JP7224016B2 - Blood vessel diameter sensor and blood vessel diameter measuring device - Google Patents

Description

The present invention relates to a blood vessel diameter sensor and a blood vessel diameter measuring device using ultrasonic waves.

Conventionally, there is known a blood vessel diameter sensor that measures the diameter of a blood vessel such as an arterial blood vessel using ultrasonic waves (for example, Patent Document 1). Measurement using ultrasound has many advantages, such as no radiation exposure unlike CT, use for pregnant women or fetuses, and real-time measurement.

JP 2014-111209 A

When measuring a blood vessel diameter using a blood vessel diameter sensor, the blood vessel diameter sensor is attached to the neck or the forearm. At this time, the attachment position of the blood vessel diameter sensor may deviate due to the skill level of the measurer or the individual difference of the person to be measured. Also, an ultrasonic element used in a blood vessel diameter sensor is made of a hard material such as piezoelectric ceramics and arranged on a planar substrate. On the other hand, since the blood vessel to be measured has a circular cross section, the more the position of the blood vessel diameter sensor shifts from the measurement target, the greater the incident angle of the ultrasonic waves. In addition to misalignment when attaching the sensor, if the part of the body to which the sensor is attached, such as the neck or forearm, is rotated, the blood vessel diameter sensor attached to the body surface and the measurement target inside the body will be misaligned, resulting in a large incident angle of the ultrasonic waves. Become. As a result, the reflected signal cannot be received , or the measurement accuracy of the blood vessel diameter is lowered.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a blood vessel diameter sensor and a blood vessel diameter measuring device capable of suppressing deterioration in measurement accuracy due to positional deviation.

A blood vessel diameter sensor according to the present invention is a blood vessel diameter sensor that is attached to the epidermis of a human body, and includes a flexible substrate and a plurality of ultrasonic elements arranged in a row in the lateral direction on the substrate. The plurality of ultrasonic elements transmit ultrasonic waves and receive reflected signals from the object to be measured, and the ultrasonic wave transmission/reception surface formed by the plurality of ultrasonic elements is concave, Even if it is attached to a non-flat area, the transmitting/receiving surface is in close contact with the attached area .

As described above, according to the present invention, by making the transmitting/receiving surface of ultrasonic waves formed by a plurality of ultrasonic elements concave, it is possible to prevent positional deviation when attaching the blood vessel diameter sensor , or to Even when the body part rotates , it is possible to suppress the incident angle of the ultrasonic wave to the blood vessel from becoming large, to suppress the inability to receive the reflected signal, and to suppress the deterioration of the measurement accuracy of the blood vessel diameter.

1 is a schematic configuration diagram of a blood vessel diameter measuring device according to Embodiment 1. FIG. 1 is a schematic configuration diagram of a blood vessel diameter sensor according to Embodiment 1. FIG. 4A and 4B are diagrams for explaining the driving of the blood vessel diameter sensor according to the first embodiment; FIG. FIG. 4 is a schematic configuration diagram of a blood vessel diameter sensor according to Modification 1 of Embodiment 1; FIG. 10 is a schematic configuration diagram of a blood vessel diameter sensor in Modification 2 of Embodiment 1; FIG. 10 is a schematic configuration diagram of a blood vessel diameter sensor in Modification 3 of Embodiment 1; FIG. 11 is an external perspective view of an ultrasonic element in Modification 4 of Embodiment 1; FIG. 11 is an external perspective view of an ultrasonic element in Modification 5 of Embodiment 1; FIG. 11 is a diagram for explaining driving of a blood vessel diameter sensor in Modification 6 of Embodiment 1; FIG. 20 is a diagram illustrating driving of a blood vessel diameter sensor in Modification 7 of Embodiment 1; FIG. 10 is a schematic configuration diagram of a blood vessel diameter sensor according to Embodiment 2; FIG. 10 is a diagram illustrating a method for estimating the position of a blood vessel according to Embodiment 2; FIG. FIG. 10 is a schematic configuration diagram of a blood vessel diameter sensor in Modification 1 of Embodiment 2; FIG. 11 is a schematic configuration diagram of a blood vessel diameter sensor in Modification 2 of Embodiment 2; FIG. 11 is a schematic configuration diagram of a blood vessel diameter sensor in Modification 3 of Embodiment 2; FIG. 11 is a schematic configuration diagram of a blood vessel diameter measuring device according to Modification 4 of Embodiment 2; FIG. 11 is a schematic configuration diagram of a blood vessel diameter sensor according to Embodiment 3;

