Single-lead ECG and PPG combined circuit

Abstract

This invention discloses a single-lead ECG and PPG combined circuit, including a mixed signal acquisition module for synchronously acquiring ECG and PPG signals; a main control unit connected to the mixed signal acquisition module for controlling signal acquisition and synchronously processing the acquired signals; a power management circuit for supplying power to the entire circuit system; and mechanical structural components. The mixed signal acquisition module includes ECG and PPG channels, and the main control unit enables synchronous sampling of dual-mode signals. A thumb contact chamber is provided on the mechanical structural components. The contact impedance compensation circuit of this invention results in a signal attenuation rate of <15%, superior to the 40% attenuation of traditional dry electrodes; the dual-wavelength PPG design reduces the blood oxygen saturation detection error to <1.5%; the pressure-triggered power-on mechanism reduces the false trigger rate to <0.1% during 72-hour battery life; and the modular design supports Bluetooth 5.2 data transmission and is compatible with iOS / Android platforms.

Description

Technical Field

[0001] This invention relates to the field of biomedical signal processing technology, and in particular to a single-lead ECG and PPG combined circuit. Background Technology

[0002] Traditional ECG monitoring technology faces three main technical bottlenecks: ① Conventional surface electrodes require wet conductive gel to maintain contact impedance, which can easily cause skin allergies with prolonged wear; ② Multi-lead wiring in Holter monitors restricts user freedom of movement, and motion artifacts interfere with waveform quality; ③ A single ECG signal is difficult to simultaneously acquire hemodynamic parameters, limiting the early warning effectiveness of cardiovascular events. While dry electrode technology avoids the use of conductive gel, it suffers from large fluctuations in contact impedance. PPG (photoplethysmography) detection, although capable of acquiring blood oxygen parameters, is easily affected by ambient light. A more prominent contradiction lies in the relationship between ECG and PPG signals. Timing alignment requires a sampling synchronization error of <5ms, while existing discrete detection circuits suffer from feature point matching deviations of 12-15ms due to clock asynchrony. The innovative breakthrough of this technology lies in: integrating ECG dry electrodes and PPG optical sensors in the thumb contact area to construct a mixed signal acquisition front end with a common-mode rejection ratio >100dB; using a timestamp interpolation algorithm to achieve sub-millisecond synchronization of dual-mode signals; and developing an adaptive contact impedance compensation circuit to improve the motion artifact suppression ratio to 42dB. Preliminary verification shows that this scheme can maintain a P-wave detection rate of 91.2% and a pulse wave rising edge detection error of <1.8ms in the test.

[0003] Existing portable ECG monitoring devices suffer from three major technical defects: ① Traditional wet electrodes require the application of conductive paste to maintain contact impedance, which can easily lead to skin allergies and contact impedance fluctuations of 30-50% with long-term use; ② Discrete ECG and PPG acquisition circuits are out of sync with each other, resulting in a timing alignment error of more than 10ms for feature points, affecting the accuracy of pulse wave conduction time (PTT) calculation; ③ The mechanical power switch design carries the risk of accidental triggering. Clinical tests show that approximately 17% of devices experience a reduction in battery life of more than 23% due to misoperation. Specifically, during dynamic monitoring, traditional lead cables restrict limb movement, and motion artifacts reduce the R-wave detection rate to 82.6%; the PPG optical sensor is susceptible to ambient light interference, with a signal-to-noise ratio degradation of up to 15dB under strong light; existing low-power solutions employ a timed sampling strategy, which misses 12.4% of occasional arrhythmia events. A more significant contradiction is that existing devices cannot simultaneously meet the requirements of a static current of <200μA and a common-mode rejection ratio of >60dB for dual-mode signals. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of traditional equipment, such as dry electrode impedance fluctuation (>40%), PPG optical interference (SNR degradation of 15dB), and dual-mode signal loss of synchronization, and to propose a single-lead ECG and PPG combined circuit.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: A single-lead ECG and PPG combined circuit includes: a hybrid signal acquisition module for simultaneously acquiring ECG signals and photoplethysmography (PPG) signals; a main control unit connected to the hybrid signal acquisition module for controlling signal acquisition and synchronously processing the acquired signals; a power management circuit for supplying power to the entire circuit system; and a mechanical structure assembly for housing the circuit and providing a human contact interface; wherein the hybrid signal acquisition module includes an ECG channel and a PPG channel, and the main control unit realizes synchronous sampling of dual-mode signals; the mechanical structure assembly is provided with a thumb contact chamber, which integrates dry electrodes for acquiring ECG signals and optical sensors for acquiring PPG signals.

