[0025] In order to make the technical solution proposed by the present invention clearer, the present invention will be described and introduced in detail below in conjunction with the accompanying drawings and specific embodiments, but the following embodiments are only illustrative, not restrictive.
[0026] A wireless blood pressure monitoring system based on PWTT, see appendix figure 1 , including a coordinator, a wearable ECG chest strap terminal, a wearable pulse wristband terminal and a host computer; the coordinator is responsible for setting up a sensor network and controlling the synchronous collection and transmission of terminal data; the wearable ECG chest strap terminal, Responsible for the collection of ECG signals and wireless transmission to the coordinator, including the ECG main circuit module, ECG housing, and chest strap; the wearable pulse wristband terminal is responsible for the collection of PPG signals and wireless transmission to the coordinator, including the pulse Main circuit module, pulse housing and wristband; after the host computer receives the data sent by the coordinator, it performs preprocessing of the ECG signal and the PPG signal, and displays the filtered waveform and blood pressure detection results in real time; the coordinator The device, wearable ECG chest strap terminal, and wearable pulse wristband terminal build a network according to the IEEE802.15.4 standard. Based on the TIMAC protocol stack, the beacon network is set up, serial data is sent and received, and the terminal synchronously collects signals and other functions.
[0027] For the block diagram of the coordinator, see the attached figure 2, including wireless transmission module, power management module and serial port conversion module. Among them, the wireless transmission module adopts TI's CC2530 series, based on the IEEE802.15.4 standard Zigbee module to establish a beacon-enabled sensor network, trigger the serial port interrupt service function through the button interrupt, scan the channel in the interrupt service function and select the appropriate channel Build a network, set the extended address, short address, and Beacon frame attributes of the coordinator to set the MAC layer parameters, enable the beacon network, and periodically send beacon frames after the network is successfully established. The serial port module adopts CH340 conversion chip, and the terminal data received by the coordinator can realize data compatibility and transmit to the host computer through the conversion chip.
[0028] Block diagram of ECG main circuit module, as attached image 3 As shown, it includes ECG electrode A, ECG electrode B, MCU module, ECG detection module, power management module and wireless transmission module. Among them, the MCU module adopts MSP430F5528 microcontroller of TI Company, which is mainly responsible for controlling the data acquisition and data transmission of the ECG detection module, and data transmission with the wireless transmission module. ECG electrode A and ECG electrode B use disposable medical electrodes to touch the skin to obtain human ECG signals, and are connected to the ECG detection module through wires. The ECG detection module uses ADS1298 model high-precision biological analog front-end to convert ECG signals into digital signals , set the sampling rate of 250sps, the internal gain is 12, the data is transmitted to the MCU module through the SPI bus, and the wireless transmission module uses the CC2530 microprocessor to complete the functions of terminal network access, beacon frame analysis and data wireless transmission.
[0029] The wearable ECG chest belt terminal is powered on and initialized, completes the system clock setting, serial port setting, and initializing the ADS1298 module. Receive the beacon frame sent by the coordinator, analyze the beacon load to trigger the local acquisition task, start the ADS1298 data conversion and enable the interrupt, ADS1298 completes a conversion every 4ms, and transmits data with the MCU module through SPI communication. After receiving the converted data from ADS1298, the MCU module packs the data and sends it to the wireless transmission module through the serial port. After receiving the data transmitted by the serial port, the wireless transmission module triggers the serial port interruption time, encapsulates the data frame into a MAC layer message, and transmits it wirelessly to the coordinator.
[0030] The block diagram of the pulse main circuit module, as attached image 3 As shown, it includes MCU module, photoelectric pulse detection module, power management module and wireless transmission module. The MCU module adopts the MSP430F5528 microcontroller of TI Company, which contains a 12-bit ADC analog-to-digital conversion module, which performs analog-to-digital conversion on the PPG at a sampling rate of 250Hz, and transmits the data to the wireless transmission module. The photoelectric pulse detection module includes a photoelectric sensor, a filter amplifier circuit, and a level-up circuit. The photoelectric sensor is an NJL5310R surface-mounted photosensor, which is equipped with an LED light-emitting diode with a wavelength of 525nm and a high-sensitivity photodiode to detect the pulse at the wrist. PPG signal. The filter amplifier circuit performs noise reduction and amplification on the PPG signal to improve the signal-to-noise ratio. The wireless transmission module uses a CC2530 microprocessor to complete functions such as networking requests, beacon frame analysis, and data wireless transmission.
[0031] The wearable pulse wristband terminal is powered on and initialized, completes the system clock setting, serial port setting, ADC module basic parameter setting and other steps, waits for the coordinator to network successfully, presses the networking button to trigger the serial port interrupt, and sends a network access request. After the network is successfully connected Regularly receive the beacon frame sent by the coordinator, analyze the beacon load to trigger the local acquisition task, enable the internal ADC interrupt, and set the ADC internal sampling rate to 250Hz. The MCU packs the data converted by the ADC module and sends it to the wireless transmission module through the serial port. After receiving the data transmitted by the serial port, the wireless transmission module triggers the serial port interruption time, encapsulates the data frame into a MAC layer message, and wirelessly transmits it to the coordinator.
[0032] In the beacon network, the acquisition process of the two terminal main circuit modules is controlled by an appropriate delay function. After testing, the average time error between the two from parsing the beacon frame to issuing the acquisition command is controlled at about 38us. The beacon network of the Zigbee system specifies the structure of the superframe. The active area of the superframe is divided into 16 equal-length time slots GTS. After the time slot, data transmission is only performed in a specific time slot, so as to avoid data rush-in and loss caused by different terminals using contention access mode to transmit data.
[0033] In the beacon network, the wearable ECG chest strap terminal collects human ECG signals, and the wearable pulse wristband collects PPG signals. Different terminals access the channel in a time-division multiplexing manner. The coordinator converts the data through the serial port after receiving the data transmitted by the terminal. The module sends data to the host computer.
[0034] The upper computer has the functions of signal preprocessing, display, calculation and storage, and is responsible for performing amplitude conversion and filtering processing on the ECG and PPG signals transmitted by the coordinator, and selecting the R wave peak value of the ECG signal and the PPG signal wave peak value as feature points to calculate the ECG signal. The characteristic point time difference between the PPG signal and the PPG signal is the pulse transit time PWTT, and the calculated value is substituted into the blood pressure estimation equation to obtain the estimated value of blood pressure. Among them, BP in the blood pressure estimation equation can be systolic blood pressure SBP or diastolic blood pressure DBP, and the parameters of the two sets of equations are obtained by fitting the test data of ten volunteers: a=110.3, k=-0.176 and a=70.86, k= -0.095, the estimation equation of systolic blood pressure is SBP=110.3-0.176*PWTT, and the estimation equation of diastolic blood pressure is DBP=70.86-0.095*PWTT. Substituting the real-time calculated PWTT value into the equation can estimate SBP and DBP. The upper computer completes the real-time display of the detected ECG and PPG waveforms and gives the calculation results of systolic and diastolic blood pressure, see the attached Figure 5.
[0035] Based on the signals collected synchronously by the wireless continuous blood pressure monitoring system, vital signs such as respiration, heart rate, and heart rate variability can be further monitored in real time, which can be expanded as needed.
[0036] It should be noted that the above-mentioned embodiments are not used to limit the protection scope of the present invention, and equivalent transformations or replacements made on the basis of the above-mentioned technical solutions all fall within the protection scope of the claims of the present invention.
