Electronic device including a wake-up circuit employing deformation detection

Abstract

The present description relates to an electronic device (100) configured to operate at least in a standby state or in an awake state, comprising at least: - a deformation sensor (102) comprising at least one piece of piezoelectric material (103) the thickness of which is less than 50 µm; - a wake-up circuit (104) comprising at least one comparator (110) configured to compare a value obtained from a measurement signal of the deformation sensor (102) with a wake-up threshold value and to output a signal to wake up the electronic device (100) when the value obtained from the measurement signal is greater than the wake-up threshold value.

Description

DESCRIPTION TITLE: ELECTRONIC DEVICE WITH WAKE-UP CIRCUIT BY DEFORMATION DETECTION The present application claims priority from French patent application number 24 / 07461, filed on July 9, 2024, entitled "Electronic device with wake-up circuit by strain detection", which is incorporated by reference to the fullest extent permitted by law. technical field

[0001] This description generally relates to the field of monitoring, in particular vibration monitoring or more generally deformation monitoring, applied for example to structures, infrastructures, machines, etc. Previous technique

[0002] It is possible to monitor the fatigue state of a structure or infrastructure, such as a building or a pipeline network, or even the condition of a machine, using IoT (Internet of Things) beacons, or wirelessly connected sensors. Such a beacon typically includes one or more sensors, possibly a circuit for analyzing the measurements taken, and a wireless communication circuit. One of the major constraints for these beacons is maximizing their battery life. This involves optimizing the management of the beacons' standby phases, or states or modes, during which their functionality is limited to reduce energy consumption, and their active or wake-up phases. tags, during which the tags are fully functional.

[0003] One possible approach to managing the sleep and wake phases of a beacon involves periodically waking it up arbitrarily and taking a measurement during the wake phase to see if a monitored event, such as vibrations, is occurring. If the event is occurring, measurements are taken. Otherwise, the beacon is returned to sleep. However, this approach is not efficient because many wake-ups may be unnecessary when the monitored event does not occur. Furthermore, the beacon may be in a sleep state when the monitored event does occur, i.e., at a time when taking measurements would have been relevant.

[0004] A second possible method for managing the sleep and wake phases of a beacon involves using a low-power, local detection device. For example, when the event to be monitored is the occurrence of vibrations in the element to which the beacon is attached, the beacon can be equipped with an accelerometer to detect acceleration related to these vibrations and wake the beacon if such acceleration is detected. However, this method has the drawback that the accelerometer has a continuous power consumption that can be significant, for example, exceeding 10 pA. Furthermore, the acceleration threshold value at which the accelerometer wakes the beacon is fixed and cannot be easily modified.Finally, this solution results in a significant delay between the moment the accelerometer detects an acceleration and the moment the beacon is woken up and makes the desired measurement, because the transition from an acceleration measurement to a corresponding deformation value requires the setting. implementing two integrations of the measured acceleration value.

[0005] These drawbacks can also be found in other types of electronic devices that have to manage wake-up and standby phases. Summary of the invention

[0006] There is a need to offer an electronic device that can be in a standby state and whose management of standby and wake-up phases does not pose the problems of existing devices.

[0007] One embodiment overcomes all or part of the drawbacks of known solutions and proposes an electronic device configured to operate at least in a standby or awake state, comprising at least:

[0008] - a strain sensor comprising at least a portion of piezoelectric material whose thickness is less than 50 pm;

[0009] - a wake-up circuit comprising at least one comparator configured to compare a value obtained from a measurement signal of the strain sensor with a wake-up threshold value and to output a wake-up signal of the electronic device when the value obtained from the measurement signal is greater than the wake-up threshold value.

[0010] In a particular embodiment, the portion of piezoelectric material comprises a piezoceramic material.

[0011] In a particular embodiment, the electronic device corresponds to a strain measurement device and further includes a measurement acquisition circuit configured to receive and process the measurement signal from the strain sensor, or a signal from the measurement signal of the strain sensor, when the electronic device is awake.

