A signal measurement device

Abstract

A signal measurement device (100) comprises: an electrode (110) attached to a human body for collecting an electromyography signal of the human body in a target frequency range; an alternating excitation source (120) electrically connected to the electrode (110) for providing an excitation signal of a first frequency to generate a detection signal reflecting a contact impedance between the electrode (110) and the human body; and a gain circuit (130) for providing a gain for the electromyography signal and the detection signal. The signal measurement device (100) provides a gain for the collected electromyography signal and the detection signal by setting the gain circuit (130), thereby improving the strength and quality of the electromyography signal and the detection signal, so that the signal measurement device (100) can accurately monitor.

Description

Technical Field

[0001] This specification relates to the field of circuit design, and in particular to the circuit structure of a signal measurement device. Background Technology

[0002] Signal measurement devices, widely used in physiological monitoring, disease diagnosis, and experimental research, can acquire data related to a user's physical condition by collecting physiological signals. For example, signal measurement devices can monitor and utilize electromyographic signals to make clinical diagnoses of various diseases such as muscle fatigue, myasthenia gravis, myotonia, and muscle atrophy.

[0003] However, when signal measurement devices collect physiological signals, the contact impedance between the electrodes and the human body often increases due to poor contact between the electrodes and the human body, or the skin being almost insulated in a dry environment, which affects the acquisition. Alternatively, the low signal intensity caused by insufficient human movement results in poor quality of the collected physiological signals, making it difficult to monitor them accurately.

[0004] Therefore, it is hoped that a device can be proposed that can improve the quality of physiological signals. Summary of the Invention

[0005] One embodiment of this specification provides a signal measurement device. The device includes: electrodes, which are attached to a human body for acquiring electromyographic signals of the human body within a target frequency range; an AC excitation source electrically connected to the electrodes for providing an excitation signal of a first frequency to generate a detection signal reflecting the contact impedance between the electrodes and the human body; and a gain circuit for providing gain for the electromyographic signal and the detection signal.

[0006] In some embodiments, the target frequency range may include 20Hz-400Hz, and the first frequency is not less than 250Hz.

[0007] In some embodiments, the difference between the first frequency and any integer multiple of 50Hz is not less than 1Hz; or, the difference between the first frequency and any integer multiple of 60Hz is not less than 1Hz.

[0008] In some embodiments, the first frequency is higher than the target frequency range.

[0009] In some embodiments, the gain circuit for the electromyographic signal is not less than 1 / 10 of the gain for the detection signal, and not greater than 10 times the gain for the detection signal.

[0010] In some embodiments, the frequency response of the gain circuit has one or more peaks in a first frequency range, wherein the frequencies in the first frequency range are higher than 50 Hz and lower than the first frequency.

[0011] In some embodiments, the ratio of the gain of the gain circuit at 100Hz to the gain at 10Hz is a first signal-to-noise ratio, and the first signal-to-noise ratio is not less than 4.

[0012] In some embodiments, the ratio of the gain of the gain circuit at 100Hz to the gain at 50Hz is a second signal-to-noise ratio, and the second signal-to-noise ratio is not less than 2.

[0013] In some embodiments, the gain circuit further includes a high-pass filter circuit, which is used to filter the acquired electromyographic signals and detection signals.

[0014] In some embodiments, the gain circuit further includes a low-pass filter circuit connected to a high-pass filter circuit, the low-pass filter circuit being used to filter high-frequency noise in the electromyography signal and the detection signal; and the signal measurement device further includes an analog-to-digital converter, the analog-to-digital converter being used to perform analog-to-digital conversion on the filtered electromyography signal and the detection signal.

[0015] In some embodiments, the sampling rate of the analog-to-digital converter is greater than twice the third frequency, which is the larger of the first frequency and the frequency of the electromyographic signal.

[0016] In some embodiments, the ratio of the gain of the gain circuit at 100Hz to the gain at a second frequency is the third signal-to-noise ratio, the second frequency is the frequency corresponding to half of the sampling rate of the analog-to-digital converter, and the third signal-to-noise ratio is not less than 10.

[0017] In some embodiments, the high-pass filter circuit includes an active band-pass filter, which is also used to provide a first gain for the electromyographic signal and the detection signal; the low-pass filter circuit includes a passive low-pass filter, which is coupled to the active band-pass filter.

[0018] In some embodiments, the high-pass filter circuit includes a fifth-order high-pass filter, the input of which receives an electromyographic signal and a detection signal, and the fifth-order high-pass filter is also used to provide a first gain for the electromyographic signal and the detection signal; the low-pass filter circuit includes a seventh-order low-pass filter, which is coupled to the fifth-order high-pass filter, and the seventh-order low-pass filter is also used to provide a second gain for the electromyographic signal and the detection signal.

[0019] In some embodiments, the fifth-order high-pass filter and the seventh-order low-pass filter are Chebyshev type filters.

[0020] In some embodiments, a secondary gain circuit is further provided between the electrode and the high-pass filter circuit, the secondary gain circuit providing a secondary gain that is less than the first gain and the second gain.

[0021] In some embodiments, the electrodes include a first electrode and a second electrode, which respectively acquire the first electromyographic signal and the second electromyographic signal from the electromyographic signals; the AC excitation source includes two excitation sources, which are respectively connected to the first electrode and the second electrode, and respectively provide two excitation signals to generate the first detection signal and the second detection signal from the detection signals; the gain circuit includes a differential amplifier, which differentially amplifies the first electromyographic signal and the second electromyographic signal, as well as the first detection signal and the second detection signal.

[0022] In some embodiments, the gain circuit provides gain to both the electromyographic signal and the detection signal simultaneously; or, the gain circuit provides gain to the electromyographic signal and the detection signal separately at different time periods.

[0023] In some embodiments, the signal measuring device acquires electromyographic signals and detection signals simultaneously; or, the signal measuring device acquires electromyographic signals and detection signals separately at different time periods.

[0024] In some embodiments, the signal measuring device is a wearable device.

[0025] In the embodiments of this specification, a gain circuit can be set to provide gain for the acquired electromyographic signals and detection signals, thereby improving the strength and quality of the electromyographic signals and detection signals, so that the signal measurement device can accurately monitor them. Attached Figure Description

[0026] This specification will be further described by way of exemplary embodiments, which will be described in detail with reference to the accompanying drawings. These embodiments are not limiting; in these embodiments, the same reference numerals denote the same structures, wherein:

[0027] Figure 1 This is a structural block diagram of a signal measuring device according to some embodiments of this specification;

[0028] Figure 2A This is a frequency response curve of a signal measuring device shown in some embodiments of this specification;

[0029] Figure 2B This is a logarithmic frequency response curve of the signal measuring device shown in some embodiments of this specification;

[0030] Figure 3 This is a structural block diagram of an exemplary signal measuring device according to some embodiments of this specification;

[0031] Figures 4A-4B This is a schematic diagram of the structure of an exemplary high-pass filter circuit shown in some embodiments of this specification;

[0032] Figures 5A-5BThis is a schematic diagram of the structure of an exemplary low-pass filter circuit shown in some embodiments of this specification;

[0033] Figure 6 This is a schematic diagram of the structure of an exemplary secondary gain circuit according to some embodiments of this specification;

[0034] Figure 7A This is a circuit block diagram of the signal measurement device of Example 1 shown in some embodiments of this specification;

[0035] Figure 7B This is a circuit diagram of the signal measuring device of Example 1 shown in some embodiments of this specification;

[0036] Figure 8A This is a circuit block diagram of an exemplary signal measurement device according to some embodiments of this specification, as shown in Example 2.

[0037] Figure 8B This is a circuit diagram of an exemplary signal measuring device according to some embodiments of this specification, as shown in Example 2.

[0038] Figure 9 This is a circuit diagram of Example 3 of a bandpass gain signal measurement device according to some embodiments of this specification;

[0039] Figure 10 yes Figure 7B , Figure 8B and Figure 9 Frequency response curve of the signal measuring device. Detailed Implementation

[0040] To more clearly illustrate the technical solutions of the embodiments in this specification, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are merely some examples or embodiments of this specification. For those skilled in the art, these drawings can be applied to other similar scenarios without creative effort. Unless obvious from the context or otherwise specified, the same reference numerals in the drawings represent the same structures or operations.

[0041] It should be understood that the terms “system,” “device,” “unit,” and / or “module” used herein are one way to distinguish different components, elements, parts, sections, or assemblies at different levels. However, if other terms can achieve the same purpose, they may be replaced by other expressions.

[0042] As indicated in this specification and claims, unless the context clearly indicates otherwise, the words "a," "an," "an," and / or "the" do not specifically refer to the singular and may also include the plural. Generally speaking, the terms "comprising" and "including" only indicate the inclusion of expressly identified steps and elements, which do not constitute an exclusive list, and the method or apparatus may also include other steps or elements.

[0043] Flowcharts are used in this specification to illustrate the operations performed by the system according to embodiments of this specification. It should be understood that the preceding or following operations are not necessarily performed in exact order. Instead, the steps can be processed in reverse order or simultaneously. Furthermore, other operations can be added to these processes, or one or more steps can be removed from them.

[0044] The signal measurement device described in one or more embodiments of this specification can be applied to devices that collect one or more physiological signals, such as smart wearable devices, medical testing devices, or signal analysis devices. In some embodiments, the smart wearable device can be placed on various parts of the human body (e.g., calves, thighs, waist, back, chest, shoulders, neck, etc.) to collect physiological signals from various parts of the user's body in different states, and the collected signals can be further processed. In some embodiments, the smart wearable device may include smart bracelets, smart shoes and socks, smart glasses, smart helmets, smartwatches, smart clothing, smart backpacks, smart accessories, etc., or any combination thereof.

[0045] In some embodiments, physiological signals are detectable signals that reflect the body's state. For example, physiological signals may include various signals such as respiratory signals, electrocardiogram (ECG) signals, electromyography (EMG) signals, blood pressure signals, and temperature signals. In some embodiments, the frequency range of the physiological signals may include 0.05 Hz to 2 kHz, wherein the frequency range of the ECG signals may include 0.05 Hz to 100 Hz, and the frequency range of the EMG signals may include 10 Hz to 850 Hz.

[0046] In some embodiments, the intensity of the physiological signals acquired by the signal measurement device is affected by various factors, such as the contact impedance between the human body and the electrodes, and the activation level of the human muscles. In some embodiments, the contact impedance is the impedance generated when the human skin contacts the electrodes of the signal measurement device, and its impedance value can be affected by the dryness of the skin in contact with the resistor and the contact state between the human body and the skin. For example, the drier the skin, the greater the contact impedance value, resulting in a lower quality of the acquired physiological signal; conversely, the more moist the skin, the smaller the contact impedance value, and the better the quality of the acquired physiological signal. Furthermore, poor contact between the human body and the skin can lead to a larger contact impedance value, resulting in a lower quality of the physiological signal. In some embodiments, the activation level of the muscles is the active state of the muscles during work, which can affect the intensity of the electromyographic signals released by the muscles. For users, there are many daily movement monitoring needs (e.g., walking, standing posture, etc.). Compared to fitness monitoring needs (e.g., squatting, running, etc.), daily movement has a lower activation level of muscles, resulting in lower electromyographic intensity, affecting subsequent recognition and processing.

