WO2007045208A2

WO2007045208A2 - Vibration sensor having a micromechanically produced vibration structure

Info

Publication number: WO2007045208A2
Application number: PCT/DE2006/001750
Authority: WO
Inventors: Jens Makuth; Dirk Scheibner
Original assignee: Siemens Aktiengesellschaft
Priority date: 2005-10-19
Filing date: 2006-10-06
Publication date: 2007-04-26
Also published as: WO2007045208A3; DE102005050159A1

Abstract

The invention relates to a vibration sensor (19) and to a method for producing said type of vibration sensor (19). According to the invention, the vibration sensor (19) comprises at least one first micromechanically produced vibration structure which can be excited by push-like excitation and which comprises a first resonance frequency in the ultrasound range in order to measure the push-like excitation in the most economical and simple way possible.

Description

description

vibration sensor

The invention relates to a vibration sensor and a method for producing such a vibration sensor.

Such a vibration sensor is used for example in automation and drive technology. The invention fertil can here z. B. for condition monitoring wear-prone components. In addition, the invention can be used to monitor manufacturing processes that can be disturbed by a vibrating environment.

Production downtime due to unexpected machine defects can cause significant direct and consequential damage, depending on the industry and type of process. In order to increase the reliability of production and machine tools, process engineering systems, transport systems and the like, and thus to reduce downtime of these production means, premature wear and defect detection is becoming increasingly important.

For example, in electric machines, failure of the production equipment or one of its components (e.g., the bearings) is often manifested by a change in vibration behavior. By a vibration analysis, these changes can be detected. In this way, affected components can be replaced prematurely before it comes to the failure of the entire system and thus to a longer production downtime.

In the vibration or vibration analysis, the frequency range up to 10 kHz is evaluated spectrally in general. Usually, the time signal is detected by means of a broadband sensor and evaluated by means of a subsequent Fourier analysis. In some cases, frequency selec- Tive sensors are used, which directly perform a spectral filtering of a narrow frequency band.

US Pat. No. 6,412,131 B1 discloses a system produced by microsystems, which uses mechanical sensors for measuring input signals, such as, for example, Has vibrations. Such a MEMS-based system can be implemented as a single chip system.

For example, for bearing monitoring, for the detection of leakage, cavitation, glass breakage or electrical discharge is also a measurement of short impulsive excitations of interest, which have a broadband frequency spectrum. Such suggestions are also referred to as "acoustic emission".

Object of the present invention is to allow the simplest possible and cost-effective measurement of jerky suggestions.

The object is achieved by a vibration sensor having at least one first micromechanically produced oscillatable structure, which can be excited by a pulse-shaped excitation and has a first resonance frequency in the ultrasonic range.

Furthermore, the object is achieved by a method for producing a vibration sensor, in which at least one first oscillatable structure, which can be excited by a shock-shaped excitation and has a first resonant frequency in the ultrasonic range, is manufactured micromechanically.

Micromechanics refers to an area of microtechnology that deals with mechanical structures in the micrometer range. In micromechanical production, known processes are frequently used from semiconductor process technology, in particular microchip manufacturing. The invention is based on the finding that shock-shaped excitations, which generate a broadband frequency spectrum, can be detected particularly well in the ultrasonic range. Ultrasound range is understood here and in the entire document as the frequency range between 20 and 200 kHz. The advantage of detecting impulsive excitations by measuring in the ultrasonic range is that disturbing background noise in the spectrum of the excitation at such high frequencies has already decayed. Such Störsig- signals arise for example by structural resonance of the measurement object. In the case of a measurement in the ultrasound range, only the signals of interest are thus detected, by means of which a condition monitoring of components subject to wear can be carried out. This allows a simplified evaluation, since no spectral distinction in measurement signal and superimposed background noise is necessary.

Examples of typical sound emission sources in the ultrasonic range are bearings with damaged raceway, lubrication problems, tool wear or breakage.

According to the invention, such a vibration sensor for the ultrasonic range is manufactured micromechanically. Micromechanically manufactured vibration sensors have e.g. compared to piezoelectric sensors has the advantage that the geometric parameters of the corresponding oscillatory structures can be realized for example by processing methods such as lithography with very low tolerances. The possibility of setting these parameters within very narrow tolerances also makes it possible to dimension the resonance frequency and the bandwidth of such a vibratable structure extremely precisely. As a result, the micromechanical sensors can consequently also be adapted very easily to a specific application.

