DE102017204669A1 - sensor device - Google Patents

Abstract

The invention relates to a sensor device (1) having a sensor (2) comprising a first static element (3) and a second movable element (4) spaced from the first static element (3) in a starting position, wherein movement of the second element ( 4) depends on a physical quantity to be detected such that the second element (4) is such that when a predetermined value of the physical quantity to be detected is exceeded, the second element (4) contacts the first element (3) second element (4) is such that the second element (4) still contacts the first element (3) even if the physical quantity to be detected falls below the predetermined value again, wherein a detection device (16) detects the contact of the second with the first element (4, 3) is provided.

Description

State of the art

From the CN 103373538 A a transport monitoring system is known in which an acceleration, temperature and humidity sensor is connected to an evaluation unit.

From the WO 2016/091964 A1 For example, a moisture sensor consisting of two layers arranged next to each other is known, in which one of the layers swells on contact with moisture. The two layers are arranged in such a way to each other that the second layer is interrupted by the swelling. Such an interruption is measured electronically and the information is transmitted via an RFID connection.

Disclosure of the invention

The sensor device according to the invention with the features of the independent claim has the advantage that a non-destructive and yet permanent determination of a state to be detected is made possible. Thus, it may also be possible to release the contact by further means and reuse the sensor. Furthermore, a contacting of two elements is both particularly easy and very reliable detectable. In particular, the contacting can depend on the narrowest possible measuring limit, so that it can be determined more accurately whether a limit value has been exceeded or not. In addition, can be dispensed with a permanent power supply, if the sensor itself allows a permanent contact of both elements. Additional energy, which would be used, for example, for a plastic deformation, is not needed. Thus, a reliable and accurate sensor device is possible.

The second movable element is designed such that a contacting of the first element, which then takes place permanently, is only achieved when a limit value is exceeded for a predetermined physical quantity to be monitored. Compliance with a monitored upper limit for an acting acceleration, for example, to determine whether a strong impact has occurred, can thus be reliably detected. The same applies to exceeding a predetermined temperature or, for example, for exceeding a maximum limit for a moisture.

Further advantages result from the developments specified in the dependent claims. Thus, it is advantageous that the second, movable element bends due to an acceleration acting on the second element or to the presence of a chemical substance. In particular, a micromechanical realization of the sensor is thus made possible, wherein a dependence of the bending on the external influence can be set by a design of the second element. Namely, when the second movable member is made thinner, the same external influence results in more bending as compared with a thicker second movable member. Furthermore, it is also possible to determine with a sensor both an acceleration and the presence of a chemical substance.

A particularly durable and secure connection of the first static and the second movable element is achieved when a mechanical or electrostatic connection between the two elements is created upon contact of the first element by the movable second element. This connection also remains if the physical quantity responsible for moving the second moving element no longer exists. This makes it possible to still be able to determine a contact of the first and the second element at a later time. A secure mechanical connection is made possible either by a latching hook connection or by a reversing bistable spring.

In the event that an electrostatic connection is shown, an electret layer is advantageously arranged on the first and / or the second element. Such an electret layer induces, after successful charging of the electret layer in the opposite layer, an electrical counter charge, which contributes to the electrostatic attraction of both elements. If a movement of the second movable element causes the second element to contact the first element, as a result of the charged electret layer, both elements adhere electrostatically to one another. With an appropriate design and size of the electret layer and the resulting electrostatic attraction, it is thus possible that a force which would possibly result from a change in the physical quantity to be measured, which would lead to a return movement and removal of the second element, being overcompensated by the resulting electrostatic force becomes. As a result, the second element remains arranged on the first element. An additional electrical power supply for providing an electrostatic force is not required, but this electrostatic force is provided by the electrically charged electret layer.

A particularly simple detection of a change in a contacting of the first and the second element can be represented by incorporating a contacting of the first and / or the second element in a resonant circuit, for example, to detect a change in resistance or a capacitive change with respect to the first and the second element , Such a resonant circuit is in turn particularly easy to read by an RFID unit with which a measurement result can be transmitted to an external output unit. An advantage of an RFID configuration is that no power supply to the sensor device is required by a passive embodiment of the RFID element. In addition, a coding of a sensor device and thus an identification can be carried out via the RFID unit in a simple manner, which sensor has provided the corresponding measurement data.