[0012] In a particular embodiment, the measurement acquisition circuit comprises at least:

[0013] - a signal processing circuit for the measurement signal from the deformation sensor or the signal derived from the measurement signal of the deformation sensor;

[0014] - a wake-up control circuit configured to receive as input the wake-up signal and the measurement signal from the strain sensor, or to receive as input the wake-up signal and the signal from the measurement signal from the strain sensor, and to control, upon receipt of the wake-up signal, the sending of the measurement signal from the strain sensor or the signal from the measurement signal from the strain sensor to the input of the processing circuit and the power supply to the processing circuit.

[0015] In one particular embodiment, the wake-up control circuit includes at least one microcontroller configured to operate in a low-power mode when the electronic device is in standby.

[0016] In a particular embodiment, the wake-up control circuit includes at least one transmission gate comprising at least one data input configured to receive the measurement signal from the strain sensor or the signal from the measurement signal from the strain sensor, at least one output coupled to an input of the processing circuit, and at least one control input coupled to an output of the microcontroller.

[0017] In a particular embodiment, the processing circuit includes at least one amplifier, and at least one switch configured to control the amplifier's power supply according to a signal of command intended to be issued by the microcontroller and such that the amplifier is not electrically powered when the electronic device is in standby.

[0018] In a particular embodiment, the processing circuit further includes at least one analog-to-digital converter and / or at least one anti-aliasing filter.

[0019] In a particular embodiment, the electronic device further comprises at least one wireless communication circuit configured to transmit over a wireless network data obtained from an output signal of the processing circuit.

[0020] In a particular embodiment, the electronic device further includes a wake-up threshold circuit which is programmable and configured to apply the wake-up threshold value to the comparator input, and in which the wake-up threshold value is defined as a function of a value received by the wireless communication circuit.

[0021] In a particular embodiment, the electronic device is configured to switch the microcontroller from low-power mode to active mode upon receiving a new wake-up threshold value through the wireless communication circuit, then to update the wake-up threshold circuit with the new threshold value received, and then to switch the microcontroller from active mode to low-power mode.

[0022] In a particular embodiment, the electronic device is configured to turn the switch on and to switch the microcontroller from a low-power mode to an active mode when the value of the measurement signal from the strain sensor or the signal derived from the measurement signal from the strain sensor becomes greater than the wake-up threshold value, then start acquiring the measurement signal from the strain sensor or the signal from the measurement signal from the strain sensor, then stop acquisition when the value of the measurement signal from the strain sensor or the signal from the measurement signal from the strain sensor becomes less than the wake-up threshold value, then calculate and transmit data obtained from the acquisition performed, then to switch the microcontroller from active mode to low power mode and put the switch in the blocked state.

[0023] In a particular embodiment, the wake-up circuit further includes a biasing circuit configured to receive as input the measurement signal from the strain sensor and to bias the measurement signal from the strain sensor and deliver on an input of the comparator an output signal representative of the absolute value of the measurement signal from the strain sensor.

[0024] In one particular embodiment, the electronic device further includes a power supply battery.

[0025] Also described is a vibration monitoring system, comprising at least one electronic device as described herein and computer equipment to which said at least one electronic device is connected through a computer network. Brief description of the drawings

[0026] These features and advantages, as well as others, will be described in detail in the following description of particular embodiments, given by way of non-limiting example, in relation to the attached figures, among which:

[0027] - Figure 1 schematically represents an example of an electronic device according to a particular embodiment;

[0028] - Figure 2 schematically represents an example of the implementation of the electronic device according to a particular embodiment;

[0029] - Figure 3 schematically represents an example of the implementation of a biasing circuit for the electronic device;

[0030] - Figure 4 schematically represents an example of the implementation of an amplifier of the electronic device;

[0031] - Figure 5 schematically represents an example of the implementation of an anti-aliasing filter for the electronic device;

[0032] - Figure 6 represents a logic diagram implemented by an electronic device according to a particular embodiment;

[0033] - Figure 7 represents examples of signals obtained during an awakening and a deformation measurement carried out by an electronic device according to a particular embodiment. Description of the implementation methods

[0034] The same elements may be designated by the same references in the different figures. In particular, structural and / or functional elements common to the different embodiment examples may have the same references and may have identical structural, dimensional and material properties.

