SEISMOCARDIOGRAPHY

Abstract

Seismocardiographic reading device (120) comprising: - two charge amplifiers (210, 220) configured to receive an input from an accelerometer (110) and each to generate a first output signal, wherein the accelerometer (110) comprises two mechanical capacitors connected in series, the mechanical capacitors changing their capacitance according to acceleration pulses, wherein two feedback loops via respective switches (330, 340) in the reading device are connected via a differential amplifier, and - the differential amplifier (230) configured to receive the first output signals and amplify a difference between the first output signals to generate two second output signals, wherein, when the switches (330, 340) are open, a resistance of the switches (330,340) in the locked state, a resistance feedback is suppressed and an active high-pass filter functionality is generated, wherein the active high-pass filter functionality suppresses a constant acceleration component in the input from the accelerometer (110).

Description

AREA

[0001] The present invention relates to monitoring cardiac activity, such as monitoring a human heart. GENERAL STATE OF THE ART

[0002] Heart activity can be monitored using various methods, including auscultation, ultrasound examinations, and electrocardiography (ECG). Auscultation involves listening for sounds produced by the heart, for example, using a stethoscope. Different methods are suitable for different settings and require varying levels of expertise. In a home setting, an ECG can be a useful option, as it requires only a basic level of user knowledge.

[0003] Performing an ECG measurement involves establishing an electrical connection with a person's skin to access electrical signals originating from the heart. For example, two electrodes spaced approximately 5 to 10 centimeters apart can be used to generate ECG sensor data that characterize heart activity.

[0004] Cardiac data obtained using ECG or other methods can be analyzed by human professionals or automated expert systems to classify the monitored cardiac activity as normal or abnormal. If the activity is classified as abnormal, the abnormality can be further classified to determine, for example, whether the heart is in a state of tachycardia, bradycardia, or ventricular fibrillation.

[0005] Another method for monitoring heart activity is seismocardiography, which involves the non-invasive measurement of accelerations in the chest wall generated by myocardial movements. Unlike an ECG, seismocardiography does not require an electrical connection to the person's skin. Instead, an accelerometer can be placed on the person's chest, where it generates accelerometer data that characterizes heart activity.

[0006] Since seismocardiography does not require an electrical connection to the skin, it is more suitable and practical for long-term cardiac monitoring. On the other hand, accelerometer data obtained from an accelerometer placed on the person's chest includes various types of unwanted signals, such as those generated by the person's movement and breathing. BRIEF SUMMARY OF THE INVENTION

[0007] The invention is defined by the features of the independent claims. Some specific embodiments are defined in the dependent claims.

[0008] According to a first aspect of the present invention, a device is provided comprising two charge amplifiers configured to receive an input from an accelerometer and each to generate a first output signal, and a differential amplifier configured to receive the first output signals and amplify a difference between the first output signals to generate two second output signals.

[0009] Different embodiments of the first aspect may include at least one feature from the following list: • The second output signals of the differential amplifier are connected, via switches, to lines that carry the first output signals. • When the switches are closed, an output state of the differential amplifier is reset. • When the switches are open, the resistance of the switches in the closed state forms a resistance feedback, and an active high-pass filter functionality is generated, whereby the active high-pass filter functionality suppresses a constant acceleration component in the input from the accelerometer. • The switches are connected in parallel with capacitors. • at least one processing core configured to trigger a measurement state in response to a finding that motion disturbances are below a threshold. • that at least one processing core is configured to keep the device in a motion detection state when the motion disturbances are not below the threshold • which is configured, based on the second output signals, to determine whether a person being measured by the accelerometer is experiencing atrial fibrillation • a differential analog-to-digital converter configured to receive the two second output signals and output a digital representation of them.

[0010] According to a second aspect of the present invention, a method is provided which comprises receiving, in two charge amplifiers, an input from an accelerometer, generating, in each of the charge amplifiers, a first output signal and amplifying, in a differential amplifier, a difference between the first output signals to generate two second output signals.