The size of micromechanically fabricated vibrating structures is significantly smaller than the size of conventional piezoelectric Sensors. Thus, a high degree of integration is possible if several oscillating structures are to be integrated on a vibration sensor.

In an advantageous embodiment of the invention, the vibration sensor is provided for measuring structure-borne noise. Structure-borne sound refers to sound that propagates in a solid body. Examples of such a body are e.g. In the field of automation and drive technology, electrical machines or their bearings that trigger a sound wave due to self-excited or externally excited shocks. Such a sound wave is only acoustically perceptible when it leaves the corresponding solid.

In an advantageous embodiment of the invention, the first oscillatable structure is made of a wafer of semiconducting material. In the semiconductor industry, there are a large number of technological processes that permit the exact production of the smallest vibratory structures. As a wafer material, silicon is suitable for cost reasons.

However, the use of a substrate material of Galiummarsenit or silicon carbide, etc. is also conceivable.

In addition to the comparatively low material costs, silicon is also characterized by its very easy processability. In an advantageous embodiment of the invention, therefore, the first oscillatable structure by means of Siliziumbulk- mechanics and / or silicon surface micromechanics is made. In the Siliziumbulkmechanik detached mechanical structures are obtained from a silicon wafer by ^• sided etching. The silicon surface micromechanics distinguishes that the wafer surface is mechanically structured by several etching and deposition processes.

In such methods also micromechanical structures can be combined with electrical circuits on a single microchip. For example, appropriate In this case, the oscillatable structure can be implemented here together with electronics on a chip, the electronics being provided for evaluating the measurement results. By such an integration, manufacturing costs can be reduced and solutions can be achieved in which due to the extremely small separation of electrical and mechanical components parasitic effects in the measurement or their evaluation can be almost neglected.

Depending on the direction of the radiated sound, it may be advantageous, in an expedient embodiment of the invention, to execute the first oscillatable structure so that it can oscillate perpendicularly to the wafer plane.

Alternatively, in a further advantageous embodiment of the invention, it may be expedient to make the first oscillatable structure oscillatable parallel to the wafer plane. In particular with the aid of silicon bulb mechanics and / or silicon surface micromechanics, the direction of oscillation of the first oscillatable structure can be selected with very many degrees of freedom.

A very simple detection of impulsive excitations can be achieved if, in an advantageous embodiment of the invention, the oscillation sensor has means for determining the collision-type excitation on the basis of a measurement of the electrical capacitance of the first oscillatable structure in an excited state. The first oscillatory structure can be designed such that it forms a capacitor whose capacity depends on the deflection of the

Structure is. The relationship between the capacity of the vibratable structure and its deflection can be adjusted by the geometry of the structure. From a measurement of the capacitance of the first oscillatable structure, the deflection of the oscillatable structure can be determined in this way, in order in turn to draw conclusions about the pulsed excitation. A corresponding electronics, which makes such an evaluation, can be especially at a micro-mechanical implementation of the vibration sensor on a semiconductor chip very well integrate.

A further advantageous embodiment of the invention is characterized in that the vibration sensor has at least one second micromechanically produced oscillatory structure with a second resonance frequency in the ultrasonic range. If the first resonance frequency differs from the second resonance frequency, two measurement frequencies in the ultrasonic range are available for later evaluation.

In this case, it is also possible that, in a further advantageous embodiment of the invention, the first oscillatable structure has a first measuring range which partially overlaps with a second measuring range of the second oscillatable structure. The overlap may e.g. be adjusted by appropriate choice of the quality of the oscillatory structures. If the first and second oscillatable structures have a relatively low quality, an overlapping of the measuring ranges can be achieved even if the first and second resonant frequencies are relatively far apart. In this way it is possible to cover a relatively large frequency spectrum in the ultrasonic range with two oscillatory structures. Of course, it is also conceivable and encompassed by the invention that more than two oscillatable structures with more than two resonance frequencies for measuring impulsive excitation are implemented on the vibration sensor. Thus, an entire array of micromechanically manufactured oscillatable structures can be implemented on a single chip in order to have as large a frequency spectrum as possible for the subsequent evaluation.