[0047] In some embodiments, to improve the intensity and quality of acquired physiological signals (e.g., electromyographic signals), a detection signal corresponding to the contact impedance can be pre-acquired to detect the magnitude of the contact impedance and assess the quality of the physiological signal. In some embodiments, gain can also be provided to the electromyographic signal and the detection signal to enhance their intensity, enabling subsequent high-resolution reading of the electromyographic signal. The signal measurement device provided in this application embodiment is described in detail below using electromyographic signals as an example.

[0048] In some embodiments, if the user wears the electrodes incorrectly or the user's skin is too dry during the electromyography (EMG) signal acquisition process, the contact impedance between the human body and the electrodes may be relatively high, resulting in insufficient intensity of the acquired EMG signal, making it difficult to accurately monitor the user's physiological state. Furthermore, in some embodiments, insufficient activation of the muscles in the area to be monitored during signal acquisition can also lead to insufficient intensity of the EMG signal generated by the muscles, making it difficult for the signal acquisition device to recognize and process the EMG signal.

[0049] Therefore, according to some embodiments of this application, a detection signal reflecting the contact impedance between the human body and the electrodes can be acquired simultaneously with the acquisition of electromyographic (EMG) signals. This allows for subsequent adjustment of the contact impedance to ensure appropriate acquisition of high-quality EMG signals. Furthermore, appropriate gain is provided to both the EMG and detection signals to ensure high-resolution reading, recognition, and processing of the EMG signals in subsequent operations.

[0050] Figure 1 This is a structural block diagram of a signal measurement device according to some embodiments of this specification. For example... Figure 1As shown, the signal measurement device 100 may include an electrode 110, an AC excitation source 120, and a gain circuit 130. The electrode 110 is electrically connected to the AC excitation source 120, and the gain circuit 130 is electrically connected to both the electrode 110 and the AC excitation source 120. In some embodiments, the electrode 110 can acquire electromyographic signals from the human body within a target frequency range; the AC excitation source 120 is used to provide an excitation signal of a first frequency to generate a detection signal reflecting the contact impedance between the electrode 110 and the human body; the gain circuit 130 is used to provide gain for the electromyographic signal and the detection signal.

[0051] Electrode 110 can be a circuit element that inputs or outputs current through contact. In some embodiments, electrode 110 can be attached to the human body to acquire physiological signals (e.g., electromyography (EMG) signals, ECG signals, blood pressure signals, etc.). In some embodiments, electrode 110 can acquire EMG signals from the human body within a target frequency range. In some embodiments, EMG signals are physiological signals generated by human muscles that can reflect the activity state of the human neuromuscular system. In some embodiments, the target frequency range can include the frequencies of most EMG signals generated by muscles, or it can include the frequencies of the EMG signals that are expected to be acquired.

[0052] In some embodiments, a detection signal corresponding to electrode 110 can also be generated under external stimulation (e.g., an excitation signal). This detection signal can reflect the contact impedance between electrode 110 and the human body. In some embodiments, the detection signal can be a signal reflecting the magnitude of the contact impedance, and correspondingly, can be used to reflect the quality of the electromyographic signal. By analyzing the detection signal corresponding to a single electrode, or the difference between the detection signals of multiple electrodes, the quality of the electromyographic signal acquired by a single electrode or multiple electrodes can be evaluated. For example, if the detection signal corresponding to a certain electrode indicates that the contact impedance between the electrode and the human body is greater than a certain threshold, it means that the electrode is not worn correctly or the user's skin is too dry. As another example, if the difference between the detection signals corresponding to two electrodes is large, it indicates that the difference in contact impedance between the two electrodes and the human body is large, meaning that at least one of the electrodes is not worn correctly or the user's skin is too dry, and the quality of the acquired electromyographic signal is poor; conversely, if the difference between the detection signals corresponding to two electrodes is small, it indicates that the difference in contact impedance between the two electrodes and the human body is small, meaning that the quality of the acquired electromyographic signal is good. In some embodiments, the detection signal can also reflect other information such as the user's electrode wearing status, body composition information, and skin condition.

[0053] In some embodiments, the electrode 110 can be attached to different parts of the human body to collect physiological signals from different sites. For example, the electrode 110 can be attached to the user's chest, wrist, back, legs, arms, head, etc. In some embodiments, there can be one or more electrodes. For example, one electrode can be used to collect signals from one site, and two electrodes can be used as a group to collect electromyographic signals from the same site.

[0054] In some embodiments, the electrodes may be in contact with the human body in the form of flexible patches, which may be regular shapes such as circles, ovals, rectangles, and rhombuses, or other irregular shapes. In some embodiments, the electrodes may be made of metallic conductive materials (e.g., copper, aluminum, nickel, chromium, alloys, etc.), non-metallic conductive materials (e.g., conductive plastics, conductive rubber, conductive silicone, conductive fabrics), or other conductive materials.

[0055] In some embodiments, the signal measuring device 100 may further include one or more reference ground electrodes. Figure 1 (Not shown in the image), the reference ground electrode can serve as a reference ground in the signal measurement device 100. In some embodiments, the one or more reference ground electrodes can be used to conform to the human body so that the excitation signal generated by the AC excitation source 120 can flow through the human body to the reference ground electrode, forming a closed loop. In some embodiments, the one or more reference ground electrodes can be placed on flat and relatively stable (less dynamic) parts, such as the back or head of the human body, thereby effectively reducing noise.

[0056] The AC excitation source 120 can be a circuit element that provides electrical energy. In some embodiments, the AC excitation source 120 can provide an excitation signal of a first frequency to generate a detection signal reflecting the contact impedance between the electrode 110 and the human body. In some embodiments, the AC excitation source 120 can be a current source or a voltage source. As an example only, the excitation signal can be understood as forming a closed loop after flowing through the human body via the electrode 110. In this case, the detection signal can correspond to the voltage division of the contact impedance between the electrode 110 and the human body in the closed loop. The higher the intensity of the AC excitation source, the easier it is to detect the signal. It should also be noted that the intensity of the AC excitation source needs to be set considering the safe voltage or safe current of the human body to ensure human safety; the intensity of the AC excitation source should not be too high. In some embodiments, the current intensity of the AC excitation source can be less than 1 mA. Further, in some embodiments, the current intensity of the AC excitation source can be less than 100 μA. Even further, in some embodiments, the current intensity of the AC excitation source can be 10 μA.

[0057] In some embodiments, the number of AC excitation sources 120 can be one, which can be connected to multiple electrodes 110 through multiple branches to provide excitation signals to multiple electrodes 110, wherein each branch can be provided with one electrode 110. In some embodiments, there can be multiple AC excitation sources 120, and each AC excitation source 120 can be connected to one or more electrodes 110 respectively to provide an excitation signal to each electrode 110.

[0058] In some embodiments, the AC excitation source 120 can simultaneously generate multiple excitation signals with different frequencies, and can provide multiple electrodes 110 with excitation signals of the same or different frequencies, thereby generating detection signals of different frequencies. For example, the AC excitation source 120 can provide multiple electrodes 110 with excitation signals of different frequencies to acquire different detection signals. The multiple electrodes 110 can be spaced relatively far apart (e.g., greater than or equal to 5 cm) so that the closed-loop circuit through which the excitation signals flow can pass through different human tissues. With this configuration, the detection signals of different frequencies corresponding to the multiple electrodes 110 can be used to reflect body composition information, such as body fat percentage, bone density, body fluid content, etc. Specifically, the AC excitation source 120 can provide a second excitation signal different from the first frequency to generate a second detection signal. The second detection signal can reflect impedance information on the closed-loop circuit formed between each electrode and the human body at another frequency (i.e., a frequency different from the first frequency), including the contact impedance between the electrode and the human body and the impedance of the human tissue on the closed-loop circuit. In some embodiments, body composition information of a human body can be determined using a first detection signal generated by a first excitation signal (e.g., an excitation signal having a first frequency) and a second detection signal generated by a second excitation signal.

[0059] In some embodiments, the excitation signal can be a voltage signal or a current signal. In some embodiments, the excitation signal can be an AC signal with a first frequency, so that the generated detection signal also has a first frequency. The first frequency can be set in a frequency range that is less susceptible to external interference (e.g., power line interference) and has less interference with electromyographic signals.

[0060] In some embodiments, a voltage divider impedance may also be provided between the AC excitation source 120 and the electrode 110. Since the electrode 110 and the voltage divider impedance are in the same loop, the detection signal can correspond to the voltage division of the contact impedance between the electrode 110 and the human body in the closed loop, or to the voltage division of the voltage divider impedance in the closed loop. Because the magnitude of the detection signal is affected by the contact impedance between the electrode 110 and the human body, the magnitude of the detection signal can reflect the magnitude of the contact impedance, thereby allowing for the assessment of the quality of the electromyographic signal. For example, a higher detection signal intensity corresponding to a certain electrode 110 indicates a higher corresponding contact impedance, meaning that the quality of the electromyographic signal acquired by that electrode is poor; conversely, a lower detection signal intensity indicates a lower corresponding contact impedance, meaning that the quality of the electromyographic signal acquired by that electrode is good.

[0061] In some embodiments, when the voltage divider impedances corresponding to the two electrodes have the same parameters, the difference in the detection signals corresponding to the two electrodes can reflect the difference in contact impedance with human skin. For example, the greater the difference between the two detection signals, the greater the difference between their corresponding contact impedances, and the worse the quality of the corresponding electromyographic (EMG) signal; conversely, the smaller the difference between the two detection signals, the smaller the difference between their corresponding contact impedances, and the better the quality of the corresponding EMG signal. Thus, by comparing the differences between the detection signals, it is possible to determine whether the two electrodes are in good contact with the human body, and consequently whether the EMG signal collected by the electrodes meets the requirements.

[0062] In some embodiments, the target frequency range can be set according to the desired frequency range of the electromyographic signal. In some embodiments, the target frequency range may include 10Hz to 850Hz. In some embodiments, the target frequency range may include 20Hz to 400Hz. In some embodiments, the first frequency can be set according to the desired frequency range of the detected signal. In some embodiments, the first frequency may be not less than 250Hz.

[0063] In some embodiments, the first frequency of the excitation signal can be set according to a target frequency range. In some embodiments, the first frequency can be higher than the target frequency range to avoid most of the frequency band where the electromyographic signal is located, thereby reducing the mutual interference between the electromyographic signal and the excitation signal. In some embodiments, the first frequency can be no less than 850 Hz. In some embodiments, the first frequency can be no less than 400 Hz. If the intensity of the excitation signal is large or the contact impedance corresponding to the electrode at the measurement site can receive a sufficient amount of voltage, the interference of the electromyographic signal on the excitation signal is low, and the excitation signal (e.g., an excitation signal with a first frequency of no less than 400 Hz) can tolerate a small portion of the electromyographic signal (e.g., electromyographic signals with frequencies between 400 Hz and 850 Hz).

