阅读说明：本技术 非接触式心肺信号测量系统 (Non-contact cardiopulmonary signal measurement system ) 是由 彭顺 陈炜 于 2021-08-03 设计创作，主要内容包括：本发明属于医疗设备技术领域,具体为一种非接触式心肺信号测量系统。本发明系统包括参考电极、两块感应电极、信号采集模块和信号处理软件；参考电极从底部覆盖两块感应电极并构成整体,改善共模抑制性能；信号采集模块包含缓冲器电路、差分放大器和右腿驱动电路；信号处理软件包含对原始信号预处理算法和从原始信号中提取呼吸信号的呼吸提取算法。两块感应电极采用电容耦合的工作方式测量皮肤电信号,使系统在使用者睡眠时能够非接触式测量心电信号,并且获得呼吸信号。本发明系统舒适便捷、使用安全、信号质量高并且能够进行整夜稳定工作,解决了传统生命体征监测产品用在睡眠监护时舒适感低、信号质量差的问题。(The invention belongs to the technical field of medical equipment, and particularly relates to a non-contact cardiopulmonary signal measuring system. The system comprises a reference electrode, two induction electrodes, a signal acquisition module and signal processing software; the reference electrode covers the two induction electrodes from the bottom to form a whole, so that the common mode rejection performance is improved; the signal acquisition module comprises a buffer circuit, a differential amplifier and a right leg driving circuit; the signal processing software contains a pre-processing algorithm on the raw signal and a breath extraction algorithm that extracts a breath signal from the raw signal. The two induction electrodes adopt a capacitive coupling working mode to measure skin electric signals, so that the system can measure electrocardiosignals in a non-contact manner when a user sleeps and obtain respiratory signals. The system is comfortable and convenient, safe to use and high in signal quality, can stably work all night, and solves the problems of low comfort and poor signal quality when the traditional vital sign monitoring product is used for sleep monitoring.)

1. A non-contact cardiopulmonary signal measurement system is characterized by comprising a reference electrode, two induction electrodes, a signal acquisition module and signal processing software; wherein:

the induction electrodes comprise a first induction electrode and a second induction electrode, wherein the first induction electrode is arranged near the position of the scapula when the human body lies flat; the second induction electrode is arranged between the waist and the hip; when working, each induction electrode forms a coupling capacitor with the skin of a human body, so that a skin electric signal is induced in a non-contact manner;

the induction electrode comprises an induction layer, an insulating layer and a connecting layer from top to bottom; the induction layer adopts flexible conductive cloth and induces the skin electrical signal in a capacitive coupling mode; the insulating layer is made of flexible insulating cloth and is used for electrically isolating the sensing layer from the reference electrode; the connecting layer adopts high-strength adhesive and is used for physically connecting the sensing electrode and the reference electrode to form a whole;

the signal acquisition module comprises a differential amplifier and a right leg driving circuit and acquires electrocardiosignals of the two induction electrodes in a differential mode; the common mode rejection performance can be improved;

the reference electrode is made of flexible conductive cloth, and covers the two induction electrodes from the bottom, so that the reference electrode plays a role in shielding electromagnetic noise; in addition, the reference electrode is also connected with a right leg driving circuit and used for feeding back the common-mode signals of the two induction electrodes to the human body;

the signal processing software is used for preprocessing the electrocardiosignals and extracting the respiratory signals from the electrocardiosignals.

2. The system for measuring heart-lung signals in a non-contact mode according to claim 1, wherein the two sensing electrodes are in the shape of long strips with the length being more than 70cm, and the length of the two sensing electrodes is enough to cover the turning range of a person in a sleeping process, so that the stability of signal measurement is ensured; when the device works, the device forms a coupling capacitor with human skin, so that skin electric signals are non-contact induced.

3. The system of claim 1, wherein the signal acquisition module comprises two input terminals electrically connected to the two sensing electrodes, each input terminal comprising a buffer circuit for increasing input impedance and improving common mode rejection performance.

