Method for detecting contamination of MEMS sensor

Abstract

The invention relates to a method for detecting contamination of a microelectromechanical sensor of a sensor module using a heating device, said sensor module having a temperature sensor arranged at a distance from the heating device and the microelectromechanical sensor. According to the invention, the sensor is heated by the heating device, which is measured by the temperature sensor. Further, physical quantities are measured at different times by a sensor. The measured physical quantity is compensated on the basis of the temperatures measured at different times, and whether the microelectromechanical sensor is pollution-free or pollution-free is determined on the basis of the compensated physical quantity and the temperature difference between the different times. The invention also relates to a system for detecting microelectromechanical sensor contamination of a sensor module, a computer program and a machine-readable storage medium.

Description

Technical Field

[0001] The invention relates to a method for detecting contamination of a micro-electro-mechanical sensor, a system for detecting contamination of a micro-electro-mechanical sensor, a computer program and a machine-readable storage medium. Background Art

[0002] Patent document DE 10 2020 203 910 B3 discloses a method for detecting contamination of a MEMS sensor element. Summary of the invention

[0003] The object of the present invention is to provide a concept for detecting contamination of a microelectromechanical sensor of a sensor module.

[0004] This object is achieved by the present invention. An advantageous embodiment of the present invention is an expanded technical solution.

[0005] According to a first aspect, a method is provided for detecting contamination of a microelectromechanical sensor of a sensor module using a heating device, wherein the sensor module has a temperature sensor which is arranged at a distance from the heating device and from the microelectromechanical sensor, wherein the method comprises the following steps:

[0006] The output control signal is used to control the heating device so that the heating device generates heat energy for heating the micro-electromechanical sensor.

[0007] receiving a sensor output signal and a temperature sensor output signal, wherein the sensor output signal represents a physical quantity measured by the micro-electromechanical sensor at different time points during the generation of heat energy by the heating device, and the temperature sensor output signal represents a temperature measured by the temperature sensor at different time points during the generation of heat energy by the heating device,

[0008] The sensor output signal is compensated based on the temperature sensor output signal to generate a compensated sensor output signal, wherein the compensated sensor output signal represents the compensated physical quantity measured at different time points,

[0009] Based on the compensated sensor output signal and the temperature sensor output signal, it is determined whether the MEMS sensor is free of pollution or has pollution.

[0010] According to a second aspect, a system for detecting contamination of a microelectromechanical sensor of a sensor module is proposed, comprising a heating device and a sensor module, wherein the sensor module comprises a microelectromechanical sensor and a temperature sensor arranged at a distance from the heating device and the microelectromechanical sensor, wherein the system is configured to perform all steps of the method according to the first aspect.

[0011] According to a third aspect, a computer program is provided, comprising instructions which, when executed by a computer, for example by a system according to the second aspect, cause the computer to perform a method according to the first aspect.

[0012] According to a fourth aspect, a machine-readable storage medium is provided, on which a computer program according to the third aspect is stored.

[0013] The present invention is based on and includes the following recognition: The solution to the above-mentioned task is to heat up the micro-electromechanical sensor with the help of a heating device. Thus, a temperature change in the sensor is caused by the heating device. At different time points, the temperature is measured by a temperature sensor, wherein the physical quantity is measured by the sensor at these different time points. Therefore, at these different time points, not only the measured temperature but also the measured physical quantity can be provided. Based on this information, it is determined whether the sensor is contaminated. Specifically, the sensor output signal is compensated based on the temperature sensor output signal. The compensated sensor output signal represents the compensated physical quantity measured at different time points. This means that the measured physical quantity is compensated based on the corresponding measured temperature. Based on the compensated physical quantity and based on the corresponding measured temperature, it is determined whether the micro-electromechanical sensor is free of pollution or has pollution.

[0014] The concept is based on the following knowledge: contamination of the micro-electromechanical sensor leads to a different temperature change characteristic than in the non-contamination case. This means that the micro-electromechanical sensor, when heated by the same heating device, exhibits or has a different temperature change characteristic than in the non-contamination case of the micro-electromechanical sensor. This is caused in particular by the fact that in the presence of contamination, the micro-electromechanical sensor and the contamination have a different thermal capacity than in the non-contamination case.