[0011] Different embodiments of the second aspect may include at least one feature from the following list: • The second output signals of the differential amplifier are connected, via switches, to lines that carry the first output signals. • Resetting the output state of the differential amplifier is achieved by closing the switches. • When the switches are open, the resistance of the switches in the closed state forms a resistance feedback, and an active high-pass filter functionality is generated, whereby the active high-pass filter functionality suppresses a constant acceleration component in the input from the accelerometer. • The switches are connected in parallel with capacitors. • Triggering, by at least one processing core, a measurement state in response to a finding that motion disturbances are below a threshold value, • Maintain, by at least one processing core, a motion detection state when the motion disturbances are not below the threshold. • Determine, by at least one processing core, based on the second output signals, whether a person being measured by the accelerometer is experiencing atrial fibrillation • Receiving the two second output signals in a differential analog-to-digital converter, which outputs a digital representation of the same.

[0012] According to a third aspect of the present invention, a device is provided comprising means for receiving, in two charge amplifiers, an input from an accelerometer, generating, in each of the charge amplifiers, a first output signal and amplifying, in a differential amplifier, a difference between the first output signals in order to generate two second output signals.

[0013] According to a fourth aspect of the present invention, a non-volatile, computer-readable medium is provided which has stored on it a set of computer-readable instructions which, when executed by at least one processor, cause a device to receive an input from an accelerometer in two charge amplifiers, to generate a first output signal in each of the charge amplifiers, and to amplify a difference between the first output signals in a differential amplifier in order to generate two second output signals.

[0014] According to a fifth aspect of the present invention, a computer program is provided which is configured to cause a method according to the second aspect to be carried out. List of characters Fig. Figure 1 illustrates an exemplary system according to at least some embodiments of the present invention. Fig. Figure 2 illustrates an exemplary device according to at least some embodiments of the present invention. Fig. Figure 3 illustrates an exemplary device according to at least some embodiments of the present invention. Fig. Figure 4 illustrates an exemplary device according to at least some embodiments of the present invention. Fig. 5 illustrates filtering carried out in a reading device according to at least some embodiments of the present invention, Fig. Figure 6 illustrates an exemplary device capable of supporting at least some embodiments of the present invention, and Fig. Figure 7 is a flowchart of a method according to at least some embodiments of the present invention. EXECUTION FORMS

[0015] This paper describes a three-amplifier architecture for seismocardiographic accelerometer data, such that one of the three amplifiers is a differential amplifier configured to amplify the difference between the outputs of the other two amplifiers. An output of the differential amplifier can be fed into a differential analog-to-digital converter, which is well-suited for seismocardiographic signals because such signals are noisy and the actual signal characterizing cardiac activity has a low amplitude. A bandpass filtering function can be generated from a combination of a lowpass filter and a highpass filter resulting from a resistive feedback connection across the differential amplifier.

[0016] Fig. Figure 1 illustrates an exemplary system according to at least some embodiments of the present invention. The chest 101 of a person is schematically illustrated. An accelerometer is located on the chest. 110 placed, which generates accelerometer data and the generated accelerometer data, via a connection 112 , to a reading device 120 transmitted. The connection 112 can be a wired connection or, at least partially, a wireless connection where applicable. In some embodiments, the reading device 120 and the accelerometer 110 enclosed in the same physical device, in this case the connection 112 for example, it may be internal to this device.

[0017] The reading device 120, can be configured, for example by equipping it with suitable analog and / or components, to cause the acceleration sensor data stored in the acceleration sensor to be 110 They arise and are processed when they pass through the reading device. 120 The data undergoes processing. Such processing can include, for example, filtering, such as bandpass filtering. In principle, bandpass filtering can be performed by a bandpass filter, by a combination of a lowpass and a highpass filter, or by components that effectively function as both a lowpass and a highpass filter. The accelerometer data can be converted into a digital form in an analog-to-digital converter, either in the reading device. 120or subsequently. For example, a differential analog-to-digital converter can be used to convert the output of a differential amplifier located in the reading device. 120 This includes converting it into a digital form.

[0018] In Fig. 1 is also an optional analytical device 130 illustrated, which is connected via a connection 123 to the reading device 120 is connected. The analytical facility 130 It can be configured to make determinations about heart activity based on accelerometer data provided by the accelerometer. 110 be obtained. For example, the analytical facility can be... 130 It must be configured to determine whether the person's heart is in an abnormal state, such as bradycardia, tachycardia, or atrial fibrillation. The analytical device 130It can be configured to provide an alarm in response to a detection that the person's heart is in an abnormal state.