By further embodiment of the invention, it is even possible to be able to detect vibration directions in all three spatial dimensions with a vibration sensor. In such an advantageous embodiment of the invention, the vibration sensor has a third oscillatable structure whose vibration direction is substantially orthogonal to both the vibration direction of the first and to the vibration direction of the second structure. As a result, a complete three-dimensional vector space is spanned by the oscillation directions of the first, second and third oscillatable structures. This enables the detection of shock-shaped excitations from all three spatial dimensions.

A particularly simple vibration measurement can be realized with a micromechanical measuring system, comprising at least one vibration sensor according to one of the embodiments described above and electronics for conditioning a measurement signal detected by the vibration sensor. In such an embodiment of the invention vibration sensor and electronics can be integrated in a common housing, so that there is a very compact measuring system and the wiring can be kept extremely low. As a result, parasitic effects that can falsify the measurement, largely avoided.

In a further advantageous embodiment of the invention, such electronics on components for analog and digital signal processing. For example, a signal obtained with the vibration sensor is first amplified with analog modules and then evaluated by means of digital logic modules for determining characteristic values such as rms value, peak value, curtosis, crest factor, etc. Such a signal evaluation with the aid of the micro-measuring system can be adapted to the specific target application so that adjustment by a user of the micro-measuring system is no longer necessary.

Finally, the wiring effort for the vibration measurement can be further reduced if, in an advantageous embodiment, the measuring system has an energy source for supplying the micromechanical system with electrical energy. Such a self-sufficient energy supply can be obtained, for example, from a micro-mechanical measuring system in the micro-mechanical measuring system. integrated battery. Alternatively, depending on the place of application of the micromechanical measuring system, it is conceivable to use a regenerative energy source such as, for example, a solar cell for supplying energy. Further examples would be thermal generators or vibratory transducers based on the piezoelectric or electrodynamic principle, which obtain the energy for supplying the micromechanical measuring system from the environment of the system.

As a rule, the quantities detected and / or evaluated by means of the measuring system are to be sent to an evaluation unit, for example a maintenance station, which is provided for monitoring a system in which the measuring system is used. In particular, for such purposes, an embodiment of the micromechanical measuring system is advantageous in which the measuring system has a transmitting device for the wireless transmission of the processed by the electronics measurement signal.

Modern semiconductor technology methods enable a particularly compact and cost-effective embodiment of the micromechanical measuring system, wherein the vibration sensor and the electronics are integrated in particular monolithically on a common substrate. In this case, for example, methods such as silicon bulk mechanics or silicon surface micromechanics can be used if the substrate also comprises silicon. A monolithic integration of electronics and vibration sensor on a single chip makes the wide use of the micrometer system for permanent monitoring of engines, gearboxes, generators and other

Facilities also possible from an economic point of view.

In a non-monolithic integration, individual chips are arranged on a common silicon or ceramic substrate. To connect the individual chips to one another and / or to the substrate, it is possible, for example, to use the wire bonding technique or, alternatively, the so-called flip-flop technique. Chip technology. Such a system-on-chip design generally provides greater reliability of the measurement system as compared to a conventional discrete component wired configuration.

Furthermore, an embodiment of the micromechanical measuring system is advantageous in which the vibration sensor and the electronics are arranged on different carriers, which are integrated in a common housing. The individual carriers can be manufactured from printed circuit board material and stacked vertically one above the other to reduce the volume of construction.

Regardless of the production technology used for the measuring system, an embodiment of the micromechanical measuring system is conceivable and advantageous in which the measuring system has sensor elements for measuring further measured variables. For example, these may be temperature measurements or acceleration measurements. If such sensors are integrated into the micromechanical measuring system, a large number of possible operating parameters for condition monitoring can be detected with the aid of a comparatively small component.