[0015] In other words, the temperature drop or temperature gradient between the sensor and the temperature sensor increases when the sensor is contaminated compared to when the sensor is not contaminated. This means that when the sensor is not contaminated, the temperature gradient between the sensor and the temperature sensor is smaller than when the sensor is contaminated.

[0016] A specific temperature compensation of a sensor is usually defined for a non-contaminated sensor. This means that if the sensor is contaminated, the specific temperature compensation no longer works correctly. Therefore, if, for example, the change in the sensor output signal over the absolute temperature difference is compared with the characteristic change over a comparable temperature range, it can be effectively determined whether contamination is present.

[0017] Therefore, the contamination of MEMS sensors can be effectively detected.

[0018] In one specific embodiment of the method, it is provided that, based on the change in the compensated sensor output signal relative to the change in the temperature sensor output signal, it is determined whether the microelectromechanical sensor is free of contamination or has contamination.

[0019] This results in the technical advantage, for example, that the determination of whether the micro-electromechanical sensor is free of contamination can be carried out efficiently.

[0020] According to the described embodiment, it is thus provided that the change in the measured physical quantity is analyzed with respect to the change in the measured temperature in order to detect contamination based on the analysis result.

[0021] In one embodiment of the method, it is provided that a change in the compensated sensor output signal is correlated with a change in the temperature sensor output signal, in particular divided, to determine a correlated change, in particular a relative change, of the compensated sensor output signal, wherein, based on the correlated change in the compensated sensor output signal, it is determined whether the micro-electromechanical sensor is contaminated or not.

[0022] This results in the technical advantage, for example, that it is possible to efficiently determine whether the micro-electromechanical sensor is free of contamination or has contamination.

[0023] The association includes, for example, dividing the change of the compensated sensor output signal by the change of the temperature sensor output signal to obtain the relative change of the compensated sensor output signal. For example, based on the relative change of the compensated sensor output signal, it is determined whether the MEMS sensor is free of contamination or has contamination.

[0024] In one specific embodiment of the method, provision is made for a relative change, in particular a relative change, of the compensated sensor output signal to be compared with a predetermined change threshold value, wherein it is determined based on the comparison whether the microelectromechanical sensor is free of contamination or has contamination.

[0025] This results in the following technical advantage, for example: it is possible to efficiently determine whether the micro-electromechanical sensor is contaminated.

[0026] For example, if the associated change, especially the relative change, of the compensated sensor output signal is greater than or equal to a predetermined change threshold, it is determined that the sensor is contaminated. Otherwise, it is determined that the micro-electromechanical sensor is not contaminated.

[0027] In one embodiment of the method, it is provided that after reaching a target temperature and / or a target temperature difference with respect to the temperature for activating the heating device, a control signal for controlling the heating device is output such that the heating device sets the generation of thermal energy for heating the microelectromechanical sensor.

[0028] This results in, for example, the technical advantage that no thermal energy is consumed unnecessarily.

[0029] In one embodiment of the method, it is provided that when the microelectromechanical sensor element is free of contamination, a calibration process is performed, wherein the calibration process includes outputting a control signal for controlling the heating device so that the heating device generates heat energy for heating the microelectromechanical sensor, and the calibration process includes receiving a sensor output signal and a temperature sensor output signal, wherein the sensor output signal represents a physical quantity measured by the microelectromechanical sensor at different time points during the generation of heat energy by the heating device, and the temperature sensor output signal represents the temperature measured by the temperature sensor at different time points during the generation of heat energy by the heating device, and the calibration process includes compensating the sensor output signal based on the temperature sensor output signal to generate a compensated sensor output signal, which represents the compensated physical quantity measured at different time points, and the calibration process includes obtaining one or more calibration parameters based on the compensated sensor output signal and the temperature sensor output signal, and obtaining whether the microelectromechanical sensor is free of contamination or has contamination based on the calibration parameters in time after the execution of the calibration process.

[0030] This results in the following technical advantage, for example: calibration parameters can be determined efficiently, based on which it can be determined at a later point in time whether the sensor is free of contamination.

[0031] In one embodiment of the method, the calibration process includes associating the change of the compensated sensor output signal with the change of the temperature sensor output signal, in particular dividing them, to obtain the associated change, in particular the relative change, of the compensated sensor output signal, wherein the calibration process includes confirming the associated change of the compensated sensor output signal as a predetermined threshold as one of the one or more calibration parameters.

