Radial displacement pulse wave measuring device and application method thereof

Abstract

The invention provides a radial displacement pulse wave measuring device and an application method thereof. The radial displacement pulse wave measuring device comprises a shell, an air bag, a pressure control module, a displacement sensing module and a calculation unit. The housing has a transparent portion. The air bag is located below the transparent part, and the displacement sensing module is located above the transparent part. The pressure control module controls the internal pressure of the air bag so as to adjust the pressing depth of the air bag on the skin of the testee. A measurement signal of the displacement sensing module penetrates through the transparent part and the air bag, and the dynamic distance between the skin of the testee and the displacement sensing module caused by pulse beat of the artery is measured. The calculation unit controls the pressure control module and the displacement sensing module and receives and records the dynamic distance so as to obtain radial displacement pulse waves.

Description

Radial displacement pulse wave measuring device and application method thereof

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to U.S. patent application No. 18 / 098,729, filed on January 19, 2023, entitled “Chinese Pulse Wave Measuring Device And Use Method Thereof,” which is incorporated herein by reference in its entirety. Technical Field

[0003] This specification relates to a physiological characteristic measurement system and its use method, and more particularly to a radial displacement pulse wave measurement device and its use method. Background Art

[0004] Pulse waves are used to assess cardiovascular function and health. Based on the characteristics they measure, pulse waves can be categorized as pressure pulse waves, vascular volume pulse waves, photoplethysmography (PPE), and vascular radial displacement pulse waves.

[0005] These pressure pulse waves typically use piezoresistive pressure sensors, such as piezoelectric, strain gauge, and thin film, as sensors to measure the pulse wave. The pressure sensor then indirectly measures the pressure caused by blood vessel expansion. During use, the pressure sensor is placed between the airbag and the skin. When the airbag, which is pressed against the skin, inflates, it compresses the blood vessels below. Because the pulse wave changes the diameter of the blood vessels, squeezing the pressure sensor and airbag above them, the pressure sensor can indirectly measure the blood vessel's pressure pulse wave through this change in blood vessel diameter. Common issues with this method of measuring pulse waves include a small measurement dynamic range, susceptibility to noise, complex pressure sensor calibration methods, and poor reproducibility of measurement results.

[0006] The aforementioned vascular volume pulse wave is typically measured using an air cuff, with the cuff pressure then measured by a pressure sensor. During use, the cuff is placed over a blood vessel and gradually inflated. The pressure sensor then measures the pressure change inside the cuff. This measurement is equivalent to integrating the changes in diameter of all blood vessels beneath the cuff to convert them into a change in pressure within the cuff. The problem with this method of measuring pulse waves is that when the air inside the cuff is compressed, the details of the vascular volume pulse wave disappear, leaving only the amplitude of the vascular volume pulse wave for reference.

[0007] The aforementioned photoplethysmography (PPG) is obtained using a PPG (Photo Plethysmograph) sensor, which detects changes in the intensity of light reflected from blood vessels beneath the skin. A common problem with this method of measuring pulse waves is that individual physiological parameters (such as subcutaneous tissue thickness and tissue light absorption) may affect the PPG results at the measurement site.

[0008] Although the aforementioned radial displacement pulse wave of the blood vessels can be measured using ultrasound echo images, it often requires a large amount of complex calculations and corrections to obtain good image resolution and contrast to estimate the change in the radial displacement of the blood vessels.

[0009] Summary of the Invention

[0010] To address the aforementioned issues, one of the objectives of the present disclosure is to provide a radial displacement pulse wave measuring device for measuring the radial displacement pulse wave of an artery in a measured portion of a subject. The radial displacement pulse wave measuring device includes a housing, a transparent airbag, a pressure control module, a displacement sensing module, and a computing unit.

[0011] The housing has a transparent portion, and the transparent portion includes a hole or a first transparent flat plate. A transparent airbag is located below the transparent portion, and the main material of the transparent airbag is a material that is not easily stretched and deformed. The pressure control module is used to control the internal pressure of the transparent airbag, thereby controlling the downward pressure applied by the transparent airbag to the part to be measured to amplify the signal of the pulse beating of the artery. The displacement sensing module is located above the transparent portion, and is used to sense the pulse beating of the artery, measure the dynamic distance between the skin of the part to be measured and the displacement sensing module caused by the pulse beating of the artery, and obtain the radial displacement pulse wave. The calculation unit is communicatively connected to the pressure control module and the displacement sensing module respectively, and is used to transmit control signals to the pressure control module and the displacement sensing module respectively, and receive information transmitted by the pressure control module and the displacement sensing module respectively and perform calculations.

[0012] According to one embodiment of the present disclosure, the main material of the transparent airbag includes polymethyl methacrylate, cellulose acetate, nylon-66 polyamide resin, nylon-6 polyamide resin, polybutylene terephthalate, polyethylene terephthalate, polyphenylene, polycarbonate, ethylene-vinyl acetate copolymer, polyethylene, polypropylene, polyvinyl chloride, polyacetal or polyurethane.

[0013] According to an embodiment of the present disclosure, when the transparent portion is the hole, the transparent airbag further includes a transparent window overlapping with the transparent portion of the housing, and the transparent window includes a second transparent flat plate.

[0014] According to one embodiment of the present disclosure, an anti-reflection film is formed on the outer surface of the transparent window.

[0015] According to an embodiment of the present disclosure, the area of ​​the second transparent plate is larger than the area of ​​the hole. When the internal pressure of the transparent airbag is too high, the second transparent plate will press against the bottom of the hole and will not be squeezed above the hole.

[0016] According to one embodiment of the present disclosure, the transparent airbag further includes a contact portion, which is used to tightly fit the skin of the measured part of the subject, and the material of the contact portion is a soft and stretchable thermoplastic elastomer polymer material, and the thermoplastic elastomer polymer material includes at least one material selected from thermoplastic polyurethane, polyolefin elastomer, dynamically vulcanized polyolefin elastomer, polystyrene elastomer, polyether ester elastomer, polyamide elastomer, and polyvinyl chloride.

[0017] According to an embodiment of the present disclosure, a reflective layer or a dichroic layer is formed on the inner surface of the contact portion.

[0018] According to one embodiment of the present disclosure, the radial displacement pulse wave measurement device further includes a wearable portion, wherein the subject's limb portion to be measured is accommodated within the interior space of the wearable portion. The wearable portion includes a soft inner layer and a hard outer layer. The soft inner layer includes the transparent airbag. The hard outer layer is positioned outside the soft inner layer to form the interior space of the wearable portion together with the soft inner layer. During the radial displacement pulse wave measurement process, the hard outer layer maintains a fixed distance between the displacement sensing module and the farthest point on the hard outer layer from the displacement sensing module.

[0019] According to an embodiment of the present disclosure, the soft inner layer further includes a plurality of auxiliary airbags, and the internal pressures of the auxiliary airbags are controlled by the pressure control module.

[0020] According to one embodiment of the present disclosure, the pressure control module includes a pressure sensor and a pressure adjustment module. The pressure sensor is used to sense the internal pressure of the transparent airbag. The pressure adjustment module is used to adjust the internal pressure of the transparent airbag. The pressure adjustment module includes a pump.

[0021] According to an embodiment of the present disclosure, the pressure adjustment module further includes a pulse width modulation circuit to adjust the rotation speed of the motor of the pump.

[0022] According to an embodiment of the present disclosure, the displacement sensing module includes a transmitter and a receiver. The transmitter and the receiver are aligned with the transparent portion, and a measurement signal emitted by the transmitter can pass through the transparent portion and the transparent airbag.

[0023] According to an embodiment of the present disclosure, the displacement sensing module includes a photoelectric displacement sensor.

[0024] According to one embodiment of the present disclosure, the photoelectric displacement sensor includes a laser displacement meter, a fiber optic displacement meter, a three-dimensional scanning laser displacement meter, a time-of-flight ranging device, a three-dimensional time-of-flight ranging device, a laser Doppler rangefinder, a laser Doppler velocimeter, a scanning laser vibrometer, a Michelson interferometer, or a laser interferometer ranging device.

[0025] According to an embodiment of the present disclosure, the displacement sensing module further includes a filter.

[0026] According to one embodiment of the present disclosure, the radial displacement pulse wave measuring device further includes a scanning position control module, which is communicatively connected to the computing unit and is used to control the displacement sensing module to perform distance measurement scanning in the measured part, wherein the scanning position control module includes a single-axis position controller or a dual-axis position controller.

[0027] Another object of the present disclosure is to provide a radial displacement pulse wave measuring device for measuring the radial displacement pulse wave of an artery of a measured part of a subject. The radial displacement pulse wave measuring device includes a housing, a non-transparent airbag, a pressure control module, a displacement sensing module, and a calculation unit.

[0028] The housing has a transparent portion containing a hole or a first transparent plate. An opaque airbag is located below the transparent portion. The main body of the opaque airbag is made of a non-stretchable material and includes a transparent window that overlaps the transparent portion of the housing. The transparent window is made of a non-stretchable transparent material or a second transparent plate. A pressure control module is used to control the internal pressure of the transparent airbag, thereby controlling the downward pressure exerted by the transparent airbag on the measured area to amplify the arterial pulse signal. A displacement sensing module is located above the transparent portion and is used to sense the arterial pulse and measure the dynamic distance between the skin of the measured area and the displacement sensing module caused by the arterial pulse to obtain the radial displacement pulse wave. A computing unit is communicatively connected to the pressure control module and the displacement sensing module, respectively, and is used to transmit control signals to the pressure control module and the displacement sensing module, respectively, and receive and calculate information transmitted by the pressure control module and the displacement sensing module.

[0029] According to one embodiment of the present disclosure, the transparent material that is not easily stretched or deformed of the main body material of the non-transparent airbag includes polymethyl methacrylate, cellulose acetate, nylon-66 polyamide resin, nylon-6 polyamide resin, polybutylene terephthalate, polyethylene terephthalate, polyphenylene, polycarbonate, ethylene-vinyl acetate copolymer, polyethylene, polypropylene, polyvinyl chloride, polyacetal or polyurethane, glass, quartz, polystyrene or acrylonitrile-butadiene-styrene copolymer.

[0030] According to one embodiment of the present disclosure, the transparent material of the transparent window that is not easily stretched or deformed includes polymethyl methacrylate, cellulose acetate, nylon-66 polyamide resin, nylon-6 polyamide resin, polybutylene terephthalate, polyethylene terephthalate, polyphenylene, polycarbonate, ethylene-vinyl acetate copolymer, polyethylene, polypropylene, polyvinyl chloride, polyacetal or polyurethane, glass, quartz, polystyrene or acrylonitrile-butadiene-styrene copolymer.

[0031] According to one embodiment of the present disclosure, an anti-reflection film is formed on the outer surface of the transparent window.

[0032] According to an embodiment of the present disclosure, when the transparent portion is the hole, the transparent window is the second transparent plate.

[0033] According to an embodiment of the present disclosure, the area of ​​the second transparent plate is larger than the area of ​​the hole. When the internal pressure of the transparent airbag is too high, the second transparent plate will press against the bottom of the hole and will not be squeezed above the hole.

[0034] According to one embodiment of the present disclosure, an anti-reflection film is formed on the outer surface of the transparent window.

[0035] According to one embodiment of the present disclosure, the non-transparent airbag further includes a contact portion, wherein the contact portion is used to closely fit the skin of the measured part of the subject, and the material of the contact portion is a soft and stretchable thermoplastic elastomer polymer material, and the thermoplastic elastomer polymer material includes at least one material selected from thermoplastic polyurethane, polyolefin elastomer, dynamically vulcanized polyolefin elastomer, polystyrene elastomer, polyether ester elastomer, polyamide elastomer, and polyvinyl chloride.

[0036] According to an embodiment of the present disclosure, a reflective layer or a dichroic layer is formed on the inner surface of the contact portion.

[0037] According to one embodiment of the present disclosure, the radial displacement pulse wave measurement device further includes a wearable portion, wherein the subject's limb portion to be measured is accommodated within the interior space of the wearable portion. The wearable portion includes a soft inner layer and a hard outer layer. The soft inner layer includes the transparent airbag. The hard outer layer is positioned outside the soft inner layer to form the interior space of the wearable portion together with the soft inner layer. During the radial displacement pulse wave measurement process, the hard outer layer maintains a fixed distance between the displacement sensing module and the farthest point on the hard outer layer from the displacement sensing module.

[0038] According to an embodiment of the present disclosure, the soft inner layer further includes a plurality of auxiliary airbags, and the internal pressures of the auxiliary airbags are controlled by the pressure control module.

[0039] According to one embodiment of the present disclosure, the pressure control module includes a pressure sensor and a pressure adjustment module. The pressure sensor is used to sense the internal pressure of the transparent airbag. The pressure adjustment module is used to adjust the internal pressure of the transparent airbag. The pressure adjustment module includes a pump.