Embodiment 1.
A blood vessel diameter sensor 1 and a blood vessel diameter measuring device 100 according to Embodiment 1 of the present invention will be described below. FIG. 1 is a schematic configuration diagram of a blood vessel diameter measuring device 100 according to Embodiment 1. As shown in FIG. As shown in FIG. 1, the blood vessel diameter measuring device 100 includes a blood vessel diameter sensor 1, a pulser receiver 2, a control device 3, and a display device 4.

As shown in FIG. 1 , the pulser receiver 2 transmits a drive signal (pulse voltage) to the blood vessel diameter sensor 1 and receives a reflected signal from the blood vessel diameter sensor 1 . The blood vessel diameter sensor 1 is attached to the epidermis of the human body via ultrasonic gel or an ultrasonic gel sheet, and is driven by the pulser receiver 2 to transmit ultrasonic waves to the epidermis of the human body. The blood vessel diameter sensor 1 receives a reflected signal from the inner side of the anterior wall of the blood vessel and a reflected signal from the inner side of the posterior wall of the blood vessel (the boundary between the blood and the inner wall of the blood vessel), and transmits them to the pulser receiver 2 . The pulser receiver 2 transmits the received reflected signal to the control device 3 .

The control device 3 is composed of a PC or the like having a CPU and a memory. The control device 3 controls driving of the blood vessel diameter sensor 1 by the pulser receiver 2 and obtains the blood vessel diameter d based on the reflected signal received by the pulser receiver 2 . Note that the blood vessel diameter d is the inner diameter of the blood vessel. Specifically, the control device 3 measures the reception time of the reflected signal from the inner side of the anterior wall of the blood vessel and the reflected signal from the inner side of the posterior wall of the blood vessel. Then, the time difference is converted into a distance using the speed of sound as in the following formula (1), and the blood vessel diameter d is calculated.

なお、式（１）の「Ｃ」は音速であり、「ｔ１」は血管前壁の内側からの反射信号を受信した時間であり、「ｔ２」は血管後壁の内側からの反射信号を受信した時間である。

In addition, "C" in Equation (1) is the speed of sound, "t1" is the time at which the reflected signal is received from the inside of the anterior wall of the blood vessel, and "t2" is the time at which the reflected signal is received from the inside of the posterior wall of the blood vessel. It's time to

The reflected signal received by the pulser receiver 2 may be displayed on a display 4 such as an oscilloscope. It should be noted that the pulser receiver 2 may also serve as the control device 3 . Alternatively, the control device 3 may also serve as the display device 4 .

FIG. 2 is a schematic diagram of the blood vessel diameter sensor 1 according to the first embodiment. As shown in FIG. 2 , the blood vessel diameter sensor 1 of this embodiment includes a substrate 11 and a plurality of ultrasonic elements 12 arranged on the substrate 11 . The substrate 11 is made of a flexible material such as polyimide or vinyl chloride. In addition, it is desirable that the substrate 11 has flexibility and does not expand or contract.

The ultrasonic element 12 is made of piezoelectric ceramics or the like, transmits ultrasonic waves to an object to be measured, and receives reflected signals from the object to be measured. The plurality of ultrasonic elements 12 have a rectangular parallelepiped shape and are arranged in a line in the horizontal direction across a gap. In the example of FIG. 2, the ultrasonic elements 12 have a vertically long shape and are arranged so that the long sides of adjacent ultrasonic elements 12 face each other. The vertical length L of the ultrasonic element 12 is, for example, 0.2 to 2.0 mm. The horizontal pitch P of the ultrasonic elements 12 is 0.04 mm to 4.0 mm. The pitch P is the sum of the lateral width of the ultrasonic element 12 and the width of the air gap. The thickness of the ultrasonic element 12 is set according to the frequency of the applied pulse voltage. The number of ultrasonic elements 12 is not limited to the example in FIG. 2, and may be two or more.