[0032] This results in, for example, the following technical advantage: the predetermined threshold value can be determined efficiently.

[0033] In one embodiment of the system, the system is configured such that a first temperature gradient between the temperature sensor and the microelectromechanical sensor when the heating device is switched on and the microelectromechanical sensor is not contaminated is smaller by at least a predetermined factor than a second temperature gradient between the temperature sensor and the microelectromechanical sensor when the heating device is switched on and the microelectromechanical sensor is contaminated.

[0034] This results in the following technical advantage, for example: it is possible to efficiently determine whether the micro-electromechanical sensor is free of contamination.

[0035] In one embodiment of the system, it is provided that the predetermined coefficient is within a closed interval from 10 to 100.

[0036] This results in the technical advantage, for example, that the temperature gradient in the presence of contamination is greater than the temperature gradient in the absence of contamination, so that contamination can be effectively detected.

[0037] In one embodiment of the system, it is provided that the microelectromechanical sensor is covered by a protective layer having a thickness in the closed range from 1 μm to 100 μm.

[0038] This results in the technical advantage, for example, that the sensor can be effectively protected.

[0039] The protective layer in the sense of this specification includes, for example, gel. The protective layer is, for example, a gel layer.

[0040] Contamination can thus for example be deposited on the gel or on a gel layer.

[0041] The expression “the sensor is free of contamination” includes in particular that the gel or the gel layer is free of contamination.

[0042] The expression “the sensor is contaminated” includes in particular that the gel or the gel layer is contaminated.

[0043] In one embodiment, the system comprises a first substrate, in particular a first wafer, in particular a silicon wafer, having an electrical circuit.

[0044] In one embodiment of the system, the microelectromechanical sensor is comprised by a second substrate, in particular a second wafer, in particular a silicon wafer, wherein the second substrate is arranged at a distance from the first substrate and is materially connected to the first substrate by means of an adhesive.

[0045] This results in the following technical advantage, for example: a unit consisting of sensor and circuit is created.

[0046] In one embodiment of the system, it is provided that the first substrate comprises a microelectromechanical sensor.

[0047] This results in the technical advantage, for example, that only one substrate is required to carry, implement or arrange the circuit and the sensor.

[0048] In one embodiment of the system, it is provided that the first substrate comprises a temperature sensor.

[0049] This results in the technical advantage, for example, that the first substrate can be used effectively if it carries both the temperature sensor and the circuit.

[0050] In one embodiment of the system, the system comprises a housing having a bottom, on which a first substrate is arranged, wherein the housing is filled with a protective material in such a way that the microelectromechanical sensor is covered by a protective layer.

[0051] This results in the technical advantage, for example, that the sensor can be effectively protected.

[0052] What is explained in relation to the system applies analogously to the method and vice versa. This means that method characteristics follow directly from system characteristics and vice versa.

[0053] The method according to the first aspect is performed, for example, by means of the system according to the second aspect.

[0054] The sensor of the system according to the second aspect is for example a sensor used in conjunction with the method according to the first aspect.

[0055] A substrate in the sense of the present specification is, for example, a silicon wafer, ie, a Si wafer.

[0056] A sensor in the sense of this specification is a micro-electromechanical sensor, even if the expression “micro-electromechanical” is not explicitly used.

[0057] A sensor in the sense of this specification is, for example, one of the following sensors: pressure sensor, gas sensor, voltage sensor, current sensor, resistance sensor, graph sensor, video sensor, lidar sensor, ultrasonic sensor, magnetic field sensor, infrared sensor, radar sensor and temperature sensor.

[0058] Contamination in the sense of this description includes, for example, fluids and / or dust and / or solids and / or biofilms.

[0059] The fluid comprises, for example, water and / or one or more other liquids.

[0060] For the “microelectromechanical” concept, for example, the abbreviation “MEMS” may be used.

[0061] The system is configured, for example, in terms of programming technology, to execute the computer program according to the third aspect.

[0062] The method according to the first aspect is for example a computer-implemented method.

[0063] The embodiments and examples described herein may be combined with one another in any manner, even if not explicitly stated.

[0064] The heating device is, for example, included by the sensor module. The heating device is, for example, not included by the sensor module. This means that the heating device can be located, for example, outside the sensor module, ie externally.