[0040] According to an embodiment of the present disclosure, the pressure adjustment module further includes a pulse width modulation circuit to adjust the rotation speed of the motor of the pump.

[0041] According to an embodiment of the present disclosure, the displacement sensing module includes a transmitter and a receiver. The transmitter and the receiver are aligned with the transparent portion, and a measurement signal emitted by the transmitter can pass through the transparent portion and the transparent window.

[0042] According to an embodiment of the present disclosure, the displacement sensing module includes a photoelectric displacement sensor.

[0043] According to one embodiment of the present disclosure, the photoelectric displacement sensor includes a laser displacement meter, a fiber optic displacement meter, a three-dimensional scanning laser displacement meter, a time-of-flight ranging device, a three-dimensional time-of-flight ranging device, a laser Doppler rangefinder, a laser Doppler velocimeter, a scanning laser vibrometer, a Michelson interferometer, or a laser interferometer ranging device.

[0044] According to an embodiment of the present disclosure, the displacement sensing module further includes a filter.

[0045] According to one embodiment of the present disclosure, the radial displacement pulse wave measuring device further includes a scanning position control module, which is communicatively connected to the computing unit and is used to control the displacement sensing module to perform distance measurement scanning in the measured part, wherein the scanning position control module includes a single-axis position controller or a dual-axis position controller.

[0046] Another purpose of the present disclosure is to provide a method for optimizing the measurement conditions of radial displacement pulse waves of blood vessels, and the Y-axis is defined as being substantially perpendicular to the direction of the artery and substantially parallel to the skin surface of the part to be measured. The method includes using the above-mentioned radial displacement pulse wave measuring device; placing the transparent airbag or the non-transparent airbag on the skin of the part to be measured of the subject, and stopping the displacement sensing module at an initial position, wherein the displacement sensing module is a point-type displacement sensor or a matrix-type displacement sensor; maintaining the pressure of the transparent airbag or the non-transparent airbag at a first pressure, and after the transparent airbag or the non-transparent airbag is pressed down to a first depth on the part to be measured, the displacement sensing module is scanned along the Y-axis on the surface of the part to be measured until the blood vessels of the artery are found. The method comprises the steps of: positioning the displacement sensing module at a first measurement position when the amplitude signal of the radial displacement pulse wave of the artery is maximum; allowing the displacement sensing module to remain at the first measurement position, adjusting the pressure of the transparent airbag or the opaque airbag, and finding a second pressure applied when the amplitude signal of the radial displacement pulse wave of the artery is maximum; and maintaining the pressure of the transparent airbag or the opaque airbag at the second pressure, so that the transparent airbag or the opaque airbag presses the measured part to a second depth, wherein the first measurement position and the second depth serve as measurement conditions for the radial displacement pulse wave of the artery.

[0047] According to one embodiment of the present disclosure, the first pressure is applied by gradually increasing the pressure of the transparent airbag or the opaque airbag, allowing the transparent airbag or the opaque airbag to vertically press down the measured part until the maximum amplitude signal of the vascular volume pulse wave of the artery is found.

[0048] According to one embodiment of the present disclosure, the method for optimizing measurement conditions of a vascular radial displacement pulse wave further includes having the displacement sensing module scan along the direction of the artery until a second measurement position where the local maximum signal of the vascular radial displacement pulse wave of the artery is found is found, thereby replacing the first measurement position as the measurement condition of the vascular radial displacement pulse wave of the artery.

[0049] Another object of the present disclosure is to provide a method for optimizing measurement conditions for a vascular radial displacement pulse wave. The method comprises finding a first measurement position above an artery at a portion to be measured of a subject; using the radial displacement pulse wave measuring device described above; placing the transparent airbag or the opaque airbag on the skin of the portion to be measured of the subject; aligning the displacement sensing module with the first measurement position, wherein the displacement sensing module is a point-type displacement sensor or a matrix-type displacement sensor; gradually increasing the pressure of the transparent airbag or the opaque airbag, causing the transparent airbag or the opaque airbag to vertically press down on the portion to be measured, until a measurement pressure is found at which a maximum signal of the vascular radial displacement pulse wave of the artery is generated; maintaining the pressure of the transparent airbag or the opaque airbag at the measurement pressure, and pressing the transparent airbag or the opaque airbag against the portion to be measured to a measurement depth, wherein the first measurement position and the measurement depth serve as measurement conditions for the vascular radial displacement pulse wave of the artery.

[0050] According to one embodiment of the present disclosure, the method for optimizing measurement conditions of a vascular radial displacement pulse wave further includes having the displacement sensing module scan along the direction of the artery until a second measurement position where the local maximum signal of the vascular radial displacement pulse wave of the artery is found is found, thereby replacing the first measurement position as the measurement condition of the vascular radial displacement pulse wave of the artery.

[0051] Another object of the present disclosure is to provide a method for optimizing measurement conditions of a radial displacement pulse wave of a blood vessel, the method comprising using the aforementioned radial displacement pulse wave measuring device; placing the transparent airbag or the non-transparent airbag on the skin of the subject's skin at the portion to be measured; maintaining the pressure of the transparent airbag or the non-transparent airbag at a first pressure; moving the displacement sensing module above the portion to be measured, wherein the displacement sensing module is a matrix-type displacement sensor having a measurement area intersecting the direction of the blood vessel; and finding the maximum amplitude signal. One of the point-type displacement sensors numbered indicates that the point-type displacement sensors are located at a first measurement position; the pressure of the transparent airbag or the non-transparent airbag is adjusted to find a second pressure applied when the maximum signal of the radial displacement pulse wave of the blood vessel of the artery is reached; and the pressure of the transparent airbag or the non-transparent airbag is maintained at the second pressure so that the transparent airbag or the non-transparent airbag presses down the measured part to a second depth, wherein the first measurement position and the second depth serve as measurement conditions for the radial displacement pulse wave of the blood vessel of the artery.

[0052] According to one embodiment of the present disclosure, the first pressure is applied by gradually increasing the pressure of the transparent airbag or the opaque airbag, allowing the transparent airbag or the opaque airbag to vertically press down the measured part until the maximum amplitude signal of the vascular volume pulse wave of the artery is found.

[0053] According to one embodiment of the present disclosure, the method for optimizing measurement conditions of a vascular radial displacement pulse wave further includes having the displacement sensing module scan along the direction of the artery until a second measurement position where the local maximum signal of the vascular radial displacement pulse wave of the artery is found is found, thereby replacing the first measurement position as the measurement condition of the vascular radial displacement pulse wave of the artery.

[0054] Another object of the present disclosure is to provide a blood pressure measurement method, comprising using the above-mentioned radial displacement pulse wave measuring device; placing the transparent airbag or the non-transparent airbag on the part to be measured; using the above-mentioned vascular radial displacement pulse wave measurement condition optimization method to find the position of the artery in the part to be measured of the subject to measure the vascular radial displacement pulse wave of the artery; gradually pressurizing the transparent airbag or the non-transparent airbag until the vascular radial displacement pulse wave of the artery appears and then disappears; gradually depressurizing the transparent airbag or the non-transparent airbag until the vascular radial displacement pulse wave of the artery begins to appear, and the pressure of the transparent airbag or the non-transparent airbag is the systolic pressure of the artery; and continuing to gradually depressurize the transparent airbag or the non-transparent airbag until the vascular radial displacement pulse wave of the artery begins to disappear, and the pressure of the transparent airbag or the non-transparent airbag is the diastolic pressure of the artery.

[0055] Another object of the present disclosure is to provide a pulse wave velocity measurement method, comprising: measuring a proximal radial displacement pulse wave at a proximal measurement position of a proximal artery closer to the heart of a subject using the aforementioned radial displacement pulse wave measurement device while simultaneously recording an electrocardiogram; simultaneously recording the radial displacement pulse wave of the proximal artery and the electrocardiogram of the subject to obtain a delay time T1 of the proximal radial displacement pulse wave of the proximal artery relative to the R wave of the electrocardiogram; and simultaneously recording the electrocardiogram at a distance from the subject. A distal radial displacement pulse wave is measured at a distal measurement location on a distal artery distal to the heart using the radial displacement pulse wave measuring device. The radial displacement pulse wave at the distal artery and the subject's electrocardiogram (ECG) are simultaneously recorded to determine a delay time T2 of the distal radial displacement pulse wave at the distal artery relative to the R wave of the ECG. The delay time difference ΔT between T1 and T2 is calculated as T2-T1. The distance ΔD between the proximal artery and the distal artery is measured. The pulse wave velocity (PWV) is calculated as ΔD / ΔT.

[0056] According to one embodiment of the present disclosure, the proximal measurement position and the distal measurement position are the first measurement position found using the above-mentioned method for optimizing the measurement conditions of the vascular radial displacement pulse wave, or the second measurement position found using the above-mentioned method for optimizing the measurement conditions of the vascular radial displacement pulse wave.

[0057] Another object of the present disclosure is to provide a pulse wave velocity measurement method, comprising measuring a proximal radial displacement pulse wave at a proximal measurement location at a proximal artery closer to the heart of the subject without recording an electrocardiogram; and simultaneously measuring a distal radial displacement pulse wave at a distal measurement location at a distal artery farther from the heart of the subject without recording an electrocardiogram, wherein the proximal measurement location and the distal measurement location simultaneously measure the proximal radial displacement pulse wave and the distal radial displacement pulse wave using one or two of the above-mentioned radial displacement pulse wave measurement devices; calculating a delay time difference ΔT between the proximal radial displacement pulse wave and the distal radial displacement pulse wave; measuring a distance ΔD between the proximal artery and the distal artery; and calculating pulse wave velocity (PWV) = ΔD / ΔT.

[0058] According to one embodiment of the present disclosure, the proximal measurement position and the distal measurement position are the first measurement position found using the above-mentioned method for optimizing the measurement conditions of the vascular radial displacement pulse wave, or the second measurement position found using the above-mentioned method for optimizing the measurement conditions of the vascular radial displacement pulse wave.

[0059] Another object of the present disclosure is to provide a continuous blood pressure measurement method, comprising using the above-mentioned blood pressure measurement method to measure the diastolic blood pressure of the subject in an initial state and a corresponding first depression depth of the transparent airbag or the non-transparent airbag on the measured part, as well as the systolic blood pressure in the initial state and a corresponding second depression depth of the transparent airbag or the non-transparent airbag, wherein the difference between the first depression depth and the second depression depth is the blood vessel diameter R of the subject; calculating the change in the blood vessel diameter ΔR of the subject from a graph of the radial displacement pulse wave of the subject that changes with time; measuring the pulse wave velocity PWV of the subject using the above-mentioned pulse wave velocity measurement method; obtaining the blood density ρ of the subject; and calculating the blood pressure change ΔP using the following Branwell-Hill formula: ΔP = ρ × PWV 2 (ΔR / R); and calculate the subject's real-time systolic blood pressure (=initial systolic blood pressure + ΔP) and real-time diastolic blood pressure (=initial diastolic blood pressure + ΔP).

[0060] The above-mentioned radial displacement pulse wave measuring device has the following technical advantages. First, the above-mentioned radial displacement pulse wave measuring device can directly measure the radial displacement pulse wave of the blood vessel, and provide more accurate results compared to the traditional pressure pulse wave measurement method. Secondly, the above-mentioned radial displacement pulse wave measuring device has high accuracy, which can reach below 100 microns, providing detailed pulse wave details, which is helpful for a variety of pulse wave analysis applications. Thirdly, the above-mentioned radial displacement pulse wave measuring device can be applied to many non-invasive measurement methods, is convenient and stable, can provide real-time measurement results and waveform diagrams, and allows long-term continuous monitoring. Combining these advantages, the above-mentioned radial displacement pulse wave measuring device has a wide range of application value in the fields of cardiovascular medicine and biomedicine, and supports better personalized medical care and health monitoring. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] FIG. 1 is a schematic diagram showing the functional block structure of a radial displacement pulse wave measuring device according to an embodiment of the present disclosure.

[0062] FIG2 is a schematic cross-sectional view of a wearable portion of a radial displacement pulse wave measuring device according to an embodiment of the present disclosure.

[0063] FIG3A is a schematic diagram illustrating an operation flow of using the scanning position control module 140 to automatically find a measurement point of a radial displacement pulse wave according to an embodiment of the present disclosure, wherein the displacement sensing module 130 is a point-type displacement sensor.

[0064] FIG3B is a schematic diagram illustrating an operation flow of manually finding a measurement point of a radial displacement pulse wave according to another embodiment of the present disclosure, wherein the displacement sensing module 130 is a point-type displacement sensor.

[0065] FIG3C is a schematic diagram illustrating an operation flow of finding a measurement point of a radial displacement pulse wave according to another embodiment of the present disclosure, wherein the displacement sensing module 130 is a linear matrix displacement sensor.