4. The system of claim 1, wherein the signal processing software comprises an ecg signal preprocessing algorithm and a breath extraction algorithm, wherein the ecg signal preprocessing algorithm is configured to remove power frequency interference from the signal, and a FIR low pass filter with a passband upper limit frequency of 40 Hz, a passband maximum ripple of 0.1 db, a stopband lower limit frequency of 45 Hz, and a stopband minimum attenuation of 60 db is used to remove power frequency interference of 50Hz/60 Hz; the respiration extraction algorithm adopts an IIR band-pass filter with the passband frequency of 0.2-0.6Hz, the maximum passband ripple of 1 dB and the minimum stopband attenuation of 60 dB, and is used for extracting respiration signals with the main frequency range of 0.2-0.6 Hz.

Technical Field

The invention belongs to the technical field of medical equipment, and particularly relates to an electrocardio and respiratory signal measuring system.

Background

Conventional vital signs monitors often employ wet electrodes, such as Ag/AgCl electrodes. Under the condition that the electrodes are attached to the skin, the equipment can acquire electrocardiosignals and respiratory signals with high quality, but has a plurality of defects in comfort and convenience, and particularly can seriously interfere with sleep when being applied to sleep monitoring. For this reason, many non-contact electrocardiographic sensors have been studied. For example, the utility model "an electrocardio monitoring mattress based on non-contact electrode array" (CN 202699127U) discloses a non-contact electrocardio sensor made of a double-sided Printed Circuit Board (PCB), which can be arranged on the mattress in an array manner to measure the electrocardiosignals of the person lying thereon across clothes. The invention patent application 'a heart-lung signal sensing and collecting system for sleep monitoring' (CN 110236517A) discloses a flexible electrocardio-electrode designed by using an M/NWs/PDM composite material, which ensures the comfort of a user. One electrocardio-electrode of the system is arranged on the pillow, the other electrocardio-electrode is arranged on the right side of the upper limb, and electrocardio acquisition tests are carried out under three sleeping postures.

For the research of applying the non-contact electrocardio sensor to sleep monitoring, the comfort is greatly improved, but the problem of poor signal quality exists. The main reasons are two reasons: firstly, the physiological electric signal is weak, and the measurement through clothes is easily interfered by noise; secondly, in order to overcome the stability problem of signal measurement in unconstrained sleep, the electrodes on the mattress are often designed to be larger, so that the electromagnetic radiation interference in the environment is serious. These two factors greatly limit the application of the contactless electrocardiograph sensor in sleep monitoring.

Disclosure of Invention

The invention aims to provide a non-contact cardiopulmonary signal measuring system for sleep monitoring, which is comfortable, convenient and fast, safe to use, high in signal quality and capable of working stably all night.

The invention provides a non-contact cardiopulmonary signal measurement system, which comprises a reference electrode, two induction electrodes, a signal acquisition module and signal processing software; wherein:

the induction electrodes comprise a first induction electrode and a second induction electrode, wherein the first induction electrode is arranged near the position of the scapula when the human body lies flat; the second induction electrode is arranged between the waist and the hip; when working, each induction electrode forms a coupling capacitance with the skin of a human body, so that the skin electric signal is induced in a non-contact manner.

The induction electrode comprises an induction layer, an insulating layer and a connecting layer from top to bottom; the induction layer adopts flexible conductive cloth and induces the skin electrical signal in a capacitive coupling mode; the insulating layer is made of flexible insulating cloth and is used for electrically isolating the sensing layer from the reference electrode; and the connecting layer adopts high-strength adhesive for physically connecting the sensing electrode and the reference electrode to form a whole.

Furthermore, each sensing electrode is in a long strip shape (such as a rectangle with the length of (4-6 cm) × 70-85 cm) which is more than 70cm, and the length of each sensing electrode is enough to cover the turning range (usually within the range of 70 cm) of a general person in the sleeping process, so that the stability of signal measurement is ensured; when the device works, the device forms a coupling capacitor with human skin, so that skin electric signals are non-contact induced.

The signal acquisition module comprises a differential amplifier and a right leg driving circuit and acquires electrocardiosignals of the two induction electrodes in a differential mode; the common mode rejection performance can be improved.

Furthermore, two input ends of the signal acquisition module are electrically connected with the two induction electrodes, and each input end comprises a buffer circuit for increasing input impedance and improving common mode rejection performance.

The reference electrode is made of flexible conductive cloth, and covers the two induction electrodes from the bottom, so that the reference electrode plays a role in shielding electromagnetic noise; in addition, the reference electrode is also connected with a right leg driving circuit and used for feeding back the common-mode signals of the two induction electrodes to a human body (the position between the two induction electrodes), so that the common-mode rejection performance is further improved, and the signal quality is improved.