[0064] Because the signal acquisition device 100 also experiences interference from power frequency noise (e.g., 50Hz or 60Hz AC power supply and its harmonics), in some embodiments, the first frequency can be set according to the frequency range of the power frequency noise. For example, the set first frequency can avoid the influence of power frequency noise to avoid interference from power frequency and its harmonic noise. In some embodiments, the difference between the first frequency and any integer multiple of 50Hz can be not less than 1Hz, or the difference between the first frequency and any integer multiple of 50Hz can be not less than 2%. In some embodiments, the difference between the first frequency and any integer multiple of 60Hz can be not less than 1Hz, or the difference between the first frequency and any integer multiple of 60Hz can be not less than 2%.

[0065] It should be noted that during signal measurement, a large number of interference signals, i.e., motion artifacts (MA), exist in the low-frequency band due to minute movements of the head, limbs, chin, tongue, and swallowing. Avoiding setting the first frequency of the excitation signal to a lower frequency can prevent interference from motion artifacts. In some embodiments, the first frequency can also be set based on the sampling frequency of the subsequent processing circuit to prevent the sampling frequency provided by the processing circuit from being insufficient for effective sampling of the detection signal, thus ensuring signal quality. For a detailed description of the relationship between the sampling frequency and the first frequency, please refer to other parts of this application specification, such as... Figure 2A-2B And its description.

[0066] The gain circuit 130 is a signal processing circuit capable of amplifying signals. In some embodiments, the gain circuit 130 can be used to provide gain for electromyographic (EMG) signals and detection signals. For example, the EMG signals and detection signals can be used as inputs to the gain circuit 130, and the gain circuit 130 amplifies the EMG signals and detection signals, thereby improving the strength and signal-to-noise ratio of the EMG signals and detection signals and enhancing the signal quality.

[0067] It should be noted that the contact impedance between the human body and the electrode may be relatively low at the first frequency, resulting in a low intensity of the detection signal generated by the voltage division, making it difficult to identify and process the detection signal subsequently. In this embodiment, the gain circuit 130 provides gain to both the electromyographic signal and the detection signal simultaneously, which can improve the intensity of both signals and ensure accurate identification and processing of them subsequently.

[0068] In some embodiments, the gain circuit 130 can provide gain for signals across the entire frequency band, or for signals in a specific frequency band. Taking electromyography (EMG) signals as an example, most EMG signals are distributed in the frequency band of 10Hz to 850Hz. Therefore, the gain circuit 130 can provide gain for EMG signals in the 10Hz to 850Hz frequency band to avoid providing gain for other frequency bands (e.g., those other than the 10Hz to 850Hz frequency band), thereby suppressing noise interference with EMG signals and improving the signal-to-noise ratio of EMG signals.

[0069] In some embodiments, gain can be expressed as the degree to which the electromyographic signal and the detection signal are amplified. For example, the greater the gain provided by the gain circuit 130, the greater the amplification of the electromyographic signal and the detection signal; conversely, the smaller the gain provided by the gain circuit 130, the smaller the amplification of the electromyographic signal and the detection signal.

[0070] In some embodiments, the gain can be set based on the actual signal strength and the desired signal strength. In some embodiments, the gain can be set based on the actual signal strength and the desired signal strength of the electromyographic (EMG) signal and the detection signal. For example, since the actual signal strength of the EMG signal and the detection signal is approximately 10 μV or less, and the resolution of a commonly used 12-bit analog-to-digital converter (ADC) is approximately 0.8 mV (i.e., the desired signal strength) under a 3.3 V power supply, the gain circuit 130 can provide a gain of hundreds to thousands of times, so that the signal strength of the amplified EMG signal and the detection signal can reach 1 mV to 10 mV.

[0071] In some embodiments, the gain circuit 130 can provide the same or different gains to the electromyographic (EMG) signal and the detection signal, respectively. In some embodiments, the amplified EMG signal and the detection signal can be processed by the same circuit, such as filtering. To prevent excessive difference in gain that would lead to a large difference in intensity between the amplified EMG signal and the detection signal, in some embodiments, the gain of the gain circuit 130 on the EMG signal can be no less than 1 / 10 of the gain on the detection signal, and no more than 10 times the gain on the detection signal. That is, the relative value between the gain provided to the EMG signal and the gain provided to the excitation signal can be set within 10 times, thereby ensuring that the intensity difference between the amplified EMG signal and the detection signal is not significant, facilitating subsequent identification and processing.

[0072] Since the gain circuit 130 needs to provide gain for both electromyographic (EMG) signals and excitation signals, the frequency response of the circuit must not only gain the EMG frequency band but also the excitation source frequency band, while sufficiently suppressing frequencies that are lower than the EMG frequency and higher than the excitation frequency.

[0073] In some embodiments, the frequency response of the gain circuit 130 may have one or more peaks within a first frequency range. The first frequency range may include the frequency of the electromyographic signal and the frequency of the detection signal. For example, the first frequency range may be a frequency range with frequencies higher than 50 Hz and lower than the first frequency. Since the gain circuit 130 needs to provide gain for both the electromyographic signal and the detection signal, in some embodiments, the number of peaks in the frequency response of the gain circuit 130 may be determined based on the frequencies of the electromyographic signal and the detection signal. In some embodiments, the frequency response of the gain circuit 130 may be bimodal, with the two peaks located near the target frequency range of the electromyographic signal and the first frequency, respectively. In some alternative embodiments, the frequency response of the gain circuit 130 has only one peak with a relatively wide bandwidth within the first frequency range, providing higher gain for frequencies within the first frequency range compared to other frequency bands, thereby suppressing signals with frequencies lower than the electromyographic signal and / or higher than the excitation signal, reducing interference to the electromyographic signal and the excitation signal.

[0074] Taking an AC excitation source providing excitation signals of two frequencies (e.g., the aforementioned first and second excitation signals) as an example, if the frequencies of the first and second excitation signals are 620Hz and 820Hz respectively, the frequency response of the gain circuit 130 can be designed to have a peak with a width covering 51Hz to 820Hz within the first frequency range, or it can be designed to have two peaks with widths covering 51Hz to 400Hz and 620Hz to 820Hz respectively within the first frequency range, or it can have three peaks with widths covering 51Hz to 400Hz, around 620Hz, and around 820Hz respectively within the first frequency range, to ensure that it can provide a large gain for electromyographic signals in the target frequency range and for each detection signal. For the structure of the gain circuit 130 to achieve different frequency responses, please refer to other parts of this application specification, such as... Figures 4A-6 And its description.

[0075] Figure 2A This is a frequency response curve of the gain circuit 130 shown in some embodiments of this specification. Figure 2B This is a logarithmic frequency response curve of the gain circuit 130 shown in some embodiments of this specification.

[0076] See Figure 2A-2B Curve 210 exhibits a bimodal shape, while curve 220, after being converted to logarithmic coordinates, shows a bandpass shape with a relatively flat passband. Curve 210 has two peaks (e.g., ...). Figure 2APeaks 211 and 212 are shown. Peak 211 is located near 183 Hz, with a corresponding gain of 1160 times; peak 212 is located near 873 Hz, with a corresponding gain of 664.3 times. According to curve 210, the gain circuit 130 can provide a gain greater than 900 times for electromyographic signals in a frequency range of approximately 100 Hz to 300 Hz, and a gain of 100 to 700 times for signals in a frequency range of approximately 800 Hz to 1000 Hz (e.g., the detection signal can be set to 820 Hz). In some embodiments, the gain requirement can be determined based on the intensity obtained after voltage division of the contact impedance (i.e., the intensity of the detection signal), thereby adjusting the gain provided by the gain circuit 130. For example, the gain provided by the gain circuit 130 can be adjusted between (133 times, 1000 Hz) and (664.3 times, 873 Hz).

[0077] Because many interference signals exist during signal measurement, such as motion artifacts, power frequency and its harmonics, and aliasing noise, there are two main issues. First, providing excessive gain to these interference signals can cause the amplified interference signals to exceed the circuit's measurement range, leading to circuit saturation and data loss, making data recovery through algorithms difficult. Second, providing excessive gain to high-frequency noise can result in aliasing due to sampling rate limitations, increasing the noise floor and causing high-frequency noise to overlap with electromyographic signals, making them difficult to distinguish and process.

[0078] To suppress the gain provided by the gain circuit 130 to the aforementioned interference signal, in some embodiments, the gain of the gain circuit 130 to the frequency corresponding to the interference signal can be limited by adjusting the gain signal-to-noise ratio (SNR). The gain SNR can be the ratio of the gain at the frequency of the electromyographic signal to the gain at the frequency of the interference signal. In some embodiments, the gain SNR may include one or more of the following: motion artifact (MA) SNR, power line SNR, and aliasing SNR. The three gain SNRs are described below.

[0079] In some embodiments, the gain at 10Hz can be expressed as the gain of the motion artifact, and the ratio of the gain of the gain circuit 130 at 100Hz to the gain at 10Hz can be a first signal-to-noise ratio (i.e., the aforementioned MA signal-to-noise ratio). To improve the gain signal-to-noise ratio of the gain circuit 130, this first signal-to-noise ratio can be set to be not less than 4. Figure 2A Taking curve 210 as an example, the gain at 100Hz is approximately 940 times, and the gain at 10Hz is approximately 0.00186, so the first signal-to-noise ratio can be 505376.

[0080] In some embodiments, the gain at 50 Hz can represent the gain of the power frequency noise, and the ratio of the gain of the gain circuit 130 at 100 Hz to the gain at 50 Hz is the second signal-to-noise ratio (i.e., the aforementioned power frequency signal-to-noise ratio). To improve the gain signal-to-noise ratio of the gain circuit 130, this second signal-to-noise ratio can be not less than 2. Figure 2A Taking curve 210 as an example, the gain at 100Hz is approximately 940 times, and the gain at 50Hz is approximately 8.26, so the second signal-to-noise ratio can be 114.

[0081] In some embodiments, since the generation of aliasing noise is related to the sampling rate, the frequency of half the sampling rate of the analog-to-digital converter can be represented as the frequency of the aliasing noise, also called the second frequency. For example, when the sampling frequency is 4kHz, the frequency of the aliasing noise can be 2kHz. The ratio of the gain of the gain circuit 130 at 100Hz to the gain at the second frequency can be the third signal-to-noise ratio (i.e., the aforementioned aliasing signal-to-noise ratio). To improve the gain signal-to-noise ratio of the gain circuit 130, this third signal-to-noise ratio can be not less than 10. Figure 2A Taking curve 210 as an example, the gain at 100Hz is approximately 940 times, and the gain at 2kHz is approximately 0.185, so the third signal-to-noise ratio can be 5081.

[0082] It should be noted that the gain signal-to-noise ratio can also be used to measure the quality of the gain circuit. The higher the gain signal-to-noise ratio of the signal measurement device, the better the strength and quality of the acquired electromyographic signal, and the higher the quality of the gain circuit.

[0083] In this embodiment, by adjusting the gain signal-to-noise ratio, excessive gain can be avoided for interference signals, thereby preventing data loss due to interference signals exceeding the circuit's measurement range. It can also reduce the possibility of high-frequency noise overlapping with electromyographic signals, improving the quality of electromyographic and detection signals, so as to enable high-resolution reading of electromyographic and detection signals in the future.