[0066] FIG. 4 is a schematic diagram illustrating waveform changes of a vascular volume pulse wave and a radial displacement pulse wave with pressure and time according to an embodiment of the present disclosure.

[0067] FIG. 5 is a flow chart illustrating a process of measuring blood pressure using the radial displacement pulse wave measuring device 100 of FIG. 1 .

[0068] FIG6A is an enlarged schematic diagram of the radial displacement pulse wave during period III (t2-t3) of FIG4.

[0069] FIG. 6B is a diagram showing the relationship between heartbeat intervals and time.

[0070] FIG6C is a diagram showing the RRI spectrum distribution obtained by calculating HRV through discrete Fourier transform.

[0071] FIG. 7A is a schematic diagram illustrating an electrocardiogram-assisted method for measuring pulse wave velocity according to an embodiment of the present disclosure.

[0072] FIG. 7B is a schematic diagram illustrating simultaneous use of two pulse wave measuring devices to measure pulse wave velocity according to an embodiment of the present disclosure.

[0073] FIG. 7C is a flow chart of a method for measuring pulse wave velocity using the method shown in FIG. 7A .

[0074] FIG8 is a flow chart of a method for measuring continuous blood pressure.

[0075] Reference numerals: 100: Radial displacement pulse wave measuring device 110: Air bag 110a: Measuring portion 112: Transparent window 114: Contact portion 120: Pressure control module 122: Pressure sensor 124: Pressure adjustment module 130: Displacement sensing module 130a: Transmitted signal 130b: Reflected signal 132: Transmitter 134: Receiver 136: Filter 140: Scanning position control module 150: Calculation unit 151: Power supply module 152: Memory module 153: Communication module 154: Operation module 155: Display module 156: Processing module 157: Control module 158: Analysis module 160: Detected part 200: Wearable part 210: Hard outer layer 212: Farthest point 220: Soft inner layer 230: Outer shell 232: Transparent part 240: Limb part 250: Artery 305-850: Steps D1, D2, D3, D4, D5: Depth MD: Distance P1, P2, P3, P4, P5: Pressure R: R wave R1: Trough R2: Peak T1: Delay time of proximal radial displacement pulse wave T2: Delay time of distal radial displacement pulse wave ΔT: Delay time difference DETAILED DESCRIPTION

[0076] Therefore, the present disclosure provides a radial displacement pulse wave measurement device and its application method. Through the coordinated design of an airbag, a pressure control module, and a displacement sensing module, this radial displacement pulse wave measurement device can directly measure the waveform of the radial displacement pulse wave of a blood vessel with an accuracy of less than 100 microns. Therefore, it can provide extensive details of the vascular radial displacement pulse wave waveform, enabling various applications and analyses of radial displacement pulse waves. The following describes the measurement of blood pressure, heart rate variability, and pulse wave velocity, as well as continuous blood pressure measurement. These measurement methods represent only a small subset of applications, and the application methods of the radial displacement pulse wave measurement device are not limited to these.

[0077] Coordinate Axis Definition: The XY plane is substantially parallel to the subject's skin surface. The X-axis is substantially parallel to the direction of the subject's blood vessels, and the Y-axis is substantially perpendicular to the direction of the blood vessels. Therefore, the Z-axis is substantially perpendicular to the subject's skin surface. The definitions of the X-axis, Y-axis, and Z-axis mentioned below are the same.

[0078] Radial displacement pulse wave measuring device

[0079] FIG1 illustrates the functional block diagram of a radial displacement pulse wave measurement device according to one embodiment of the present disclosure. In FIG1 , radial displacement pulse wave measurement device 100 includes an airbag 110, a pressure control module 120, a displacement sensing module 130, a scanning position control module 140, and a computing unit 150. Pressure control module 120, displacement sensing module 130, and scanning position control module 140 are each communicatively connected to computing unit 150.

[0080] FIG2 is a schematic cross-sectional view of the wearable portion of a radial displacement pulse wave measuring device according to an embodiment of the present disclosure. In order to better allow the airbag 110 to fit securely and tightly with the subject's part to be measured 160 and to fix the relative position between the displacement sensing module 130 and the subject's part to be measured 160, thereby effectively reducing the problem of noise generated when the subject changes posture or shakes their body, a wearable portion is designed for the radial displacement pulse wave measuring device 100 to increase the accuracy of pulse wave measurement. In FIG2 , the radial displacement pulse wave measuring device 100 may further include a wearable portion 200 and a housing 230. The wearable portion 200 includes a hard outer layer 210 and a soft inner layer 220, while the housing 230 has a transparent portion 232. In the aforementioned radial displacement pulse wave measuring device 100, the airbag 110 is disposed below the transparent portion 232 (located outside the housing 230), the displacement sensing module 130 is disposed above the transparent portion 232 (located inside the housing 230), and the remaining calculation unit 150, pressure control module 120, and scanning position control module 140 can be optionally encapsulated within the housing 230 or disposed outside the housing 230. To simplify the diagram, only the displacement sensing module 130 is depicted within the housing 230 in FIG2 . When using the wearable portion 200 and housing 230 of FIG2 , the airbag 110 can be positioned between the subject's measured portion 160 and the housing 230, and the displacement sensing module 130 can be aligned with the transparent portion 232 of the housing 230, allowing the transmitted signal 130a and reflected signal 130b of the displacement sensing module 130 to pass through the transparent portion 232.

[0081] Next, each component of the radial displacement pulse wave measuring device 100 is introduced one by one.

[0082] In Figures 1 and 2, the airbag 110 has three functions. The first is to generate downward pressure to compress the subcutaneous tissue. The second is to allow the measurement signal from the displacement sensing module 130 (i.e., transmitted signal 130a and reflected signal 130b) to penetrate the interior of the airbag 110 and be reflected back to the displacement sensing module 130. The third function is that when the airbag 110 is in close contact with the skin, it can serve as a space to accommodate the increase in arterial diameter during each pulse beat.

[0083] The main body material of the airbag 110 can be made of any available polymer material that is not easily stretched or deformed and is transparent, or it can be made of any available polymer material that is not easily stretched or deformed and is non-transparent. In the present disclosure, non-transparent includes opaque and translucent. The above-mentioned transparent or non-transparent polymer material can be, for example, (but not limited to) polymethyl methacrylate (PMMA), cellulose acetate (CA), nylon-66 polyamide resin (PA-66), nylon-6 polyamide resin (PA-6), polybutylene terephthalate (PBT), polyethylene terephthalate (PET), polyphenylene oxide (PPO), polycarbonate (PC), ethylene-vinyl acetate copolymer (EVA), polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), polyacetal (POM) or polyurethane (PU).

[0084] When the airbag 110 is constructed of a transparent polymer material, the measurement signal from the displacement sensing module 130 (i.e., the transmitted signal 130a and the reflected signal 130b) can penetrate the main material of the airbag 110. When the transparent portion 232 of the housing 230 in FIG2 is a hole, to increase the penetration of the measurement signal from the displacement sensing module 130 into the main material of the airbag 110 or to reduce the impact of refraction and reflection of the measurement signal from the displacement sensing module 130 on the main material of the airbag 110, which could affect measurement accuracy, the upper portion of the airbag 110 constructed of a transparent polymer material in FIG2 may further include a transparent window 112 formed of a non-deformable transparent flat plate. The transparent plate of the transparent window 112 has an area larger than the hole in the transparent portion 232 to prevent the transparent plate of the transparent window 112 from being squeezed into the interior of the housing 230 when the pressure from the airbag 110 is excessive. During use, the transparent window 112 of the airbag 110 must be aligned with the transparent portion 232 of the housing 230 (i.e., the transparent window 112 and the transparent portion 232 must at least partially overlap). This allows the measurement signals from the displacement sensing module 130 (i.e., the transmitted signal 130a and the reflected signal 130b) to vertically penetrate the transparent window 112 formed of a transparent flat plate and thus penetrate the interior space of the airbag 110. If the transparent portion 232 of the housing 230 in FIG. 2 is a non-deformable transparent flat plate, the airbag 110 constructed of a transparent polymer material does not require a transparent window 112 formed of a transparent flat plate. Furthermore, regardless of whether the transparent portion 232 of the housing 230 is a hole or a transparent flat plate, because the housing 230 is located above the airbag 110, during the pressurization of the airbag 110, the housing 230 can also serve as a baffle to limit the upward expansion of the airbag 110, allowing the transparent window 112 in contact with the transparent portion 232 to form a flat surface, and allowing the increased pressure in the airbag 110 to be used almost exclusively to press down the subject's part to be tested 160.

[0085] However, when the airbag 110 is constructed of a non-transparent polymer material, the measurement signal from the displacement sensing module 130 cannot easily or only partially penetrate the main material of the airbag 110. Therefore, the airbag 110 must at least have a transparent window 112 to allow the measurement signal from the displacement sensing module 130 to pass through. During use, the transparent window 112 of the airbag 110 must also be aligned with the transparent portion 232 of the housing 230 (i.e., the transparent window 112 and the transparent portion 232 must at least partially overlap). This allows the measurement signal from the displacement sensing module 130 (i.e., the transmitted signal 130a and the reflected signal 130b) to pass through the transparent window 112 and the transparent portion 232, and thus into the interior space of the airbag 110. When the transparent portion 232 of the housing 230 in FIG. 2 is a hole, the transparent window 112 of the airbag 110, which is made of a non-transparent polymer material, must be formed using a non-deformable transparent flat plate. Furthermore, the transparent flat plate of the transparent window 112 must be larger in area than the hole in the transparent portion 232 to prevent the transparent flat plate of the transparent window 112 from being squeezed into the interior of the housing 230 when the internal pressure of the airbag 110 is excessive. The remaining conditions are similar to those described above for the airbag 110 made of a transparent polymer material, and therefore will not be described in detail. When the transparent portion 232 of the housing 230 in FIG. 2 is a non-deformable transparent flat plate, the transparent material used for the transparent window 112 of the airbag 110, which is made of a non-transparent polymer material, is not limited to a transparent flat plate. A non-deformable transparent material can also be used to form the transparent window 112. The transparent material that is not easily stretched and deformed may be, for example, polymethyl methacrylate, cellulose acetate, nylon-66 polyamide resin, nylon-6 polyamide resin, polybutylene terephthalate, polyethylene terephthalate, polyphenylene, polycarbonate, ethylene-vinyl acetate copolymer, polyethylene, polypropylene, polyvinyl chloride, polyacetal or polyurethane, which is similar to the situation of the airbag 110 made of the transparent polymer material mentioned above, so the remaining details are not repeated.

[0086] Therefore, in FIG2 , both the transparent window 112 of the airbag 110 formed by the transparent plate and the transparent portion 232 of the housing 230 can restrict the upward expansion of the airbag 110, allowing the increased pressure in the airbag 110 to be applied downwardly to the subject's part to be measured 160 almost exclusively through the contact portion 114 of the airbag 110. Consequently, the radial displacement of the blood vessels caused by the pulse can be maximized, facilitating measurement by the displacement sensor 130.

[0087] The material of the non-deformable transparent plate constituting the transparent window 112 or the transparent portion 232 may be, for example, (but not limited to) glass, quartz, polystyrene (PS), or acrylonitrile butadiene styrene (ABS), or the same transparent material as used in the airbag. The transparent window 112 and the transparent portion 232 may be made of the same or different materials. In some embodiments, the transparent portion 232 of the housing 230 and the transparent window 112 of the airbag 110 may be combined into one, using a single transparent plate with high rigidity.

[0088] According to some further embodiments, the outer surface of the transparent window 112 facing the outside of the airbag 110 may be coated with an anti-reflection film to increase the penetration of the measurement signal of the displacement sensing module 130 through the transparent window 112, thereby reducing noise generated by the measurement signal reflected by the transparent window 112 and increasing the wear resistance of the transparent window 112.

[0089] Since the main body of airbag 110 is made of a material that is not easily stretched or deformed, the height of the skin or the reflective surface where the airbag is in close contact with the skin will be reduced. To reduce the lateral tension of the material while maintaining the downward pressure inside the airbag, a soft, stretchable polymer material can be used in a localized area. Airbag 110 can also have a contact portion 114, as shown in Figures 1 and 2. This contact portion 114 is used to contact the skin of the subject's test area 160. Since the skin of the test area 160 will bounce up and down due to the pulsation of the underlying artery 250 (see Figure 2), a soft, stretchable polymer material (with a hardness range of 20C to 72D on the Shore A scale) can be used to reduce the lateral tension on the constantly beating skin of the test area 160. In conjunction with the aforementioned non-deformable airbag 110 body and its transparent window 112, the soft and elastic contact portion 114 can effectively transmit the downward pressure exerted by the airbag 110 on the portion to be measured 160. Alternatively, the airbag 110 can be entirely made of the same non-stretchable material as the airbag. After inflation, the compressible and elastic air layer within the airbag 110 serves as the elastic absorption space required by pulse vibrations, while also reducing lateral tension on the material. This allows the displacement sensing module 130 to more easily detect the measurement signal of the radial displacement of the blood vessel caused by the pulse. The contact portion 114 can be transparent, translucent, or opaque. The above-mentioned polymer material can be the same as the main material of the airbag or can be, for example, a thermoplastic elastomer (TPE). The thermoplastic elastomer that can be used can be, for example, thermoplastic polyurethane (TPU), polyolefin elastomer (TPO), dynamically vulcanized polyolefin elastomer (TPV), polystyrene elastomer (TPS / TPR), polyether ester elastomer (TPEE), polyamide elastomer (TPA), and polyvinyl chloride (PVC).