[0019] The analytical facility 130 It can, for example, be enclosed in a server or a cloud server farm. The analytics setup 130 It can store accelerometer data, in raw and / or processed form, for later use. In some embodiments, the analytical unit 130 enclosed in the same physical device as the reading device 120 and / or the accelerometer 110 For example, a device intended for domestic use can integrate the accelerometer 110 and the reading device into the same device. 120 and the analytical facility 130This includes, for example, an accelerometer, reading circuits, and a processor or control unit configured by software and / or hardware to perform analytical determinations on the accelerometer data.

[0020] The analytical facility 130or another device designed to make determinations regarding the accelerometer data can process the accelerometer data, for example, after it has been filtered and converted into a digital format. The processing can include, for example, Fourier transforms, pulse detection, and zero-data detection. The processing can be performed, for example, by software. Fourier transforms can be used to identify frequencies in the sensor data. Pulse detection can be used, for example, to identify heartbeats. Zero-data detection can be used to identify a state in which the accelerometer is not functioning. 110It has been disconnected from chest 101, so it cannot observe vibrations caused by the person's heart. In the event that zero data is observed, a signal can be provided to the person, for example, regarding the placement of the accelerometer. 110 to correct.

[0021] A seismocardiological signal can have a low frequency, with the main components having a frequency of less than 20 Hz. The maximum amplitude can be less than 0.05 g, where g is the standard acceleration due to gravity. Suitable seismocardiography can be obtained, for example, by measuring from the chest towards the back to capture the strongest possible signal.

[0022] Fig. 1 also has a graphical representation 140 , which is an output from the accelerometer 110The relationship to time is illustrated. Specifically, in the graphical representation, the horizontal axis corresponds to time, with time progressing from left to right, and the vertical axis corresponds to an acceleration signal voltage from the accelerometer. 110 The illustrated signal can correspond to a movement impulse generated by the person's heart, such that an initial positive acceleration signal is followed by a negative acceleration impulse. The output signal of the accelerometer 110 In general, this can be, for example, an analog voltage signal.

[0023] Fig. Figure 2 illustrates an exemplary device according to at least some embodiments of the present invention. The same numbering denotes the same structure as in Figure 2. Fig. 1. The accelerometer 110 is located on the left, with the reading device120 right.

[0024] The output from the accelerometer 110 is, as illustrated, with a first charge amplifier 210 and a second charge amplifier 220 connected. For example, the first charge amplifier can 210 be configured to amplify a charge pulse caused by positive acceleration, and the second charge amplifier 220 can be configured to amplify a charge pulse caused by negative acceleration

[0025] The outputs of the first charge amplifier 210 and the second charge amplifier 220 are equipped with inputs of a differential amplifier 230 connected. The differential amplifier 230 is configured to amplify a difference between its inputs, that is, a difference between the outputs of the first and second charge amplifiers.210 , 220 to amplify. The outputs of the differential amplifier can be provided to an analog-to-digital converter, such as a differential analog-to-digital converter (ADC).

[0026] The accelerometer 110 It can consist of two mechanical capacitors connected in series, whose capacitance changes according to acceleration pulses. Two trigger signals with a 50% duty cycle and opposite phase can be applied to the upper and lower plates of the sensor, allowing complementary acceleration-induced charge pulses to be read at a central node. Successive transition edges of the trigger signals provide the positive and negative edges of the acceleration-induced charge pulse.

[0027] When used, seismocardiographic measurements can be performed using the in Fig. The system shown in the two illustrations is used to monitor a heart. The illustrated three-amplifier architecture utilizes the edges of both positive and negative acceleration-induced charge pulses to increase the achieved gain level. Furthermore, a differential amplifier provides an advantage in that a differential ADC can be used. Differential ADCs are less susceptible to noise than single-input ADCs. This is particularly useful in seismocardiography, as seismocardiographic signals have a small amplitude and can be noisy.

[0028] Low-pass filtering can be used, for example, after charge amplifiers to control high-frequency noise. High-pass filtering can also be used to control low-frequency components, such as chest movement due to breathing and the standard acceleration due to gravity, g. When both low-pass and high-pass filtering are present, the resulting filtering can be considered band-pass filtering.

[0029] The system of Fig. 2. The device may further comprise a processor or processing core and memory, which may, for example, be enclosed within the processor or processing core. Consequently, the device may be able to operate in two states, for example, a motion detection state and a measurement state, under the control of the processor or processing core. A motion detection state may involve the cardiac monitoring being inactive and the device waiting until it is determined that motion disturbances are below a threshold. In response to the determination that the motion disturbances are below the threshold, the device may switch itself to a measurement state in which cardiac monitoring is active.Performing cardiac monitoring when motion disturbances are below a threshold offers the advantage of less noisy accelerometer data, allowing seismocardiographic procedures to proceed with a cleaner signal. During motion detection, the device's gain factor can be different, for example, lower, than during measurement. Similarly, limiting active cardiac monitoring to times when motion disturbances are below the threshold reduces the device's energy consumption.