[0084] In some embodiments, the gain circuit 130 can simultaneously provide gain to both the electromyographic (EMG) signal and the detection signal. Correspondingly, in some embodiments, the signal measurement device 100 can simultaneously acquire both the EMG signal and the detection signal. That is, the signal acquisition device 100 can simultaneously receive both the EMG signal and the detection signal as input signals and provide gain to them simultaneously. In this way, the detection signal can reflect the contact impedance between the human body and the electrodes in real time, thereby allowing for timely determination of the quality of the EMG signal.

[0085] In some embodiments, the signal measurement device 100 can acquire electromyographic (EMG) signals and detection signals separately during different time periods. Correspondingly, the gain circuit 130 can provide gain for the EMG signals and detection signals respectively during different time periods. For example, the signal measurement device 100 can acquire EMG signals during a first time period and provide gain to them through the gain circuit 130. The signal measurement device 100 can acquire detection signals during a second time period and provide gain to the detection signals through the gain circuit 130. For example, the signal measurement device 100 may include a switching circuit connected to the electrode 110. The switching circuit can control the conduction state of the electrode 110 and the gain circuit 130, and can also control the conduction state of the electrode 110 and the AC excitation source 120, so that only the electrode and the gain circuit 130 remain electrically conductive at any given time, or only the electrode 110 and the AC excitation source 120 remain electrically conductive. Thus, by acquiring and processing the detection signals and EMG signals in a time-division manner, mutual interference between signals can be avoided, reducing the processing pressure on the device and saving computing resources.

[0086] It should be noted that in some other embodiments, the signal measurement device 100 can acquire electromyographic signals and detection signals in a time-division multiplexing manner, and then simultaneously use the gain circuit 130 to provide gain for the electromyographic signals and detection signals; it can also acquire electromyographic signals and detection signals simultaneously, and then use the gain circuit 130 to provide gain for the electromyographic signals and detection signals in a time-division multiplexing manner. In some embodiments, the time-division multiplexing or simultaneous acquisition and processing of signals can be selected according to signal quality and device resources.

[0087] In some embodiments, the gain circuit 130 may include multi-stage amplification sub-circuits for multi-stage amplification of input signals (e.g., electromyographic signals and detection signals) to provide gain. In some embodiments, the amplification sub-circuits may be independently configured in the signal measurement device 100, such as the secondary gain circuits mentioned elsewhere in this specification. In some embodiments, the amplification sub-circuit may also be configured as a component in a circuit with other functions, integrated with other functional circuits, providing gain while implementing other functions, such as the gain provided by high-pass and low-pass filter circuits elsewhere in this specification. In some embodiments, different stages of the multi-stage amplification sub-circuit may provide different amplification gains to the input signal. For example, the gain of a preceding stage amplification sub-circuit (e.g., the secondary gain provided by a secondary gain circuit) may be less than the gain of a subsequent stage (e.g., the first gain provided by high-pass filter circuit 140 or the second gain provided by low-pass filter circuit 150). For a detailed description of the amplification sub-circuit's structure, please refer to other parts of this specification, such as... Figures 5A-6 And its description.

[0088] In some embodiments, the gain circuit 130 can also perform signal processing on the electromyographic signal and the detection signal.

[0089] In some embodiments, the gain circuit 130 may refer to a structural module with certain signal processing functions, such as amplification, rectification, A / D conversion, filtering, logic processing, etc. In some embodiments, the gain circuit 130 may include a processor ( Figure 3 (Not shown in the image), such as Digital Signal Processor (DSP) chips, Central Processing Unit (CPU), Microcontroller Unit (MCU), etc.

[0090] As an example only, in some embodiments, the gain circuit 130 can process the detection signal corresponding to a specific electrode individually and use it to evaluate the electromyographic signal acquired by that electrode. For instance, the gain circuit 130 can amplify the detection signal corresponding to the electrode 110, and then perform analog-to-digital (A / D) conversion on it using an analog-to-digital converter. The detection signal can individually reflect the contact impedance between the electrode 110 and the human body, thereby reflecting the adhesion state between the electrode 110 and the human body, and thus determining the quality of the electromyographic signal.

[0091] In some embodiments, the processor can combine the detection signals corresponding to multiple electrodes to comprehensively evaluate the electromyographic signals acquired by these electrodes. For example, the processor can perform operational amplification (e.g., differential amplification) on the detection signals corresponding to multiple electrodes 110, and then perform analog-to-digital (A / D) conversion on the amplified result. The differentially amplified detection signals can comprehensively reflect the difference in contact impedance between the two electrodes and the human body, thereby reflecting whether both electrodes are in good contact with the human body, thus determining the quality of the electromyographic signal.

[0092] In some embodiments, the gain circuit 130 may further filter the detection signal corresponding to the electrode 110 to distinguish the electromyographic signals acquired by the electrode 110. In some embodiments, the gain circuit 130 may directly calculate the difference between the detection signals corresponding to the first electrode 111 and the second electrode 112, and then evaluate the aforementioned electromyographic signals based on the difference. In some embodiments, the evaluation of the aforementioned electromyographic signals by the gain circuit 130 may include determining the quality of the aforementioned electromyographic signals and evaluating the fit between one or more electrodes 110 and the human body. In some embodiments, the gain circuit 130 may also determine whether to output an electromyographic signal based on the evaluation result of the electromyographic signal. In some embodiments, the gain circuit 130 may also output user instructions based on the evaluation result of the electromyographic signal to instruct the user to perform commands such as adjusting the wearing status of the electrodes or instructing the user to continue warming up, so as to improve the quality of the subsequently acquired electromyographic signals. In some embodiments, the gain circuit 130 may also perform signal processing algorithms (such as signal filtering, wavelet transform, machine learning, etc.) on the electromyographic signals to improve the quality of the electromyographic signals.

[0093] In some embodiments, the gain circuit 130 may further include transceiver circuits, such as voice input / output circuits, display circuits, wireless / wired communication circuits, etc. The evaluation results of the electromyographic signals acquired by the aforementioned electrodes by the gain circuit 130 can be output through the transceiver circuits. In some embodiments, the gain circuit 130 can transmit the electromyographic signals and / or the evaluation results of the electromyographic signals to other terminals via wired or wireless means (e.g., Bluetooth, WiFi, etc.), and output them through other terminals (e.g., displayed on a screen or broadcast through a speaker).

[0094] It should be noted that the transceiver circuit can be set as a circuit component within the gain circuit 130 and connected to the processor for transmitting data and signals; or it can be integrated into the processor so that the processor can perform input and output functions through the built-in communication components.

[0095] In some embodiments, the gain circuit 130 can also assess the human body condition based on multiple detection signals of different frequencies. For example, the gain circuit 130 can determine body composition information reflecting the human body condition, such as body fat percentage, bone density, and body fluid content, based on multiple detection signals of different frequencies.

[0096] It should be noted that the processing functions of the gain circuit 130 may include, but are not limited to, the contents listed above. For example, in some embodiments, the gain circuit 130 may also calculate the sum of the detection signals corresponding to the multiple electrodes 110, and then evaluate the aforementioned physiological signal based on the sum. In some cases, considering that evaluating the electromyographic signal based on the difference of the detection signals (or the value after differential amplification by an operational amplifier) ​​is more reflective of the quality of the electromyographic signal than evaluating it based on the sum of the detection signals, the embodiments of this specification mainly use the difference of the detection signals (or the value after differential amplification by an operational amplifier) ​​as an example to describe the signal measurement device 100.

[0097] Figure 3 This is a structural block diagram of an exemplary signal measuring device 100 shown according to some embodiments of this specification. Figure 3 As shown, the gain circuit 130 may further include a high-pass filter circuit 140, which may be connected to the electrode 110.

[0098] The high-pass filter circuit 140 can be a circuit structure for high-pass filtering of signals. In some embodiments, the high-pass filter circuit 140 can be used to filter low-frequency interference signals in the electromyography (EMG) signal and the detection signal, such as motion artifacts, power line noise, and other low-frequency noise. In some embodiments, the high-pass filter circuit 140 can allow signals above a first cutoff frequency (e.g., EMG signals and detection signals) to pass through, while blocking interference signals below or equal to the first cutoff frequency, thereby achieving signal filtering. In some embodiments, the first cutoff frequency can be set according to the frequencies of the EMG signal and the detection signal, or it can be set according to the frequency of the low-frequency noise to be filtered. In some embodiments, the first cutoff frequency can be less than or equal to the frequency in the target frequency range and the lowest frequency in the first frequency range. For example, if the target frequency range corresponding to the EMG signal is 20Hz to 400Hz, and the first frequency of the detection signal is 250Hz, then the first cutoff frequency can be less than or equal to 20Hz. In some embodiments, the first cutoff frequency can be greater than or equal to the highest frequency among the frequency of motion artifacts and the power line frequency. If the frequency range of motion artifacts, power frequency and its harmonics is 10Hz to 50Hz, then the first cutoff frequency can be greater than 50Hz.

[0099] In some embodiments, the high-pass filter circuit 140 can be replaced by a band-pass filter circuit. Similarly, the bandwidth frequency range of the band-pass filter circuit can be related to the frequency of the electromyographic signal and the detection signal, or to the frequency of low-frequency noise. For example, the bandwidth frequency range of the band-pass filter circuit can include frequencies in the target frequency range and a first frequency, and the intersection with the frequency range of motion artifacts and power frequency noise can be empty.

[0100] In this embodiment, by setting a high-pass filter circuit 140, low-frequency noise such as motion artifacts, power frequency and its harmonics can be filtered in a timely manner, preventing the gain circuit 130 from providing gain for high-intensity low-frequency noise, and ensuring that the signal after gain does not exceed the measurement range.

[0101] In some embodiments, the amplification sub-circuit in the high-pass filter circuit 140 ( Figure 3 (Not shown) can also provide a first gain for the electromyographic signal and the detection signal to achieve a gain function. In some embodiments, the first gain can be a portion of the gain provided to the electromyographic signal and the detection signal. In some embodiments, the magnitude of the first gain can be adjusted by adjusting the component parameters (e.g., the size of capacitors and resistors) in the high-pass filter circuit 140.

[0102] The following are some examples of high-pass filter circuits 140, and the specific implementation of high-pass filter circuits 140 are described in detail.

[0103] Figures 4A-4B This is a schematic diagram of an exemplary high-pass filter circuit 140 according to some embodiments of this specification. In some embodiments, the high-pass filter circuit 140 may include a fifth-order high-pass filter 410, the input of which is coupled to the electrode 110 to filter electromyographic signals and detection signals as inputs.

[0104] like Figure 4A As shown, the fifth-order high-pass filter 410 may include operational amplifiers U2A-U2B, resistors R1-R2 and R4-R8, and capacitors C1-C3 and C7-C10. The non-inverting input of operational amplifier U2A can be connected to the series capacitors C1-C3. The non-inverting input of operational amplifier U2A can also be connected to the power supply VCC2 through resistor R2. The inverting input of operational amplifier U2A can be connected to the output of operational amplifier U2A through resistor R6, and can also be connected to the power supply VCC2 through resistor R5. The power supply terminal of operational amplifier U2A is connected to the power supply VCC, and the ground terminal of operational amplifier U2A is grounded. The non-inverting input of operational amplifier U2B can be connected to the output of operational amplifier U2A through the series capacitors C7-C8, and the inverting input of operational amplifier U2B can be connected to the output of operational amplifier U2B. The power supply terminal and ground terminal of operational amplifier U2B are not connected.