Furthermore, a sensor system is advantageously provided which has a plurality of sensor devices, the sensor devices each being aligned with a threshold value for a variable to be detected, but this threshold value is different for each of the sensor devices in the sensor system. By such a sensor system, the exceeding of various thresholds can be determined.

Corresponding advantages arise for a measuring method according to the invention.

list of figures

• 1 einen schematischen Aufbau einer Sensorvorrichtung,
• 2 eine Verwendung einer Sensorvorrichtung zur Überwachung eines Transportgutes,
• 3 ein erstes Ausführungsbeispiel einer Sensorvorrichtung,
• 4 und 5 ein zweites Ausführungsbeispiel einer Sensorvorrichtung,
• 6 ein drittes Ausführungsbeispiel einer Sensorvorrichtung,
• 7 ein viertes Ausführungsbeispiel einer Sensorvorrichtung,
• 8 und 9 ein fünftes Ausführungsbeispiel einer Sensorvorrichtung,
• 10 und 11 ein sechstes Ausführungsbeispiel einer Sensorvorrichtung,
• 12 ein siebtes Ausführungsbeispiel einer Sensorvorrichtung.

Embodiments of the invention are illustrated in the drawings and explained in more detail in the following description. Show it:

• 1 a schematic structure of a sensor device,
• 2 a use of a sensor device for monitoring a transported good,
• 3 A first embodiment of a sensor device,
• 4 and 5 A second embodiment of a sensor device,
• 6 A third embodiment of a sensor device,
• 7 A fourth embodiment of a sensor device,
• 8th and 9 A fifth embodiment of a sensor device,
• 10 and 11 A sixth embodiment of a sensor device,
• 12 A seventh embodiment of a sensor device.

Embodiments of the invention

In the 1 is a sensor device 1 shown in which a sensor 2 to a detection device 16 connected. The detection device 16 and the sensor 2 may also be integrated in a package or on a substrate. The sensor 2 has a first static element 3 and a second movable element 4 on. The second element 4 moves depending on one on the sensor 2 acting, physical quantity to be measured. About contacts 5 can the detection device 16 with an evaluation circuit 7 on the sensor 2 and the first element 3 and / or the second element 4 access.

In the first embodiment, the detection device 16 a transmission unit 8, which is embodied, for example, as an in particular passive RFID unit. From an evaluation device 10 can be over a wireless connection 11 a measured value information of the sensor 2 read out and in an output unit 12 the evaluation device 10 be displayed, such as a display. In a further embodiment, it is also possible, alternatively or additionally, an evaluation device 10 ' via a wire connection 13 to the detection device 16 to join.

In a first embodiment, the energy required for the operation of the detection device 16 via the radio link 11 from the evaluation device 10 to the detection device 16 be transmitted. In this case, for example, in the transmission unit 8th induced a corresponding operating voltage. Accordingly, it is also possible in the further embodiment, electrical energy via the wire connection 13 to the detection device 16 transferred to. In a further embodiment, it is also possible to have a power supply unit 14 , For example, an energy storage or an energy harvester, in the detection device 16 and the sensor device 1 to integrate.

In a preferred embodiment, the sensor 2 designed such that it does not require any electrical energy for its measuring operation itself. Due to physical influences such as acceleration, temperature or humidity, there is a movement of the second element 4 instead of. Exceeds the physical variable to be measured in particular by the geometry of the second element 4 given size, so contacted the second element 4 the first element 3 , The second element 4 is such that, even in the event that the physical variable to be measured falls below the predetermined limit again, the contacting of the first element 3 through the second element 4 preserved.

In a particular embodiment, it is also possible that the detection device 16 is designed such that after triggering by the evaluation devices 10, 10 ', the contacting of the first element 3 and the second element 4 by controlling a reset unit 15 is reversed again, for example by energizing a reset element. This will allow the sensor 2 again for a measurement. To prevent unauthorized reset, the function for resetting the sensor may be protected by a password, for example.