[0030] In general, the processor or processing core can monitor motion disturbances from the accelerometer data, either in analog or digital format. In some embodiments, the processor or processing core is located in the analytics unit. 130 , instead of in the reading device 120, included, and the analytical facility 130 is configured to cause the reading device 120 switches between the measurement state and the motion detection state.

[0031] Fig. Figure 3 illustrates an exemplary device according to at least some embodiments of the present invention. The device resembles that shown in Fig. 2, but in Fig. 3 is more structured. The same numbering indicates the same structure as in Fig. 1 and Fig. 2.

[0032] The device of Fig. 3 closes low-pass filter 310 and 320 one of which, as described above, can be used to control high-frequency noise. Furthermore, the device of Figure 3 excludes feedback via the differential amplifier. 230 One. Specifically, the feedback loops are, as illustrated, via switches. 330 and 340arranged. These switches can include, for example, RF switches. These switches can be arranged as shown in Fig. Figure 3 illustrates that they can be connected in parallel with capacitors.

[0033] If the switches 330 , 340 Being in the closed state is an output state of the differential amplifier. 230 reset. When switches 330 and 340 are in the open state, that is, in the blocked state, the resistance of the switches forms 330 , 340 In the locked state, resistance feedback is provided via the differential amplifier. 230 , and an active high-pass filter functionality is created, whereby the active high-pass filter functionality suppresses a constant acceleration component in the sensor data from the accelerometer. An example of a constant acceleration component is the standard acceleration g. Together with the low-pass filters 310 , 320Therefore, a bandpass filter functionality is generated from the resistance feedback and the lowpass filters 310 and 320. This bandpass filter functionality can improve the quality of seismocardiographic procedures and findings performed using accelerometer data filtered by the bandpass filter functionality.

[0034] The system of Fig. 3 can also, like that of Fig. 2. The device comprises a processor or processing core and memory, which may, for example, be enclosed within the processor or processing core. Consequently, the device can be enabled to operate in two states, for example, a motion detection state and a measurement state, under the control of the processor or processing core. A motion detection state may involve the cardiac monitoring being inactive and the device waiting until a determination is made that motion disturbances are below a threshold. In response to the determination that the motion disturbances are below the threshold, the device may switch itself to a measurement state in which cardiac monitoring is active.When cardiac monitoring is performed while motion disturbances are below a certain threshold, an advantage is gained in that the accelerometer data is less noisy, allowing seismocardiographic procedures to proceed with a cleaner signal. In motion detection mode, the device's gain factor may differ, for example, from that used in measurement mode.

[0035] Fig. Figure 4 illustrates an exemplary device according to at least some embodiments of the present invention. The device resembles the one in Fig. 3, but in Fig. 4 is more structured. The same numbering indicates the same structure as in Fig. 1, Fig. 2 and Fig. 3.

[0036] In addition to the one in Fig. 3 existing structure illustrated Fig. 4 further holding capacitors 430 and 440 Further feedback loops 410 ,420 , with switches, are, as illustrated, each placed above the charge amplifiers. 210 or 220 Provided. As illustrated, these switches can be connected in parallel with capacitors. A switchable voltage source 460 can be used to control the (-) inputs for the charge amplifiers 210 and 220 to generate switches 472 and 474 They can be used to select a negative or a positive channel, to read a negative and a positive charge pulse. Switches 476 and 478 can each be used to power the holding capacitors 430 or 440 to load.