As shown in FIG. 2, since the plurality of ultrasonic elements 12 are arranged on the substrate 11 having flexibility, the ultrasonic transmitting/receiving surface formed by the plurality of ultrasonic elements 12 can be concave. . More specifically, the horizontal cross-sectional shape of the ultrasonic transmission/reception surface formed by the plurality of ultrasonic elements 12 can be concaved toward the substrate side, for example curved. As a result, reflected signals from blood vessels can be received regardless of the positions of the ultrasonic elements 12, compared to the case where the transmitting/receiving surface formed by the plurality of ultrasonic elements 12 is flat.

The blood vessel diameter sensor 1 is manufactured using techniques such as photolithography and patterning, for example. A ground electrode (not shown) is arranged between the substrate 11 and the ultrasonic element 12 . Also, each ultrasonic element 12 is individually wired to the pulser receiver 2 . Thereby, each ultrasonic element 12 is driven individually.

3A and 3B are diagrams for explaining the driving of the blood vessel diameter sensor 1 according to the first embodiment. As shown in FIG. 3, in the present embodiment, adjacent ultrasonic elements 12 among the ultrasonic elements 12a to 12g are simultaneously driven. In the example of FIG. 3, three ultrasonic elements 12c, 12d and 12e are driven simultaneously. As a result, even when the ultrasonic element 12 is small, it is possible to generate an ultrasonic beam and measure the depth of the object to be measured. The number and positions of the ultrasonic elements 12 to be driven are not limited to the example in FIG. 3, and are set according to the object to be measured.

As described above, according to the present embodiment, by providing the substrate 11 having flexibility, the transmitting/receiving surface of ultrasonic waves formed by the plurality of ultrasonic elements 12 can be made concave. As a result, even when the blood vessel diameter sensor 1 is attached and misaligned, it is possible to suppress an increase in the angle of incidence of the ultrasonic waves on the blood vessel, thereby suppressing deterioration in measurement accuracy of the blood vessel diameter. In addition, even when the blood vessel diameter sensor 1 is attached to a non-flat location such as a human body, the transmitting and receiving surfaces of the blood vessel diameter sensor 1 can be brought into close contact with each other.

The configuration of the blood vessel diameter sensor 1 is not limited to the example of FIG. 2, and various modifications are possible. FIG. 4 is a schematic configuration diagram of a blood vessel diameter sensor 1A according to Modification 1 of Embodiment 1. As shown in FIG. As shown in FIG. 4, the gaps between adjacent ultrasonic elements 12 may be filled with a material 13 having flexibility. The flexible material 13 is, for example, silicone resin or polyurethane. As a result, the blood vessel diameter sensor 1 can have flexibility as a composite structure (in this case, a 2-2 composite structure), and the efficiency of ultrasonic wave transmission and reception to and from the living body can be improved.

Also, the gaps between adjacent ultrasonic elements 12 may be filled with a hard substance. In this case, the plurality of ultrasonic elements 12 may be fixed in a state in which the ultrasonic transmission/reception surface formed by the plurality of ultrasonic elements 12 is set to have a desired concave shape. Also in this case, the same effect as in the first embodiment can be obtained.

FIG. 5 is a schematic configuration diagram of a blood vessel diameter sensor 1B according to Modification 2 of Embodiment 1. As shown in FIG. As shown in FIG. 5, a flexible film 14 covering the transmission/reception surface of the ultrasonic element 12 may be provided. The flexible film 14 is made of polyimide, for example. By providing the flexible film 14, the function as an acoustic matching layer can be provided, and ultrasonic waves can be efficiently transmitted and received. Moreover, by covering the transmitting/receiving surface of the ultrasonic element 12 with the flexible film 14, deterioration of the ultrasonic element 12 can be suppressed, and the transmitting/receiving surface can be easily wiped, thereby improving sanitation.