Furthermore, an advantageous embodiment of the invention is conceivable in which a sensor network comprises a plurality of measuring systems and a central monitoring unit which has a receiving device for receiving and an evaluation unit for evaluating the processed measuring signals. In particular, in an embodiment of the measuring systems with a transmitting device for wireless transmission of the processed signal from the electronics, the individual measuring systems of the network can be very easily and without considerable effort connected to the evaluation. Such a sensor network can also be easily extended by additional measuring systems if additional oscillatory components are added to a system. The sensor network can be provided in a further embodiment of the invention for particular permanent monitoring of used in industrial processes, wear-prone components. Measuring systems are attached to the corresponding components, which, for example, wirelessly evaluate the result of the signals recorded with the aid of the vibration sensors and processed by the electronics.

An alternative application of such a sensor network characterizes a further embodiment of the invention, in which the sensor network is provided for the particular permanent stability monitoring of buildings. Here, the measuring systems can be installed in places that are classified as critical for static reasons. Acoustic emissions in the ultrasonic range, which indicate fatigue-bearing parts of the building to be monitored, are detected early by means of the measuring systems and can be monitored by means of the evaluation unit and / or the electronics integrated in the measuring systems.

In the following, the invention will be explained in more detail with reference to the embodiments illustrated in the figures.

Show it:

1 shows a vibration sensor with a first, perpendicular to the wafer plane oscillatable structure,

2 shows a vibration sensor with a second, parallel to the wafer plane oscillatable structure,

3 shows a schematic representation of a vibration sensor with an array of oscillatable structures with different resonance frequencies,

4 shows a frequency response of the vibration sensor with the

Array of vibratory structures with different

Resonant frequencies, 5 shows a schematic representation of a vibration sensor with an array of different structures with different vibration directions and

6 shows a layout of a micromechanically manufactured vibration sensor,

7 shows a micromechanical measuring system as a system-on-chip,

8 shows a micromechanical measuring system as a printed circuit board stack,

9 shows a micromechanical measuring system in Star-Flex printed circuit board technology,

10 shows a schematic representation of a micromeasurement system for the wired connection to a sensor network,

11 shows a schematic representation of a micromeasurement system for the wireless connection to a sensor network,

12 shows a sensor network for structure-borne sound measurement on a machine tool and

13 shows a sensor network for structure-borne noise measurement on a building.

1 shows a vibration sensor with a first, perpendicular to the wafer plane oscillatable structure. By means of lithography and etching steps customary in semiconductor technology, a first chip 3 having a seismic mass 1 has been produced from a first wafer and is movably supported by spring elements 2. This first chip 3 has been connected by means of silicon fusion bonding to a second chip 4 which has been produced on a second wafer. The Silicon Fusion Bonding allows the first chip 3 and the process second chip 4 initially on separate wafers and then to bond them together, so that a solid bond 5 between the two semiconductor chips 3,4 is formed. The second chip 4 is, for example, mounted on a circuit carrier 6 via a solder connection.

The preferred direction of the illustrated oscillatable structure is in this case perpendicular to the wafer plane. This is also called an out-of-plane arrangement. When excited perpendicular to the wafer plane, the seismic mass 1 is moved relative to the second wafer 4.

The partial structures fabricated on the first and second chip form an electrical capacitance whose value is dependent on the deflection of the seismic mass 1 relative to the second chip 4. This capacitance change can e.g. be measured by the fact that on the first and second chip 3.4 metallized contacts 7 are applied, which are contacted via bonding wires 8 to the circuit substrate 6. On the circuit carrier 6 is finally an amplifier circuit with which the Umladeströme generated by the dynamic capacitance changes can be amplified. Furthermore, an evaluation circuit is provided on the circuit carrier 6, with which the shock-shaped excitations, which excite the vibration sensor shown to vibrate, can be determined on the basis of the measured Umladeströme.

The measuring range of the vibration sensor shown is in the ultrasonic range. To ensure this, the resonant frequency of the oscillatory structure has been dimensioned to the ultrasonic range. A dimensioning of the resonance frequency can be achieved for example by appropriate design of the spring element 2 and by selecting the seismic mass 1. The heavier the seismic mass 1, the lower the resonant frequency of the oscillatory structure. FIG. 2 shows a vibration sensor with a second structure which can be oscillated parallel to the wafer plane. The illustrated vibration sensor has likewise been produced from two silicon wafers with the aid of silicon bulk mechanics or silicon surface micromechanics and serves to determine jerky excitations in the ultrasonic range. For this purpose, first a pit 9 has been etched in a first wafer. Subsequently, a second wafer was bonded by silicon fusion bonding on the first wafer and thinned to the desired structural height. In the following process step, the second wafer was partially completely etched by dry etching (DRIE), so that a freely movable seismic mass 1 is formed above the pit 9. The preferred direction for the vibration of such a vibratory structure is parallel to the wafer plane. Such an arrangement is also referred to as in-plane arrangement.