The signal processing software is used for preprocessing the electrocardiosignals and extracting the respiratory signals from the electrocardiosignals.

The signal processing software comprises an electrocardiosignal preprocessing algorithm and a respiration signal extraction algorithm, wherein the electrocardiosignal preprocessing algorithm is used for removing power frequency interference in signals, and a FIR low-pass filter with the passband upper limit frequency of 40 Hz, the passband maximum ripple of 0.1 dB, the stopband lower limit frequency of 45 Hz and the stopband minimum attenuation of 60 dB is adopted to remove the power frequency interference of 50Hz/60 Hz; the breathing signal extraction algorithm adopts an IIR band-pass filter with the passband frequency of 0.2-0.6Hz, the maximum passband ripple of 1 dB and the minimum stopband attenuation of 60 dB, and is used for extracting the breathing signal with the main frequency range of 0.2-0.6 Hz.

Compared with the prior art, the invention has the beneficial effects that:

the non-contact electrocardio measuring technology is used for sleep monitoring at present and is often limited by poor signal quality. The principle of the right leg driving circuit for improving the signal quality is as follows: the right leg circuit extracts the common mode signal of the two sensing electrodes and then feeds back the common mode signal to the human body through the reference electrode to suppress the common mode signal. In the prior art, a reference electrode for feeding back a common-mode signal is often placed in the region of the right leg or the lower limb. However, when measuring electrocardiograms in a non-contact manner, the ability of the reference electrode to feed back common mode signals across clothing is impaired. In the invention, the reference electrode is arranged below the two induction electrodes, and the common-mode signal is fed back to the body area between the two induction electrodes, so that the common-mode rejection effect can be more effectively exerted.

In addition, the reference electrode covers the two induction electrodes from the bottom, so that the electromagnetic noise shielding effect can be achieved on the induction electrodes, and the quality of the electrocardiosignals is further improved.

The system is comfortable and convenient, safe to use and high in signal quality, can stably work all night, and solves the problems of low comfort and poor signal quality when the traditional vital sign monitoring product is used for sleep monitoring.

Drawings

Fig. 1 is a general embodiment of a non-contact cardiopulmonary signal measurement.

Fig. 2 is a schematic diagram of an electrode structure and layout. Wherein (a) is a front view; (b) is a side view.

Fig. 3 is a schematic diagram of a signal acquisition module.

FIG. 4 is a comparison graph of electrocardiographic measurements of different positions of the reference electrode. Wherein, (a) is that the reference electrode is positioned at the bottom of the two induction electrodes (the invention); (b) is located in the lower limb area as a reference electrode.

FIG. 5 is a non-contact measurement of the cardiac and respiratory signals.

Reference numbers in the figures: 10 is a first sensing electrode, 20 is a second sensing electrode, 30 is a reference electrode, 40 is a signal acquisition module, 50 is signal processing software, 101/201 is a sensing electrode sensing layer, 102/202 is a sensing electrode insulating layer, 103/203 is a sensing electrode connecting layer, 401/402 is a buffer, 403 is a differential amplifier, 404 is an analog-to-digital converter, 405 is a right leg driving circuit, 406 is a microprocessor, and 407 is a bluetooth communication module.

Detailed Description

In order to make the technical means of the invention more clearly understood, the invention can be further described with reference to the accompanying drawings and the detailed description. It should be noted that the embodiment is only an example of the application, and any application without substantial innovation based on the invention is within the protection scope of the invention.

FIG. 1 is an overall embodiment of a non-contact cardiopulmonary signal measurement system for sleep. The non-contact cardiopulmonary signal measurement system includes a reference electrode 30, a first sensing electrode 10, a second sensing electrode 20, a signal acquisition module 40, and signal processing software 50, wherein the reference electrode 30 covers the two sensing electrodes 10 and 20 from the bottom. The two induction electrodes are used for inducing skin electric signals from two different positions of a human body; the signal acquisition module 40 performs difference on the signals of the two induction electrodes to generate an electrocardiosignal, extracts a common-mode signal at the same time, and feeds the common-mode signal back to the human body through the reference electrode; the signal processing software is used for preprocessing the original electrocardiosignals and extracting respiratory signals from the electrocardiosignals.