[0065] For example, a circuit is provided, such as the circuit described above. Such a circuit may be included, for example, by a sensor module. The circuit is, for example, configured to receive a sensor output signal and / or a temperature sensor output signal. The circuit is, for example, configured to compensate the sensor output signal based on the temperature sensor output signal to generate a compensated sensor output signal. In other words, the circuit is, for example, configured to perform a compensation step.

[0066] For example, an analysis and evaluation unit arranged outside the sensor module is provided, and the analysis and evaluation unit is configured to compensate the sensor output signal based on the temperature sensor output signal to generate a compensated sensor output signal. In other words, the compensation of the sensor output signal can also be performed outside the sensor module. For example, the circuit is configured to receive the temperature sensor output signal and the sensor output signal and transmit them to the external analysis and evaluation unit.

[0067] The determination of whether the microelectromechanical sensor is free of contamination or has contamination can thus be performed, for example, by means of an electrical circuit and / or by means of an external evaluation unit.

[0068] For example, the circuit can be configured to (in particular generate and) output a control signal for controlling the heating device.

[0069] For example, a control device is provided outside the control module, which is configured to (in particular generate and) output a control signal for controlling the heating device.

[0070] The step of generating a control signal is for example explicitly comprised by the method.

[0071] Such a control device is, for example, comprised by the system.

[0072] Such an analysis and evaluation unit is, for example, comprised by the system.

[0073] The circuit is implemented as an ASIC, for example. Here, ASIC stands for application specific integrated circuit, which is "application specific integrated circuit" in English. BRIEF DESCRIPTION OF THE DRAWINGS

[0074] The present invention is further described below with the aid of preferred embodiments. The accompanying drawings show:

[0075] Figure 1 According to the flowchart of the method of the first aspect,

[0076] Figure 2 According to the system of the second aspect,

[0077] Figure 3 According to the machine-readable storage medium of the fourth aspect,

[0078] Figure 4 Sensor module,

[0079] Figure 5 Another flow chart of the method according to the first aspect,

[0080] Figure 6 The first graph and

[0081] Figure 7 Second graph. DETAILED DESCRIPTION

[0082] Figure 1 A flow chart of a method for detecting contamination of a microelectromechanical sensor of a sensor module using a heating device is shown, wherein the sensor module has a temperature sensor which is arranged at a distance from the heating device and the microelectromechanical sensor, wherein the method comprises the following steps:

[0083] Output 101 is used to control a control signal of the heating device, so that the heating device generates heat energy for heating the micro-electromechanical sensor.

[0084] receiving 103 a sensor output signal and a temperature sensor output signal, the sensor output signal representing a physical quantity measured at different times by means of the micro-electromechanical sensor during the generation of heat energy by the heating device, the temperature sensor output signal representing a temperature measured at different times by the temperature sensor during the generation of heat energy by the heating device,

[0085] The compensation 105 is based on the temperature sensor output signal to generate a compensated sensor output signal, wherein the compensated sensor output signal represents the physical quantity measured at different times after compensation.

[0086] Based on the compensated sensor output signal and the temperature sensor output signal, it is determined 107 whether the micro-electromechanical sensor is free of contamination or has contamination.

[0087] In one embodiment of the method, the method comprises the step of generating a control signal for controlling the heating device.

[0088] The control signal can be generated, for example, by the circuit. The control signal is generated, for example, by a control device arranged outside the sensor module.

[0089] Figure 2 A system 201 for detecting contamination of a micro-electromechanical sensor 207 of a sensor module 205 is shown, comprising:

[0090] Heating device 203 and

[0091] The sensor module 205 includes:

[0092] MEMS sensor 207 and

[0093] a temperature sensor 209 arranged at a distance from the heating device 203 and the micro-electromechanical sensor 207,

[0094] The system 201 is configured to execute all the steps of the aforementioned method.

[0095] Figure 3 A machine-readable storage medium 301 is shown, on which is stored a computer program 303. The computer program 303 comprises instructions which, when executed by a computer, cause the computer to perform the method according to the first aspect.

[0096] Figure 4 A sensor module 401 is shown, which has a MEMS sensor 403 as well as a heating device 405 and a temperature sensor 407 and an electrical circuit 409. The electrical circuit 409 is located on a bottom 411 of a housing 413 in which the sensor module 401 is arranged.

[0097] The housing 413 is filled with a gel 415 as an example of a protective material in such a way that the surface of the sensor 403 is covered by a thin layer of gel.