FIG. 3 shows a schematic representation of a vibration sensor with an array of oscillatable structures 11... 18 with different resonance frequencies, wherein all resonance frequencies lie in the ultrasonic range. For example, the respective seismic masses 1 of the individual oscillatable structures 11... 18 of the array are shown schematically. All oscillatable structures 11 ... 18 are realized on a single silicon chip. By selecting the seismic masses 1, the resonant frequency of each individual oscillatory structure can be adjusted. In this case, a first oscillatable structure 11 has the largest seismic mass 1 and thus has the lowest resonance frequency. Overall, the structure has eight seismic masses 1, wherein the seismic masses continuously decrease from the first oscillatable structure 11 via a second and third oscillatable structure 12, 13 up to an eighth oscillatable structure 18. Larger seismic masses 1 are represented here by larger rectangles, smaller seismic masses 1 by smaller rectangles. The resonance frequencies of the individual oscillatable structures 11... 18 of the array are arranged in a stepped manner in order to cover a complete frequency range in the ultrasound to be able to cover richly. By way of example, the illustrated eight oscillatable structures 11... 18 of the array cover a frequency range between 30 and 100 kHz, the individual resonant frequencies differing by 10 kHz in each case.

4 shows the frequency response of the vibration sensor with the array of oscillatable structures 11 ... 18 with different resonance frequencies, which is shown in FIG. In this exemplary embodiment, the quality of these individual oscillatable structures of the array has been selected such that their respective frequency ranges overlap. In this way, a frequency window in the ultrasonic range can be detected almost continuously.

FIG. 5 shows a schematic representation of a vibration sensor with an array of oscillatable structures with different directions of vibration. By way of example, only two oscillatable structures are shown here, the preferred directions of the two oscillatable structures being oriented orthogonally to one another. With such an arrangement, shock-shaped excitations can be detected, wherein a resolution with respect to two spatial dimensions can be achieved. Finally, in order to be able to image the third spatial dimension, the oscillation measuring system shown here could be supplemented by a further oscillatable structure whose preferred direction is oriented orthogonally to the oscillation direction of both oscillatory structures shown here.

6 shows a layout of a micromechanically manufactured vibration sensor. This is an in-plane oscillator, ie the preferred direction of the oscillatable structures is aligned parallel to the wafer plane. In this case, the vibration sensor comprises a comb-like seismic mass 1, which engages on two sides at least partially in measurement electrons 10, which are also comb-like. The seismic mass 1 is on four spring elements 2 hung up. The resonant frequency of the illustrated vibration sensor in the ultrasonic range is adjusted over the length of the spring elements 2 and the weight of the seismic mass 1. Again, the signal is obtained by evaluating the capacitance change between the seismic mass 1 and the measuring electrons. The dimension of such a vibratable structure is about 500 x 500 microns.

7 shows a micromechanical measuring system 23 as a system-on-chip. The measuring system 23 comprises a vibration sensor 19, which corresponds to one of the previously described embodiments and is shown here only schematically. Furthermore, the micromechanical measuring system 23 has an analog signal processor 20 and a digital signal processor 21. All three components 19, 20, 21 are on a common substrate 22, which may consist of silicon or ceramic applied. On the substrate 22 are copper tracks, with which the vibration sensor 19 and the analog signal processing 20 is connected via bonding wires 8. The analog signal processing 20, the gain and

Filtering the signal detected by the vibration sensor 19 is provided, finally, the digital signal processing 21 is connected downstream. One or more chips provided for digital signal processing are applied to the substrate 22 with the aid of the so-called flip-chip bonding technology. The chips of the digital signal processing 21 are connected with their electrically active side via so-called bumps 29 with the substrate 22 serving as a circuit carrier. The flip-chip bonding technology represents an elegant alternative to wire bonding technology, as it allows for an even more compact design and in general a higher reliability and lower susceptibility to interference can be achieved.