For a measurement of an acceleration is the second element 4 For example, designed as a particular one-sided suspended movable mass element, such as a bending beam. Also a two-sided suspension is possible. For detection of a temperature, the second movable element 4 can also be designed as a bimetallic element. Furthermore, it is also possible that a bimetallic element is arranged on the movable mass element. Correspondingly, for the detection of a chemical substance to be detected, for example water, a corresponding material that expands on contact with moisture can be arranged on the movable mass element and connected to it. As a result of the expansion of the arranged element due to the presence of the chemical substance to be detected, as a result of the connection with the movable mass element, a force is exerted on the mass element which bends as a result of the force action. By geometrically designing a size of the mass element and optionally the additional elements arranged on the mass element, a limit value for the physical quantity to be detected can be determined, since this design determines the degree of bending and thus the required force required for the second Element reaches the first element. This force is in turn dependent on the value of the physical quantity to be measured.

Spaced to the second element 4 is the first, immovable element 3 arranged. If the physical size dependent bending of the second element 4 sufficient, the first element 3 to contact, so are the first and the second element 3 . 4 such that such contact is maintained, even if the physical size falls below the predetermined limit again.

In another embodiment, it is also possible to detect a decrease in a physical quantity below a corresponding limit. In this case, the contact is retained even if the limit rises again above the predetermined limit.

The sensor is z. B. capped by Waferbonden. In an embodiment as a gas sensor, a media access is provided for an exchange of gases with a surrounding atmosphere.

In the 2 is an embodiment of a sensor device according to the 1 shown. A package 20 is located in a transport loading room. On the package 20 is one on a carrier 22 arranged sensor device 21 appropriate. The sensor device 21 has a first sensor 23 , a second sensor 24 , a third sensor 25 and a fourth sensor 26 on. The sensors 23, 24, 25, 26 are basically identical and correspond to the sensor 2 according to the 1 , However, each of these sensors is designed so that it responds to a different physical limit, in particular the same physical size. Thus, it is possible to provide four different limit values, for example four temperatures or four different accelerations. In particular, with accelerations, it is also possible for each sensor to measure an acceleration in a spatial direction, the sensors being possibly arranged so that they can measure acceleration values in all three spatial directions. For this purpose, then three sensors are required, the measuring directions are aligned orthogonal to each other.

The sensors 23 . 24 . 25 . 26 are to a detection device 27 connected, wherein a detection device 27 all sensors can monitor. In another embodiment, it is also possible for each sensor 23 . 24 . 25 . 26 to provide a separate detection device. The measurement result of the detection device 27 is preferably wirelessly readable. The detection device preferably transmits 27 a code. Thus, it is also possible to monitor a plurality of transport goods, which are arranged in the same load compartment, with an evaluation device, wherein the measured value can be clearly assigned on the basis of the transmitted code to a respective transported goods to be transported. In the data transmission from the sensor device to the evaluation device, the sensor can be read in addition to an identification of the transported good as further information.

In the 3 a first embodiment of a sensor is shown. The sensor is in this case preferably designed in microsystem technology. Parallel to a substrate is a flexible arm 31 at a substrate anchorage 30 arranged at his anchorage 30 opposite side at right angles in a latching arm 32 angling. The substrate anchoring 30 is a structure that is on a Substrate is anchored while the arm 31 above the substrate at a certain distance of typically a few microns is free.

At the end of the latching arm 32 is a locking element 33 with a sliding surface 34 arranged by the arm 31 rejects. At one of the arm 31 in the direction of the latching arm 32 acting force, for example, as a result of an acceleration in the direction of the arrow 35 the arm moves 31 in the direction of the arrow 36 and bends against anchoring 30 , This also moves the latching hook 33 in the direction of the arrow 35 , Adjacent to the second element thus formed is a first element 37 arranged in which on a support 38 a latching hook 39 with a sliding surface 40 is arranged. Now moves the locking arm 32 as a result of acceleration on the latching hook 39 too, so slides the first sliding surface 34 on the second sliding surface 40 until the locking hook 33, the tip of the latching hook 39 passes and on a side away 41 of the second latching hook 39 locks. Even if then no further acceleration force more on the latching arm and thus on the second movable element 32 acts, the second element remains 32 in contact with the first element 37 as a result of the locking. For detecting such a contact is a measuring device 42 provided, for example, for a resistance measurement or voltage measurement, which contacts the first latching element 39 and the second element, in particular the arm 31 , This measuring device 42 is arranged in the detection device.