FIG. 6 is a schematic configuration diagram of a blood vessel diameter sensor 1C according to Modification 3 of Embodiment 1. As shown in FIG. As shown in FIG. 6, a backing 15 may be provided between the ultrasonic element 12 and the substrate 11, more specifically between an electrode (not shown) and the substrate 11. As shown in FIG. The backing 15 may be provided corresponding to each ultrasonic element 12 as shown in FIG. 6(a), or may be provided for a plurality of ultrasonic elements 12 as shown in FIG. 6(b). Two backings 15 may be provided. When one backing 15 is provided for a plurality of ultrasonic elements 12, the backing 15 also needs to be flexible. The backing 15 is a damping material, and is made of, for example, a mixture of epoxy resin and tungsten powder. By providing the backing 15, it is possible to attenuate unnecessary vibrations of the ultrasonic element 12 and shorten the pulse width of the ultrasonic waves. In addition, the backing 15 can suppress return of ultrasonic waves from the substrate 11 side.

Further, the shape of the ultrasonic element 12 in the blood vessel diameter sensor 1 is not limited to the example of FIG. 2, and various modifications are possible. FIG. 7 is an external perspective view of an ultrasonic element 12A in Modification 4 of Embodiment 1. FIG. As shown in FIG. 7, the surface forming the transmitting/receiving surface of the ultrasonic element 12 may be configured such that the vertical cross-sectional shape is concave toward the substrate 11 side.

FIG. 8 is an external perspective view of an ultrasonic element 12B according to Modification 5 of Embodiment 1. FIG. As shown in FIG. 8, an acoustic lens 120 may be provided on the surface forming the transmitting/receiving surface of the ultrasonic element 12 . The acoustic lens 120 is made of a material such as polyvinylidene fluoride that has an appropriate acoustic impedance on the surface of the ultrasonic oscillation surface, and has a convex shape with respect to the transmission direction of ultrasonic waves.

With the configuration of Modification 4 or Modification 5, it is possible to suppress the spread of transmitted ultrasonic waves and obtain a stronger reflected signal from the object to be measured. The acoustic lens 120 may cover each ultrasonic element 12 or may cover a plurality of adjacent ultrasonic elements 12 .

Further, the driving of the blood vessel diameter sensor 1 is not limited to the example of FIG. 3, and various modifications are possible. FIG. 9 is a diagram for explaining driving of blood vessel diameter sensor 1 in Modification 6 of Embodiment 1. In FIG. In FIG. 3, the plurality of adjacent ultrasonic elements 12 are driven simultaneously, but as shown in FIG. 9, the plurality of ultrasonic elements 12 may be driven with a time lag.

For example, as shown in FIG. 9A, first, the ultrasonic elements 12b and 12f located second from the outside are driven, and after a predetermined time has passed, the ultrasonic elements 12c and 12e located third from the outside are driven. After a predetermined period of time has elapsed, the central ultrasonic element 12d may be driven. As a result, linear ultrasonic waves can be transmitted, and the transmission width in the vicinity of the epidermis can be widened.

Alternatively, as shown in FIG. 9B, the ultrasonic elements 12b to 12f may be sequentially driven with a time lag. As a result, the incident angle of the ultrasonic beam can be adjusted, and wide-angle measurement in the deep part becomes possible.

Furthermore, a configuration may be adopted in which the plurality of ultrasonic elements 12 used for measuring the blood vessel diameter are automatically determined according to the positional relationship with the blood vessel. 10A and 10B are diagrams for explaining the driving of the blood vessel diameter sensor 1 in Modification 7 of Embodiment 1. FIG. In this modification, the pulser receiver 2 sequentially drives a group of adjacent ultrasonic elements among the ultrasonic elements 12a to 12g. Specifically, the ultrasonic elements 12a, 12b, and 12c are driven first, and then the ultrasonic elements 12b, 12c, and 12d are driven. Then, the ultrasonic elements 12c, 12d, and 12e, then the ultrasonic elements 12d, 12e, and 12f are shifted one by one, and each group is driven. The number of ultrasonic elements in one group is not limited to three. Then, the control device 3 determines the group that received the strongest reflected signal, and controls the pulser receiver 2 so that the ultrasonic elements 12 included in the group are used to measure the blood vessel diameter.