[0098] Sensor 403 is connected to electrical circuit 409 in a material-bonded manner by means of adhesive 417 .

[0099] exist Figure 4 In the exemplary illustration shown, the sensor 403 has contamination 419. This contamination can be detected according to the approach described herein.

[0100] The circuit 409 is arranged on a first substrate 421, which is arranged on a bottom 411 of a housing 413. The sensor 403 is arranged on a second substrate 423, which is bonded to the circuit 409 by means of an adhesive 417.

[0101] The bottom 411 of the housing 413 may be a third substrate, such as a silicon wafer.

[0102] Due to the surface tension of gel 415, the gel surface course along sensor 403 corresponds essentially to a meniscus. The surface course is marked by reference numeral 425. In surface course 425 there is a region marked by reference numeral 427 which deviates from the meniscus shape. This is due in particular to the fact that in this region there are conductors or electrical contacts for sensor 403. These conductors or electrical contacts are not shown for the sake of clarity.

[0103] Figure 5 A flow chart of another method according to the first aspect is shown.

[0104] According to step 501, the heating device is switched on so that heat is generated. According to step 503, the temperature measured by means of the temperature sensor is recorded. According to step 505, the sensor output signal is recorded. In step 507, the heating device is switched off so that the heating is suspended or terminated. According to step 509, the sensor output signal is compensated by the temperature signal. According to step 511, the change of the compensated sensor output signal is divided by the change of the temperature. In step 513, it is determined whether the relative signal change is greater than or greater than or equal to a predetermined threshold value. If this is the case, it is determined that there is contamination on the sensor.

[0105] Figure 6 A first diagram 601 is shown, which has an abscissa 603 and an ordinate 605 .

[0106] The temperature change caused by the heating device is plotted on the abscissa 603. The compensated sensor output signal change is plotted on the ordinate 605.

[0107] A point in the graph 601 in which the sensor is clean, ie has no contamination, is marked with reference numeral 609. A point in the graph 601 in which the sensor has contamination is marked with reference numeral 611.

[0108] There is a region 607, wherein it is determined that the sensor has no contamination when the signal change is within the region 607. It is determined that the sensor has contamination when the signal change is above an upper boundary 613. The upper boundary 613 of the region 607 is a predetermined threshold value in the sense of the present specification.

[0109] Figure 7 A second graph 701 is shown, having an abscissa 703 and a left-hand ordinate 705 and a right-hand ordinate 707 .

[0110] The time is plotted on the abscissa 703. The output signal of the sensor is plotted on the left ordinate 705. The output signal of the temperature sensor is plotted on the right ordinate 707.

[0111] Reference numeral 709 shows the time curve of the temperature as measured by the temperature sensor. Reference numeral 711 denotes the output signal of the sensor, wherein the sensor is not contaminated. Reference numeral 713 denotes the output signal of the sensor, wherein the sensor is contaminated.

[0112] In summary, the solution described here particularly includes a sensor module with a MEMS sensor and a control module as an example of a circuit, wherein the control module has an embedded heating device, in particular a heating element. The control module also includes a temperature sensor, for example. The temperature measurement value of the temperature sensor is used to compensate the sensor signal related to temperature. During compensation, it is assumed that the sensor and the control module have a small temperature difference or temperature gradient. When the heating device is turned on, the entire sensor is heated, with a small temperature drop between the sensor and the control module. If there is an additional hot substance, such as contamination on the sensor, the temperature drop between the two becomes larger and the temperature compensation no longer works correctly. If the change of the sensor output signal with respect to the absolute temperature difference is compared with the characteristic change with respect to the comparable temperature range, it can be confirmed whether there is contamination. This is particularly useful for sensors that come into contact with external media, such as media-resistant sensors with a gel layer on the sensor. If the gel surface is thin enough, contamination always has a significant effect on the temperature gradient between the sensor and the control module. In particular, when the sensor is used in an environment where the sensor comes into contact with a liquid, such as water, it can be confirmed in this way whether the sensor is dry enough or whether the signal is still affected by water on the sensor surface.