[0035] For the sake of clarity, only the steps and elements useful for understanding the methods and examples of implementation are included. The described components have been represented and are detailed. In particular, various elements and circuits of the electronic device (strain sensor, microcontroller, analog-to-digital converter, wireless communication circuit, etc.) are not detailed. A person skilled in the art will be able to implement these elements in detail from the functional description provided here.

[0036] Unless otherwise specified, when referring to two connected elements, this means directly connected without any intermediate elements other than conductors, and when referring to two coupled elements, this means that these two elements can be connected or linked through one or more other elements.

[0037] Unless otherwise specified, the expressions "approximately", "roughly", "about", and "on the order of" mean within 10%, preferably within 5%.

[0038] An example of an electronic device 100 according to a particular embodiment is described below in relation to figure 1.

[0039] In the example described, device 100 corresponds to a deformation measurement device configured to monitor a deformation of an element and / or the appearance of vibrations of the element which can be a structure, an infrastructure, a machine, etc.

[0040] Advantageously, device 100 corresponds to an IoT beacon used within a monitoring system, for example a vibration monitoring system, comprising at least one such IoT beacon and at least one computer equipment to which the beacon(s) are wirelessly connected through a computer network.

[0041] To limit its power consumption, the device 100 is configured to operate in different states. In the particular embodiment described here, the device 100 can be either in a standby state or in an awake or active state. Alternatively, the device 100 can have other operating states, such as one or more deep or intermediate sleep states.

[0042] The device 100 includes at least one strain sensor 102. The sensor 102 comprises at least one portion of piezoelectric material 103 with a thickness of less than 50 µm, preferably less than 25 µm, and even more preferably less than 10 µm. For example, the value of the thickness-to-width ratio, and / or the thickness-to-length ratio, of this portion of piezoelectric material 103 is, for example, less than 0.1, preferably less than 0.05, and even more preferably less than 0.01.

[0043] In the described embodiment, the piezoelectric material of portion 103 corresponds to a piezoceramic material, for example PZT (lead zirconate titanate), LiNbO3 (lithium niobate), or LiTaO3 (lithium tantalate). Other piezoelectric materials are also conceivable for the realization of portion 103, such as BaTiO3 (barium titanate), PbTiO3 (lead titanate), KNbO3 (potassium niobate), and NBT (Na Of 5 Bi 0f 5 TiO3 (sodium bismuth titanate), BiFeO3 (bismuth ferrite), ZnO (zinc oxide), AIN (aluminum nitride), or BNT (Bi Of 5 NaO2,5TiO3 or sodium bismuth titanate) or a crystal such as quartz, or a polymeric piezoelectric material such as BVD F.

[0044] Other details of the realization of such a sensor 102 are described for example in the document by T. Dufay et al., “Flexible PZT thin film transferred on polymer substrate”, Surface and Coatings Technology, Elsevier, 2018, 343, pp.148-152.

[0045] In the example of Figure 1, the portion of piezoelectric material 103 of the sensor 102 is arranged between a first electrode coupled to a reference electrical potential and a second electrode on which a measurement signal called "ch_in" is delivered at the output of the sensor 102.

[0046] The device 100 also includes a wake-up circuit 104 whose function is to detect, with high precision, the occurrence of a deformation triggering the transition from the standby state to the awake state of the device 100. The wake-up circuit 104 is configured to operate with very low power consumption.

[0047] In the example shown in Figure 1, the wake-up circuit 104 includes a biasing circuit 106 configured to receive as input the measurement signal ch_in from the sensor 102 and to bias this signal so as to obtain at the output of the biasing circuit 106 an output signal, here a voltage, called "voltage_out", which is representative of the absolute value of the measurement signal ch_in. In the described embodiment, the biasing circuit 106 is used to allow comparison of the measurement signal ch_in to a reference value regardless of the sign of the measurement signal ch_in, since the measurement signal ch_in can be positive or negative depending on the deformation to which the sensor 102 is subjected.