For example, in FIG. 10(a), group G1 including ultrasonic elements 12c, 12d and 12e is driven. In FIG. 10(b), group G2 including ultrasonic elements 12d, 12e and 12f is driven. Here, since the group G2 is positioned above the blood vessel, it receives a stronger reflected signal than the group G1. Therefore, the ultrasonic elements 12d, 12e, and 12f included in group G2 are used to measure the blood vessel diameter.

According to Modified Example 7, even if the attachment position of the blood vessel diameter sensor is displaced from the blood vessel, or if the position is displaced after attachment, the ultrasonic element 12 positioned above the blood vessel is used. Blood vessel diameter can be measured. As a result, it is possible to suppress deterioration in the measurement accuracy of the blood vessel diameter measuring device 100 even when positional displacement occurs.

Embodiment 2.
Next, Embodiment 2 of the present invention will be described. A blood vessel diameter sensor 20 of the present embodiment differs from that of the first embodiment in that it consists of two blood vessel diameter sensors 10A and 10B. Other configurations of blood vessel diameter measuring apparatus 100 are the same as those of the first embodiment.

FIG. 11 is a schematic configuration diagram of blood vessel diameter sensor 20 according to the second embodiment. As shown in FIG. 11, the blood vessel diameter sensor 20 comprises a flexible sheet 16, and blood vessel diameter sensors 10A and 10B arranged in a row on the flexible sheet 16 with a predetermined distance therebetween. Blood vessel diameter sensor 10A and blood vessel diameter sensor 10B each have the same configuration as blood vessel diameter sensor 1 in the first embodiment.

In the present embodiment, control device 3 estimates the position of the blood vessel from the reflection signals received by blood vessel diameter sensor 10A and blood vessel diameter sensor 10B. FIG. 12 is a diagram explaining a method for estimating the position of a blood vessel according to the second embodiment. To estimate the position of the blood vessel, first, the controller 3 determines the position where the strongest reflected signal is received by the blood vessel diameter sensor 10A and the position where the strongest reflected signal is received by the blood vessel diameter sensor 10B. Here, as described in Modification 7 of Embodiment 1, the ultrasonic elements 12 are sequentially driven to determine the position where the strongest reflected signal is received. In the example of FIG. 12, it is assumed that the position of the ultrasonic element 12g of the blood vessel diameter sensor 10A and the position of the ultrasonic element 12d of the blood vessel diameter sensor 10B receive the strongest reflected signals.

Then, the control device 3 estimates that the blood vessel runs along the line L1 connecting the ultrasonic element 12g of the blood vessel diameter sensor 10A and the ultrasonic element 12d of the blood vessel diameter sensor 10B. Then, the angle of the line L1 connecting the ultrasonic elements 12g and 12d with respect to the line L2 connecting the center of the blood vessel diameter sensor 10A and the center of the blood vessel diameter sensor 10B is determined. The angle θ between the running of the blood vessel and the In other words, the angle θ is the inclination of the running blood vessel with respect to the vertical direction of the ultrasonic element 12 in the blood vessel diameter sensor 10A and the blood vessel diameter sensor 10B. The control device 3 may display the angle θ on the display 4 . Further, when the angle θ exceeds a threshold value, the control device 3 may notify the measurement person of the positional deviation of the blood vessel diameter sensor 20 or correct the measured blood vessel diameter based on the angle θ.

As described above, in the present embodiment, even when the blood vessel diameter sensor 20 is attached with a positional deviation, the positional deviation is detected, the position of the blood vessel is estimated, and the measurement person is notified or the measured value is detected. can be corrected. As a result, the measurement person can appropriately correct the positional deviation, thereby suppressing a decrease in measurement accuracy of the blood vessel diameter.