In an alternative embodiment, also further locking element 43 . 44 on the first element 37 with a greater distance to the initial position of the locking arm 32 on the first element 37 is arranged. This makes it possible for a larger on the latch arm 32 acting acceleration not only the first, nearby catch hook 39 but optionally also further latch hooks of the first locking element 33 overlined and the locking arm 32 is held behind the respective locking element. Preferred is a measuring device 29 . 45 separately connected to each latching hook. In an embodiment, it is possible to use the first element 37 otherwise statically arranged by a reset means 46 in the direction 47 the anchor 30 to move, so that the locking connection is released. Preferred is a spring 48 provided that the first element 37 returns to the static starting position. Thus, a new measurement with the sensor is possible.

In a further embodiment, it is also possible to use a gas- or moisture-sensitive material 49 in particular on a first element 37 opposite side of the arm 31 to install. Is in the vicinity of the sensor, the corresponding gas or moisture present, whereupon the sensitive material 49 responds, so the sensitive material expands.

For use in monitoring the humidity, for example, polymers such. B. polyimides used in which a change in volume, namely a swelling, takes place by an incorporation of water. Alternatively, silicones such as PDMS may also be used, which also have a volume change as a function of air humidity. In another embodiment, it is also possible to use Al ₂ O ₃ , wherein a moisture-dependent phase transition of alpha-Al ₂ O ₃ to gamma-Al ₂ O ₃ can be exploited.

The sensitive material 49 is in particular fixed via an adhesive bond or as a coating or as an otherwise material application, ie non-positively, with the material of the arm 31 connected. By receiving the gas to be detected or moisture through the sensitive material 49 it happens that the sensitive material 49 expands. As a result of expansion, there is a force on the arm 31 on which the sensitive material 49 is applied. As a result of the action of force, the arm bends 31 in the direction 35 , so that a corresponding effect occurs as with a mechanical force. In a further embodiment, it is also possible for the gas-sensitive material to have a negative volume change or to be detected. In this case, the gas-sensitive material is on the opposite side of the arm 31 and thus to install on the side facing the latch hooks.

in a particular embodiment also possible to carry out a mechanical sensor and a sensitive gas or moisture sensor in a sensor. Although it can not be determined in this case by reading the sensor, whether a limit value for the moisture or the acceleration has been exceeded, but at least one of the two limits has been exceeded. Thus, for example, a harmful effect on a good to be transported can be determined.

In a further embodiment, the arm can also 31 be formed from the sensitive material itself. However, the sensitive material 49 is particularly preferably on a free bending beam made of a different material, for. As silicon, applied, which bends at a change in length.

In a further embodiment, it is also possible to avoid errors due to transverse sensitivities of a humidity or gas sensor to other measured variables such as temperature or acceleration, a gas or moisture sensor be combined with a temperature and / or an acceleration sensor, that is, in each case sensors in which no sensitive material for receiving the gas to be detected or the moisture is arranged. For an acceleration sensor, instead of the material sensitive to gas or moisture, a larger structure made of a material such as silicon can be applied, which serves as a mass and thus leads to a higher sensitivity to acceleration. The temperature or acceleration sensor can also be advantageously designed as a threshold value sensor. If the temperature or the acceleration sensor does not trigger, but the humidity or gas sensor, it can be concluded that the limit value for moisture or the gas to be detected is exceeded. If all sensors have triggered, then a very strong impact may have caused the humidity or gas sensor to trigger.