[0105] In some embodiments, the fifth-order high-pass filter 410 is further used to provide a first gain for the electromyography (EMG) signal and the detection signal. In some embodiments, operational amplifiers U2A and U2B can provide a first gain for the input signals (e.g., EMG signals and detection signals). The magnitude of the first gain can be related to the parameters of resistors R1-R2, R4-R8, and capacitors C1-C3, C7-C8. In some embodiments, the first gain can be provided after the fifth-order high-pass filter 410 has filtered the EMG signal and the detection signal. In some embodiments, the output of operational amplifier U2B can be used to output the high-pass filtered and partially gained EMG signal and detection signal.

[0106] One end of resistor R1 can be connected to the junction of capacitors C1 and C2, and the other end can be connected to virtual ground VCC2 to boost the circuit voltage, ensuring that the electromyography (EMG) signal and detection signal are greater than 0V for subsequent reading by the analog-to-digital converter. One end of resistor R4 can be connected to the junction of capacitors C2 and C3, and the other end can be connected to the output of operational amplifier U2A. One end of resistor R7 can be connected to the non-inverting input of operational amplifier U2B, and the other end can be connected to virtual ground VCC2. One end of resistor R8 can be connected to the inverting input of operational amplifier U2B, and the other end can be connected to the non-inverting input of operational amplifier U2B. Capacitors C10 and C9 are connected in parallel, with one end connected to the power supply VCC and the other end grounded. Capacitors C10 and C9 can be used to filter noise from the power supply VCC.

[0107] In some embodiments, the fifth-order high-pass filter 410 can utilize operational amplifiers U2A and U2B to perform high-pass filtering on the detection signal and electromyography signal. In some embodiments, the first cutoff frequency of the fifth-order high-pass filter 410 can be adjusted by adjusting the component parameters of operational amplifiers U2A and U2B. In some embodiments, the fifth-order high-pass filter 410 can be a Chebyshev filter. Chebyshev filters attenuate faster in the transition band than other filters (e.g., Butterworth filters), and their frequency response curve is closer to that of an ideal filter, resulting in better filtering performance.

[0108] In some embodiments, the high-pass filter circuit 140 may include an active bandpass filter 420, the input of which may be coupled to the electrode 110 to filter the electromyographic signal and the detection signal as input.

[0109] like Figure 4BAs shown, the active bandpass filter 420 may include operational amplifiers U2A-U2B, resistors R4, R6-R7, and capacitors C1, C7-C11. The non-inverting input of operational amplifier U2A can be connected to virtual ground VCC2. The inverting input of operational amplifier U2A can be connected to a series capacitor C1 and resistor R4. The inverting input of operational amplifier U2A can also be connected to the output of operational amplifier U2A through a parallel capacitor C8 and resistor R7. The power supply terminal of operational amplifier U2A is connected to the power supply VCC, and the ground terminal of operational amplifier U2A is grounded. The inverting input of operational amplifier U2B can be connected to the output of operational amplifier U2A through a series resistor R6 and capacitor C11. The non-inverting input of operational amplifier U2B can be connected to virtual ground VCC2. The inverting input of operational amplifier U2B can be connected to the output of operational amplifier U2A through a parallel capacitor C7 and resistor R5. The power supply terminal and ground terminal of operational amplifier U2B are unconnected.

[0110] In some embodiments, similar to the high-pass filter 410 described above, the active bandpass filter 420 is also used to provide a first gain for the electromyography (EMG) signal and the detection signal. In some embodiments, operational amplifiers U2A and U2B of the active bandpass filter 420 can provide a first gain for the input signals (e.g., EMG signals and detection signals). The magnitude of the first gain can be related to the parameters of resistors R4 and R7, and capacitors C1 and C8. In some embodiments, the active bandpass filter 420 can provide the first gain after filtering the EMG signal and the detection signal.

[0111] In some embodiments, similar to the high-pass filter 410 described above, the output of the operational amplifier U2B of the active band-pass filter 420 can be used to output electromyography signals and detection signals that have undergone band-pass filtering and partial gain. Capacitors C10 and C9 are connected in parallel, with one end connected to the power supply VCC and the other end grounded.

[0112] In some embodiments, the active bandpass filter 420 can perform bandpass filtering on electromyographic signals and detection signals using resistors R4, R5-R7, and capacitors C1, C7-C8, and C11. In some embodiments, the bandwidth frequency range of the active bandpass filter 420 can be adjusted by adjusting the component parameters of the aforementioned resistors R4, R5-R7, and capacitors C1, C7-C8, and C11.

[0113] Continue to refer to Figure 3 In some embodiments, the gain circuit 130 may include a low-pass filter circuit 150 connected to a high-pass filter 140, the low-pass filter circuit 150 being used to filter high-frequency noise in electromyography signals and detection signals.

[0114] The low-pass filter circuit 150 can also be a circuit structure that performs low-pass filtering on the signal. In some embodiments, the low-pass filter circuit 150 can be used to filter high-frequency interference signals, such as aliasing noise or other high-frequency noise, from the electromyography (EMG) signal and the detection signal. In some embodiments, the low-pass filter circuit 150 can allow signals below the second cutoff frequency (e.g., EMG signals and detection signals) to pass through, while blocking interference signals above or equal to the second cutoff frequency, thereby achieving signal filtering. Similar to the high-pass filter circuit 140 described above, in some embodiments, the second cutoff frequency can be set according to the frequency of the EMG signal and the detection signal, or it can be set according to the frequency of the high-frequency noise that is to be filtered. In some embodiments, the second cutoff frequency can be greater than or equal to the frequency in the target frequency range and the highest frequency in the first frequency range. In some embodiments, the second cutoff frequency can be less than or equal to half of the sampling rate.

[0115] In this embodiment, by sequentially setting up a signal processing architecture of high-pass filtering and low-pass filtering, and providing gain during the high-pass filtering and low-pass filtering processes, on the one hand, low-frequency noise can be suppressed in a timely manner while avoiding providing gain for high-intensity low-frequency signals, preventing the signal after gain from exceeding the measurement range and causing data loss, thus improving the stability of signal acquisition; on the other hand, the architecture of gain first and then low-pass filtering can filter out high-frequency noise introduced during signal amplification, avoiding the introduction of aliasing noise in the subsequent analog-to-digital conversion process.

[0116] In some embodiments, the amplification sub-circuit in the low-pass filter circuit 150 may also provide a second gain for the electromyographic signal and the detection signal to achieve a gain function. In some embodiments, the second gain may be a portion of the gain provided to the electromyographic signal and the detection signal. In some embodiments, the magnitude of the second gain can be adjusted by adjusting the component parameters (e.g., the size of capacitors and resistors) in the low-pass filter circuit 150. In some embodiments, the component providing the second gain in the low-pass filter circuit 150 may be located at the beginning stage of the low-pass filter circuit 150 so that the signal is amplified before being low-pass filtered.

[0117] The following are some examples of low-pass filter circuits 150, and the specific implementation of the low-pass filter circuit 150 is described in detail.

[0118] Figures 5A-5B This is a schematic diagram of an exemplary low-pass filter circuit according to some embodiments of this specification. In some embodiments, the low-pass filter circuit 150 may include a seventh-order low-pass filter 510, the input of which is coupled to the high-pass filter circuit 140 to filter the amplified electromyography signal and the detection signal as input.

[0119] like Figure 5A As shown, the seventh-order low-pass filter 510 may include operational amplifiers U3A-U3C, resistors R9-R12 and R16-R20, and capacitors C11-C15, C17, and C19. The non-inverting input of operational amplifier U3A can be connected to the series resistors R9-R11. The non-inverting input of operational amplifier U3A can also be connected to virtual ground VCC2 through resistor R12. The inverting input of operational amplifier U3A can be connected to the output of operational amplifier U3A through resistor R16. The power supply terminal of operational amplifier U3A is connected to the power supply VCC, and the ground terminal of operational amplifier U3A is grounded. The non-inverting input of operational amplifier U3B can be connected to the output of operational amplifier U3A through the series resistors R16 and R18, and the inverting input of operational amplifier U3B can be connected to the output of operational amplifier U3B. The power supply terminal and ground terminal of operational amplifier U3B are unconnected. The non-inverting input of operational amplifier U3C can be connected to the output of operational amplifier U3B through series resistors R19-R20. The inverting input of operational amplifier U3C can be connected to the output of operational amplifier U3C. The power supply and ground terminals of operational amplifier U3C are left unconnected.

[0120] In some embodiments, the amplification sub-circuit in the seventh-order low-pass filter 510 can provide a second gain for the input signal. In some embodiments, operational amplifiers U3A-U3C can provide a second gain for the input signal (e.g., the electromyographic signal and detection signal after the first gain). The magnitude of the second gain can be related to the parameters of resistors R9-R12, R16-R20, and capacitors C11-C15, C17, and C19. In some embodiments, the output of operational amplifier U2C can be used to output the electromyographic signal and detection signal after low-pass filtering and partial gain (e.g., the second gain).

[0121] One end of capacitor C11 can be connected to the junction of resistors R9 and R10, and the other end can be connected to virtual ground VCC2. One end of capacitor C13 can be connected to the junction of resistors R10 and R11, and the other end can be connected to the output of operational amplifier U3A. One end of capacitor C14 can be connected to the non-inverting input of operational amplifier U3B, and the other end can be connected to virtual ground VCC2. One end of capacitor C15 can be connected to the junction of resistors R17 and R18, and the other end can be connected to the output of operational amplifier U3B. One end of capacitor C17 can be connected to the non-inverting input of operational amplifier U3C, and the other end can be connected to virtual ground VCC2. One end of capacitor C19 can be connected to the junction of resistors R19 and R20, and the other end can be connected to the output of operational amplifier U3C.

[0122] In some embodiments, the seventh-order low-pass filter 510 can utilize operational amplifiers U3A-U3C to perform low-pass filtering on the detection signal and electromyography signal. In some embodiments, the second cutoff frequency of the seventh-order low-pass filter 510 can be adjusted by adjusting the component parameters of operational amplifiers U3A-U3C.

[0123] Similar to the aforementioned fifth-order high-pass filter 410, in some embodiments, the seventh-order low-pass filter 510 can also be a Chebyshev filter.

[0124] In some embodiments, the low-pass filter circuit 150 may include a passive low-pass filter 520, the input of which is coupled to the high-pass filter circuit 140 to filter the amplified electromyographic signal and the detection signal as input.

[0125] like Figure 5B As shown, the passive low-pass filter 520 may include resistors R1-R2 and R8-R9, and capacitors C2-C3 and C12-C13. Resistors R8-R9, R2, and R1 are connected in series. One end of capacitors C2-C3 and C12-C13 is connected to the virtual ground VCC2. The other end of capacitor C12 is connected to the connection point of resistors R8-R9, the other end of capacitor C13 is connected to the connection point of resistors R9 and R2, the other end of capacitor C2 is connected to the connection point of resistors R2 and R1, and the other end of capacitor C3 is connected to resistor R1.