[0037] During an integration phase, positive and / or negative charge pulses can be converted into the voltage domain and collected in the feedback circuit of the charge amplifier of the positive and / or negative channel, respectively. Before each positive and / or negative charge pulse, the input capacitor, which, as illustrated, is located between the voltage sources, can be charged. 450 and 460 is arranged by means of switches to a certain potential through the voltage sources 450 and 460 The voltage source switches will be reset. The voltage source switches will change to a locked state, and the positive or negative channel can be selected using the channel selector switches. 472 , 474 They can be selected. During the integration phase, the switches are located in the feedback circuits. 410 and 420 In the locked state. Positive and / or negative charge pulses from the sensor. 110They can apply a charge change to the input capacitor, which will further induce a potential change in the input of the positive and / or negative charge amplifier. The amplifier can amplify this potential change and store it in the feedback circuit. An integration cycle can, for example, include the following steps: resetting the input capacitor, reading and storing a positive charge pulse, resetting the input capacitor, and reading and storing a negative charge pulse. During the integration phase, the feedback switches are in the 330 and 340 of the differential amplifier in the pass-through position, consequently the differential amplifier is in reset mode.

[0038] After N integration cycles, the sampling phase can begin, and the differential amplifier can exit reset mode, specifically the holding capacitors. 430 and 440to their locked positions. A cumulative voltage, representing the acceleration, can be measured by the scanning switches. 476 and 478 to the holding capacitors 430 and 440 The differential amplifier 230 can also amplify the difference of the complementary voltage signal that is in the holding capacitors. 430 and 440 The stored data is amplified. The sampling switches 476 and 478 They can then switch to their blocking states and the feedback switches 410 and 420 of the charge amplifiers switch to their on / off positions, which the charge amplifiers 210 , 220 resets. A differential signal at the output of the differential amplifier. 230 can be further amplified, filtered, or converted into the digital realm by other devices that are in Fig. 4 cannot be illustrated. After the sampling phase, the feedback switches can be used. 330 and 340of the differential amplifier are switched to their pass positions, which resets the differential amplifier through the next integration phase.

[0039] The charge amplifiers 210 , 220 can be pre-tensioned to the same voltage as the voltage source 460 In some embodiments, the trigger signals of the accelerometer are located 110 between the voltages of the voltage sources 450 , 460 , for example, halfway between these voltages. For example, if the charge amplifiers are biased at 600 mV, the voltage source 460 also be at 600 mV, and if the voltage source 450 With a bias voltage of 200 mV, the trigger signal from the accelerometer is 110 , in these embodiments, preferably 400 mV.

[0040] The system of Fig. 4 can also, like that of Fig. 2 or Fig. 3. The device comprises a processor or processing core and memory, which may, for example, be enclosed within the processor or processing core. Consequently, the device can be enabled to operate in two states, for example, a motion detection state and a measurement state, under the control of the processor or processing core. A motion detection state may involve the cardiac monitoring being inactive and the device waiting until a determination is made that motion disturbances are below a threshold. In response to the determination that the motion disturbances are below the threshold, the device may switch itself to a measurement state in which cardiac monitoring is active.When cardiac monitoring is performed while motion disturbances are below a certain threshold, an advantage is gained in that the accelerometer data is less noisy, allowing seismocardiographic procedures to proceed with a cleaner signal. In motion detection mode, the device's gain factor may differ, for example, from that used in measurement mode. Energy harvesting techniques can be employed to reduce the system's noise. Fig. 4 or parts thereof or actually the system of Fig. 2 or Fig. 3 or parts thereof. III-V semiconductors and / or techniques can enable very low energy consumption.

[0041] In general, the onset of the measurement state when motion disturbances are below the threshold can reduce the amount of memory used to store and handle data from the accelerometer.110This occurs because data that is unusable when making determinations regarding cardiac activity is not stored and can be discarded. If the device can be built with less memory, the reduced memory size itself reduces the device's energy consumption. The size of the device is also easier to minimize when it has less memory. In at least some embodiments, cardiac monitoring is not performed when the device is not in a measurement state, for example, when the device is in a motion detection state. Similarly, the device's energy consumption is reduced by limiting cardiac monitoring to times when motion disturbances are below the threshold.For example, an ADU can be switched off when no measurements are being recorded and when the motion detection state can be maintained using analog signals. Reduced energy consumption results in increased operating times if the devices are battery-powered. Generally, the device is configured to interrupt the measurement state and transition to the motion detection state when the measurement state is active and motion disturbances exceed the threshold.

[0042] Devices according to Fig. 2, Fig. Figure 3 and / or Figure 4 can be used to determine the condition of a person's heart using seismocardiography by analyzing accelerometer data provided by the accelerometer. 110 will be obtained as they are in the reading device 120The data can be processed. For example, a condition of atrial fibrillation can be detected from the processed accelerometer data, for example by comparing the processed accelerometer data with a set of reference sensor data vectors to determine a sensor data vector with the closest match that most closely resembles the processed accelerometer data transmitted by the person via the accelerometer. 110 and the reading device 120 The sensor data vector with the closest match can be obtained, for example, based on the least squares method or the Nelder-Mead method. If the sensor data vector with the closest match is a reference vector for atrial fibrillation, it can be determined that the person is experiencing atrial fibrillation.