[0048] Alternatively, it is possible that the wake-up circuit 104 does not include the biasing circuit 106.

[0049] In the example of Figure 1, the wake-up circuit 104 further includes a wake-up threshold circuit 108 configured to output a wake-up threshold value called "vth", here a voltage, to which the output signal voltage_out is intended to be compared to determine whether the device 100 should be woken up and exit the sleep state.

[0050] Advantageously, the wake-up threshold circuit 108 is programmable and the wake-up threshold value vth can be set as a function of a value received by the wake-up threshold circuit 108, for example wirelessly.

[0051] Although not shown in Figure 1, the device 100 described in this example includes a wireless communication circuit configured to transmit and receive data over a wireless network. When the wake-up threshold circuit 108 is programmable, the wake-up threshold value vth delivered by the wake-up threshold circuit 108 may have been initially received by the wireless communication circuit. Different communication protocols and / or standards can be used for data exchanges implemented with the device 100. Alternatively, the device 100 may communicate via a wired connection.

[0052] The wake-up circuit 104 further includes a comparator 110 configured to compare the value of the output signal voltage_out to the wake-up threshold value vth and output a wake-up signal called "wake_up" of device 100. The value of this signal triggers the awakening of device 100 when the value of the output signal voltage_out is greater than the wake-up threshold value vth. For example, the wake_up signal may have a non-zero value when device 100 needs to transition from standby to wake-up mode. When the wake-up circuit 104 does not include the circuit polarization 106, comparator 110 can perform a comparison between the measurement signal ch_in and the wake-up threshold value vth.

[0053] In the particular embodiment described, the device 100 is a deformation measuring device in which the measurement signal ch_in from the sensor 102 serves both as a wake-up function and for the precise measurement of the deformation to be evaluated by the device 100. To this end, the device 100 further includes a measurement acquisition circuit 112 for receiving as input the wake-up signal wake_up and the measurement signal ch_in. The measurement acquisition circuit 112 is designed to process the measurement signal ch_in when the device 100 is in the awake state. At least some of the elements of the measurement acquisition circuit 112 are designed to be woken up and / or powered when the device 100 transitions from the sleep state to the awake state.

[0054] Alternatively, the measurement acquisition circuit 112 could receive the output signal voltage_out as input instead of the measurement signal ch_in.

[0055] As an alternative to the particular embodiment described, it is possible that the device 100 is not configured to process the deformation measurement obtained by the sensor 102, but serves only to wake up another device, for example a camera, another sensor, etc. In this case, the device 100 may not include the measurement acquisition circuit 112.

[0056] In the example of Figure 1, the measurement acquisition circuit 112 includes a processing circuit 114 configured to process the measurement signal ch_in when the device 100 is in the awake state.

[0057] In the example described, the processing circuit 114 includes an amplifier 116 configured to receive the measurement signal ch_in as input, an anti-aliasing filter 118 configured to receive the amplified measurement signal obtained from the output of amplifier 116 as input, and an analog-to-digital converter 120 configured to receive the amplified and filtered measurement signal obtained from the output of filter 118 as input. The type of amplifier 116 used depends on the nature of the signal to be amplified. In the embodiment described here, amplifier 116 is a load amplifier.

[0058] Alternatively, the processing circuit 114 may include other components or circuits performing one or more additional operations or processing on the measurement signal ch_in.

[0059] In the example of Figure 1, the measurement acquisition circuit 112 also includes a wake-up control circuit 122 configured to receive as input the wake_up signal and the measurement signal ch_in, and to control, upon receipt of a value of the wake-up signal indicating that the device 100 should switch from the sleep state to the wake-up state, the wake-up of the processing circuit 114.

[0060] In the example shown in Figure 1, the alarm clock control circuit 122 includes a microcontroller 124, a switch 126, and a transmission gate 128. The switch 126 and the transmission gate 128 are controlled by the microcontroller 124. For example, the switch 126 contains a MOSFET transistor. Furthermore, the transmission gate 128 can contain at least two MOSFET transistors. When the amplifier 116 is a two-input amplifier, the control circuit 122 can contain two transmission gates 128, each coupled to one of the inputs of the amplifier 116.

