CN-122004927-A - MEMS piezoelectric film based flexible array type blood pressure monitoring method and system

CN122004927ACN 122004927 ACN122004927 ACN 122004927ACN-122004927-A

Abstract

The invention relates to a MEMS piezoelectric film-based flexible array type blood pressure monitoring method and system, and belongs to the technical field of blood pressure monitoring. The method comprises the steps of S1, aligning a flexible ultrasonic sensing array to a target artery, S2, controlling the array to work in a preset resonant frequency, converting an input alternating electric signal into mechanical vibration, transmitting ultrasonic waves to the target artery, transmitting the ultrasonic waves to the inside of a target monitoring position, generating reflected echoes, S3, translating mechanical deformation caused by the reflected echoes into electric signals by the flexible ultrasonic sensing array, receiving the electric signals, S4, respectively obtaining the received time of two reflected echoes of the front wall and the rear wall of a blood vessel, calculating the difference between the two reflected echoes to obtain the blood vessel diameter of the target artery, S5, repeating the steps S2 to S4 according to the preset frequency, and obtaining the blood vessel diameters of the target artery at different time points to form a real-time dynamic change waveform, thereby obtaining a blood pressure monitoring result. The invention improves the anti-interference capability of blood pressure monitoring and improves the measurement accuracy.

Inventors

HE XINGLI
Che Chengwei
XU JIANLONG
Yi Shanqing
XU DACHENG
Zhang Caishuo

Assignees

苏州大学

Dates

Publication Date: 20260512
Application Date: 20260312
Priority Date: 20251225

Claims (10)