[0113] According to one embodiment, the sensor module includes a MEMS sensor, which is also referred to as a measurement value receiver, for measuring a physical quantity. The sensor module includes, for example, a control module. The control module and the MEMS sensor are, for example, arranged in a housing. The measurement value receiver, i.e., the sensor, and the control module can, for example, be combined in one physical element or two separate elements, which are connected to each other in the housing. In addition, a heating device is provided, which can also be referred to as a heating module, which can, for example, be arranged in a separate control module, in a housing, or outside the sensor near the sensor. The position of the heating device is, for example, selected so that in the absence of contamination, the temperature gradient between the measurement value receiver, i.e., the sensor, and the temperature sensor is minimized during the heating phase. For example, the position of the heating device is selected so that in the presence of contamination, the maximum temperature gradient is generated between the sensor and the temperature sensor.

[0114] For example, the sensor and the control module are arranged in two different components stacked one above the other. In this case, the control module is located, for example, at the bottom in a housing and the sensor is located, for example, at the top on the control module. The temperature sensor is located, for example, in the control module, for example, like the heating element. For example, a thin gel layer is arranged above the sensor so that any contamination can reach the vicinity of the sensor. This results in strongly different temperature gradients between the sensor and the control module when there is contamination.

[0115] The solution described here comprises in particular a method in which an in particular embedded heating module, i.e. a heating device, is used to increase the temperature of the entire sensor with the aid of a defined amount of thermal energy. This results in an increase in the temperature of the sensor. This temperature is measured by a temperature sensor during the heating period. At the same time, the output signal of the sensor is recorded. The output signal is temperature-dependent and is therefore compensated, for example, with the aid of temperature measurement values ​​according to a predefined compensation formula. The maximum expected output signal change caused by the induced temperature change is specified. If there is a high temperature gradient between the sensor and the temperature sensor, the compensation will not work properly and the compensated output signal of the sensor, i.e. the compensated sensor output signal, will be inaccurate.

[0116] This behavior is used to detect contamination of the sensor. When there is contamination, the additional hot mass of the contamination on the sensor will cause a larger temperature gradient between the sensor and the temperature sensor, which in turn leads to increased errors. In this case, the change in the temperature-compensated sensor output signal with respect to temperature exceeds a certain value, so it can be confirmed that the sensor has contamination.

[0117] In summary, this solution particularly relates to a method for detecting contamination of a microelectromechanical sensor of a sensor module using a heating device, wherein the sensor module has a temperature sensor arranged spaced apart from the heating device and the microelectromechanical sensor. For example, it is provided that the sensor is heated by the heating device, which is measured by the temperature sensor. Furthermore, for example, a physical quantity is measured by the sensor at different times. The measured physical quantity is compensated, for example, based on the temperature measured at different times, wherein, for example, based on the compensated physical quantity and the temperature difference between different times, it is determined whether the microelectromechanical sensor is free of contamination or has contamination.

Claims

1. A method for detecting contamination (419) of a microelectromechanical sensor (207) of a sensor module (205) using a heating device (203), wherein: The sensor module (205) has a temperature sensor (209) which is arranged spaced apart from the heating device (203) and the micro-electromechanical sensor (207), wherein the method comprises the following steps: output (101) a control signal for controlling the heating device (203), so that the heating device (203) generates heat energy for heating the micro-electromechanical sensor (207), receiving (103) a sensor output signal and a temperature sensor output signal, the sensor output signal representing a physical quantity measured at different times by means of the micro-electromechanical sensor (207) during the generation of thermal energy by the heating device (203), and the temperature sensor output signal representing a temperature measured at different times by the temperature sensor (209) during the generation of thermal energy by the heating device (203), compensating (105) the sensor output signal based on the temperature sensor output signal to generate a compensated sensor output signal, wherein the compensated sensor output signal represents the physical quantity measured at different times after compensation, Based on the compensated sensor output signal and the temperature sensor output signal, it is determined (107) whether the micro-electromechanical sensor (207) is free of contamination (419) or has contamination (419).

2. The method according to claim 1, wherein: Based on the change of the compensated sensor output signal relative to the change of the temperature sensor output signal, the determination of whether the micro-electromechanical sensor (207) is free of contamination (419) or has contamination (419) is performed.

3. The method according to claim 2, wherein: The change of the compensated sensor output signal is correlated with the change of the temperature sensor output signal, in particular divided, to obtain a correlated change, in particular a relative change, of the compensated sensor output signal, wherein based on the correlated change of the compensated sensor output signal, it is determined whether the micro-electromechanical sensor (207) is contaminated (419) or has contamination (419).