[0061] The microcontroller 124 is configured to receive the wake_up signal as input. When the wake_up signal value indicates that the device 100 should transition from sleep to wake, the microcontroller 124 sends a control signal called "shut_dwn" to the switch 126 to turn it on and energize the amplifier 116, and sends another control signal called "voltage_en" to the transmission gate 128 to turn it on and energize the measurement signal ch_in to the input of the amplifier 116. In the described embodiment, the amplifier 116 is intended not to be powered when the device 100 is in sleep mode.

[0062] Thus, once the device 100 is in the awake state, the deformation experienced by the sensor 102 can be measured by the measurement acquisition circuit 112 until the device 100 returns to standby mode. The measurements obtained can be stored and / or transmitted from the device 100, for example via the wireless communication circuit, to a server or a computer device designed to collect the deformation measurements performed by the device 100. It is also possible that the device 100 includes one or more measurement analysis circuits, and that the transmitted data corresponds not to the measured deformation values, but, for example, to the results of calculations performed based on the measured values.

[0063] An example of the implementation of device 100 according to a particular embodiment is described below in relation to figure 2.

[0064] In this example implementation, the biasing circuit 106, the amplifier 116, the filter 118, the switch 126 and transmission gates 128 are made within an analog front-end circuit 130 (AFE, or "Analog Front-End" in English) configured to receive as input the measurement signal ch_in.

[0065] In addition, the comparator 110, the analog-to-digital converter 120, and the microcontroller 124 are implemented within a separate integrated circuit 132 distinct from the AFE 130. In this example, the amplified and filtered measurement signal obtained at the output of the filter 118 is called charge_out and is transmitted from the AFE 130 to the integrated circuit 132. Furthermore, in the described example, the integrated circuit 132 also includes a nested vectored interrupt controller 134 (NVIC, or "Nested Vectored Interrupts Controller") configured to receive the wake_up signal as input and send wake-up instructions from the device 100 to the microcontroller 124 depending on the value of the wake_up signal.In the example described, the circuit 132 further includes a current amplifier 136 configured to supply current while maintaining a stable reference voltage vref to the AFE 130, as well as a digital-to-analog converter 138 that receives the reference voltage vref as input and delivers the wake-up threshold value vth as output. In the example in Figure 2, the reference voltage vref is supplied by a reference voltage circuit 140. The elements 136, 138, and 140 can be seen as forming the wake-up threshold circuit 108. The integrated circuit 132 may include other elements such as various memories (RAM, static, dynamic, flash, etc.), computing and communication circuits such as the wireless communication circuit described previously, etc.

[0066] In the example described, the biasing circuit 106 is used particularly when the permissible range of the the input voltage on the analog-to-digital converter 120 and / or comparator 110 is not symmetrical and the measurement signal ch_in must be biased to center its quiescent value in the middle of the permissible range of the input voltage.

[0067] In the embodiment shown in Figure 2, the AFE 130 and the integrated circuit 132 are powered by a voltage Vcc with a value, for example, between 2.7 V and 3.6 V. As can be seen in Figure 2, the signals voltage_out, vref, shut_dwn, Vcc, charge_out, and voltage_en are transmitted between the AFE 130 and the integrated circuit 132. In an alternative embodiment, the shut_dwn and voltage_en signals can correspond to a single signal controlling the switch 126 and the transmission gates 128.

[0068] An example of the implementation of the biasing circuit 106 is shown in Figure 3. In this example, the biasing circuit 106 includes a resistive bridge comprising first and second resistors 142 and 144, the first electrodes of which are electrically coupled to each other. The reference voltage vref is applied across the terminals of this resistive bridge formed by the second electrodes of these resistors 142 and 144. An output electrode of the sensor 102 is coupled to the first electrodes of resistors 142 and 144, from which the output signal voltage_out is obtained.

[0069] An example of the implementation of amplifier 116 is shown in Figure 4. In this figure, amplifier 116 corresponds to a load amplifier.