The configuration of the blood vessel diameter sensor 20 is not limited to the example of FIG. 11, and various modifications are possible. FIG. 13 is a schematic configuration diagram of a blood vessel diameter sensor 20A according to Modification 1 of Embodiment 2. As shown in FIG. As shown in FIG. 13, a blood vessel diameter sensor 10A and a blood vessel diameter sensor 10B may be arranged on a flexible sheet 16, respectively, and connected by a connecting portion 17 such as a cable.

Further, a display device such as an LED array for displaying the estimated position of the blood vessel may be further provided on the back surface of the flexible sheet 16 in the blood vessel diameter sensor 20 of the second embodiment. The back surface of the flexible sheet 16 refers to the surface on which the blood vessel diameter sensor 10A and the blood vessel diameter sensor 10B are not arranged. This allows the measurer to easily grasp the positional deviation between the blood vessel diameter sensor 20 and the blood vessel.

Alternatively, the estimated position of the blood vessel may be displayed on the skin to which the blood vessel diameter sensor 20 is attached. FIG. 14 is a schematic configuration diagram of a blood vessel diameter sensor 20B according to Modification 2 of Embodiment 2. As shown in FIG. As shown in FIG. 14, the flexible sheet 16A of the blood vessel diameter sensor 20B of this modification has an opening 18 between the blood vessel diameter sensor 10A and the blood vessel diameter sensor 10B. A display device 19 is provided near the opening 18 on the back surface of the flexible sheet 16A. The display device 19 comprises, for example, a light source and a microscanner, and is controlled by the control device 3 . The display device 19 displays running blood vessels by irradiating light on the skin of the opening 18 . As a result, the measurement person can grasp the course of the blood vessel, which can be used as a mark when collecting blood.

FIG. 15 is a schematic configuration diagram of a blood vessel diameter sensor 20C according to Modification 3 of Embodiment 2. As shown in FIG. This modification is obtained by applying the second modification of the second embodiment to the first modification of the second embodiment. In this case, the connecting portion 17 is arranged offset from the center of the flexible sheet 16 . As a result, a space for displaying the running of the blood vessel can be secured between the blood vessel diameter sensor 10A and the blood vessel diameter sensor 10B.

Furthermore, as a fourth modification of the second embodiment, control device 3 may measure the hardness of the blood vessel wall and the intravascular pressure based on the reflected signals received by blood vessel diameter sensor 10A and blood vessel diameter sensor 10B. FIG. 16 is a schematic configuration diagram of a blood vessel diameter measuring device 100A according to Modification 4 of Embodiment 2. As shown in FIG.

Specifically, a pulse wave associated with contraction of the heart can be measured from changes in the blood vessel diameters measured by the blood vessel diameter sensors 10A and 10B. Then, the pulse wave velocity T is obtained from the distance between the blood vessel diameter sensors 10A and 10B and the difference in pulse wave propagation time between the blood vessel diameter sensors 10A and 10B.

Then, the stiffness of the artery is determined by the following Maens-Kortebeek equation (2), which indicates the relationship between the pulse wave velocity and the incremental elastic modulus of the arterial wall (when the blood pressure rises).

ここで、Ｅｉｎｃは増分弾性係数（血管壁の材質としての硬さ、ヤング率に相当）、ｈは壁の厚さ、ρは血液の密度、Ｔは脈波伝播速度、ｄは血管径（血管内径）である。図１６に示すように、深さ方向の分解能（距離分解能）が高い場合、血管径センサ２０によって、血管前壁と血管周囲組織の間の反射波、および血管後壁と血管周囲組織の間の反射波を計測することができ、血管の外径Ｄを測定することができる。そして、血管径（内径）ｄと外径Ｄとから、壁の厚さｈを計測できる。血管密度ρは文献値を用いることができる。または、血管径センサ２０装着時に一般的な血圧計であるカフ式の血圧計を一時的に用いて、血管径センサ２０装着時の最高血圧と最低血圧を計測する。そして、血管径センサ２０によって同時に計測した最大血管径と最小血管径の値を用いて、下記の式（３）からＥｉｎｃを求め、本センサにより測定したＴ、ｄ、ｈの値を用いてρを算出しても良い。