[0090] According to some embodiments, the inner surface of the contact portion 114 facing the airbag 110 may be smooth, or a reflective layer or a dichroic layer may be additionally formed on the inner surface of the contact portion 114. For example, when a red laser light source is used, the dichroic layer coated on the inner surface of the contact portion 114 of the airbag 110 can reflect the light of the red laser while allowing the remaining visible light to pass through, thereby increasing the reflection intensity of the measurement signal (i.e., the red laser) and facilitating simultaneous alignment with the alignment mark below the contact portion 114. In this way, the reflection intensity and uniformity (rather than scattering) of the measurement signal emitted by the displacement sensing module 130 by the inner surface of the contact portion 114 can be increased. The contact portion 114 may also be translucent, which can simultaneously increase the reflection intensity of the measurement signal and facilitate simultaneous alignment with the alignment mark or reflective patch below the contact portion 114.

[0091] The pressure control module 120 in Figure 1 controls the internal pressure of the airbag 110 by inflating or deflating the interior of the airbag 110 to adjust the depth to which the airbag 110 presses against the portion to be measured 160. According to some embodiments, the pressure control module 120 may include, for example, a pressure sensor 122 and a pressure adjustment module 124 (comprising a pump, a gas line, and a valve) that are signal-connected to each other. The pressure sensor 122 senses the internal pressure of the airbag 110 and can therefore be used to measure the subject's vascular volume pulse wave. The gas line of the pressure adjustment module 124 is connected to the pump and the airbag 110 at both ends, respectively, and the valve is installed at an appropriate location in the gas line. Therefore, by controlling the direction (forward / reverse) of the pump motor, or by using a pulse width modulation (PWM) circuit to adjust the pump motor's speed, or by using two motors in the pump, one for air intake and one for exhaust, and by switching an air valve to control the amount of gas flowing in and out of the airbag 110, the internal pressure of the airbag 110 can be quickly and accurately controlled, thereby controlling the depth of pressure applied by the airbag 110 along the Z-axis to the skin of the subject's test area 160. Therefore, the aforementioned pump can be combined with an air valve, a pulse width modulation circuit, or a combination of the two, along with the maximum amplitude of the blood vessel volume detection, to quickly determine the desired airbag pressure, and thus the approximate depth of pressure applied to the subject's skin by the pulse wave for detecting radial vascular displacement.

[0092] The displacement sensing module 130 in Figures 1 and 2 is used to measure the distance in the Z-axis direction from the displacement sensing module 130 to the skin of the measured part 160 of the subject (when the contact part 114 of the airbag 110 is made of a transparent material), or to measure the distance in the Z-axis direction from the displacement sensing module 130 to the contact part 114 of the airbag 110 (when the contact part 114 of the airbag 110 is made of an opaque material), thereby measuring the radial displacement pulse wave of the subject's blood vessels, hereinafter referred to as the radial displacement pulse wave.

[0093] The displacement sensing module 130 can be any suitable displacement sensor, comprising a transmitter 132 for emitting a measurement signal and a receiver 134 for receiving the reflected measurement signal. The above classifications are based on the shape of the maximum detectable area of ​​the displacement sensing module 130. The displacement sensing module 130 can be a point-type displacement sensor or a matrix-type displacement sensor composed of multiple point-type displacement sensors, such as a linear or planar matrix-type displacement sensor. The measurement resolution of the displacement sensing module 130 can be below 100 microns, for example, a displacement sensor having a resolution of 100 microns, 90 microns, 80 microns, 70 microns, 60 microns, 50 microns, 40 microns, 30 microns, 20 microns, 10 microns, 1 micron, or below 1 micron.

[0094] The displacement sensor may be, for example, a photoelectric displacement sensor that uses light sources of various wavelengths (i.e., the emitter 132 ) to measure distance. Examples of the photoelectric displacement sensor include a laser displacement meter, a fiber-optic displacement sensor, a three-dimensional laser scanner (3D laser scanner), a binocular depth CCD coupled with a programmable structured light system, a time-of-flight (TOF) device, a three-dimensional TOF device, a laser doppler stadimeter, a laser doppler velocimeter, a scanning laser vibrometer, a Michelson interferometer, or a laser interferometer.

[0095] According to some embodiments, the displacement sensing module 130 may further include a filter 136 for removing various noises mixed in the measurement signal to further increase the signal-to-noise ratio of the measurement signal.

[0096] The scanning position control module 140 in Figure 1 is used to control the movement of the displacement sensing module 130 above the subject's measured area 160 and to control the displacement sensing module 130 to perform a range scan within the measured area 160. The position control coordinates, combined with the pulse wave amplitude at a fixed point detected by the displacement sensing module 130, are used to locate the subject's blood vessels within the measured area 160. Alternatively, the module 140 can be used to locate a radial displacement pulse wave measurement position with a better signal-to-noise ratio along the blood vessel's path, thereby obtaining a better radial displacement pulse wave measurement signal. Therefore, the scanning position control module 140 is an optional component, meaning it can be omitted. When the scanning position control module 140 is not present, the user can move the displacement sensing module 130 to the subject's portion to be measured 160, allowing the displacement sensing module 130 to perform a distance measurement scan of the subject's portion to be measured 160. Alternatively, the user can manually touch the point where the pulse beats the most, attach a reflective sheet, and align the laser light source with the reflective sheet. The displacement sensing module 130 can be a photoelectric displacement sensor with a point, line, or area detection area. According to some embodiments, the scanning position control module 140 can include a single-axis position controller or a dual-axis position controller (e.g., an XY dual-axis motion platform or a cylindrical coordinate motion mechanism).

[0097] The computing unit 150 in Figure 1 includes multiple modules composed of multiple electrically connected hardware circuits. The computing unit 150 can be any available machine with computing capabilities, such as various types of computers, microprocessors, cloud computing units, mobile computing devices, and edge computing for artificial intelligence. According to some embodiments, the computing unit 150 includes a power module 151, a memory module 152, a communication module 153, an operation module 154, a display module 155, and a processing module 156, all electrically or signal-connected to each other. Combinations of these modules can also be integrated into a single chip.

[0098] The power module 151 is used to supply power to the computing unit 150. The power module 151 can be an AC power source (e.g., power from a power plant via a common power socket) or a DC power source (e.g., various dry cells or rechargeable batteries).

[0099] The memory module 152 may be any available volatile or non-volatile data storage device to store any data generated during the measurement process of the displacement sensing module 130 .

[0100] The communication module 153 is signal-connected to the pressure control module 120, displacement sensing module 130, and scanning position control module 140, respectively, to transmit control signals from the calculation unit 150 to the pressure control module 120, displacement sensing module 130, and scanning position control module 140, or to receive information from the pressure control module 120, displacement sensing module 130, and scanning position control module 140 for analysis by the analysis module 158 or storage in the memory module 152. The communication module 153 can also be signal-connected to a cloud database, a cloud computing center, or both to obtain pulse wave interpretation reference data and perform analysis and calculations to facilitate subsequent pulse wave analysis and interpretation. The aforementioned cloud database may include, for example, acupuncture point and meridian databases, pulse comparison databases, Chinese herbal medicine databases, pulse wave analysis, vascular elasticity, pulse wave velocity (PWV) databases, continuous blood pressure analysis databases, cloud-based artificial intelligence computing, and other databases related to pulse wave analysis to enhance the accuracy of pulse wave analysis interpretation. Communication module 153 may also transmit the acquired monitoring data to a cloud computing center for data analysis and computation to generate interpretation results.

[0101] The operation module 154 provides a user interface for the radial displacement pulse wave measurement device 100, allowing the user to issue control commands through the operation module 154 to control the operation of the pressure control module 120, the displacement sensing module 130, and the scanning position control module 140. The user interface can also be displayed on a remote display device through the communication module 153, facilitating remote operation required for telemedicine.

[0102] The processing module 156 may include a control module 157 and an analysis module 158. The control module 157 is responsible for providing control instructions to the pressure control module 120, the displacement sensing module 130, and the scanning position control module 140. The analysis module 158 is responsible for calculating and analyzing the information transmitted by the pressure control module 120, the displacement sensing module 130, and the scanning position control module 140. For example, the radial displacement pulse wave measurement signal obtained by the displacement sensing module 130 may include both the Z-axis displacement generated by the pulse (a dynamic AC signal) and the Z-axis displacement generated by the airbag 110 pressing down on the part to be measured 160 (i.e., the Z-axis pressure depth, a static DC signal). To clearly measure the Z-axis displacement caused by the airbag 110 pressing down on the portion to be measured 160, the analysis module 158 of the computing unit 150 can filter out the dynamic Z-axis displacement caused by the pulse from the radial displacement pulse wave measurement signal, leaving only the static Z-axis displacement caused by the airbag 110 pressing down on the portion to be measured 160. This static DC signal can be used to easily determine the Z-axis pressure depth and pressure value of the airbag 110 corresponding to the pulse wave signal with the maximum signal-to-noise ratio, which can be used as the target setting for the pressure control module 120. This improves the accuracy and repeatability of the measurement signal, facilitating the capture of the radial displacement pulse wave signal of the subject's blood vessels.

[0103] The display module 155 is used to display the user interface of the control module 157; display information transmitted from the pressure control module 120, the displacement sensing module 130, and the scanning position control module 140 to the analysis module 158; and display the analysis results of this information by the analysis module 158. If the display module 155 is located remotely, the above information can also be displayed on the remote display module 155 via the communication module 153, facilitating telemedicine.

[0104] The wearable device 200 in Figure 2 is fixed to the outer shell 230. The interior space of the wearable device 200 accommodates the limb portion 240 where the measured portion 160 is located. Furthermore, an artery 250 passes beneath the skin of the measured portion 160, allowing the displacement sensing module 130 to measure the radial displacement pulse wave of the artery 250. The wearable device 200 includes a hard outer layer 210 and a soft inner layer 220. The hard outer layer 210 is substantially cylindrical, while the soft inner layer 220 is essentially formed by extending the airbag 110.

[0105] The hard outer layer 210 of the wearable device 200 maintains a constant distance MD between the displacement sensing module 130 and the point 212 on the hard outer layer 210 that is furthest from the displacement sensing module 130, ensuring a stable measurement baseline during pulse wave measurement. Therefore, the material of the hard outer layer 210 must possess a certain mechanical strength to maintain this constant distance MD even after the wearable device 200 is secured to the subject and the airbag 110 is pressurized. According to some embodiments, maintaining a constant distance MD is more easily achieved when the airbag 110 is located only in the upper half of the hard outer layer 210.

[0106] The available configurations of the hard outer layer 210 can have different structural designs depending on the shape of the limb part of the subject where the part to be measured 160 is located. Therefore, FIG2 shows only a simple schematic diagram, and the actual structure of the hard outer layer 210 should not be limited thereto. For example, the hard outer layer 210 can be designed similar to a metal watchband and a watch buckle, so that the length of the metal watchband can be varied, making it convenient to apply to the limb part of the subject where the part to be measured 160 is located, and convenient to store and carry. If the hard outer layer 210 is designed with a single annular sheet hard shell structure, the circumference of the hard outer layer 210 is fixed, as long as the limb part where the part to be measured 160 is located can pass directly through it. Alternatively, the hard outer layer 210 can be designed with a structure of two or more annular sheet hard shells, and suitable hard outer layer fixing members (such as buckles, etc.) are added to fix the overlapping parts of the different annular sheet hard shells. Alternatively, the hard outer layer 210 may be designed as a C-shaped structure. During measurement, the wrist is placed through the notch of the C-shaped structure, and the soft inner layer 220 is disposed inside the notch.

[0107] As described above, the soft inner layer 220 is essentially composed of the airbag 110, so the internal gas pressure of the soft inner layer 220 can also be controlled by the pressure control module 120. Therefore, the opening size of the hard outer layer 210 can be easily adjusted, allowing the wearable portion 200 to more conveniently adapt to limbs of varying sizes where the measured portion 160 is located, facilitating pulse wave measurement. Similarly, the soft inner layer 220 can be constructed in various structural designs depending on the shape of the subject's limb where the measured portion 160 is located. Therefore, Figure 2 is merely a simplified schematic diagram, and the actual structure of the soft inner layer 220 should not be limited to this. For example, the soft inner layer 220 can be constructed directly from a cylindrical airbag 110. Alternatively, the soft inner layer 220 can be constructed using a sheet-like airbag 110, with the ends of the airbag 110 overlapping and secured with suitable soft inner layer fasteners (such as Velcro). Even more, the soft inner layer 220 only needs to leave the measuring portion 110 a as shown in FIG. 2 (the measuring portion 110 a includes the transparent window 112 and the contact portion 114 of the airbag 110 ), and other parts of the airbag 110 can be omitted.