[0070] In this example of amplifier implementation 116, a first operational amplifier 146 performs the function of a load amplifier. A biasing circuit 148 is coupled to the non-inverting input of the first amplifier. Operational amplifier 146 is used to maintain, during the active phase, a bias of the output of sensor 102 at the same value as that of the biasing circuit 106 during the inactive phase. This ensures a very short stabilization time for the charge amplifier during an inactive / active phase change and vice versa. The output of sensor 102 is coupled to the inverting input of the first operational amplifier 146, and the electrical charges generated by sensor 102 are integrated into a feedback capacitor 150 for a time corresponding to the product of the value Ci of capacitor 150 and the value Ri of a feedback resistor 152 connected in parallel with capacitor 150. The resulting gain is 1 / Ci V / C (Volts per Coulomb), and the resulting low cutoff frequency is equal to 1 / (2*n*Ri*Ci).The amplifier example 116 shown in Figure 4 also includes a second operational amplifier 154 which performs a common mode modification to center the rest value of the sensor 102 in the middle of the voltage range admissible by the analog-to-digital converter 120. This makes it possible to digitize a charge variation, both positive and negative, resulting from a positive or negative deformation of the sensor 102.

[0071] An example of the implementation of filter 118 is shown in Figure 5. In this figure, filter 118 corresponds to an RC low-pass filter.

[0072] An example of the operation of the device 100 described above is given below, linked to figure 6 which represents a flowchart of the steps implemented during this operation.

[0073] Reference 200 designates the standby state of device 100. In this state, the AFE 130 is off and the integrated circuit 132 operates in a low power mode. In particular, when device 100 is in standby mode, amplifier 116 is not powered and some of the functions of microcontroller 124 are in standby. In this standby state, however, device 100 remains listening for a request to modify the threshold value vth (step 202) and also compares the value of the measurement signal ch_in with the threshold value vth (step 204).

[0074] When a request to modify the threshold value vth is received, the microcontroller 124 is woken up (step 206), the threshold value vth is updated with the new value received (step 208) and the microcontroller 124 returns to low power mode (step 210), the device 100 returning to the standby state (return to step 200).

[0075] When the value of the measurement signal ch_in (or the value of the voltage_out signal in the presence of the biasing circuit 106) becomes greater than the threshold value vth, the microcontroller 124 and the AFE 130 are woken up (step 212). This wake-up of the AFE 130 notably involves powering the amplifier 116. The values ​​measured by the sensor 102 are processed by the processing circuit 114 (step 214) until the value of the measurement signal ch_in (or the voltage_out signal in the presence of the biasing circuit 106) becomes less than the threshold value vth (comparison of the measurement with the threshold value vth performed in step 216). At this point, data acquisition is stopped (step 218). The AFE 130 is then switched off (step 220). A KPI (Key Performance Indicator) is then calculated (step 222) and then transmitted out of device 100, for example wirelessly in the example described (step 224).This KPI can correspond, for example, to a peak-to-peak value, an RMS value, dominant frequency values, energy in a particular frequency band, or a. power spectral density. The microcontroller 124 returns to low power mode (step 226), and the device 100 returns to standby with the shutdown of the AFE 130 (return to step 200).

[0076] Figure 7 shows examples of signals obtained in device 100 during a deformation measurement by sensor 102.

[0077] Reference 230 designates the measurement signal ch_in delivered by the sensor 102 when it is subjected to a deformation whose value increases.

[0078] Reference 232 designates the threshold value vth, and reference 234 designates the voltage_out signal obtained at the output of the biasing circuit 106. At time ti, the value of the voltage_out signal becomes greater than the threshold value vth. The shut_dwn signal, designated by reference 236, then changes from a high value to a low value, causing switch 126 to become conductive and power amplifier 116. Reference 238 designates the charge_out signal obtained at the output of the anti-aliasing filter 118, which corresponds to the amplified and filtered measurement signal ch_in.