The illustrated microsystem measuring system can finally be housed in an IC housing customary in microelectronics. The illustrated micromechanical measuring system represents only one exemplary embodiment of a structure-borne sound measuring system, which has an integrated signal processing. Micromechanical acoustic sensors, analog signal processing 20 and digital signal processing 21 can both be realized as discrete components on discrete silicon chips and then electrically connected to one another by means of a suitable bonding technique as well as monolithically integrated on a single chip.

8 shows a micromechanical measuring system 23 as a printed circuit board stack. Here, a vibration sensor 19, an analog signal processing 20 and a digital signal processing 21 are implemented on individual carriers, wherein the carriers are stacked to reduce the volume of construction. As a base material for the stack construction board material (FR4) or ceramic can be used.

9 shows a micromechanical measuring system 23 in Star-Flex printed circuit board technology. Here, a vibration sensor 19, an analog signal processor 20 and a digital signal processor 21 are also implemented to reduce the overall build volume on stacked carriers using Star-Flex printed circuit board technology. The connection between the individual functional layers happens here via flexible printed circuit boards, in contrast to FIG. 8, where the connection of the individual functional layers has been realized via a rigid frame.

10 shows a schematic representation of a micromeasuring system 23 for the wired connection to a sensor network. The micromechanical measuring system 23 has a wired communication interface 24 and a wired power supply interface 25. About the communication interface parts 24, the micro-measuring system 23 with more

Vibrational sensors or micro-measuring systems communicate and connected to a central evaluation unit. The energy supply interface 25 can be used for the evaluation tion of the signals detected with the vibration sensor necessary energy are supplied. The illustrated micromechanical measuring system 23 is suitable for a wired sensor network.

Alternatively, the communication interface 24 and the power supply interface 25 may be implemented as a common interface. A cable used for both energy and data transmission is then connected to such a common interface. Communication techniques such as PowerLine Communication (= possibility of data transmission via the power network) or Power over Ethernet can be used here.

A simpler structure of a sensor network is possible with a micromechanical measuring system 23, as shown in FIG. 11 shows a schematic representation of a micrometer system for the wireless connection to a sensor network. The micromechanical measuring system 23 comprises a transmitting device 27 in the form of an antenna, via which the measuring system 23 can communicate with further measuring systems 23 of the sensor network and / or with a central evaluation or monitoring unit. A completely wireless realization of such a sensor network is achieved in that an energy source 26, for example in the form of a battery, is integrated in the measuring system 23.

FIG. 12 shows a sensor network for body sound measurement on a machine tool. By using a cost-effective self-sufficient micrometer system 23 according to one of the embodiments described above, all sound sources of the machine tool, such as spindles, drives, bearings and tools, can be continuously monitored. For this purpose, micromechanical measuring systems 23 for detecting the radiated structure-borne noise, which communicate with a central monitoring unit 28, are respectively mounted at the critical points. The central monitoring unit 28 evaluates the signals transmitted to it and can therefore be used for maintenance purposes. be. A premature tool failure can be detected prematurely, for example, by the structure-borne noise measurement and thus prevented. A wireless sensor technology, as can be realized, for example, with a micromechanical measuring system according to FIG. 11, is particularly advantageous in tools with a rotatable tool holder and is often the only useful embodiment.

FIG. 13 shows a sensor network for structure-borne noise measurement on a building. Here, individual micromechanical measuring systems 23 with wireless communication capability and self-sufficient energy supply are attached to critical points of the building for statics. Structural damage to buildings can be detected with the aid of the vibration sensors integrated in the measuring system and sent to a central monitoring unit 28 via a wireless transmitting device. For example, such a sensor network could be used to detect an overload by a snow load. If this is detected and sent to the monitoring unit 28, a corresponding alarm can be triggered via the monitoring unit 28 and the building can be cleared early. Such monitoring by means of a sensor network is also applicable to glass fiber structures of wind turbine blades, which are also subject to a strong mechanical stress.