[0126] In some embodiments, the end of resistor R8 furthest from resistor R9 can be used to receive the amplified electromyography (EMG) signal and detection signal, and the end of resistor R1 furthest from resistor R2 can be used to output the low-pass filtered EMG signal and detection signal. In some embodiments, the passive low-pass filter 520 includes four RC low-pass filter units. For example, the passive low-pass filter 520 may include capacitor C12-resistor R8, capacitor C13-resistor R9, capacitor C2-resistor R2, and capacitor C3-resistor R1. In some embodiments, the passive low-pass filter 520 can utilize the aforementioned RC low-pass filter units to perform low-pass filtering on the detection signal and EMG signal. In some embodiments, the second cutoff frequency of the passive low-pass filter 520 can be adjusted by adjusting the component parameters in the aforementioned RC low-pass filter units.

[0127] In this embodiment, since the passive low-pass filter 520 does not require an additional power supply (e.g., power supply VCC), the aliasing noise that the passive low-pass filter 520 may introduce is small, thereby improving the quality of electromyography signals and detection signals.

[0128] It should be noted that the passive low-pass filter 520 may not provide a gain (e.g., a second gain) to the input signal (e.g., the electromyography signal and the detection signal after the first gain). Instead, it may utilize the amplification sub-circuit in the aforementioned active bandpass filter 420 to provide the first gain to the electromyography signal and the detection signal, thereby achieving the gain function. In some embodiments, the second gain may also be provided by separately setting an active amplification sub-circuit at the input of the passive low-pass filter 520, thereby achieving the gain function. Furthermore, the aforementioned filters (e.g., the fifth-order high-pass filter 410, the active bandpass filter 420, the seventh-order low-pass filter 510, and the passive low-pass filter 520) are merely examples, and the types, structures, and parameters of the filter components can be adjusted according to the filtering and gain requirements.

[0129] In some embodiments, a secondary gain circuit may also be provided between the electrode 110 and the high-pass filter circuit 140. Figure 3 (Not shown), the secondary gain circuit provides secondary gain, which is less than the first gain and the second gain.

[0130] In some embodiments, the secondary gain circuit can be a separately configured amplification sub-circuit that provides secondary gain for the electromyography (EMG) signal and the detection signal to achieve a gain function. In some embodiments, the secondary gain can provide partial gain for the EMG signal and the detection signal. In some embodiments, the magnitude of the secondary gain can be adjusted by adjusting the component parameters (e.g., the values ​​of capacitors and resistors) in the secondary gain circuit.

[0131] In some embodiments, the secondary gain circuit can provide a secondary gain of 1 to 1000 times. In some embodiments, the secondary gain circuit is located in the preceding stage relative to other amplification sub-circuits, and the gain provided by the secondary gain circuit can be less than the gain provided by other amplification sub-circuits. In some embodiments, the secondary gain circuit can provide a secondary gain of 10 times.

[0132] Figure 6 This is a schematic diagram of the structure of an exemplary secondary gain circuit 610 according to some embodiments of this specification. Figure 6 As shown, in some embodiments, the secondary gain circuit 610 may include an operational amplifier U1. The non-inverting and inverting input terminals of the operational amplifier U1 are connected to electrodes, respectively, to receive electromyographic signals and detection signals as input signals. The power supply terminal of the operational amplifier U1 is connected to the power supply VCC, and the ground terminal of the operational amplifier U1 is grounded. The reference terminal of the operational amplifier U1 is connected to a virtual ground VCC2, and the output terminal of the operational amplifier U1 is used to output the amplified signal. The value of the amplified signal can be equal to the difference between the output terminal and the reference terminal of the operational amplifier U1.

[0133] The first and second gain control terminals of operational amplifier U1 can be connected via resistor R3. In some embodiments, the resistance value of resistor R3 corresponds to the amplification factor of operational amplifier U1. In some embodiments, the secondary gain provided by secondary gain circuit 610 to the input signal can be adjusted by adjusting the resistance value of resistor R3. For example, increasing the resistance value of resistor R3 can decrease the secondary gain; conversely, decreasing the resistance value of resistor R3 can increase the secondary gain.

[0134] In some embodiments, the operational amplifier U1 can be an amplifier such as a differential amplifier or an instrumentation amplifier, so that the operational amplifier U1 has a high input impedance, which can reduce the change of the input signal when the circuit is connected. In some embodiments, the secondary gain circuit 610 has a high input impedance, which can reduce the signal change when the circuit is connected, making the acquired detection signal more stable.

[0135] Continue reading Figure 3 In some embodiments, the signal detection device 100 may further include an analog-to-digital converter 160, which may be connected to a low-pass filter circuit 150 and is used to perform analog-to-digital conversion on the filtered electromyographic signal and the detection signal.

[0136] In some embodiments, the analog-to-digital converter 160 can sample the electromyographic (EMG) signal and the detection signal according to a sampling rate to generate digital signals corresponding to the EMG signal and the detection signal. In some embodiments, the sampling rate of the analog-to-digital converter 160 can be set in conjunction with the frequency of the AC excitation source (i.e., a first frequency). Specifically, in order to acquire the EMG signal and the detection signal at the target frequency, the sampling rate of the analog-to-digital converter 160 can be greater than twice the third frequency, wherein the third frequency is the larger of the first frequency and the maximum target frequency of the EMG signal. To reduce errors, in some embodiments, the sampling rate can be four times or more the third frequency. It should be noted that since the signal measurement device 100 has a large number of channels, most circuits cannot support extremely high sampling rates for multiple channels, so the single-channel sampling rate and the first frequency of the AC excitation source should not be too high. For example, the first frequency can be 1 kHz, and the single-channel sampling rate can be 8 kHz.

[0137] Because the electromyographic (EMG) signal and the detection signal are processed simultaneously, the EMG signal and the detection signal are mixed together. In some embodiments, the signal detection device 100 may also include digital circuitry located at the output of the analog-to-digital converter 160. Figure 3(Not shown in the image), this digital circuit is used to extract and separate the electromyographic signal after analog-to-digital conversion and the detection signal after analog-to-digital conversion. In some embodiments, the signal detection device 100 may further include a second low-pass filter circuit and a second high-pass filter circuit located at the output of the analog-to-digital converter 160. The second low-pass filter circuit can be used to extract the electromyographic signal after analog-to-digital conversion, and the second high-pass filter circuit can be used to extract the detection signal after analog-to-digital conversion.

[0138] In this embodiment, by extracting the electromyographic signal and the detection signal separately, the detection signal can be used independently to more accurately evaluate the quality of the electromyographic signal and the adhesion between the electrode and the human body.

[0139] In some embodiments, electrode 110 may include a first electrode and a second electrode to acquire a first electromyographic signal and a second electromyographic signal from the electromyographic signals, respectively. AC excitation source 130 includes two excitation sources (e.g., a first AC excitation source and a second AC excitation source), connected to the first electrode and the second electrode, respectively, and providing two excitation signals (e.g., a first excitation signal and a second excitation signal) to generate a first detection signal and a second detection signal from the detection signals. Correspondingly, gain circuit 130 includes a differential amplifier to differentially amplify the first electromyographic signal and the second electromyographic signal, as well as the first detection signal and the second detection signal.

[0140] In some embodiments, the frequencies of the first excitation signal and the second excitation signal provided by the AC excitation source 120 may be different, resulting in different frequencies of the generated first detection signal and the second detection signal. In some embodiments, the first electrode and the second electrode may have a large distance between them (e.g., greater than or equal to 5 cm), so that the closed loop through which the first excitation signal and the second excitation signal flow can pass through different human tissues, resulting in the first detection signal and the second detection signal of different frequencies corresponding to the first electrode and the second electrode, respectively, being used to reflect the body composition information of the human body.

[0141] In some embodiments, the first excitation signal and the second excitation signal provided by the AC excitation source 120 may each contain multiple frequencies, such that the generated first detection signal and the second detection signal also contain corresponding multiple frequencies. Thus, by amplifying the first detection signal and the second excitation signal, impedance information of the human body at different frequencies can be obtained, thereby reflecting the body composition information of the human body.

[0142] In some embodiments, the frequencies of the first excitation signal and the second excitation signal provided by the AC excitation source 120 may also be the same, so that the frequencies of the first detection signal and the second detection signal generated are also the same, thereby enabling the simultaneous acquisition of multiple detection signals and multiple electromyographic signals for timely evaluation and feedback of the signals.

[0143] In this embodiment, a detection signal reflecting contact impedance can be acquired simultaneously with the acquisition of electromyographic (EMG) signals to evaluate the EMG signals. Subsequently, the contact impedance can be adjusted appropriately to acquire high-quality EMG signals. Gain can then be provided to both the EMG signals and the detection signals. Even if the signal strength is low, the strength and quality of the EMG signals can be improved through gain, ensuring the subsequent identification and processing of the EMG signals.

[0144] In some embodiments, the signal measurement device 100 can be applied to wearable devices. In some embodiments, wearable devices may include smart bracelets, smart shoes and socks, smart glasses, smart helmets, smartwatches, smart clothing, smart backpacks, smart accessories, etc., or any combination thereof. Taking smart clothing (e.g., fitness wear or sportswear) as an example, the signal measurement device 100 can acquire physiological signals collected by any two electrodes or two electrodes with a specific association (e.g., two electrodes attached to the same muscle to receive electromyographic signals from the same muscle), and evaluate the quality of the physiological signals based on the difference between the physiological signals collected by the two electrodes or the two electrodes with a specific association, or evaluate the fit between the two electrodes or the two electrodes with a specific association and the human body.

[0145] In some embodiments, the signal measuring device 100 may also perform wear status analysis, warm-up status analysis, size fit analysis, clothing life analysis, motion monitoring, skin condition analysis, body composition analysis, etc., based on the evaluation results of the aforementioned physiological signals.

[0146] The following provides three exemplary signal measurement devices, and describes in detail the specific implementation of the signal measurement devices.

[0147] Example 1:

[0148] Figure 7A This is a circuit block diagram of a signal measurement device according to Example 1 of some embodiments of this specification. Figure 7B This is a circuit diagram of the signal measurement device of Example 1, based on some embodiments of this specification. Figures 7A-7B As shown, this embodiment provides a signal measurement device 700, which may include: electrodes, an AC excitation source (not shown in the figure), a secondary gain circuit 720, an active bandpass filter 730, a passive low-pass filter 740, and an analog-to-digital converter 750. The electrodes may include a first electrode 711 and a second electrode 712, which are respectively connected to the secondary gain circuit 720. The secondary gain circuit 720, the active bandpass filter 730, the passive low-pass filter 740, and the analog-to-digital converter 750 are connected sequentially.

[0149] In some embodiments, the first electrode 711 and the second electrode 712 (e.g. Figure 7B The function generators XFG1 and XFG2 shown can respectively acquire electromyographic signals and send them to the secondary gain circuit 720. An AC excitation source can provide an excitation signal of a first frequency to generate a detection signal reflecting the contact impedance between the first electrode 711 and the second electrode 712 and the human body. In some embodiments, the structure and function of the first electrode 711 and the second electrode 712 can be the same as or similar to the electrode 110 described above. For specific implementations of the electrodes, please refer to other parts of this application specification, such as... Figures 1-6 And its description.