[0043] As an alternative to using reference sensor data vectors, a determination regarding a cardiac condition can be based on identifying hallmarks from the processed accelerometer data and comparing these hallmarks with reference hallmarks. For example, atrial fibrillation can be detected based on a set of reference hallmarks in the processed accelerometer data that are characteristic of atrial fibrillation.

[0044] Fig. Figure 5 illustrates, in simulation, filtering carried out in a reading device according to at least some embodiments of the present invention. The graphical representation ACC. INPUT represents an output of the accelerometer. 110This represents information that characterizes the state of the heart, as well as various noise components. The graphical representation OUTPUT READ represents an output of the differential amplifier. 230 The reading output signal is in the reading device. 120 processed, for example by filtering and amplifying the constant one-g acceleration signal.

[0045] Fig. Figure 6 illustrates an exemplary device capable of supporting at least some embodiments of the present invention. The device illustrated is a 600 , which may include, for example, a reading device or an integrated device that incorporates reading and analytical functions. In the device 600Included is a Processor 610, which may, for example, comprise a single-core or multi-core processor, wherein a single-core processor comprises one processing core and a multi-core processor comprises more than one processing core. The Processor 610 may comprise more than one processor. A processing core may, for example, comprise a Cortex-A8 processing core manufactured by ARM Holdings or a Steamroller processing core manufactured by Advanced Micro Devices Corporation. The Processor 610 may comprise at least one Qualcomm Snapdragon and / or Intel Atom processor. The Processor 610 may comprise at least one application-specific integrated circuit (ASIC). The Processor 610 may comprise at least one field-programmable gate array (FPGA). The Processor 610 may include a means for performing process steps in the device. 600The 610 processor can be configured, at least in part, by computer instructions to perform actions.

[0046] The device 600 The memory 620 can comprise a memory 620. The memory 620 can comprise random-access memory and / or persistent memory. The memory 620 can comprise at least one RAM chip. The memory 620 can, for example, comprise solid-state, magnetic, optical, and / or holographic memory. The memory 620 can be at least partially accessible to the processor 610. The memory 620 can be at least partially enclosed within the processor 610. The memory 620 can be a means of storing information. The memory 620 can comprise computer instructions that the processor 610 is configured to execute. If computer instructions configured to cause the processor 610 to perform certain actions are stored in the memory 620 and the device 600Since the entire system is configured to run under the direction of the processor 610, which uses computer instructions from the memory 620, the processor 610 and / or its at least one processing core can be considered configured to perform the specific actions. The memory 620 may be at least partially enclosed within the processor 610. The memory 620 may be at least partially located outside the device. 600 , but accessible to the device 600 , be.

[0047] The device 600 It can include a 630 transmitter. The device 600The system can include a receiver 640. The transmitter 630 and the receiver 640 can each be configured to send or receive information according to at least one communication standard. The transmitter 630 can include more than one transmitter. The receiver 640 can include more than one receiver. The transmitter 630 and / or the receiver 640 can be configured to operate, for example, according to the standards Global System for Mobile Communication (GSM), Wideband Code Division Multiple Access (WCDMA), 5G, Long Term Evolution (LTE), LTE, IS-95, Wireless Local Area Network (WLAN), Ethernet, and / or Worldwide Interoperability for Microwave Access (WiMAX).

[0048] The device 600 The reading circuit 650 may include a reading device, as described herein in conjunction with... Fig. 2, Fig. 3 and / or Fig. 4 described, include.

[0049] The device 600The UI 660 may include a user interface (UI). The UI 660 may include at least one of the following: a display, a keyboard, a touchscreen, or a vibrator arranged to signal to a user, by causing the device to 600 It vibrates and includes a speaker and a microphone. A user may be able to use the device. 600 to operate via the UI 660, for example to start and stop monitoring of heart activity.