1. The MEMS piezoelectric film-based flexible array type blood pressure monitoring method is characterized by comprising the following steps of: S1, attaching a flexible patch to a target monitoring position, wherein the flexible patch is provided with a flexible ultrasonic sensing array; S2, controlling the flexible ultrasonic sensing array to work in a preset resonant frequency, converting an input alternating electric signal into mechanical vibration by utilizing an inverse piezoelectric effect, and transmitting high-frequency ultrasonic waves to the target artery, wherein the high-frequency ultrasonic waves propagate in the target monitoring part and generate reflection echoes when encountering different acoustic impedance interfaces; s3, the flexible ultrasonic sensing array translates the mechanical deformation caused by the reflected echo into an electric signal and receives the electric signal; S4, acquiring a first receiving time of the first reflected echo and a second receiving time of the second reflected echo received by the flexible ultrasonic sensing array; S5, repeating the steps from S2 to S4 according to preset frequency, obtaining the blood vessel diameters of the target artery at different time points, connecting to form a real-time dynamic change waveform of the artery diameter, and obtaining a continuous blood pressure monitoring result according to the real-time dynamic change waveform.
2. The MEMS piezoelectric film based flexible array blood pressure monitoring method of claim 1, wherein the flexible ultrasonic sensing array is prepared by the steps of: Dividing a plurality of ultrasonic transducer array element areas on the surface of a silicon substrate according to preset intervals; Sequentially depositing a silicon layer, a piezoelectric seed layer, a first electrode, a piezoelectric film layer and a second electrode on the surface of the silicon substrate of each ultrasonic transducer array element area to obtain ultrasonic transducer array elements; And turning over the prepared substrate of the ultrasonic transducer array element, defining a back cavity area through photoetching, etching the current substrate to form a plurality of independent array element back cavity structures, and filling flexible polymer materials into the cavity of each array element back cavity structure to obtain the flexible ultrasonic sensing array.
3. The MEMS piezoelectric film flexible array type blood pressure monitoring method according to claim 2, wherein the step of sequentially depositing a silicon layer, a piezoelectric seed layer, a first electrode, a piezoelectric film layer and a second electrode on the surface of the silicon substrate in each ultrasonic transducer array element region to obtain an ultrasonic transducer array element comprises the steps of: etching a groove with a preset high depth-to-width ratio on the surface of a silicon substrate; depositing a first silicon dioxide layer in the groove, wherein the first silicon dioxide layer is flush with the surface of the silicon substrate; continuously depositing a layer of silicon dioxide on the surfaces of the first silicon dioxide layer and the silicon substrate to obtain a second silicon dioxide layer; Depositing a first electrode on the piezoelectric seed layer, and depositing a piezoelectric film layer on the surface of the first electrode; and depositing a second electrode on the surface of the piezoelectric film layer to obtain the ultrasonic transducer array element.
4. The MEMS piezoelectric film based flexible array type blood pressure monitoring method according to claim 3, wherein the process of depositing a second electrode on the surface of the piezoelectric film layer to obtain the ultrasonic transducer array element comprises the steps of sequentially etching through the piezoelectric film layer, the first electrode, the piezoelectric seed layer, the silicon layer and the second silicon dioxide layer according to a preset radius to form a through hole, and removing the first silicon dioxide layer in the groove by using the through hole.
5. A MEMS piezoelectric film based flexible array blood pressure monitoring method as claimed in claim 3 wherein the first electrode surface is divided into a first region and a second region, the piezoelectric film layer being deposited within the first region.
6. A MEMS piezoelectric film based flexible array blood pressure monitoring system comprising: The flexible ultrasonic sensing module comprises a flexible patch and a flexible ultrasonic sensing array, wherein the flexible ultrasonic sensing array is connected with the flexible patch, the flexible patch is attached to a target monitoring position, and the flexible ultrasonic sensing array is used for aligning to a target artery in the target monitoring position; The control module is used for controlling the flexible ultrasonic sensing array to work in a preset resonant frequency, converting an input alternating electric signal into mechanical vibration by utilizing an inverse piezoelectric effect, transmitting high-frequency ultrasonic waves to the target artery, transmitting the high-frequency ultrasonic waves to the inside of the target monitoring part, generating reflection echoes when encountering different acoustic impedance interfaces, wherein the reflection echoes comprise first reflection echoes generated by the front wall of a blood vessel in the target artery and second reflection echoes generated by the rear wall of the blood vessel in the target artery, translating mechanical deformation caused by the reflection echoes into electric signals by the flexible ultrasonic sensing array and receiving the electric signals, acquiring first receiving time of the flexible ultrasonic sensing array for receiving the first reflection echoes and second receiving time of the second reflection echoes, and calculating the time difference between the first receiving time and the second receiving time to obtain the blood vessel diameter of the target artery; the monitoring module is used for sending the preset frequency to the control module, obtaining the blood vessel diameters of the target artery at different time points, connecting the blood vessel diameters to form a real-time dynamic change waveform of the artery diameter, and obtaining a continuous blood pressure monitoring result according to the real-time dynamic change waveform.
7. The MEMS piezoelectric film based flexible array type blood pressure monitoring system of claim 6, wherein the flexible ultrasonic sensing array comprises a plurality of ultrasonic transducer array elements, each of the plurality of ultrasonic transducer array elements comprises a silicon substrate, a silicon layer, a piezoelectric seed layer, a first electrode, a piezoelectric film layer and a second electrode, the silicon layer is arranged on the upper surface of the silicon substrate, the piezoelectric seed layer is arranged on the upper surface of the silicon layer, the first electrode is arranged on the upper surface of the piezoelectric seed layer, the piezoelectric film layer is arranged on the upper surface of the first electrode, and the second electrode is arranged on the upper surface of the piezoelectric film layer.
8. The MEMS piezoelectric film based flexible array blood pressure monitoring system of claim 7, wherein the second electrode upper surface is provided with an insulating layer.
9. The MEMS piezoelectric film based flexible array type blood pressure monitoring system according to claim 6, further comprising a transmitting circuit connected with the control module, wherein the transmitting circuit is used for driving the flexible ultrasonic sensing array to transmit high-frequency ultrasonic waves.
10. A MEMS piezoelectric film based flexible array blood pressure monitoring device comprising the MEMS piezoelectric film based flexible array blood pressure monitoring system of any one of claims 6 to 9.