[0006] As a preferred embodiment of the single-lead ECG and PPG combined circuit described in this invention, the ECG channel uses an instrumentation amplifier with an input impedance greater than 1 GΩ and a common-mode rejection ratio (CMRR) greater than or equal to 110 dB.

[0007] As a preferred embodiment of the single-lead ECG and PPG combined circuit described in this invention, the PPG channel integrates an analog front-end and supports automatic gain adjustment.

[0008] As a preferred embodiment of the single-lead ECG and PPG combined circuit described in this invention, the main control unit has a built-in hardware timestamp register, and the ECG and PPG signals are synchronized through a timestamp interpolation algorithm, with a synchronization error of less than 0.5ms.

[0009] As a preferred embodiment of the single-lead ECG and PPG combined circuit of the present invention, the thumb contact chamber in the mechanical structure component includes: an 8mm diameter nickel-plated copper ECG electrode with a contact impedance of less than 100kΩ; and a PPG window integrating a 630nm / 940nm dual-wavelength LED with an optical isolation greater than 30dB.

[0010] As a preferred embodiment of the single-lead ECG and PPG combined circuit of the present invention, the power management circuit adopts a pressure-triggered power-on mechanism with a static current of less than 200μA.

[0011] As a preferred embodiment of the single-lead ECG and PPG combined circuit described in this invention, it further includes a Bluetooth 5.2 data transmission module for wirelessly transmitting the acquired and processed data to an external device.

[0012] The beneficial effects of this invention are as follows: the contact impedance compensation circuit of this invention reduces the signal attenuation rate to <15%, which is better than the 40% attenuation of traditional dry electrodes; the dual-wavelength PPG design reduces the blood oxygen saturation detection error to <1.5%; the pressure-triggered power-on mechanism reduces the false trigger rate to <0.1% for 72-hour battery life; and the modular design supports Bluetooth 5.2 data transmission and is compatible with iOS / Android platforms. Attached Figure Description

[0013] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein: Figure 1 This is the overall circuit block diagram of the present invention.

[0014] Figure 2 This is a circuit assembly diagram of the present invention.

[0015] Figure 3 This is a circuit diagram for acquiring electrocardiogram signals according to the present invention.

[0016] Figure 4 This is the circuit diagram of the AFE module of the present invention.

[0017] Figure 5 This is a circuit diagram of the power management and voltage regulation module of the present invention.

[0018] Figure 6 This is the circuit diagram of the main control unit of the present invention.

[0019] Figure 7 This is a diagram of the PPG acquisition front-end unit of the present invention.

[0020] Figure 8 This is a system block diagram of the present invention.

[0021] Figure 9 This is a diagram showing the alignment of PPG acquisition data with the baseline according to the present invention.

[0022] Figure 10 This is the ECG spectrum analysis diagram of the present invention.

[0023] Figure 11 This is a diagram showing the low-pass filtering results of the present invention.

[0024] Figure descriptions: 1. 3V3 step-down unit; 2. Voltage regulator unit a; 3. Voltage regulator unit b; 4. Rechargeable lithium polymer battery; 5. USB interface; 6. Power management unit a; 7. Power management unit b; 8. Synchronous sampling main controller; 9. Dual-color LED indicator unit; 10. Charging unit; 11. ECG electrode a; 12. PPG optical window; 13. ECG electrode a; 21. ECG preamplifier; 33. Contact detection wake-up module. Detailed Implementation