[0108] According to some embodiments, in order to accommodate a wider range of limb parts 240 where the measured part 160 is located with different sizes and shapes, in addition to the above-mentioned airbags 110, the soft inner layer 220 can also include multiple independent auxiliary airbags. The pressure of each auxiliary airbag can be independently controlled by the pressure control module 120, so that each independent airbag can easily fill the space of different sizes left between the inside of the wearable part 200 and the limb.

[0109] Method for finding radial displacement pulse wave measurement points

[0110] Next, we will describe a method for measuring pulse waves using the aforementioned radial displacement pulse wave measurement device 100. When the radial displacement pulse wave measurement device 100 includes a scanning position control module 140, the displacement sensing module 130 can be automatically controlled to scan the subject's measured portion 160 at an appropriate airbag depression depth to locate the optimal measurement position within the measured portion 160. Please refer to Figures 3A and 3B.

[0111] FIG3A is a schematic diagram illustrating an operation flow of using the scanning position control module 140 to automatically find a measurement point of a radial displacement pulse wave according to an embodiment of the present disclosure, wherein the displacement sensing module 130 is a point-type displacement sensor.

[0112] In step 310 of FIG3A , the balloon 110 of the radial displacement pulse wave measurement device 100 is first placed on the subject's skin 160, with the contact portion 114 of the balloon 110 in contact with the subject's skin 160. To detect the maximum amplitude of the vascular volume pulse wave, the balloon 110's downward pressure can be roughly adjusted to a depth sufficient to detect the vascular pulse, even if the displacement sensing module 130 is not aligned with the blood vessel, thereby accelerating the overall measurement process.

[0113] In step 320, the pressure control module 120 gradually pressurizes the interior of the balloon 110 to increase the internal pressure of the balloon 110. When the pulse signal measured by the pressure sensor 122 in the pressure control module 120 reaches a maximum value, that is, when the amplitude of the vascular volume pulse wave reaches a maximum value, the approximate compression depth is determined. The pressure control module 120 then stops pressurizing the balloon 110 to maintain the internal pressure of the balloon 110. In some embodiments, step 320 may be skipped and step 330a may be executed directly.

[0114] In step 330a, a starting position (coordinate) is first selected on the part to be measured 160 of the subject. The scanning position control module 140 is used to move the point displacement sensor above the starting position as the starting point of the scan, and the distance between the point displacement sensor and the part to be measured 160 is measured.

[0115] In step 340a, the scanning position control module 140 is used to scan the point-type displacement sensor along a direction perpendicular to the direction of the blood vessel (i.e., the direction of the Y-axis). The amplitude of the radial displacement pulse wave is measured to gradually increase and then decrease within a certain area. The point where the amplitude signal of the radial displacement pulse wave is maximum on the Y-axis is found. This is also the point where the amplitude of the radial displacement pulse wave is maximum, which is also the location of the blood vessel (the first measurement position).

[0116] In step 350 a , the scanning position control module 140 is used to align the point-type displacement sensor to the first measurement position.

[0117] In step 360, the pressure of airbag 110 is adjusted until the maximum amplitude signal of the radial displacement pulse wave is obtained at the first measurement position, thereby obtaining a radial displacement pulse wave measurement signal with relatively low noise. At this point, the pressure of airbag 110 is the optimal measurement pressure, and the depth of pressure of airbag 110 on the measured portion 160 is the optimal measurement depth. Therefore, with step 360, the process of finding the pulse wave measurement point is concluded.

[0118] However, if there are special requirements (for example, Traditional Chinese Medicine practitioners require specific pulse diagnosis locations) or the signal-to-noise ratio of the detected radial displacement pulse wave is insufficient, step 370 is necessary. In step 370, the scanning position control module 140 is used to scan the point-type displacement sensor along the blood vessel, searching for the location of the local maximum of the radial displacement pulse wave signal on the X-axis (the second measurement location). Once found, the second measurement location becomes the location for measuring the radial displacement pulse wave.

[0119] If the radial displacement pulse wave measurement device 100 does not have a scanning position control module 140 or does not want to use the scanning position control module 140, the point-type displacement sensor can be manually controlled to scan the subject's measured portion 160 to find the optimal measurement position within the measured portion 160. Because the point-type displacement sensor is manually controlled, the first half of the manual control process differs from the first half of the automatic control process. See Figure 3B .

[0120] Next, please refer to Figure 3B. Figure 3B is a schematic diagram illustrating the operational flow of manually finding the measurement point of the radial displacement pulse wave according to another embodiment of the present disclosure, wherein the displacement sensing module 130 is a point-type displacement sensor. Since the measurement point must be manually found first, at least the transparent window 112 and the contact portion 114 of the airbag 100 are preferably made of transparent materials. Alternatively, the main body of the airbag 110, the transparent window 112, and the contact portion 114 may all be made of transparent materials, or holes may be opened in the visual area of ​​the wearable portion 210 and the housing 230, or transparent materials may be used to facilitate the user's visual search for the measurement point. In step 305, a manual method can be used to replace the scanning position control module 140. After first touching the pulsating location of the artery of the measured portion 160, the location of the blood vessel of the measured portion 160 (the first measurement position) can be directly found. In this step, if the contact portion 114 is transparent or translucent, a reflective sheet that reflects the measurement signal can also be used. After the reflective sheet is attached to the skin surface where the blood vessels are located, the measurement signal emitted by the displacement sensing module 130 is aligned with the reflective sheet before proceeding to the subsequent steps 310, 350a, 360, and 370. Since the subsequent steps 310, 350a, 360, and 370 are the same or similar to those described in FIG. 3A , their further description will be omitted.

[0121] Next, please refer to Figure 3C . Figure 3C illustrates a schematic diagram of the operational flow for finding the measurement point of the radial displacement pulse wave according to another embodiment of the present disclosure, wherein the displacement sensing module 130 is a linear matrix displacement sensor. The process of Figure 3C is similar to that of Figure 3A , except that because the linear matrix displacement sensor is composed of point-type displacement sensors arranged in a linear pattern, the steps associated with scanning along the Y axis to find the first measurement position can be omitted. Therefore, only the slightly different steps 330c and 340c will be described below, and the rest will not be elaborated upon. Furthermore, step 320 can be skipped and step 330c executed to directly measure the radial displacement pulse wave.

[0122] In step 330c, the scanning position control module 140 or manual methods can be used to directly align the linear measurement area of ​​the linear matrix displacement sensors parallel to the Y-axis and across the blood vessel. In step 340c, the pressure within the balloon is gradually adjusted to observe which point-type displacement sensor in the linear matrix displacement sensors measures the maximum radial displacement pulse wave signal value. This allows determination of whether this point-type displacement sensor is located above the blood vessel. This means that the first measurement position has been found, and the subsequent step 360 can be directly performed.

[0123] If a surface matrix displacement sensor is used, the steps of scanning along the X and Y axes to find the point of maximum signal (i.e., the starting position and the first measurement position) can be omitted. The surface matrix displacement sensor can be placed directly above the measured portion 160 to observe which point-type displacement sensor in the surface matrix displacement sensor measures the maximum radial displacement pulse wave signal. The measurement depth with the lowest signal-to-noise ratio is then determined, indicating that the point-type displacement sensor is located at the aforementioned second measurement position. Therefore, the measurement signal obtained by this point-type displacement sensor can be used for various subsequent applications. Therefore, if the radial displacement pulse wave measurement device 100 uses a surface matrix or linear matrix displacement sensor, the need to scan the displacement control module 140 can be determined based on actual needs.

[0124] As can be seen from the above description, the collaboration between the airbag 110 and the pressure control module 120 can control the Z-axis pressure depth of the airbag 110 on the measured portion 160, allowing the displacement sensing module 130 to locate a pulse wave measurement depth on the Z-axis with a relatively good signal-to-noise ratio. Furthermore, when the airbag 110 is already pressing the measured portion 160, the scanning position control module 140 enables the displacement sensing module 130 to locate a pulse wave measurement position on the XY plane with a relatively good signal-to-noise ratio. Therefore, the radial displacement pulse wave measurement device 100 can easily locate a radial displacement pulse wave measurement position with a good signal-to-noise ratio within the measured portion 160 of the subject, thereby obtaining a better radial displacement pulse wave signal.

[0125] Waveform Analysis of Pulse Waves Varying with Pressure

[0126] FIG4 is a schematic diagram illustrating the waveforms of the vascular volume pulse wave and radial displacement pulse wave as a function of pressure and time, according to an embodiment of the present disclosure. In FIG4 , the horizontal axis represents time, and the vertical axis is divided into four segments: valve, pump, pressure, and depth, from top to bottom. The curve in the valve segment at the top shows the changing on / off state of the valve. The curve in the pump segment shows the changing on / off state of the pump. The curve in the pressure segment shows the changing pressure inside the airbag 110, i.e., the vascular volume pulse wave measured by the pressure sensor 122. The curve in the depth segment at the bottom shows the changing depth of the airbag's downward pressure on the measured part along the Z axis, i.e., the radial displacement pulse wave measured by the displacement sensing module 130. Referring to FIG4 and Table 1, the following describes the waveform changes during different time periods (t0-t1, t1-t2, t2-t3, and t3-t4) on the time axis.

[0127] Table 1: Relationship between pressure and depth in Figure 4 and the radial displacement pulse wave signal.

[0128] During period 1 (t0-t1), the air valve is closed to stop airbag 110 from deflating, while the pump is opened to allow air to enter, gradually increasing the pressure of the balloon 110. During the gradual pressurization to P5, the vascular volume pulse wave and radial displacement pulse wave signals can be observed to change from non-existent to the initial appearance, then gradually increase in size, then gradually decrease, and finally disappear. This indicates that the maximum pressure required to depressurize balloon 110 is P5. The operations during period 1 are optional. The balloon internal pressure can be directly adjusted and the amplitude and pressure depth of the vascular radial displacement pulse wave can be captured to obtain the vascular radial displacement pulse wave signal with the highest signal-to-noise ratio.

[0129] Period II (t1-t2): Next, at t1, the pump is turned off to stop air supply to balloon 110. The air valve is opened to gradually deflate balloon 110 until the pressure in balloon 110 reaches P4 and the compression depth reaches D4, at which point the vascular volume pulse wave and radial displacement pulse wave signals begin to appear. The pressure in balloon 110 is then gradually reduced until, at time t2, the pressure in balloon 110 reaches P3 and the compression depth reaches D3. The amplitude of the radial displacement pulse wave reaches its maximum value (at this point, the amplitude of the vascular volume pulse wave is near its maximum value). This indicates that the optimal balloon pressure for measuring the radial displacement pulse wave is P3 and the compression depth is D3. At t2, the air valve is also turned off. This state is maintained for a period of time to monitor and record the vascular volume pulse wave, radial displacement pulse wave, or both, as required for Period III. Since the pressure P3 and compression depth D3 required to achieve the maximum amplitude signal of the vascular volume pulse wave (related to the change in vascular volume) and the radial displacement pulse wave (related to the change in vascular diameter) are not necessarily the same, at this stage, the optimal pressure P3 and compression depth D3 to be maintained can be determined based on measurement requirements.

[0130] Period III (t2-t3): During this period, the pressure of the balloon is maintained at P3 and the depression depth of the balloon is maintained at D3, and the required vascular volume pulse wave, radial displacement pulse wave, or both can be monitored and recorded.

[0131] Period IV (t3-t4): At time t3, after the monitoring and recording of period III are completed, the valve is opened to gradually depressurize balloon 110. When balloon 110 pressure reaches P2 and the compression depth reaches D2, the amplitude signals of the vascular volume pulse wave and the radial displacement pulse wave disappear. Then, balloon 110 continues to depressurize until the pressure reaches zero, which marks the end of time t4.

[0132] Comparing the vascular volume pulse wave during the pressure phase of period III (t2-t3) with the radial displacement pulse wave during the depth phase reveals that the radial displacement pulse wave has greater detail. Therefore, it can be used for more data analysis, yielding multiple relevant physiological indicators and applying them to a wider range of physiological monitoring applications. An example is provided below to illustrate this.

[0133] Blood pressure measurement methods

[0134] Next, how to measure blood pressure is described. When measuring blood pressure, the subject's measured portion 160 can be, for example, the radial artery on the inside of the wrist or the brachial artery on the inside of the upper arm near the elbow joint.