In the 4 and 5 a second embodiment of a sensor device is shown. In the 4 Here is a bendable arm 51 at a substrate anchorage 50 arranged in such a way. In one embodiment, on the arm 51 optionally a sensitive material 52 or an additional ground structure. The arm 51 At the same time it forms the second, movable element of the sensor. At one end of the arm 51 is laterally to the arm 51 a static element 53 arranged that represents the first element. About a measuring device 54 is the arm 51 with the static element 53 electrically connected. In the starting position is a distance 55 between the static element 53 and the arm 51 intended. Is it due to an expansion of the sensitive material? 52 in the embodiment as a gas sensor, in an arrangement of a bimetallic material on the arm 51 instead of the sensitive material 52 (in the 4 not shown) or due to an effect of an acceleration on the arm 51 to that arm 51 a movement on the static element 53 does and that the arm 51 the static element 53 achieved, so a contact connection between the arm 51 and the static element 53 represented as they are in the 5 is shown. As a result of an acceleration in the direction of the arrow 56 or as a result of an expansion of the sensitive material 52 in the direction of the arrow 57 is the distance 55 between the first element 53 and the arm 51 disappeared.

In a first embodiment, a contact surface 58 thereby executed such that on at least one side of the contact surface, ie on the arm 51 and / or the first element 53 an adhesive is disposed so that an adhesive bond is provided. In a further embodiment, the arm 51 may also be shaped such that the arm 51 is designed as a bistable spring. With a sufficient force on the arm 51 Then, the state of the bistable spring in case of exceeding the physical threshold to be detected in a second position, in which then one end of the arm 51 with the now resulting spring force in the folded second state on the first element 53 suppressed. In a further embodiment, an electrostatic representation of a contact is also possible. Exemplary embodiments of this will be described with reference to FIG 8th ff. explained in detail.

In the 6 a further embodiment for a sensor device is shown. Here is a movable arm 61 at a distance 62 arranged above a substrate 60. The distance 62 is preferably on one side of the arm 61, which may also be designed as a flat plate, ensured by an insulating material 63. The arm 61 can be opposite the substrate 60 in a direction of movement 64 parallel to the distance 62 swing freely, so that an acting acceleration leads to a movement. In a corresponding manner according to the embodiment with reference to FIG 4 and 5 can be a contacting of the arm 61 on the substrate 60 be held once the contact has been made. A detection, for example, about a decrease in the electrical resistance between the arm 61 and the substrate 60 , can have a measuring device 65 be detected. In an alternative embodiment, in particular on one of the substrate 60 opposite side corresponding to a gas-sensitive material 66 be arranged with the arm 61 is connected and that to a bending of the arm in the direction of the substrate 60 on expansion, which occurs as a result of absorption of a chemical substance and the direction of the arrow 67 is indicated.

An alternative embodiment of this is in 7 shown. Over a substrate 70 is a membrane 71 arranged laterally over a particular insulating material 72 from the substrate 70 is spaced so that is between the substrate 70 and the membrane 71 a cavity 73 formed. For pressure equalization holes are in one embodiment 74 in the membrane 71 provided, through the gas from the cavity 73 escape or can enter into it. The membrane 71 can be above the substrate 70 swing, wherein at a contact of the membrane 71 according to the embodiment according to the 4 and 5 a contact of the membrane 71 by the measures described there on the substrate 70 preserved. Correspondingly, a sensitive material may additionally be used in this embodiment as well 75 on the side of the membrane applied to the substrate 71 be arranged. A measuring device 76 is with the membrane 71 and the substrate 70 connected, leaving a contact between the substrate 70 and the membrane 71 within the cavity 73 can be found, which is connected to a production of an electrical conductivity or a capacitance change.

In the 8th an embodiment is shown in which maintaining a contact between a first static element 80 and a second movable element 81 done electrostatically. In the embodiment shown here, the movable element 81 over a spring 82 on a substrate 83 arranged. The moving element 81 can result in a on the element 81 acting acceleration force and move the spring 82 stretch. In a first embodiment is a voltage source 84 provided, which is an electrical voltage between the first element 80 and the movable element 81 causes. By the spring 82 but becomes the moving element 81 stopped by the static element 80. However, an acceleration can cause the spring 82 be deflected so that the moving element 81 the static element 80 reached. Preferably, an insulating layer is arranged on at least one of the elements. This results in an electrostatic attraction between the two elements as a result of the induced voltage 80 . 81 , A change in the electrical capacitance or the electrical resistance can be determined by a measuring device 85. A corresponding representation of a contact is in the 9 shown. In the starting position according to the 8th is the power of the spring 82 greater than the induced electrostatic force, thus overcoming the distance between the elements 80 . 81 can not be done by the electrostatic force. Only at an occurring acceleration, which leads to an approximation of the movable element 81 into the static element 80 leads, the electrostatic force can overcome the spring force. At a contact of the elements 80 . 81 However, due to the now short distance the electrostatic force is greater than the spring force, so that even after elimination of the acting acceleration, the elements 80 . 81 keep in touch.