[0025] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0026] In the description of this invention, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0027] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0028] Example 1 Reference Figures 1 to 11 This is the first embodiment of the present invention, which provides a single-lead ECG and PPG combined circuit, comprising: The mixed signal acquisition module is used to simultaneously acquire electrocardiogram (ECG) signals and photoplethysmography (PPG) signals. The ECG channel uses an instrumentation amplifier with an input impedance greater than 1 GΩ and a common-mode rejection ratio (CMRR) greater than or equal to 110 dB. The PPG channel integrates an analog front-end and supports automatic gain adjustment. The main control unit, connected to the mixed signal acquisition module, is used to control signal acquisition and perform synchronous processing on the acquired signals. The main control unit has a built-in hardware timestamp register and uses a timestamp interpolation algorithm to synchronize ECG and PPG signals with a synchronization error of less than 0.5ms. A power management circuit is used to supply power to the entire circuit system. The power management circuit adopts a pressure-triggered power-on mechanism and has a static current of less than 200μA. The system also includes mechanical structural components for housing circuitry and providing a human contact interface. The hybrid signal acquisition module includes an ECG channel and a PPG channel, and synchronous sampling of dual-mode signals is achieved through a main control unit. The mechanical structural components are equipped with a thumb contact housing, which integrates dry electrodes for acquiring ECG signals and optical sensors for acquiring PPG signals. The thumb contact housing includes: an 8mm diameter nickel-plated copper ECG electrode with a contact impedance of less than 100kΩ; a PPG window integrating a 630nm / 940nm dual-wavelength LED with optical isolation greater than 30dB; and a Bluetooth 5.2 data transmission module for wirelessly transmitting the acquired and processed data to external devices.

[0029] In summary, the contact impedance compensation circuit of this invention reduces the signal attenuation rate to <15%, which is better than the 40% attenuation of traditional dry electrodes; the dual-wavelength PPG design reduces the blood oxygen saturation detection error to <1.5%; the pressure-triggered power-on mechanism reduces the false trigger rate to <0.1% for 72-hour battery life; and the modular design supports Bluetooth 5.2 data transmission and is compatible with iOS / Android platforms.

[0030] It should be understood that numerous specific implementation decisions can be made during the development of any practical implementation, such as in any engineering or design project. Such development efforts may be complex and time-consuming, but for those of ordinary skill in the art who benefit from this disclosure, the development effort will be a routine task in design, manufacturing, and production without requiring extensive experimentation.

[0031] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A single-lead ECG and PPG combined circuit, characterized in that, include: A mixed-signal acquisition module is used to simultaneously acquire electrocardiogram (ECG) signals and photoplethysmography (PPG) signals; The main control unit is connected to the hybrid signal acquisition module and is used to control signal acquisition and synchronously process the acquired signals. Power management circuitry is used to supply power to the entire circuit system; The system also includes mechanical structural components for housing circuitry and providing a human contact interface; wherein the hybrid signal acquisition module includes an ECG channel and a PPG channel, and synchronous sampling of dual-mode signals is achieved through a main control unit; the mechanical structural components are equipped with a thumb contact chamber, which integrates dry electrodes for acquiring ECG signals and optical sensors for acquiring PPG signals.

2. The single-lead ECG and PPG combined circuit according to claim 1, characterized in that: The ECG channel uses an instrumentation amplifier with an input impedance greater than 1 GΩ and a common-mode rejection ratio (CMRR) greater than or equal to 110 dB.

3. The single-lead ECG and PPG combined circuit according to claim 1, characterized in that: The PPG channel integrates an analog front-end and supports automatic gain adjustment.

4. The single-lead ECG and PPG combined circuit according to claim 1, characterized in that: The main control unit has a built-in hardware timestamp register, which uses a timestamp interpolation algorithm to synchronize ECG and PPG signals with a synchronization error of less than 0.5ms.

5. The single-lead ECG and PPG combined circuit according to claim 1, characterized in that: The thumb contact chamber in the mechanical structure assembly includes: an 8mm diameter nickel-plated copper electrocardiogram electrode with a contact impedance of less than 100kΩ; and a PPG window integrating a 630nm / 940nm dual-wavelength LED with an optical isolation greater than 30dB.

6. The single-lead ECG and PPG combined circuit according to claim 1, characterized in that: The power management circuit adopts a pressure-triggered power-on mechanism, with a static current of less than 200μA.

7. The single-lead ECG and PPG combined circuit according to claim 1, characterized in that: It also includes a Bluetooth 5.2 data transmission module, used to wirelessly transmit the collected and processed data to external devices.

Images