[0135] Figure 5 is a schematic diagram of the process for measuring blood pressure using the radial displacement pulse wave measurement device of Figure 1. After finding the first or second measurement position of the radial displacement pulse wave using the aforementioned method, the displacement sensing module 130 is aligned with the first or second measurement position to measure blood pressure. Although both the vascular volume pulse wave and the radial displacement pulse wave can be used to measure blood pressure, the radial displacement pulse wave signal is clearer than the vascular volume pulse wave signal. Therefore, the following discussion primarily uses the radial displacement pulse wave as the primary basis for blood pressure measurement.

[0136] Step 510 corresponds roughly to period I in FIG4 and Table 1. In step 510, the pressure control module 120 is used to gradually pressurize the interior of the airbag 110 to increase the internal pressure of the airbag 110 until the radial displacement pulse wave amplitude signal appears and disappears.

[0137] Step 520 roughly corresponds to the time t1-t2 of period II in Figure 4 and Table 1, starting when the pressure of balloon 110 reaches P4 and the depression depth reaches D4, and continues until the pressure of balloon 110 reaches P3 and the depression depth reaches D3 during period II. In step 520, pressure control module 120 gradually reduces the internal pressure of balloon 110. When the radial displacement pulse wave amplitude signal begins to reappear, the static DC signal of the vascular volume pulse wave obtained by pressure sensor 122 of pressure control module 120, after filtering out the dynamic signal of the vascular volume pulse wave from the pulse beating, becomes the internal pressure value (P4) of balloon 110, which is also the systolic pressure (P4) of the subject's blood vessels.

[0138] Step 530 roughly corresponds to the time t3-t4 of period IV in Figure 4 and Table 1, starting when the pressure of balloon 110 reaches P3 and the depression depth reaches D3, and continues until the pressure of balloon 110 reaches P2 and the depression depth reaches D2 during period IV. In step 530, pressure control module 120 continues to gradually reduce the internal pressure of balloon 110. When the radial displacement pulse wave amplitude signal begins to disappear again, the static DC signal of the vascular volume pulse wave obtained by pressure sensor 122 of pressure control module 120, after filtering out the dynamic signal of the vascular volume pulse wave from the pulse beat, becomes the internal pressure value (P2) of balloon 110, which is also the diastolic pressure (P2) of the subject's blood vessels.

[0139] Measurement and Application of Heart Rate Variability (HRV)

[0140] Figure 6A is an enlarged schematic diagram of the radial displacement pulse wave during period III (t2-t3) of Figure 4. In Figure 6A, because the peak position of the radial displacement pulse wave is clearly discernible, it can be used to simulate the R wave peak position of a typical electrocardiogram to extract data on the heartbeat interval (RR interval; RRI). If the radial displacement pulse wave signal is captured for one minute and the number of peaks is counted, the heart rate per minute can be obtained. In Figure 6A, the interval between two adjacent peaks on the radial displacement pulse wave curve is used to represent the heartbeat interval.

[0141] Heart rate variability refers to the time difference between heartbeat intervals. Under normal circumstances, heartbeats do not occur uniformly at constant intervals, but rather exhibit slight variations, which are called heart rate variability. Therefore, heart rate variability analysis is a method for measuring the degree of time variation between consecutive heartbeats. When using the above-mentioned radial displacement pulse wave measurement device 100 to measure heart rate variability, a location with thinner subcutaneous tissue (e.g., the high bone behind the wrist, or its front-to-back relative position, or the earlobe or ear artery, or the hand artery, the sole of the foot, or the toes) can be selected as the measured portion 160, and the blood vessels therein can be found to obtain a more obvious peak position of the radial displacement pulse wave.

[0142] There are two methods for analyzing heart rate variability. The first is the time domain method, which typically uses continuously measured electrocardiogram waveforms to directly calculate and analyze the dispersion of the corresponding heartbeat intervals. Common methods include:

[0143] SDNN (Standard deviation of NN intervals): Usually calculates the standard deviation of normal heartbeat intervals over a 24-hour period; the unit is milliseconds (ms).

[0144] SDANN (Standard deviation of the average NN intervals): Usually, the average of the heartbeat intervals is calculated for each five-minute period, and then the standard deviation of the average interval is calculated; the unit is milliseconds.

[0145] The following is a more detailed explanation using SDNN as an example. SDNN is a measure of the overall activation of the autonomic nervous system, that is, the sum of the activation of the sympathetic and parasympathetic nerves, which can represent the ability of the autonomic nervous system to regulate body processes. SDNN is the standard deviation of RRI within the measurement time range. Since each RRI is not necessarily the same, the unit of SDNN is milliseconds (ms). The standard deviation of RRI describes the degree of dispersion of each RRI around its average value. The greater the dispersion, the greater the standard deviation. Conversely, if the measured values ​​of all RRIs are the same, the standard deviation of RRI will be 0. After calculating all RRIs from the HRV record, the relationship between the heart rate RRI and time can be obtained in Figure 6B. SDDN can be calculated using the following formulas (1) and (2).

[0146] RR i is the i-th RRI, N is the number of all measured RRIs, and is the average of all RRIs. i is a positive integer.

[0147] The second method is frequency domain analysis, which uses a discrete Fourier transform to convert the time series of heartbeat intervals into the frequency domain and present it as a power spectral density or spectral distribution, as shown in Figure 6C. Spectral analysis of heart rate variability signals typically requires stable recordings of 200 to 500 consecutive heart rate intervals (RRIs), requiring several minutes of recording time. Typical RRI spectrum frequencies occur below 1 Hz. For example, peaks can be found in the 0-0.4 Hz range, encompassing the ultra-low frequency (ULF) region (≤ 0.003 Hz), very low frequency (VLF) region (0.0033–0.04 Hz), low frequency (LF) region (0.04–0.15 Hz), and high frequency (HF) region (0.15–0.40 Hz). The high frequency region typically reflects parasympathetic nervous system activity, while the low frequency region is regulated by both the sympathetic and parasympathetic nervous systems. The (high frequency / low frequency) ratio reflects the balance between sympathetic and parasympathetic nervous system activity.

[0148] Pulse Wave Velocity (PWV) Measurement Method

[0149] Pulse wave velocity (PWV) refers to the speed at which arterial blood fluctuations propagate through the blood vessels. These fluctuations are caused by pressure waves generated by the heart's ventricular contraction, which propagate along the arterial system. Therefore, PWV can reflect the elasticity and degree of arterial stiffness. PWV is inversely proportional to the viscoelasticity of the blood vessel wall itself; that is, the stiffer the artery, the faster the PWV, while the softer the artery, the slower the PWV.

[0150] Interpretation of pulse wave velocity depends on age, gender, disease, and risk factors. Generally speaking, a normal aortic pulse wave velocity is approximately 5-7 m / s; a value above 10 m / s indicates significant arteriosclerosis. Pulse wave velocity is closely associated with the incidence and mortality of cardiovascular disease, and therefore can serve as an important indicator for assessing cardiovascular risk and prognosis, such as in coronary artery disease, arteriosclerosis, or connective tissue disease.

[0151] The pulse wave velocity measurement method is mainly to evaluate the pulse wave velocity by simultaneously recording the pressure waveforms at two different locations in the arterial tree. The above two locations include the proximal location close to the heart and the distal location far from the periphery of the heart. Since the waveforms of the proximal and distal locations are recorded simultaneously, the delay time difference ΔT (= T2-T1) of the distal waveform relative to the proximal waveform can be directly measured. Then, by measuring the distance ΔD from the proximal to the distal end, the pulse wave velocity can be calculated, as shown in the following formula (3). PWV = ΔD / ΔT (3)

[0152] There are two methods for measuring the delay time ΔT. The first method is to use two displacement sensing modules 130 , and the second method is to use an electrocardiogram and one displacement sensing module 130 .

[0153] FIG7A is a schematic diagram illustrating a method of simultaneously using two pulse wave measurement devices to measure pulse wave velocity according to an embodiment of the present disclosure. In FIG7A , two radial displacement pulse wave measurement devices 100 are directly used to simultaneously record the proximal and distal radial displacement pulse waves. This allows for direct measurement of the trough-to-trough or peak-to-peak delay time ΔT of the proximal and distal radial displacement pulse waves. FIG7A illustrates the trough-to-trough delay time ΔT. If either of the two radial displacement pulse wave measurement devices 100 is used by manually aligning the displacement sensing module 130 with the measured portion 160, the scanning position control module 140 can be omitted, leaving only the airbag 110, pressure control module 120, displacement sensing module 130, and calculation unit 150 in the radial displacement pulse wave measurement device 100. In addition, the two radial displacement pulse wave measuring devices 100 may also share one calculation unit 150 , and thus one of the calculation units 150 may be omitted.

[0154] FIG7B is a schematic diagram of an electrocardiogram-assisted method for measuring pulse wave velocity according to an embodiment of the present disclosure. In FIG7B , the peak of the R wave of the electrocardiogram is used to align the proximal and distal pulse waves. In the upper portion (I) of FIG7B , the trough delay time of the proximal radial displacement pulse wave relative to the peak of the R wave of the electrocardiogram is T1. In the lower portion (II) of FIG7A , the trough delay time of the distal radial displacement pulse wave relative to the peak of the R wave of the electrocardiogram is T2. The time difference between T1 and T2 is the delay time ΔT. The delay time ΔT measured by the above two methods is the pulse transit time (PTT).

[0155] The distance ΔD between the proximal and distal ends can be determined by simply measuring the distance between the two measurement locations using a flexible tape measure, or by adding the distances from the heart to the two measurement locations and multiplying them by a factor. The proximal and distal ends can be, for example, the carotid, femoral, brachial, radial, ankle, digital, or posterior tibial arteries, depending on the measurement requirements. Different combinations of proximal and distal ends can result in different pulse wave velocities.

[0156] FIG. 7C is a flow chart of a method for measuring pulse wave velocity using the method shown in FIG. 7A .

[0157] In step 710, a radial displacement pulse wave measuring device 100 is placed at a first measurement position of a proximal artery. The device is automatically or manually aligned with the artery to be measured according to the operation flow of FIG. 3A or FIG. 3B to capture the radial displacement pulse wave of the artery at the first measurement position.

[0158] In step 710, a radial displacement pulse wave measuring device 100 is placed at a second measurement position of a distal artery. The device is automatically or manually aligned with the artery to be measured according to the operation flow of FIG. 3A or FIG. 3B to capture the radial displacement pulse wave of the artery at the second measurement position.

[0159] In step 730, the radial displacement pulse wave signals obtained in steps 710 and 720 are simultaneously captured to obtain the delay time ΔT of one pulse wave. Step 730 can be repeated multiple times over a period of time to obtain the successive delay time ΔTi of each pulse wave during this period, i.e., the successive pulse wave transit time PTTi.

[0160] In step 740, the distance ΔD between the first measurement location and the second measurement location is measured. Distance ΔD can be measured using, for example, point-type, linear matrix, or area matrix displacement sensors. When using point-type displacement sensors, the distance ΔD can be obtained by measuring the distance between two point-type displacement sensors placed at the first and second measurement locations using a tape measure.

[0161] According to some embodiments, when using a linear or planar photoelectric displacement sensor, only one photoelectric displacement sensor is required. Two non-adjacent sensing units of the photoelectric displacement sensor, each separated by a known distance, can be used to simultaneously measure radial displacement pulse waves at two locations. Since the measurement signal of a photoelectric displacement sensor is typically laser light, allowing the photoelectric displacement sensor's scanning range to encompass both the first and second measurement locations, the distance between the first and second measurement locations within the scanning range can be estimated using the two non-adjacent sensing units of the photoelectric displacement sensor, each separated by a known distance, and simple geometric proportions.

[0162] In step 750, the pulse wave velocity (ΔD / ΔTi=ΔD / PTTi) is calculated based on the pulse wave transit time PTTi obtained in step 730 and the distance ΔD obtained in step 740.

[0163] The cuff sphygmomanometers commonly used on the market today use the detection of vascular volume pulse waves to determine systolic and diastolic blood pressure. While convenient to use, the measurements are inaccurate and cannot monitor blood pressure in real time. Wearable continuous sphygmomanometers also typically use the correlation between pulse wave transit time and blood pressure, using the Branwell-Hill formula to estimate blood pressure. However, the use of the Branwell-Hill formula to calculate continuous blood pressure has previously resulted in errors in the pulse wave transit time calculation due to inaccurate real-time vascular diameter estimation and insufficient sensitivity in pulse wave measurement. This results in similar inaccuracies in the continuous blood pressure calculated using the Branwell-Hill formula. Therefore, one embodiment of the present disclosure provides a continuous blood pressure measurement device that can improve the accuracy of vascular diameter measurement and increase the sensitivity of pulse wave measurement to improve the measurement accuracy of wearable continuous sphygmomanometers.