In an alternative embodiment, instead of a voltage source 84 in particular on the movable element 81 an electrically charged electret layer 86 be provided. In this case, no external power source is required. The electret layer 86 is in this case represented on the in particular micromechanical structure, that is to say on the movable element 81 but can optionally also be on the static element 80 be arranged. The in the electret layer 86 stored charge carriers induce countercharges on the respective counterelectrode, which results in an electrostatic force. In a further embodiment, electret layers with different polarities can also be used on both elements 80 . 81 be arranged.

Electrets are able to store electrical charge carriers with long-term stability. This stored carrier density results in a surface potential which can range from a few volts to a few hundred volts. An electret layer may be charged, for example, by a corona discharge or by a charge by means of a combination of X-rays and the application of an electrical potential. The electret layer can generate counter charges in a substrate, creating an attractive, electrostatic force. A representation of an electret layer can be produced, for example, by deposition of Cytop®, which is spin-coated with a layer thickness of a few 100 nm to a few μm. Structuring takes place for example by means of photolithography and reactive ion etching. Alternatively, for example, parylene-C can be used. By a deposition process from the gas phase and vertical structures with high aspect ratios can be coated with layer thicknesses of a few nm to over 20 microns.

In the embodiment according to the 8th and the 9 is the acceleration to be measured by the spring constant of the spring 82 certainly. In case of contact according to 9 can the measuring device 85 compared to the spaced state according to 8th a smaller electrical resistance between the elements 80 . 81 determine.

Another embodiment is in the 10 and 11 shown in two states. A flexible arm 91 is on a substrate 90 arranged. At an end of the arm facing away from the substrate 90 91 is a mass area 92 intended. On a side surface of the arm 91 in the mass area 92 is an electret area 93 arranged. This one has a bottom 94 a static element 95 to, that on a substrate 96 is arranged. Part of the arm 91 is also in a flat area 99 down to the bottom 94 passed. In the area area 99 is an elevation on the arm 91 provided, which is formed conductive. The arm has a thickness 97 on that a mobility of the mass range 92 determined at an acting acceleration. In a further embodiment can also according to the 4 a sensitive material according to the previously explained embodiments on a particular static element 95 opposite side of the arm 91 be arranged.

Does it come to a force on the arm 91 For example, via an acting acceleration, so contacted the arm 91 the static element 95 , For a sufficient force in the direction of the arrow 98 it comes to a contact of the bottom 94 with the static element 95 , The electret 93 ensures that even after eliminating the effect of acceleration, the bottom 94 contacted the static element 95. By the arm 91 now directly in the area 99 the bottom 94 the static element 95 contacted, may be a conductive connection to the electret area 93 over between the arm 91 and the static element 95 being represented. As a result, a detection of a change in resistance with a measuring device 100 in a simple way possible.

Be different sensors with different thicknesses 97 of the arm 91 arranged side by side, different limits for an acting acceleration are detectable with the sensor.

In the 12 a further embodiment of a sensor device is shown. A micromechanical mass element 101 is over jetties 102 . 103 each on a substrate 104 . 105 held. In the jetty 102 is a piezoresesitves element 106 advantageously introduced that via an electrical contact 107 is readable. On the mass element 101 is an electrode layer 108 provided, wherein on the electrode 108 on the mass element 101 opposite side an electret layer 109 is applied. The electret layer 109 lies opposite a substrate 110. For an acting acceleration in the direction of the arrow 111 of the mass element 101 in the direction of the substrate 110 remains at a contact due to the induced counter charge of the electret layer 109 the movable mass element 101 with the electret layer on the substrate 110 be liable. This leads to a bending of the web 102 and thus to a bending of the piezoresistive element 106. As a result of the bending, the resistance of the piezoresistive element 106 changes. This bending can occur via the electrode 107 be measured. In a further embodiment is also in the bridge 103 a piezoresistive element 112 advantageously provided that is read in the same way and with a redundant evaluation is possible.