where Einc is the incremental elastic modulus (hardness of the vascular wall material, corresponding to Young's modulus), h is the wall thickness, ρ is the blood density, T is the pulse wave velocity, d is the vascular diameter (vascular inner diameter). As shown in FIG. 16, when the resolution in the depth direction (distance resolution) is high, the vascular diameter sensor 20 detects the reflected wave between the anterior wall of the blood vessel and the perivascular tissue and the reflected wave between the posterior wall of the blood vessel and the perivascular tissue. A reflected wave can be measured, and the outer diameter D of the blood vessel can be measured. Then, from the blood vessel diameter (inner diameter) d and the outer diameter D, the wall thickness h can be measured. A literature value can be used for the blood vessel density ρ. Alternatively, a cuff-type sphygmomanometer, which is a general sphygmomanometer, is temporarily used when the blood vessel diameter sensor 20 is attached to measure the systolic blood pressure and the diastolic blood pressure when the blood vessel diameter sensor 20 is attached. Then, using the values of the maximum blood vessel diameter and the minimum blood vessel diameter simultaneously measured by the blood vessel diameter sensor 20, Einc is obtained from the following equation (3), and the values of T, d, and h measured by this sensor are used to determine ρ can be calculated.

ここで、ΔＰは最高血圧－最低血圧、ΔＲｏは最大血管外半径－最小血管外半径、Ｒｉは最小血管内半径、Ｒｏは最小血管外半径、νはポアソン比で、値を０．５とする。その後は、カフ式の血圧計を外した後、求めたρの値を一定として血管径センサ２０により適宜計測したＴ、ｄ、ｈの値からＥｉｎｃを求めることができる。さらに求めたＥｉｎｃと計測した最小血管内半径、最小血管外半径および最大血管外半径の値を用いて式（３）からΔＰ（最高血圧－最低血圧）を求めることができる。

Here, ΔP is systolic blood pressure - diastolic blood pressure, ΔRo is maximum outer radius of blood vessel - minimum outer radius of blood vessel, Ri is minimum inner radius of blood vessel, Ro is minimum outer radius of blood vessel, ν is Poisson's ratio, and the value is 0.5. . After that, after removing the cuff-type sphygmomanometer, Einc can be obtained from the values of T, d, and h appropriately measured by the blood vessel diameter sensor 20 while keeping the obtained value of ρ constant. Furthermore, ΔP (systolic blood pressure - diastolic blood pressure) can be obtained from equation (3) using the obtained Einc and the measured values of the minimum inner vascular radius, the minimum outer vascular radius, and the maximum outer vascular radius.

In addition to using Einc as an index indicating the hardness of the blood vessel, as a simple method of indicating the hardness of the blood vessel, a cuff-type blood pressure gauge, which is a general blood pressure gauge, is temporarily used when the blood vessel diameter sensor 20 is attached. , the systolic blood pressure and the diastolic blood pressure are measured when the blood vessel diameter sensor 20 is attached. Then, using the values of the maximum blood vessel diameter and the minimum blood vessel diameter simultaneously measured by the blood vessel diameter sensor 20, the stiffness (difficulty in swelling when viewed as a tube) Ep can be presented as an index of blood vessel hardness from equation (4). good.
Ep=(systolic blood pressure-diastolic blood pressure)/{(maximum vessel diameter-minimum vessel diameter)/minimum vessel diameter} (4)

Furthermore, equation (5) obtained by modifying equation (4) may be used.
Ep / minimum vascular diameter=(systolic blood pressure-diastolic blood pressure)/(maximum vascular diameter-minimum vascular diameter) (5)
At this time, on a graph in which the horizontal axis is the blood vessel diameter and the vertical axis is the blood pressure, a line with a constant slope connecting the point of the maximum blood pressure and the maximum blood vessel diameter and the point of the minimum blood pressure and the minimum blood vessel diameter is drawn. Then, the blood pressure calculated from the pulse wave velocity and the blood vessel diameter measured by the blood vessel diameter sensor 20 are plotted on the above graph. In this case, the sympathetic nerve may be dominant when plotted above the line with a constant slope, and the parasympathetic nerve may be dominant when plotted below the line. Then, the gradient obtained by connecting the diastolic blood pressure/minimum blood vessel diameter points and the plotted points may be presented as the value of blood vessel hardness as Ep / minimum blood vessel diameter.