4. The method according to claim 3, wherein: The associated change of the compensated sensor output signal is compared with a predetermined change threshold, wherein it is determined based on the comparison whether the micro-electromechanical sensor (207) is free of contamination (419) or has contamination (419).

5. A method according to any one of the preceding claims, wherein: After reaching a target temperature and / or a target temperature difference with respect to a temperature for starting heating, a control signal for controlling the heating device (203) is outputted so that the heating device (203) is set to generate heat energy for heating the micro-electromechanical sensor (207).

6. A method according to any one of the preceding claims, wherein: If the micro-electromechanical sensor element is free of contamination (419), a calibration process is performed, wherein the calibration process includes: outputting a control signal for controlling the heating device (203) so that the heating device (203) generates heat energy for heating the micro-electromechanical sensor (207), and the calibration process includes: receiving a sensor output signal and a temperature sensor output signal, wherein the sensor output signal represents a physical quantity measured at different times by means of the micro-electromechanical sensor (207) during the period when the heat energy is generated by the heating device (203), and the temperature sensor output signal represents a physical quantity measured at different times by means of the micro-electromechanical sensor (207) during the period when the heat energy is generated by the heating device (203). ) is measured by a temperature sensor (209) at different times during the period when heat energy is generated, and the calibration process includes: compensating the sensor output signal based on the temperature sensor output signal to generate a compensated sensor output signal, the compensated sensor output signal represents the compensated physical quantity measured at different times, and the calibration process includes: obtaining one or more calibration parameters based on the compensated sensor output signal and the temperature sensor output signal, and determining whether the micro-electromechanical sensor (207) is free of contamination (419) or has contamination (419) based on the calibration parameters obtained in time after the calibration process is performed.

7. The method according to claim 6 as referring back to claim 4, wherein: The calibration process includes: associating the change of the compensated sensor output signal with the change of the temperature sensor output signal, especially dividing them, to obtain the associated change of the compensated sensor output signal, especially the relative change, wherein the calibration process includes: confirming the associated change of the compensated sensor output signal as a predetermined threshold as one of the one or more calibration parameters.

8. A system (201) for detecting contamination (419) of a micro-electromechanical sensor (207) of a sensor module (205), comprising: A heating device (203) and A sensor module (205), the sensor module (205) comprising: Micro-electromechanical sensors (207) and a temperature sensor (209) arranged spaced apart from the heating device (203) and the micro-electromechanical sensor (207), The system (201) is configured to perform all steps of the method according to any one of the preceding claims.

9. The system (201) according to claim 8 is configured such that a first temperature gradient between the temperature sensor (209) and the microelectromechanical sensor (207) when the heating device (203) is turned on and the microelectromechanical sensor (207) is free of contamination (419) is smaller than a second temperature gradient between the temperature sensor (209) and the microelectromechanical sensor (207) when the heating device (203) is turned on and the microelectromechanical sensor (207) is contaminated (419) by at least a predetermined factor.

10. The system (201) according to claim 9, wherein: The predetermined coefficient is within a closed interval from 10 to 100.

11. The system (201) according to any one of claims 8 to 10, wherein: The micro-electromechanical sensor (207) is covered by a protective layer having a thickness within a closed interval from 1 μm to 100 μm.

12. The system (201) according to any one of claims 8 to 11, comprising a first substrate, in particular a first wafer, in particular a silicon wafer, carrying the circuit.

13. The system (201) according to claim 12, wherein: The microelectromechanical sensor (207) is comprised by a second substrate (423), in particular a second wafer, in particular a silicon wafer, wherein the second substrate (423) is arranged spaced apart from the first substrate (421) and is connected to the first substrate (421) by means of an adhesive material.

14. The system (201) according to claim 12 or 13, wherein: The first substrate (421) includes the temperature sensor (209).

15. The system (201) according to any one of claims 12 to 14 referring back to claim 11, comprising a housing (413) with a bottom (411), the first substrate (421) being arranged on the bottom, wherein: The housing (413) is filled with a protective material so that the micro-electromechanical sensor (207) is covered by a protective layer.

16. A computer program (303) product comprising instructions which, when the computer program (303) is executed by a computer, cause the computer to perform the method according to any one of claims 1 to 7.

17. A machine-readable storage medium (301) on which a computer program (303) according to claim 16 is stored.

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