[0050] The 610 processor can be equipped with a transmitter designed to receive information from the 610 processor via electrical lines within the device. 600 , to others in the device 600to output enclosed devices. Such a transmitter can comprise a serial bus transmitter, which is arranged, for example, to output information via at least one electrical line to the memory 620 for storage therein. Alternatively to a serial bus, the transmitter can comprise a parallel bus transmitter. Likewise, the processor 610 can comprise a receiver, which is arranged to receive information in the processor 610, via electrical lines within the device 600, from other devices in the device. 600 to receive enclosed devices. Such a receiver can comprise a serial bus receiver, which is arranged, for example, to receive information via at least one electrical line from the receiver 640 for processing in the processor 610. Alternatively, instead of a serial bus, the receiver can comprise a parallel bus receiver.

[0051] The device 600may also include other facilities located in Fig. Figure 6 is not illustrated. In some embodiments, the device is missing. 600 at least one of the facilities described above.

[0052] The processor 610, the memory 620, the transmitter 630, the receiver 640, the reading circuit 650 and / or the UI 660 can be connected in a variety of different ways via electrical conductors within the device. 600 be interconnected. For example, each of the aforementioned devices can be separately connected to a master bus within the device. 600 They must be connected to allow the devices to exchange information. However, as the person with expertise in this field will recognize, this is only an example, and depending on the embodiment, various ways of connecting at least two of the aforementioned devices can be chosen without departing from the scope of the present invention.

[0053] Fig. Figure 7 is a flowchart of a method according to at least some embodiments of the present invention. The phases of the illustrated method can be, for example, in the reading device. 120 be performed.

[0054] Phase 710 comprises receiving, in two charge amplifiers, an input from an accelerometer. Phase 720 comprises generating, in each of the charge amplifiers, a first output signal. Finally, phase 730 comprises amplifying, in a differential amplifier, the difference between the first output signals to generate two second output signals.

[0055] It should be understood that the embodiments of the disclosed invention are not limited to the specific structures, process steps, or materials disclosed herein, but are extended to equivalents thereof as they would be recognizable by persons skilled in the art in the relevant fields. It should also be understood that the terminology used herein serves only to describe specific embodiments and is not intended to be limiting.

[0056] Reference to an embodiment or an embodiment in this entire description means that a particular feature, structure, or distinguishing characteristic described in connection with the embodiment is present in at least one embodiment of the present invention. Consequently, occurrences of the phrases "in an embodiment" or "in an embodiment" in different places in this entire description do not necessarily refer to the same embodiment. When a numerical value is referenced using a term such as "approximately" or "essentially," the precise numerical value is also disclosed.

[0057] As used herein, for convenience, several articles, structural elements, compositional elements, and / or materials may be presented in a single list. However, these lists should be interpreted as if each element in the list were individually identified as a separate and unique element. Consequently, no single element of such a list should be interpreted, without evidence to the contrary, solely on the basis of its presentation in a common group, as the de facto equivalent of any other element in the same list. Furthermore, reference may be made herein to various embodiments and examples of the present invention, together with alternatives for the various components thereof.It should be understood that such embodiments, examples and alternatives are not to be interpreted as de facto equivalents to one another, but are to be regarded as separate and autonomous representations of the present invention.

[0058] Furthermore, the described features, structures, or characteristics can be combined in any suitable manner in one or more embodiments. The foregoing description provides numerous specific details, such as examples of lengths, widths, shapes, etc., to ensure a thorough understanding of embodiments of the invention. However, a person in the relevant field will recognize that the invention can be implemented without one or more of these specific details or using different methods, components, materials, etc. In other cases, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring the invention.

[0059] While the foregoing examples serve to illustrate the principles of the present invention in one or more particular applications, it will be obvious to the person skilled in the art that numerous modifications in form, use, and details of implementation can be made without exercising inventive step and without departing from the principles and concepts of the invention. Accordingly, the invention is not intended to be limited, except as set forth in the claims set forth below.

[0060] The verbs "comprise" and "include" are used in this document as open limitations that neither exclude nor require the presence of features not specified. Features specified in dependent claims are freely combinable unless expressly stated otherwise. Furthermore, it should be understood that the use of "a" or "an," that is, a singular form, throughout this document does not preclude a plural form. COMMERCIAL APPLICABILITY