[0164] The Branwell-Hill equation is a mathematical model that describes the relationship between changes in blood vessel diameter and pulse wave velocity (PWV). This equation is a modification of the Moens-Korteweg equation, accounting for the decrease in arterial compliance with increasing pressure and the increase in volume with increasing pressure (arterial dilation). The Branwell-Hill equation is shown in equation (4):

[0165] Where ΔP is the change in blood pressure, ρ is the blood density, ΔD is the distance between the first and second measurement locations in the pulse wave velocity measurement, PTT is the pulse wave transit time from the first to the second measurement location, ΔR is the change in arterial diameter at the first or second wrist measurement location, and R is the arterial diameter at the first or second wrist measurement location. (ΔD / PTT) is the pulse wave velocity (PWV).

[0166] Therefore, a displacement sensor can be used to measure ΔRi for each pulse wave, and pulse wave velocity can be used to measure PWVi for each pulse wave. The Branwell-Hill equation can then be used to estimate ΔPi for each pulse wave, achieving continuous blood pressure measurement. The following details the continuous blood pressure measurement method.

[0167] FIG8 is a flow chart of a method for measuring continuous blood pressure.

[0168] In step 810, the initial diastolic and systolic pressures are first measured. According to the blood pressure measurement method described above, the subject's initial diastolic and systolic pressures P2 and P4 are measured. Furthermore, the first depression depth D2 of the balloon 110 on the measured portion 160 at the initial diastolic pressure P2 and the second depression depth D4 of the balloon 110 at the initial systolic pressure P4 are measured, as shown in FIG4 and Table 1. The blood vessel diameter R can be obtained from the difference between the first and second depression depths (D4 - D2). Therefore, the blood vessel diameter R is R = (D4 - D2).

[0169] In step 820, the vessel diameter and the change in vessel diameter are calculated. Figure 6A shows the time-varying waveform of the radial displacement pulse wave. The difference between the peak position (R2) and the trough position (R1) of each radial displacement pulse wave represents the vessel diameter change Δ(R) caused by each heartbeat.

[0170] In step 830 , the pulse wave velocity (PWV) of each pulse wave is measured according to the pulse wave measurement method described above.

[0171] In step 840, the blood pressure change ΔP is calculated using the blood vessel diameter change ΔR, blood vessel diameter R, and pulse wave velocity PWV obtained above, and the subject's blood density.

[0172] In step 850, the real-time diastolic pressure (P2+ΔP) and real-time systolic pressure (P4+ΔP) can be obtained using the initial diastolic pressure P2 and initial systolic pressure P4 measured in step 810 and the blood pressure change ΔP obtained in step 840.

[0173] Then, the steps 820 to 850 are repeated for a period of time. Then, the blood pressure can be continuously measured with high precision over a period of time, thereby achieving the purpose of continuous blood pressure monitoring.

[0174] As can be seen from the above disclosure, through the coordinated design of the airbag, pressure control module, and displacement sensing module, the radial displacement pulse wave measurement device provided by this disclosure can directly measure the waveform of the radial displacement pulse wave of the blood vessel. Compared with traditional pressure pulse wave measurement methods, this direct measurement method can provide more accurate results.

[0175] Furthermore, the radial displacement pulse wave measurement device can achieve a measurement accuracy of less than 100 microns, thus providing detailed information about the pulse wave, such as waveform shape, amplitude, and temporal characteristics. These highly accurate measurements are extremely valuable for a variety of pulse wave analysis applications. In addition to measuring common parameters such as blood pressure, heart rate variability, and pulse wave velocity, the radial displacement pulse wave measurement device can also perform numerous other analytical applications. For example, the radial displacement pulse wave measurement device can be used to assess the degree of arteriosclerosis, detect vascular elasticity, monitor cardiovascular disease risk, and study hemodynamics. This versatile application potential makes the radial displacement pulse wave measurement device widely applicable in the medical and biomedical fields.

[0176] Furthermore, using the aforementioned radial displacement pulse wave measurement device to measure pulse waves is a non-invasive method, making it convenient to monitor a subject's pulse wave changes in real time, providing real-time measurement results and waveform graphs. Coupled with the wearable design, this device facilitates long-term, continuous monitoring of the subject's pulse wave, yielding stable results. This is highly valuable for physicians and researchers, helping them better understand the subject's cardiovascular status and make appropriate diagnostic and treatment decisions, ultimately providing better personalized medicine.

[0177] In summary, the aforementioned radial displacement pulse wave measurement device offers advantages such as direct measurement of vascular radial displacement pulse waves, high accuracy, versatile analytical applications, non-invasiveness, and real-time monitoring. These advantages make it widely applicable in cardiovascular medicine and biomedical fields.

Claims

1. A radial displacement pulse wave measuring device for measuring a radial displacement pulse wave of an artery of a measured part of a subject, the radial displacement pulse wave measuring device comprising: A housing having a transparent portion, wherein the transparent portion includes a hole or a first transparent plate; A transparent airbag, located below the transparent portion, wherein the main material of the transparent airbag is a material that is not easily stretched or deformed; a pressure control module, used to control the internal pressure of the transparent airbag, so as to control the downward pressure applied by the transparent airbag to the part to be measured, so as to amplify the pulse signal of the artery; a displacement sensing module, located above the transparent portion, for sensing the pulse of the artery, measuring the dynamic distance between the skin of the measured part and the displacement sensing module caused by the pulse of the artery, so as to obtain the radial displacement pulse wave; and A calculation unit is respectively connected to the pressure control module and the displacement sensing module for communication, and is used to transmit control signals to the pressure control module and the displacement sensing module respectively, and to receive information transmitted by the pressure control module and the displacement sensing module respectively and perform calculations.

2. The radial displacement pulse wave measuring device as claimed in claim 1, wherein the main body material of the transparent airbag comprises polymethyl methacrylate, cellulose acetate, nylon-66 polyamide resin, nylon-6 polyamide resin, polybutylene terephthalate, polyethylene terephthalate, polyphenylene, polycarbonate, ethylene-vinyl acetate copolymer, polyethylene, polypropylene, polyvinyl chloride, polyacetal or polyurethane.

3. The radial displacement pulse wave measuring device as described in claim 1, wherein when the transparent portion is the hole, the transparent airbag further comprises a transparent window overlapping with the transparent portion of the housing, and the transparent window comprises a second transparent plate.

4. The radial displacement pulse wave measuring device as claimed in claim 3, wherein an anti-reflection film is provided on the outer surface of the transparent window.

5. The radial displacement pulse wave measuring device as described in claim 3, wherein the area of ​​the second transparent plate is larger than the area of ​​the hole, and when the internal pressure of the transparent airbag is too large, the second transparent plate will press against the bottom of the hole and will not be squeezed above the hole.

6. The radial displacement pulse wave measuring device as described in claim 1, wherein the transparent airbag further comprises a contact portion, the contact portion is used to closely fit the skin of the measured part of the subject, and the material of the contact portion is a soft and stretchable thermoplastic elastomer polymer material, and the thermoplastic elastomer polymer material comprises at least one material selected from thermoplastic polyurethane, polyolefin elastomer, dynamically vulcanized polyolefin elastomer, polystyrene elastomer, polyether ester elastomer, polyamide elastomer, and polyvinyl chloride.

7. The radial displacement pulse wave measuring device as claimed in claim 6, wherein a reflective layer or a color separation layer is provided on the inner surface of the contact portion.

8. The radial displacement pulse wave measuring device as claimed in claim 1 further comprises a wearable part, so that the limb part of the subject where the part to be measured is located is accommodated in the internal space of the wearable part, and the wearable part comprises: a soft inner layer, comprising the transparent airbag; and A hard outer layer is located outside the soft inner layer to form the inner space of the wearable part together with the soft inner layer. During the measurement of the radial displacement pulse wave, the hard outer layer maintains a fixed distance from the displacement sensing module to the farthest point on the hard outer layer from the displacement sensing module.

9. The radial displacement pulse wave measuring device as claimed in claim 8, wherein the soft inner layer further comprises a plurality of auxiliary airbags, and the internal pressure of the auxiliary airbags is controlled by the pressure control module.

10. The radial displacement pulse wave measuring device as claimed in claim 1, wherein the pressure control module include: a pressure sensor for sensing the internal pressure of the transparent airbag; and A pressure adjustment module is used to adjust the internal pressure of the transparent airbag, wherein the pressure adjustment module includes a pump.

11. The radial displacement pulse wave measuring device as claimed in claim 10, wherein the pressure adjustment module further comprises a pulse width modulation circuit to adjust the rotation speed of the motor of the pump.

12. The radial displacement pulse wave measuring device as claimed in claim 1, wherein the displacement sensing module comprises a transmitter and a receiver, wherein the transmitter and the receiver are aligned with the transparent portion, and a measurement signal emitted by the transmitter can pass through the transparent portion and the transparent airbag.

13. The radial displacement pulse wave measuring device as claimed in claim 1, wherein the displacement sensing module comprises a photoelectric displacement sensor.

14. The radial displacement pulse wave measuring device as claimed in claim 13, wherein the photoelectric displacement sensor comprises a laser displacement meter, an optical fiber displacement meter, a three-dimensional scanning laser displacement meter, a time-of-flight distance measuring device, a three-dimensional time-of-flight distance measuring device, a laser Doppler rangefinder, a laser Doppler velocimeter, a scanning laser vibrometer, a Michelson interferometer or a laser interferometer distance measuring device.

15. The radial displacement pulse wave measuring device as claimed in claim 1, wherein the displacement sensing module further comprises a filter.

16. The radial displacement pulse wave measuring device as described in claim 1 further comprises a scanning position control module, which is communicatively connected to the calculation unit and is used to control the displacement sensing module to perform ranging scanning in the measured part, wherein the scanning position control module comprises a single-axis position controller or a dual-axis position controller.

17. A radial displacement pulse wave measuring device for measuring a radial displacement pulse wave of an artery of a measured part of a subject, the radial displacement pulse wave measuring device comprising: A housing having a transparent portion, wherein the transparent portion includes a hole or a first transparent plate; A non-transparent airbag, located below the transparent portion, the main body material of the non-transparent airbag is a material that is not easily stretched and deformed, the non-transparent airbag includes a transparent window, overlapping with the transparent portion of the shell, the transparent window includes a transparent material that is not easily stretched and deformed or a second transparent plate; a pressure control module, used to control the internal pressure of the transparent airbag, so as to control the downward pressure applied by the transparent airbag to the part to be measured, so as to amplify the pulse signal of the artery; a displacement sensing module, located above the transparent portion, for sensing the pulse of the artery, measuring the dynamic distance between the skin of the measured part and the displacement sensing module caused by the pulse of the artery, so as to obtain the radial displacement pulse wave; and A calculation unit is respectively connected to the pressure control module and the displacement sensing module for communication, and is used to transmit control signals to the pressure control module and the displacement sensing module respectively, and to receive information transmitted by the pressure control module and the displacement sensing module respectively and perform calculations.

18. The radial displacement pulse wave measuring device as claimed in claim 17, wherein the transparent material that is not easily stretched and deformed of the main body material of the non-transparent airbag comprises polymethyl methacrylate, cellulose acetate, nylon-66 polyamide resin, nylon-6 polyamide resin, polybutylene terephthalate, polyethylene terephthalate, polyphenylene, polycarbonate, ethylene-vinyl acetate copolymer, polyethylene, polypropylene, polyvinyl chloride, polyacetal or polyurethane, glass, quartz, polystyrene or acrylonitrile-butadiene-styrene copolymer.

19. The radial displacement pulse wave measuring device as claimed in claim 17, wherein the transparent material of the transparent window that is not easily stretched and deformed comprises polymethyl methacrylate, cellulose acetate, nylon-66 polyamide resin, nylon-6 polyamide resin, polybutylene terephthalate, polyethylene terephthalate, polyphenylene, polycarbonate, ethylene-vinyl acetate copolymer, polyethylene, polypropylene, polyvinyl chloride, polyacetal or polyurethane, glass, quartz, polystyrene or acrylonitrile-butadiene-styrene copolymer.

20. The radial displacement pulse wave measuring device as claimed in claim 17, wherein an anti-reflection film is formed on the outer surface of the transparent window.

21. The radial displacement pulse wave measuring device as claimed in claim 17, wherein when the transparent portion is the hole, the transparent window is the second transparent plate.

22. The radial displacement pulse wave measuring device as described in claim 21, wherein the area of ​​the second transparent plate is larger than the area of ​​the hole, and when the internal pressure of the transparent airbag is too large, the second transparent plate will press against the bottom of the hole and will not be squeezed above the hole.

23. The radial displacement pulse wave measuring device as claimed in claim 17, wherein an anti-reflection film is formed on the outer surface of the transparent window.