Description

MEMS piezoelectric film based flexible array type blood pressure monitoring method and system Technical Field The invention relates to the technical field of blood pressure monitoring, in particular to a MEMS piezoelectric film-based flexible array type blood pressure monitoring method and system. Background The blood pressure is used as a core evaluation index of cardiovascular health condition, and the dynamic and long-term accurate monitoring of the blood pressure has important clinical significance for early screening, diagnosis and disease course management of cardiovascular diseases such as hypertension and the like. Currently, conventional blood pressure monitoring techniques in clinical and daily applications mainly include cuff-type blood pressure meters and invasive arterial catheters. The cuff type sphygmomanometer can obtain blood pressure values by inflating and pressing blood vessels, but can only provide snapshot type measurement results of discrete time points, transient blood pressure fluctuation with key clinical values such as night hypertension and morning peak blood pressure is extremely easy to miss, meanwhile, the repeated inflation operation flow of the cuff type sphygmomanometer can seriously interfere daily life and sleep of a patient, comfortableness is extremely poor, and long-term continuous monitoring cannot be achieved. Although the invasive arterial catheter is regarded as a blood pressure monitoring gold standard in critical care and can realize continuous and accurate measurement, because the invasive arterial catheter is invasive, serious complications such as infection and thrombosis are easy to cause, the invasive arterial catheter is only suitable for specific critical scenes in hospitals, has extremely low universality and cannot meet the daily monitoring requirements of common people. To break through the limitations of the traditional technology, various wearable blood pressure monitoring technologies have evolved, with the prior art approaches including piezoresistive, capacitive, photoplethysmography (PPG), and wearable ultrasound technologies. The piezoresistive blood pressure monitoring technology realizes blood pressure detection based on the piezoresistive effect, namely the resistance value of the sensor material changes along with mechanical stress generated by expansion of the blood vessel wall caused by blood pressure, and then the pressure signal is converted into an electric signal which can be acquired. The technology has the advantages of being capable of realizing dynamic and static measurement simultaneously, simple in principle and easy to realize in structure, further improving detection sensitivity through microstructure design, but being provided with a remarkably short plate, being high in power consumption, being easy to be interfered by temperature change in sensor resistance value, being insufficient in measurement stability, and being limited in service life due to stability problems in the long-term use process of materials. The capacitive blood pressure monitoring technology works based on the capacitance change principle, and the typical structure of the capacitive blood pressure monitoring technology is composed of an upper electrode, a lower electrode and an intermediate dielectric layer, when the electrode distance or the electrode overlapping area is changed due to blood pressure fluctuation, the capacitance value is correspondingly changed, and the capture of a blood pressure signal can be realized by detecting the capacitance change quantity. The technology also supports dynamic and static measurement, has the characteristics of simple structure and high potential sensitivity, is limited by a physical principle, has the capacitance which is easily influenced by environmental humidity and temperature, has weak anti-interference capability and small inherent capacitance change range, causes insufficient measurement reliability on tiny blood pressure signals, and is difficult to meet the requirement of accurate monitoring. Photoplethysmography (PPG) is a blood pressure monitoring scheme widely adopted in wearable devices such as smart watches at present, and is used for measuring light absorption changes caused by blood volume changes in skin capillaries by emitting light rays with specific wavelengths and receiving skin reflected light, so as to indirectly calculate blood pressure values. The technology has the advantages of small volume, convenient wearing and low power consumption, but also has the limitation that the penetration depth of light in human tissues is insufficient (generally less than 8 mm), only the signal of the superficial capillary bed can be perceived, and the waveform and the amplitude can be attenuated and distorted in the process of transmitting the blood pressure from the central artery to the peripheral capillary, so that the inherent deviation exists between the PPG signal and the blood pressure of the cli