For example, in an alternative or additional embodiment, the substrate may also be embodied as an n-doped silicon substrate into which p / p + dopants 113, 113 'in an environment of a contact region of the mass element 101 be arranged. Thus, it forms between the p / p + doped regions 113 . 113 ' a channel area 114 out. The p / p + doped regions are disjoint and connected to one another via a measuring device 115. Above the canal area 114 is the micromechanical structure with a negatively charged electret layer 109 , Is the electret layer located 109 before a shock event, ie before an acting acceleration, at a distance to the channel area 114 , so only a few charge carriers in the channel area 114 induced. This thus has a high electrical resistance between the p / p + doped regions 113 . 113 ' on. After an occurrence of a predetermined limit exceeding acceleration and thus made contacting the electret layer 109 with the substrate 110, the micromechanical structure adheres to the charged electret layer 109 on the canal area 114 , As a result, significantly more countercharges are induced in the channel region 114, as a result of which the channel region 114 becomes conductive and between the two p / p + doped regions 113 . 113 ' a smaller electrical resistance through the measuring device 115 can be determined.

In a further embodiment, it is possible, even in the arrangement according to the 10 and 11 a piezoresistive resistance especially in the arm 91 bring in whose resistance can be detected.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• CN 103373538 A [0001]
• WO 2016/091964 A1 [0002]

Claims (10)

Sensor device (1) having a sensor (2) comprising a first static element (3) and a second movable element (4) spaced from the first static element (3) in a starting position, wherein a movement of the second element (4) from one is to be detected such that the second element (4) is such that when a predetermined value of the physical quantity to be detected is exceeded, the second element (4) contacts the first element (3), the second element (4 ) is such that the second element (4) still contacts the first element (3) even if the physical quantity to be detected falls below the predetermined value again, wherein a detection device (16) for determining the contact of the second with the first element (4, 3) is provided. Sensor device after Claim 1 , characterized in that the second element (4) is designed such that, as a result of an acceleration acting on the second element (4) or the presence of a chemical substance, it depends on a magnitude of the acceleration or a concentration of the chemical Bend substance. Sensor device according to one of the preceding claims, characterized in that upon touching the first element (3) by the second element (4) a mechanical and / or electrostatic connection for the permanent arrangement of the second element (4) on the first element (3) he follows. Sensor device after Claim 3 , characterized in that a mechanical connection between the first and the second element (31, 37) by a latching hook connection (33, 39) takes place. Sensor device according to one of Claims 1 to 3 , characterized in that a mechanical connection between the second element (51) and the first element (53) takes place in that the second element (51) is designed as a bistable spring such that when exceeding a predetermined threshold value of the physical quantity the bistable spring turns over such that a spring force is exerted on the first element (53). Sensor device according to one of Claims 1 to 3 , characterized in that on the first and / or the second element (80, 81) an electret layer (86) is arranged. Sensor device according to one of the preceding claims, characterized in that the sensor (2) is part of a resonant circuit, and that the detection device (16) is adapted to read a change in the state of the sensor (2) via a change in a resonant frequency of the resonant circuit. Sensor device according to one of the preceding claims, characterized in that an output signal of the sensor device via an RFID unit is transferable. Sensor system having a plurality of sensor devices according to one of the preceding claims, characterized in that at least two of the sensor devices have different sensors such that the predetermined values of the physical quantity for contacting the first element are formed differently by the second element. Measuring method for a sensor having a first static element (3) and a second movable element (4) spaced from the first static element (3) in a starting position, wherein a movement of the second element (4) depends on a physical quantity to be detected in that the second element (4) contacts the first element (3) when a predetermined value of the physical quantity to be detected is exceeded, the second element (4) remaining in contact with the first element (3) when the physical variable to be detected returns falls below the predetermined value, wherein a detection device (16) detects the contact of the second with the first element.

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