[0061] At least some embodiments of the present invention find commercial application in the processing of acceleration sensor data, for example for heart monitoring. ABBREVIATION LIST ADU Analog-to-Digital Converter ECG Electrocardiography Reference symbol list 110 breast 120 Reading device 130 analytical equipment 112, 113 connections 140 Graphical representation 210, 220 charge amplifier 230 Differential amplifiers 310, 320 low-pass filter 330, 340 switches (in feedback via differential amplifier) 230 ) 410, 420 Feedback via charge amplifier 430, 440 Holding capacitor 450, 460 Switchable voltage source 472, 474, 476, 478 switches ( Fig. 4) 600 device of Fig. 6 610 - 660 Structure of the device of Fig. 6 710 - 730 Phases of the procedure of Fig. 7

Claims

[1] Seismocardiographic reading device (120), characterized by , that the device comprises the following: - two charge amplifiers (210, 220) configured to receive an input from an accelerometer (110) and each generate a first output signal, wherein the accelerometer (110) comprises two mechanical capacitors connected in series, the mechanical capacitors changing their capacitance according to acceleration pulses, wherein two feedback loops via respective switches (330, 340) in the reading device are connected via a differential amplifier, and - the differential amplifier (230) which is configured to receive the first output signals and amplify a difference between the first output signals in order to generate two second output signals. [2] Device (120) according to claim 1, wherein when the switches (330, 340) are closed, a state of the differential amplifier (230) is reset. [3] Device (120) according to claim 1 or 2, wherein, when the switches (330, 340) are open, a resistance of the switches (330, 340) in the locked state suppresses a resistance feedback and generates an active high-pass filter functionality, wherein the active high-pass filter functionality suppresses a constant acceleration component in the input from the accelerometer (110). [4] Device (120) according to one of claims 1-3, wherein the switches (330, 340) are connected in parallel with capacitors. [5] Device (120) according to one of the preceding claims, further comprising at least one processing core (610) configured to trigger a measurement state in response to a finding that motion disturbances are below a threshold value. [6] Device (120) according to claim 5, wherein the at least one processing core (610) is configured to keep the device (120) in a motion detection state when the motion disturbances are not below the threshold. [7] Device (120) according to one of claims 5-6, wherein the at least one processing core (610) is configured to determine, on the basis of the second output signals, whether a person being measured by the accelerometer (110) is experiencing atrial fibrillation. [8] Device (120) according to one of the preceding claims, further comprising a differential analog-to-digital converter configured to receive the two second output signals and output a digital representation thereof. [9] Procedures, characterized by , that the procedure includes the following: - Received (710), in two charge amplifiers, an input from an accelerometer, wherein the accelerometer comprises two mechanical capacitors connected in series, wherein the mechanical capacitors change their capacitance according to acceleration pulses, wherein two feedbacks are connected via respective switches through a differential amplifier, - Generating (720), in each of the charge amplifiers, a first output signal and - Amplifying (730), in the differential amplifier, a difference between the first output signals to generate two second output signals. [10] Method according to claim 9, which comprises resetting an initial state of the differential amplifier by closing the switches. [11] Method according to claim 9 or 10, wherein, when the switches are open, the resistance of the switches in the locked state forms a resistance feedback and an active high-pass filter functionality is generated, wherein the active high-pass filter functionality suppresses a constant acceleration component in the input from the accelerometer. [12] Method according to one of claims 9-11, wherein the switches are connected in parallel with capacitors. [13] Method according to one of claims 9-12, further comprising triggering, by at least one processing core, a measurement state in response to a finding that motion disturbances are below a threshold value. [14] Method according to claim 13, further comprising maintaining, by the at least one processing core, a motion detection state when the motion disturbances are not below the threshold. [15] Method according to one of claims 13-14, further comprising determining, by the at least one processing core, on the basis of the second output signals, whether a person being measured by the accelerometer is experiencing atrial fibrillation. [16] Method according to one of claims 9-15, further comprising receiving the two second output signals in a differential analog-to-digital converter which outputs a digital representation of the same. [17] Non-transitory computer-readable medium, characterized bythat the medium has stored on it a set of computer-readable instructions which, when executed by at least one processor, cause a device to do at least the following: - to receive an input from an accelerometer in two charge amplifiers, in each of the charge amplifiers, wherein the accelerometer comprises two mechanical capacitors connected in series, wherein the mechanical capacitors change their capacitance according to acceleration pulses, wherein two feedbacks in the device are connected via respective switches through a differential amplifier, - to generate a first output signal in each of the charge amplifiers and - to amplify the difference between the first output signals in the differential amplifier in order to generate two second output signals. [18] Computer program configured to cause a method according to any one of claims 9-16 to be carried out.