Fig. 2 shows a schematic structure and layout of the electrode, in which 2(a) is a front view and 2(b) is a side view. The first sensing electrode 10 is arranged near the position of the scapula when the human body lies flat, the second sensing electrode 20 is arranged between the waist and the hip, and each sensing electrode is in a strip shape (such as a rectangle of 6cm by 80 cm), and the length of each sensing electrode is enough to cover the turning range (usually within 70 cm) of a general person in the sleeping process, so that the stability of signal measurement is ensured. The reference electrode 30 covers the two sensing electrodes from the bottom and is formed as a whole, and is made of flexible conductive cloth, such as silver fiber conductive cloth. Each induction electrode comprises an induction layer (101/201), an insulating layer (102/202) and a connecting layer (103/203) from top to bottom, and the induction layer (101/201) adopts flexible conductive cloth (such as silver fiber conductive cloth) to induce skin electric signals in a capacitive coupling mode; the insulating layer (102/202) is made of common insulating cloth (such as pure cotton cloth) and is used for electrically isolating the sensing layer from the reference electrode; the connecting layer (103/203) is made of high-strength adhesive (such as hot-melt adhesive film) for physically connecting the sensing electrode and the reference electrode to form a whole.

Fig. 3 shows a schematic diagram of a signal acquisition module. The signal acquisition module comprises a signal buffer 401/402, a differential amplifier 403, an analog-to-digital converter 404, a right leg driving circuit 405, a microprocessor 406 and a bluetooth communication module 407. The signal input end of the signal acquisition module is connected with the sensing electrodes 10 and 20, and each input end is designed with a signal buffer for improving the input impedance and the load capacity of the signal. The buffer 401/402 is a voltage follower constructed by an operational amplifier, and can be selected from an AD8606 chip of ADI corporation. The differential amplifier 403 is configured to differentially amplify the electrical skin signal sensed by the two sensing electrodes to generate an electrical cardiac signal. The right leg driver circuit 405 is used to extract the common mode signal of the two sensing electrodes, and then feed back to the human body (the middle position of the two sensing electrodes) through the reference electrode. The analog-to-digital converter 404 is used to convert the analog signal into a digital signal, and then transmit the digital signal to the microprocessor 406. Finally, the bluetooth communication module 407 wirelessly uploads the acquired electrocardiosignals to signal processing software.

The signal processing software has two functions: the function is to preprocess the electrocardiosignals collected by the signal collecting module, and the function is to extract respiratory signals from the electrocardiosignals. The functional-electrocardiosignal preprocessing algorithm is used for removing power frequency interference in signals, and an FIR low-pass filter with the passband upper limit frequency of 40 Hz, the passband maximum ripple of 0.1 dB, the stopband lower limit frequency of 45 Hz and the stopband minimum attenuation of 60 dB is adopted, so that the power frequency interference of 50Hz/60Hz can be removed. The second function breath extraction algorithm adopts an IIR band-pass filter with the passband frequency of 0.2-0.6Hz, the maximum passband ripple of 1 dB and the minimum stopband attenuation of 60 dB, and is used for extracting the breath signals with the main frequency range of 0.2-0.6 Hz.

The reference electrode is made of flexible conductive cloth, and the two induction electrodes are covered from the bottom, so that the reference electrode plays a role in shielding electromagnetic noise; in addition, the reference electrode is also connected with a right leg driving circuit and used for feeding back the common-mode signals of the two induction electrodes to a human body (the position between the two induction electrodes), so that the common-mode rejection performance is further improved, and the signal quality is improved.

In order to verify that the position of the reference electrode is beneficial to improving the quality of electrocardiosignals, the inventor compares the signal quality of the reference electrode under the two conditions that the reference electrode is positioned at the bottom of the induction electrode and in the lower limb area of a human body. The experiment was carried out in the same environment and the same subject (1 mm thick garment) was tested with the system of the invention and the system with the reference electrode in the lower limb area, respectively, and the results are shown in fig. 4. It is fully demonstrated that the position of the reference electrode in the present invention can indeed improve the quality of the electrocardiographic signal.

In addition, fig. 5 shows the electrocardiosignal and the respiration signal which are simultaneously measured through clothes, and the effectiveness of the invention is verified.