24. The radial displacement pulse wave measuring device as described in claim 17, wherein the non-transparent airbag further comprises a contact portion, wherein the contact portion is used to closely fit the skin of the measured part of the subject, and the material of the contact portion is a soft and stretchable thermoplastic elastomer polymer material, and the thermoplastic elastomer polymer material comprises at least one material selected from thermoplastic polyurethane, polyolefin elastomer, dynamically vulcanized polyolefin elastomer, polystyrene elastomer, polyether ester elastomer, polyamide elastomer, and polyvinyl chloride.

25. The radial displacement pulse wave measuring device as claimed in claim 24, wherein a reflective layer or a color separation layer is provided on the inner surface of the contact portion.

26. The radial displacement pulse wave measuring device as claimed in claim 17, further comprising a wearable part, so that the limb part of the subject where the part to be measured is located is accommodated in the internal space of the wearable part, and the wearable part comprises: a soft inner layer, comprising the non-transparent airbag; and A hard outer layer is located outside the soft inner layer to form an internal space of the wearable part together with the soft inner layer. During the measurement of the radial displacement pulse wave, the hard outer layer maintains a fixed distance from the displacement sensing module to the farthest point on the hard outer layer from the displacement sensing module.

27. The radial displacement pulse wave measuring device as claimed in claim 26, wherein the soft inner layer further comprises a plurality of auxiliary airbags, and the internal pressure of the auxiliary airbags is controlled by the pressure control module.

28. The radial displacement pulse wave measuring device as claimed in claim 17, wherein the pressure control module include: a pressure sensor for sensing the internal pressure of the non-transparent airbag; and A pressure adjustment module is used to adjust the internal pressure of the non-transparent airbag, wherein the pressure adjustment module includes a pump.

29. The radial displacement pulse wave measuring device as claimed in claim 28, wherein the pressure adjustment module further comprises a pulse width modulation circuit to adjust the rotation speed of the motor of the pump.

30. The radial displacement pulse wave measuring device as claimed in claim 17, wherein the displacement sensing module comprises a transmitter and a receiver, wherein the transmitter and the receiver are aligned with the transparent portion, and a measurement signal emitted by the transmitter can pass through the transparent portion and the transparent window.

31. The radial displacement pulse wave measuring device as claimed in claim 17, wherein the displacement sensing module comprises a photoelectric displacement sensor.

32. The radial displacement pulse wave measuring device as described in claim 31, wherein the photoelectric displacement sensor comprises a laser displacement meter, an optical fiber displacement meter, a three-dimensional scanning laser displacement meter, a time-of-flight distance measuring device, a three-dimensional time-of-flight distance measuring device, a laser Doppler rangefinder, a laser Doppler velocimeter, a scanning laser vibrometer, a Michelson interferometer or a laser interferometer distance measuring device.

33. The radial displacement pulse wave measuring device as claimed in claim 17, wherein the displacement sensing module further comprises a filter.

34. The radial displacement pulse wave measuring device as described in claim 17 further comprises a scanning position control module, which is communicatively connected to the calculation unit and is used to control the displacement sensing module to perform ranging scanning in the measured part, wherein the scanning position control module comprises a single-axis position controller or a dual-axis position controller.

35. A method for optimizing measurement conditions of a blood vessel radial displacement pulse wave, wherein the Y axis is defined as being substantially perpendicular to the direction of the artery and substantially parallel to the skin surface of the portion to be measured, the method comprising: A device for measuring radial displacement pulse waves as described in any one of claims 1 to 34; The transparent airbag or the non-transparent airbag is placed on the skin of the to-be-tested part of the subject, and the displacement sensing module is stopped at the initial position, wherein the displacement sensing module is a point-type displacement sensor or a matrix-type displacement sensor; The pressure of the transparent airbag or the non-transparent airbag is maintained at a first pressure, and after the transparent airbag or the non-transparent airbag is pressed down to a first depth on the part to be measured, the displacement sensing module is scanned along the Y axis on the surface of the part to be measured until a first measurement position at which the maximum amplitude signal of the radial displacement pulse wave of the artery is found; Allowing the displacement sensing module to stay at the first measuring position, adjusting the pressure of the transparent airbag or the non-transparent airbag, and finding a second pressure applied when the maximum signal of the radial displacement pulse wave of the blood vessel of the artery is reached; and The pressure of the transparent airbag or the non-transparent airbag is maintained at the second pressure, so that the transparent airbag or the non-transparent airbag presses the measured part to a second depth, wherein the first measurement position and the second depth serve as measurement conditions for the radial displacement pulse wave of the blood vessel of the artery.

36. The method for optimizing the measurement conditions of the vascular radial displacement pulse wave as described in claim 35, wherein the first pressure is applied by gradually increasing the pressure of the transparent airbag or the non-transparent airbag, allowing the transparent airbag or the non-transparent airbag to vertically press down the measured part until the maximum amplitude signal of the vascular volume pulse wave of the artery is found.

37. The method for optimizing the measurement conditions of the vascular radial displacement pulse wave as described in claim 35 further comprises allowing the displacement sensing module to scan along the direction of the artery until a second measurement position at the local maximum signal of the vascular radial displacement pulse wave of the artery is found, so as to replace the first measurement position as the measurement condition of the vascular radial displacement pulse wave of the artery.

38. A method for optimizing the measurement conditions of a blood vessel radial displacement pulse wave, the method comprising: Finding a first measurement position above the artery of the part to be measured of the subject; A device for measuring radial displacement pulse waves as described in any one of claims 1 to 34; Placing the transparent airbag or the non-transparent airbag on the skin of the subject's part to be tested; Align the displacement sensing module to the first measuring position, wherein the displacement sensing module is a point-type displacement sensor or a matrix-type displacement sensor; Gradually increase the pressure of the transparent airbag or the non-transparent airbag, and allow the transparent airbag or the non-transparent airbag to vertically press down the part to be measured until a measuring pressure is applied when the maximum signal of the vascular radial displacement pulse wave of the artery is found, maintain the pressure of the transparent airbag or the non-transparent airbag at the measuring pressure, and allow the transparent airbag or the non-transparent airbag to press down the part to be measured to a measuring depth, wherein the first measuring position and the measuring depth serve as measurement conditions for the vascular radial displacement pulse wave of the artery.

39. The method for optimizing the measurement conditions of the vascular radial displacement pulse wave as described in claim 38 further comprises allowing the displacement sensing module to scan along the direction of the artery until a second measurement position at which the local maximum signal of the vascular radial displacement pulse wave of the artery is found, so as to replace the first measurement position as the measurement condition of the vascular radial displacement pulse wave of the artery.

40. A method for optimizing measurement conditions of a blood vessel radial displacement pulse wave, the method comprising: A device for measuring radial displacement pulse waves as described in any one of claims 1 to 34; Placing the transparent airbag or the non-transparent airbag on the skin of the subject's part to be tested; Maintaining the pressure of the transparent airbag or the non-transparent airbag at a first pressure; Move the displacement sensing module to the top of the part to be measured, wherein the displacement sensing module is a matrix displacement sensor having a measurement area, and the measurement area is intersected with the direction of the blood vessel; Finding one of the point-type displacement sensors that measures a maximum amplitude signal indicates that the one of the point-type displacement sensors is located at a first measuring position; Adjusting the pressure of the transparent airbag or the non-transparent airbag to find a second pressure applied when the maximum signal of the vascular radial displacement pulse wave of the artery is reached; and The pressure of the transparent airbag or the non-transparent airbag is maintained at the second pressure, so that the transparent airbag or the non-transparent airbag presses the measured part to a second depth, wherein the first measurement position and the second depth serve as measurement conditions for the radial displacement pulse wave of the blood vessel of the artery.

41. The method for optimizing the measurement conditions of the vascular radial displacement pulse wave as described in claim 40, wherein the first pressure is applied by gradually increasing the pressure of the transparent airbag or the non-transparent airbag, allowing the transparent airbag or the non-transparent airbag to vertically press down the measured part until the maximum amplitude signal of the vascular volume pulse wave of the artery is found.

42. The method for optimizing the measurement conditions of the vascular radial displacement pulse wave as described in claim 40 further comprises allowing the displacement sensing module to scan along the direction of the artery until a second measurement position at the local maximum signal of the vascular radial displacement pulse wave of the artery is found, so as to replace the first measurement position as the measurement condition of the vascular radial displacement pulse wave of the artery.

43. A method for measuring blood pressure, comprising: A device for measuring radial displacement pulse waves as described in any one of claims 1 to 34; Placing the transparent airbag or the non-transparent airbag on the part to be tested; Using the blood vessel radial displacement pulse wave measurement condition optimization method described in any one of claims 35 to 42 to find the position of the artery of the subject's test portion to measure the blood vessel radial displacement pulse wave of the artery; gradually pressurizing the transparent balloon or the non-transparent balloon until the radial displacement pulse wave of the blood vessel of the artery appears and then disappears; gradually depressurizing the transparent balloon or the non-transparent balloon until the radial displacement pulse wave of the artery begins to appear, and the pressure of the transparent balloon or the non-transparent balloon is the systolic pressure of the artery; and Allow the transparent airbag or the non-transparent airbag to continue to gradually release pressure until the vascular radial displacement pulse wave of the artery begins to disappear, and the pressure of the transparent airbag or the non-transparent airbag is the diastolic pressure of the artery.

44. A method for measuring pulse wave velocity, comprising: While simultaneously recording an electrocardiogram, at a proximal measurement position of a proximal artery of a subject closer to the heart, a proximal radial displacement pulse wave is measured using a radial displacement pulse wave measuring device as described in any one of claims 1 to 34; Simultaneously record the radial displacement pulse wave of the proximal artery and the electrocardiogram of the subject to obtain the delay time T of one proximal radial displacement pulse wave of the proximal artery relative to the R wave of the electrocardiogram. 1 ; While simultaneously recording an electrocardiogram, using the radial displacement pulse wave measuring device to measure a distal radial displacement pulse wave at a distal measurement position on a distal artery of the subject that is farther from the heart; Simultaneously record the radial displacement pulse wave of the distal artery and the electrocardiogram of the subject to obtain the delay time T of one of the distal radial displacement pulse waves of the distal artery relative to the R wave of the electrocardiogram. 2 ; Calculate T 1 and T 2 The delay time difference ΔT = T 2 -T 1 ; measuring a distance ΔD between the proximal arterial site and the distal arterial site; and Calculate the pulse wave velocity PWV = ΔD / ΔT.

45. The pulse wave velocity measurement method as described in claim 44, wherein the proximal measurement position and the distal measurement position are the first measurement position found using the measurement condition optimization method for the vascular radial displacement pulse wave as described in claim 35, 36, 38, 40 or 41, or the second measurement position found using the measurement condition optimization method for the vascular radial displacement pulse wave as described in claim 37, 39 or 42.

46. ​​A method for measuring pulse wave velocity, comprising: Without recording an electrocardiogram, measuring a proximal radial displacement pulse wave at a proximal measurement position of a proximal artery of the subject closer to the heart; Without recording an electrocardiogram, a distal radial displacement pulse wave is simultaneously measured at a distal measurement position on a distal artery of the subject that is farther from the heart, wherein the proximal measurement position and the distal measurement position use one or two radial displacement pulse wave measuring devices as described in any one of claims 1 to 34 to simultaneously measure the proximal radial displacement pulse wave and the distal radial displacement pulse wave; Calculating a delay time difference ΔT between the proximal radial displacement pulse wave and the distal radial displacement pulse wave; measuring a distance ΔD between the proximal arterial site and the distal arterial site; and Calculate the pulse wave velocity PWV = ΔD / ΔT.

47. The pulse wave velocity measurement method as described in claim 46, wherein the proximal measurement position and the distal measurement position are the first measurement position found by the measurement condition optimization method of the vascular radial displacement pulse wave as described in claim 35, 36, 38, 40 or 41, or the second measurement position found by the measurement condition optimization method of the vascular radial displacement pulse wave as described in claim 37, 39 or 42.

48. A method for continuous measurement of blood pressure, comprising: Using the blood pressure measurement method as described in claim 43, measuring the diastolic blood pressure of the subject in the initial state and a corresponding first depression depth of the transparent airbag or the non-transparent airbag on the measured part, and the systolic blood pressure in the initial state and a corresponding second depression depth of the transparent airbag or the non-transparent airbag, wherein the difference between the first depression depth and the second depression depth is the blood vessel diameter R of the subject; Calculating the change in blood vessel diameter ΔR of the subject from the graph of the radial displacement pulse wave of the subject that changes with time; Measuring the pulse wave velocity PWV of the subject using the pulse wave velocity measurement method as described in any one of claims 44 to 47; Obtain the blood density ρ of the subject; The blood pressure change ΔP is calculated using the following Branwell-Hill formula: as well as The real-time systolic blood pressure (=initial systolic blood pressure+ΔP) and real-time diastolic blood pressure (=initial diastolic blood pressure+ΔP) of the subject are calculated.

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