - even in the smallest changes. Explanation of the essence of the invention The object of the invention is to develop a membrane arrangement for pressure sensors which, by geometric / ariation of a membrane film or a membrane layer structure of any materials or material combinations and by a suitable positioning of the membrane layer structure over the surface of an AOW device, a pressure-proportional mechanical deformation According to the invention, the object is achieved in that a membrane layer structure consists of an elastically conductive 3rundschicht with a cover layer disposed thereon and that the membrane layer structure of the membrane causes a high sensitivity in the region of smallest pressure changes with a Vlembranaufnahme- and tensioning device in a basic distance of 5 to 100 μνη either via the nterdigitalwandlerstrukturen, on the converter center surface or over the entire n surface of an AOW device is ixiert.