[0079] As can be seen in Figure 7, the time during which device 100 remains in standby mode while sensor 100 begins to undergo deformation—that is, the time during which the deformation is not measured and which corresponds to the time it takes for device 100 to transition from standby to awake mode—is very short, for example, on the order of 20 ps in the case of deformation corresponding to a vibration with a frequency equal to or less than 48 kHz. The higher the cutoff frequency of the anti-aliasing filter 118, the shorter the time required to stabilize device 100. example of the order of 4 ps for a deformation corresponding to a cutoff frequency of 200 kHz.

[0080] For example, when the device 100 is in standby mode, the electrical current consumed by the AFE 130 can be on the order of 100 nA (corresponding to the leakage current of the MOS transistor forming the switch 126) to which is added approximately 120 nA consumed by the biasing circuit 106. In the awake state, the electrical current consumed by the AFE 130 can be on the order of 3 mA (corresponding to the consumption of the amplifier 116) to which is added approximately 102 pA consumed by the biasing circuit 106.

[0081] As previously mentioned, device 100 is advantageously suited as a LoT beacon. Device 100 may include a battery to power the various components and circuits described above.

[0082] Alternatively, other circuits or elements of device 100 may be put into standby mode or not be electrically powered when device 100 is in standby mode.

[0083] Device 100 has the particular advantage of maximizing its battery life, thanks in particular to the optimization of the management of transitions between the wake-up and standby phases of device 100 obtained through the wake-up circuit 104 of device 100 and the properties of sensor 102.

[0084] In the particular embodiment described above, the device 100 has the advantage of using a measured physical quantity, here deformation, to activate the device 100 with a precise and programmable detection threshold, which is possible thanks to the high-quality piezoelectric deformation sensor 102. Device 100 may have only one single sensor 102 to serve as a source for waking up Device 100 and providing measurement data, thanks to the ability of Device 100 to switch very quickly from a standby state to an active or awake state.

[0085] Device 100 can have, in standby mode, an electrical current consumption of less than 250 nA.

[0086] Device 100 allows for continuous, uninterrupted monitoring of the element on which device 100 is mounted.

[0087] Device 100 is well suited to detect different types of vibration, from small rapidly changing deformations to large slow deformations.

[0088] Device 100 eliminates latency due to decorrelation between measured acceleration and calculated deformation, because the sensor used for the alarm directly measures the deformation undergone by the alarm.

[0089] Thanks to the thin portion of piezoelectric material used, sensor 102 of device 100 exhibits a uniform frequency response, good sensitivity, and good measurement accuracy. Furthermore, the piezoelectric material in sensor 102 is thin enough that the sensor is flexible and can conform to the surface and contours of the element to which it is attached.

[0090] Device 100 can offer the possibility of modifying on the fly the wake-up threshold value of device 100, which makes it possible, for example, not to wake up device 100 when a known or expected transient event occurs for which the threshold value is suitable.

[0091] The 102 sensor with piezoelectric material also has the advantage of having lower electrical consumption than a resistive gauge.

[0092] Among the many possible applications of device 100, it is particularly well-suited for monitoring and measuring the fatigue of a penstock. Device 100 is also well-suited for detecting when someone touches a computer server card, as sensor 102 is sensitive enough to detect the deformations caused by this contact.

[0093] Various embodiments and variations have been described. A person skilled in the art will understand that some features of these various embodiments and variations could be combined, and other variations will become apparent to a person skilled in the art.

[0094] Finally, the practical implementation of the described methods and variants is within the reach of the person in the trade, based on the functional indications given above.

Claims

DEMANDS 1. Electronic device (100) configured to operate at least in a standby state or in an awake state, comprising at least: - a strain sensor (102) comprising at least a portion of piezoelectric material (103) whose thickness is less than 50 pm; - a wake-up circuit (104) comprising at least one comparator (110) configured to compare a value obtained from a measurement signal from the strain sensor (102) with a wake-up threshold value and output a wake-up signal from the electronic device (100) when the value obtained from the measurement signal is greater than the wake-up threshold value.

2. Electronic device (100) according to claim 1, wherein the portion of piezoelectric material (103) comprises a piezoceramic material.