[0150] The secondary gain circuit 720 receives electromyographic signals and detection signals at its input and provides them with secondary gain. In some implementations, the structure and function of the secondary gain circuit 720 may be the same as or similar to the secondary gain circuit 610 described above. For specific implementations of the secondary gain circuit 720, please refer to other parts of this specification, such as... Figure 6 And its description.

[0151] The active bandpass filter 730 receives electromyographic signals and detection signals from the secondary gain circuit 720, extracts the electromyographic signals and detection signals according to a preset bandwidth frequency range, filters low-frequency noise in the signals to avoid providing gain for low-frequency noise in the subsequent process, and ensures that the signals do not exceed the measurement range of the signal measuring device 700.

[0152] In some embodiments, the amplification sub-circuit in the active bandpass filter 730 can also provide a first gain for the filtered electromyography (EMG) signal and detection signal. Both the secondary gain circuit 720 and the amplification sub-circuit can implement gain functions, providing secondary and first gains for the EMG and detection signals to improve signal quality. In some embodiments, the structure and function of the active bandpass filter 730 can be the same as or similar to the active bandpass filter 420 described above. For specific implementations of the active bandpass filter 730, please refer to other parts of this specification, such as... Figure 4B And its description.

[0153] In some embodiments, the passive low-pass filter 740 can receive electromyographic (EMG) signals and detection signals from the active band-pass filter 730. After gaining the EMG and detection signals, high-frequency noise in the EMG and detection signals is filtered out according to a second cutoff frequency, thereby avoiding the introduction of high-frequency noise during the gain process and improving signal quality. In some embodiments, the structure and function of the passive low-pass filter 740 can be the same as or similar to the passive low-pass filter 520 described above. Specific implementations of the active band-pass filter 730 can be found in other parts of this specification, such as... Figure 5B And its description.

[0154] In some embodiments, the analog-to-digital converter 750 (such as...) Figure 7B The analog-to-digital converter (XSC1) shown can receive electromyography (EMG) signals and detection signals from the passive low-pass filter 740 and perform analog-to-digital conversion on them. In some embodiments, the converted EMG and detection signals can also be processed by the filter to extract the EMG and detection signals respectively for subsequent evaluation. In some implementations, the structure and function of the analog-to-digital converter 750 can be the same as or similar to the analog-to-digital converter 160 described above. For specific implementations of the analog-to-digital converter 750, please refer to other parts of this application specification, such as... Figures 1-6 And its description.

[0155] See Figure 7B In some embodiments, the passive low-pass filter 740 and analog-to-digital converter 750 assembly may also include a follower U2C. The follower U2C can be used to maintain the stability of the output voltage or current and isolate the passive low-pass filter 740 from the analog-to-digital converter 750. The non-inverting input of the follower U2C is connected to the output of the passive low-pass filter 740 for receiving electromyographic signals and detection signals, and the inverting input of the follower U2C is connected to its output. The power supply and ground terminals of the follower U2C are unconnected.

[0156] See Figure 7B In some embodiments, the signal measurement device 700 may further include a spectrum analysis device XBP1 for measuring the frequency response curve of the signal measurement device 700. One end of the spectrum analysis device XBP1 is connected to function generators XFG1 and XFG2 (i.e., the first electrode and the second electrode), respectively, and the other end of the spectrum analysis device XBP1 is connected to the output of the follower U2C.

[0157] Continue to refer to Figure 7B In some embodiments, the signal measurement device 700 may further include a power supply circuit 760, which may be connected to the power supply VCC. The output of the power supply circuit 760 may be connected to the virtual ground VCC2 to provide power to the virtual ground VCC2. In some embodiments, when the voltage of the power supply VCC is 3.3V, the power supply circuit 760 may provide the virtual ground VCC2 with a power supply of 1.65V or other power supply voltages within the dynamic range.

[0158] In some embodiments, the power supply circuit 760 may include an operational amplifier U2D. The non-inverting input of the operational amplifier U2D is connected to the power supply VCC through a resistor R14, and the non-inverting input of the operational amplifier U2D is also grounded through a parallel resistor R13 and a capacitor C18. The inverting input of the operational amplifier U2D is connected to the output of the operational amplifier U2D through a resistor R15, and the output of the operational amplifier U2D is grounded through a capacitor C16. For example, the impedance values ​​of resistors R13-R14 can be 10kΩ, the impedance value of resistor R15 can be 300Ω, the capacitive reactance value of capacitor C16 can be 10μF, the capacitive reactance value of capacitor C18 can be 10μF, and the operational amplifier U2D can be a TLC2274ACPW.

[0159] Example 2:

[0160] Figure 8A This is a circuit block diagram of an exemplary signal measurement device according to some embodiments of this specification, as shown in Example 2. Figure 8B This is a circuit diagram of an exemplary signal measurement device according to some embodiments of this specification, representing Example 2.

[0161] like Figures 8A-8B As shown, this embodiment provides a signal measurement device 800, which may include: electrodes, an AC excitation source (not shown in the figure), a secondary gain circuit 820, a fifth-order high-pass filter 830, a seventh-order low-pass filter 840, and an analog-to-digital converter 850. The electrodes may include a first electrode 811 and a second electrode 812, which are respectively connected to the secondary gain circuit 820. The secondary gain circuit 820, the fifth-order high-pass filter 830, the seventh-order low-pass filter 840, and the analog-to-digital converter 850 are connected sequentially.

[0162] In some embodiments, the first electrode 811 and the second electrode 812, the AC excitation source, the secondary gain circuit 820 and the analog-to-digital converter 850 in this embodiment are similar to the first electrode 711 and the second electrode 712, the AC excitation source, the secondary gain circuit 720 and the analog-to-digital converter 750 in Example 1 above. The specific implementation can be referred to Example 1 above, and will not be repeated here.

[0163] In some embodiments, the fifth-order high-pass filter 830 can receive electromyographic signals and detection signals from the secondary gain circuit 820, and filter low-frequency noise in the electromyographic signals and detection signals according to a first cutoff frequency to avoid subsequently providing gain for low-frequency noise and ensure that the signal does not exceed the measurement range of the signal measuring device 800. In some embodiments, the amplification sub-circuit in the fifth-order high-pass filter 830 can also provide a first gain for the filtered electromyographic signals and detection signals.

[0164] In some embodiments, the structure and function of the fifth-order high-pass filter 830 may be the same as or similar to the fifth-order high-pass filter 410 described above. For specific implementations of the fifth-order high-pass filter 830, please refer to other parts of this specification, such as... Figure 4A And its description.

[0165] In some embodiments, the seventh-order low-pass filter 840 can receive electromyographic (EMG) signals and detection signals from the fifth-order high-pass filter 830. After gaining the EMG and detection signals, high-frequency noise in the EMG and detection signals is filtered out according to a second cutoff frequency, thereby avoiding the introduction of high-frequency noise during the gain process and improving signal quality. In some embodiments, the amplification sub-circuit in the seventh-order low-pass filter 840 can also provide a second gain for the EMG and detection signals before filtering. By gaining first and then filtering, aliasing signals generated during the gain process can be suppressed, thereby improving the quality of the EMG and detection signals.

[0166] In some implementations, the structure and function of the seventh-order low-pass filter 840 can be the same as or similar to the seventh-order low-pass filter 510 described above. For specific implementations of the seventh-order low-pass filter 840, please refer to other parts of this application specification, such as... Figure 5A And its description.

[0167] In some embodiments, the secondary gain circuit 820, the amplification sub-circuit in the fifth-order high-pass filter 830, and the amplification sub-circuit in the seventh-order low-pass filter 840 can all implement gain functions, providing secondary gain, first gain, and second gain for electromyographic signals and detection signals to improve signal quality.

[0168] See Figure 8B In some embodiments, a follower U2C may be provided between the seventh-order low-pass filter 840 and the analog-to-digital converter 750. The follower U2C in this embodiment is similar to the follower U2C in Example 1 above; its specific implementation can be found in Example 1 above, and will not be repeated here.

[0169] In some embodiments, the signal measurement device 800 may further include a spectrum analysis device XBP1 and a power supply circuit 860. The spectrum analysis device XBP1 and power supply circuit 860 in this embodiment are similar to the spectrum analysis device XBP1 and power supply circuit 760 in Example 1 above; their specific implementations can be found in Example 1 above, and will not be repeated here.

[0170] Example 3:

[0171] Figure 9 This is a circuit diagram of Example 3 of a bandpass gain signal measurement device according to some embodiments of this specification;

[0172] like Figure 9 As shown, this embodiment provides a bandpass gain signal measurement device 900, which may include: electrodes, an AC excitation source (not shown in the figure), a secondary gain circuit 920, a bandpass gain circuit 930, and an analog-to-digital converter 950. The electrodes may include a first electrode 911 and a second electrode 912, which are respectively connected to the secondary gain circuit 920. The secondary gain circuit 920, the bandpass gain circuit 930, and the analog-to-digital converter 950 are connected sequentially.

[0173] In some embodiments, the first electrode 911 and the second electrode 912, the AC excitation source, the secondary gain circuit 920, and the analog-to-digital converter 950 in this embodiment are similar to the first electrode 711 and the second electrode 712, the AC excitation source, the secondary gain circuit 720, and the analog-to-digital converter 750 in Example 1 above. The specific implementation can be referred to Example 1 above, and will not be repeated here.

[0174] In some embodiments, the bandpass gain circuit 930 can receive electromyographic (EMG) signals and detection signals from the secondary gain circuit 920, extract the EMG signals and detection signals according to a third bandwidth frequency range, and simultaneously filter low-frequency and high-frequency noise in the signals, thereby improving the quality of the EMG signals and detection signals to a certain extent. In some embodiments, the third bandwidth frequency range may include the frequency range in which the EMG signals and detection signals are located. In some embodiments, the amplification sub-circuit in the bandpass gain circuit 930 can also provide a third gain for the filtered EMG signals and detection signals.

[0175] refer to Figure 9 In some embodiments, the bandpass gain circuit 930 may include an operational amplifier U2A, resistors R1-R2, R4, and R7, and capacitors C1 and C8. The non-inverting input of operational amplifier U2A may be connected to virtual ground VCC2. The inverting input of operational amplifier U2A may be connected to a series capacitor C1 and resistor R4. The inverting input of operational amplifier U2A may also be connected to the output of operational amplifier U2A through a parallel capacitor C8 and resistor R7. The power supply terminal of operational amplifier U2A is connected to the power supply VCC, and the ground terminal of operational amplifier U2A is grounded. The series resistors R1-R2 are located at the output of operational amplifier U2A.

[0176] In some embodiments, the operational amplifier U2A of the bandpass gain circuit 930 can provide a third gain for the input signal (e.g., electromyographic signal and detection signal). The magnitude of this third gain can be related to the parameters of resistors R4 and R7, and capacitors C1 and C8. In some embodiments, the third bandwidth frequency range of the bandpass gain circuit 930 can also be adjusted by regulating the component parameters of the aforementioned resistors R4 and R7, and capacitors C1 and C8.