Claims

claims

1. Vibration sensor (19) with at least one first micromechanically manufactured oscillatable structure which can be excited by a jerk-shaped excitation and has a first resonance frequency in the ultrasonic range.

2. vibration sensor (19) according to claim 1, wherein the vibration sensor is provided for the measurement of structure-borne noise.

3. vibration sensor (19) according to claim 1 or 2, wherein the first oscillatory structure is made of a wafer of semiconducting material.

4. Vibration sensor (19) according to claim 3, wherein the first oscillatable structure is manufactured by means of silicon-bulk mechanics and / or silicon surface micromechanics.

5. vibration sensor (19) according to claim 3 or 4, wherein the first oscillatory structure is oscillatable perpendicular to the wafer plane.

6. vibration sensor (19) according to claim 3 or 4, wherein the first oscillatory structure is parallel to the wafer plane oscillatory.

The vibration sensor (19) according to any one of claims 1 to 6, wherein the vibration sensor (19) has means for determining the jerk-shaped excitation based on a measurement of the electric capacitance of the first oscillatory structure in an excited state.

8. Vibration sensor (19) according to one of claims 1 to 7, wherein the vibration sensor (19) has at least one second micromechanically manufactured oscillatable structure having a second resonance frequency in the ultrasonic range.

9. The vibration sensor (19) of claim 8, wherein the first vibratable structure has a first measurement range partially overlapping with a second measurement range of the second vibratable structure.

10. vibration sensor (19) according to any one of claims 8 or 9, wherein the first and the second micromechanically fabricated structure have different directions of vibration.

The vibration sensor (19) according to any one of claims 8 to 10, wherein the vibration sensor (19) has a third oscillatable structure whose vibration direction is substantially orthogonal to both the vibration direction of the first and the vibration direction of the second structure.

12. Micromechanical measuring system (23) comprising at least one vibration sensor (19) according to one of claims 1 to 11 and an electronics for propagating a measurement signal detected by the vibration sensor (19).

13. A micromechanical measuring system (23) according to claim 12, wherein the electronics components for analog and digital signal processing (20,21).

14. Micromechanical measuring system (23) according to claim 12 or 13, wherein the measuring system (23) comprises an energy source (26) for supplying the micromechanical measuring system (23) with electrical energy.

15. Micromechanical measuring system (23) according to one of claims 12 to 14, wherein the measuring system (23) has a transmitting device (27) for the wireless transmission of the conditioned by the electronics measurement signal.

16. A micromechanical measuring system (23) according to one of claims 12 to 15, wherein the vibration sensor (19) and the electronics on a common substrate (22) are in particular monolithically integrated.

17. A micromechanical measuring system (23) according to any one of claims 12 to 16, wherein the vibration sensor (19) and the electronics are arranged on different carriers, which are integrated in a common housing.

18. The micromechanical measuring system (23) according to one of claims 12 to 17, wherein the measuring system has sensor elements for measuring further measuring variables.

19. Sensor network with a plurality of measuring systems (23) according to one of claims 12 to 18 and a central monitoring unit (28), which has a receiving device for receiving and an evaluation unit for evaluating the processed measuring signals.

20. Sensor network according to claim 19, wherein the sensor network for the particular permanent monitoring of used in industrial processes, wear-liable components is provided.

21. Sensor network according to claim 19, wherein the sensor network is provided for particular permanent stability monitoring of buildings.

22. A method for producing a vibration sensor (19), in which at least one first oscillatory structure, which can be excited by a pulse-shaped excitation and has a first resonant frequency in the ultrasonic range, is made micromechanical.

23. The method according to claim 22, wherein the vibration sensor (19) is made of a wafer of semiconducting material.

24. The method according to claim 23, wherein the vibration sensor (19) is produced by means of silicon bulk mechanics and / or silicon surface micromechanics.

25. The method according to any one of claims 22 to 24, wherein an electronics for propagating a measurement signal detected by the vibration sensor (19) is monolithically integrated together with the vibration sensor (19) on a common substrate, in particular a silicon chip.

26. The method according to any one of claims 22 to 24,

^■ wherein the vibration sensor (19) and an electronics for spreading a measurement signal detected by the vibration sensor (19) are arranged on different dies, which are integrated in a common housing.