3. Electronic device (100) according to any one of the preceding claims, corresponding to a deformation measurement device, and further comprising a measurement acquisition circuit (112) configured to receive as input and process the measurement signal from the deformation sensor (102), or a signal from the measurement signal from the deformation sensor (102), when the electronic device (100) is awake.

4. Electronic device (100) according to claim 3, wherein the measurement acquisition circuit (112) comprises at least: - a processing circuit (114) for the measurement signal from the strain sensor (102) or the signal from the measurement signal from the strain sensor (102); - a wake-up control circuit (122) configured to receive as input the wake-up signal and the measurement signal from the strain sensor (102), or to receive as input the wake-up signal and the signal from the measurement signal from the strain sensor (102), and to control, upon receipt of the wake-up signal, the sending of the measurement signal from the strain sensor (102) or the signal from the measurement signal from the strain sensor (102) to the input of the processing circuit (114) and the power supply to the processing circuit (114).

5. Electronic device (100) according to claim 4, wherein the wake-up control circuit (122) comprises at least one microcontroller (124) configured to operate in a low-power mode when the electronic device (100) is in standby.

6. Electronic device (100) according to claim 5, wherein the wake-up control circuit (122) comprises at least one transmission gate (128) including at least one data input configured to receive the measurement signal from the strain sensor (102) or the signal derived from the measurement signal from the strain sensor (102), and at least one output coupled to an input of the circuit processing (114), and at least one control input coupled to a microcontroller output (124).

7. Electronic device (100) according to claim 5 or 6, wherein the processing circuit (114) comprises at least one amplifier (116), and at least one switch (126) configured to control the power supply of the amplifier (116) according to a control signal intended to be emitted by the microcontroller (124) and such that the amplifier (116) is not powered when the electronic device (100) is in standby.

8. Electronic device (100) according to any one of claims 4 to 7, wherein the processing circuit (114) further comprises at least one analog-to-digital converter (120) and / or at least one anti-aliasing filter (118).

9. Electronic device (100) according to any one of claims 4 to 8, further comprising at least one wireless communication circuit configured to transmit over a wireless network data obtained from an output signal of the processing circuit (114) 10. Electronic device (100) according to claim 9, further comprising a wake-up threshold circuit (108) which is programmable and configured to apply the wake-up threshold value to the input of the comparator (110), and in which the wake-up threshold value is defined as a function of a value received by the wireless communication circuit.

11. Electronic device (100) according to claims 5 and 10, configured to switch the microcontroller (124) from low power mode to active mode upon receiving a new wake-up threshold value through the wireless communication circuit, then to update the wake-up threshold circuit (108) with the new threshold value received, and then to switch the microcontroller (124) from active mode to low power mode.

12. Electronic device (100) according to claim 7 and according to any one of claims 9 to 11, configured to turn on the switch (126) and to switch the microcontroller (124) from a low-power mode to an active mode when the value of the measurement signal from the strain sensor (102) or the signal from the measurement signal from the strain sensor (102) becomes greater than the wake-up threshold value, then begin acquiring the measurement signal from the strain sensor (102) or the signal from the measurement signal from the strain sensor (102), then stop the acquisition when the value of the measurement signal from the strain sensor (102) or the signal from the measurement signal from the strain sensor (102) becomes less than the wake-up threshold value, then calculate and transmit data obtained from the acquisition performed,then to switch the microcontroller (124) from active mode to low power mode and to put the switch (126) in the blocked state.

13. Electronic device (100) according to any one of the preceding claims, wherein the wake-up circuit (104) further comprises a biasing circuit (106) configured to receive as input the measurement signal from the strain sensor (102) and to bias the measurement signal from the strain sensor (102) and deliver on an input of the comparator (110) an output signal representative of the absolute value of the measurement signal from the strain sensor (102).

14. Electronic device (100) according to any one of the preceding claims, further comprising a power supply battery.

15. Vibration monitoring system, comprising at least one electronic device (100) according to any one of the preceding claims and computer equipment to which said at least one electronic device (100) is connected through a computer network.

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