[0177] For example, the capacitive reactance of capacitor C1 can be 1μF, and the capacitive reactance of capacitor C8 can be 33nF. The impedance of resistors R1-R2 can be 500Ω, the impedance of resistor R4 can be 680Ω, and the impedance of resistor R7 can be 30kΩ. The power supply VCC can be 3.3V, and the operational amplifiers U2A and U2B can be model TLC2274ACPW.

[0178] In some embodiments, the amplification sub-circuits in the secondary gain circuit 920 and the bandpass gain circuit 930 can both implement gain functions, providing secondary and tertiary gains for electromyographic signals and detection signals to improve signal quality.

[0179] See Figure 9 In some embodiments, a follower U2C may be provided between the bandpass gain circuit 930 and the analog-to-digital converter 950. The follower U2C in this embodiment is similar to the follower U2C in Example 1 above; its specific implementation can be found in Example 1 above, and will not be repeated here.

[0180] In some embodiments, the signal measurement device 900 may further include a spectrum analysis device XBP1 and a power supply circuit 960. The spectrum analysis device XBP1 and power supply circuit 960 in this embodiment are similar to the spectrum analysis device XBP1 and power supply circuit 760 in Example 1 above; their specific implementations can be found in Example 1 above, and will not be repeated here.

[0181] Figure 10 yes Figure 7B , Figure 8B and Figure 9 Frequency response curve of the signal measuring device. (Example) Figure 10 As shown, curve 1010 is Figure 7B The frequency response curve of the signal measuring device 700 shown; curve 1020 is Figure 8B The frequency response curve of the signal measuring device 800 shown; curve 1030 is Figure 9 The frequency response curve of the gain circuit of the signal measurement device 900 shown.

[0182] Depend on Figure 10 It can be seen that curve 1010 has a peak (as shown in the image). Figure 10 Peak 1021 (shown) is located approximately around 210 Hz, and its corresponding gain is approximately 1050 times. Curve 1020 is similar to the above... Figure 2A Curve 210, as shown, is similar and exhibits a bimodal shape. Curve 1030, however, has a smaller overall amplitude, reflecting the lower gain provided by the signal measuring device 900 for both electromyographic and detection signals.

[0183] Depend on Figure 10 It can be seen that, compared to signal measurement devices 700 and 900, signal measurement device 800 has improved signal-to-noise ratios (SNR) for all three gains. For example, compared to signal measurement device 700, signal measurement device 800 has a 10285-fold increase in MA SNR, a 45.8-fold increase in power frequency SNR, and an 87.7-fold increase in aliasing SNR. Compared to signal measurement device 900, signal measurement device 800 has a 75080.5-fold increase in MA SNR, an 82.44-fold increase in power frequency SNR, and a 1315.5-fold increase in aliasing SNR.

[0184] The beneficial effects that the embodiments of this specification may bring include, but are not limited to: (1) when collecting electromyographic signals, a detection signal reflecting contact impedance can be collected at the same time, so that the contact impedance can be adjusted appropriately to ensure that the electrode fits well with the human body and that high-quality electromyographic signals can be collected; (2) by setting a gain circuit, a gain is provided for the collected electromyographic signals and detection signals, thereby improving the strength and quality of the electromyographic signals and detection signals, so that the signal measuring device can accurately monitor.

[0185] The basic concepts have been described above. It is clear that the detailed disclosure above is merely illustrative and does not constitute a limitation of this specification. Although not explicitly stated herein, various modifications, improvements, and corrections may be made to this specification by those skilled in the art. Such modifications, improvements, and corrections are suggested in this specification and therefore remain within the spirit and scope of the exemplary embodiments described herein.

[0186] Furthermore, this specification uses specific terms to describe embodiments thereof. For example, "an embodiment," "one embodiment," and / or "some embodiments" refer to a particular feature, structure, or characteristic associated with at least one embodiment of this specification. Therefore, it should be emphasized and noted that references to "an embodiment," "one embodiment," or "an alternative embodiment" in different locations throughout this specification do not necessarily refer to the same embodiment. Moreover, certain features, structures, or characteristics in one or more embodiments of this specification can be appropriately combined.

[0187] Furthermore, unless expressly stated in the claims, the order of processing elements and sequences, the use of numbers and letters, or other names described in this specification are not intended to limit the order of the processes and methods described herein. Although various examples have been discussed in the foregoing disclosure of some embodiments of the invention that are currently considered useful, it should be understood that such details are for illustrative purposes only, and the appended claims are not limited to the disclosed embodiments; rather, the claims are intended to cover all modifications and equivalent combinations that conform to the spirit and scope of the embodiments described herein. For example, while the system components described above can be implemented using hardware devices, they can also be implemented solely using software solutions, such as installing the described system on existing servers or mobile devices.

[0188] Similarly, it should be noted that, in order to simplify the description disclosed herein and thus aid in the understanding of one or more embodiments of the invention, the foregoing description of embodiments in this specification may sometimes combine multiple features into a single embodiment, drawing, or description thereof. However, this method of disclosure does not imply that the subject matter of this specification requires more features than those mentioned in the claims. In fact, the embodiments contain fewer features than all the features of a single embodiment disclosed above.

[0189] In some embodiments, numbers describing the quantity of components and attributes are used. It should be understood that such numbers used in the description of embodiments are modified in some examples with the terms "approximately," "approximately," or "generally." Unless otherwise stated, "approximately," "approximately," or "generally" indicates that the numbers are allowed to vary by ±20%. Accordingly, in some embodiments, the numerical parameters used in the specification and claims are approximate values, which may be changed depending on the characteristics required by individual embodiments. In some embodiments, numerical parameters should take into account specified significant digits and employ a general method of digit reservation. Although the numerical ranges and parameters used to confirm their breadth of range in some embodiments of this specification are approximate values, in specific embodiments, such values ​​are set as precisely as feasible.

[0190] For each patent, patent application, patent application publication, and other material, such as articles, books, specifications, publications, and documents, referenced in this specification, the entire contents of which are incorporated herein by reference. This excludes historical application documents that are inconsistent with or conflict with the content of this specification, as well as documents that limit the broadest scope of the claims in this specification (currently or subsequently appended to this specification). It should be noted that in the event of any inconsistency or conflict between the descriptions, definitions, and / or terminology used in the supplementary materials to this specification and the content of this specification, the descriptions, definitions, and / or terminology used in this specification shall prevail.

[0191] Finally, it should be understood that the embodiments described in this specification are merely illustrative of the principles of the embodiments described herein. Other variations may also fall within the scope of this specification. Therefore, alternative configurations of the embodiments described herein are intended to be illustrative rather than limiting, and should be considered consistent with the teachings of this specification. Accordingly, the embodiments described herein are not limited to those explicitly introduced and described herein.

Claims

1. A signal measuring device, comprising: Electrodes, which are attached to the human body, are used to collect electromyographic signals of the human body within a target frequency range; An AC excitation source electrically connected to the electrode is used to provide an excitation signal of a first frequency to generate a detection signal reflecting the contact impedance between the electrode and the human body. as well as A gain circuit is provided for both the electromyographic (EMG) signal and the detection signal. The gain circuit includes a fifth-order high-pass filter and a seventh-order low-pass filter coupled to the fifth-order high-pass filter. The input of the fifth-order high-pass filter receives the EMG signal and the detection signal. The fifth-order high-pass filter is used to filter the acquired EMG signal and the detection signal and to provide a first gain for the EMG signal and the detection signal. The seventh-order low-pass filter is used to filter high-frequency noise in the EMG signal and the detection signal and to provide a second gain for the EMG signal and the detection signal. The frequency response of the gain circuit has one or more peaks in a first frequency range, which includes the frequency of the electromyographic signal and the frequency of the detection signal. The frequencies in the first frequency range are higher than 50 Hz and lower than the first frequency.

2. The signal measuring device according to claim 1, characterized in that, The target frequency range includes 20 Hz-400 Hz, and the first frequency is not less than 250 Hz.

3. The signal measuring device according to claim 2, characterized in that, The difference between the first frequency and any integer multiple of 50Hz is not less than 1 Hz; or, the difference between the first frequency and any integer multiple of 60Hz is not less than 1 Hz.

4. The signal measuring device according to claim 1, characterized in that, The first frequency is higher than the target frequency range.

5. The signal measuring device according to claim 1, characterized in that, The gain circuit for the electromyographic signal is not less than 1 / 10 of the gain for the detection signal, and not greater than 10 times the gain for the detection signal.

6. The signal measuring device according to claim 5, characterized in that, The frequency response of the gain circuit has two peaks in the first frequency range, one peak being close to the target frequency range and the other peak being close to the first frequency.

7. The signal measuring device according to claim 5, characterized in that, The ratio of the gain of the gain circuit at 100Hz to the gain at 10Hz is the first signal-to-noise ratio, and the first signal-to-noise ratio is not less than 4.

8. The signal measuring device according to claim 5, characterized in that, The ratio of the gain of the gain circuit at 100Hz to the gain at 50Hz is the second signal-to-noise ratio, and the second signal-to-noise ratio is not less than 2.

9. The signal measuring device according to claim 1, characterized in that, The signal measurement device further includes an analog-to-digital converter, which is used to perform analog-to-digital conversion on the filtered electromyographic signal and the detection signal.

10. The signal measuring device according to claim 9, characterized in that, The sampling rate of the analog-to-digital converter is greater than twice the third frequency, which is the larger of the first frequency and the frequency of the electromyographic signal.

11. The signal measuring device according to claim 9, characterized in that, The ratio of the gain of the gain circuit at 100Hz to the gain at the second frequency is the third signal-to-noise ratio, where the second frequency is the frequency corresponding to half of the sampling rate of the analog-to-digital converter, and the third signal-to-noise ratio is not less than 10.

12. The signal measuring device according to claim 1, characterized in that, The fifth-order high-pass filter and the seventh-order low-pass filter are Chebyshev type filters.

13. The signal measuring device according to claim 1 or 12, characterized in that, A secondary gain circuit is also provided between the electrode and the high-pass filter. The secondary gain circuit provides a secondary gain that is less than the first gain and the second gain.

14. The signal measuring device according to claim 1, characterized in that, The electrode includes a first electrode and a second electrode, which respectively acquire the first electromyographic signal and the second electromyographic signal from the electromyographic signal; The AC excitation source includes two excitation sources, which are respectively connected to the first electrode and the second electrode, and respectively provide two excitation signals to generate the first detection signal and the second detection signal in the detection signal; The gain circuit includes a differential amplifier, which differentially amplifies the first electromyographic signal and the second electromyographic signal, as well as the first detection signal and the second detection signal.

15. The signal measuring device according to claim 1, characterized in that, The gain circuit provides gain to both the electromyographic signal and the detection signal simultaneously; or, the gain circuit provides gain to the electromyographic signal and the detection signal separately at different time periods.

16. The signal measuring device according to claim 1, characterized in that, The signal measuring device acquires the electromyographic signal and the detection signal simultaneously; or, the signal measuring device acquires the electromyographic signal and the detection signal separately at different time periods.

17. The signal measuring device according to claim 1, characterized in that, The signal measuring device is a wearable device.

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