According to this modified example, the hardness and blood pressure of the blood vessel can be obtained in addition to the diameter of the blood vessel. Blood vessel stiffness is thought to reflect the tension associated with sympathetic nerve activity. Therefore, the blood vessel diameter sensor 20 can be used to detect stress reactions, abnormalities in circulating blood volume, and the like.

Embodiment 3.
Next, Embodiment 3 of the present invention will be described. A blood vessel diameter sensor 30 of the present embodiment differs from the second embodiment in that two blood vessel diameter sensors 10C and 10D are arranged with an inclination with respect to the blood vessel. Other configurations of blood vessel diameter measuring apparatus 100 are the same as those of the first embodiment. Blood vessel diameter sensor 10C and blood vessel diameter sensor 10D each have the same configuration as blood vessel diameter sensor 1 in the first embodiment.

FIG. 17 is a schematic configuration diagram of blood vessel diameter sensor 30 according to the third embodiment. The ultrasonic elements 12 in the blood vessel diameter sensor 10C and the blood vessel diameter sensor 10D are arranged in the depth direction on the paper surface. As shown in FIG. 17, in the present embodiment, on the flexible sheet 16, the transmitting and receiving surfaces of the two blood vessel diameter sensors 10C and 10D are inclined 45° with respect to the blood vessels and the flexible sheet 16. placed so that they are In addition, the blood vessel diameter sensor 10C and the blood vessel diameter sensor 10D are arranged so as to be inclined in directions facing each other.

In this embodiment, one blood vessel diameter sensor 10C is driven to transmit ultrasonic waves and the other blood vessel diameter sensor 10D is driven to receive reflected signals. The control device 3 can measure the blood flow velocity in the blood vessel from the Doppler frequency shift of the reflected signal from red blood cells moving in the blood vessel.

Also, the blood vessel diameter can be measured with the blood vessel diameter sensor 30 of the present embodiment. In this case, the blood vessel diameter is measured using either the blood vessel diameter sensor 10C or the blood vessel diameter sensor 10D. Specifically, as in the first embodiment, the blood vessel diameter sensor 10C transmits ultrasonic waves and receives reflected signals. Then, in the control device 3, the measured vascular diameter is corrected using the inclination (45°) of the vascular diameter sensor 10C, and the vascular diameter is obtained. Further, the control device 3 can obtain the blood flow rate from the blood flow velocity and the blood vessel diameter.

Further, as a first modification of the third embodiment, instead of arranging the blood vessel diameter sensor 10C and the blood vessel diameter sensor 10D at an angle, the vertical cross-sectional shape of the ultrasonic element 12 of the blood vessel diameter sensor 10C and the blood vessel diameter sensor 10D is changed. may be triangular and the transmitting/receiving plane may be inclined at 45°. As a result, the same state as shown in FIG. 17 (where the transmitting/receiving surfaces of the blood vessel diameter sensor 10C and the blood vessel diameter sensor 10D are inclined at 45° with respect to the flexible sheet 16) can be obtained.

Furthermore, as a second modification of the third embodiment, a blood vessel diameter sensor for measuring the blood vessel diameter may be additionally provided in addition to the blood vessel diameter sensor 10C and the blood vessel diameter sensor 10D. An additional vessel diameter sensor is positioned upstream or downstream of vessel diameter sensor 10C and vessel diameter sensor 10D at a predetermined distance from vessel diameter sensor 10C and vessel diameter sensor 10D. By providing an additional blood vessel diameter sensor, in addition to the blood vessel diameter and blood flow rate, the position and running of the blood vessel can be determined as in the second embodiment. In this case, the blood vessel diameter sensor 10A of the second embodiment is used as the additional blood vessel diameter sensor, and the blood vessel diameter sensor 10C or the blood vessel diameter sensor 10D is regarded as the blood vessel diameter sensor 10B.

Although the embodiments of the present invention have been described above, the present invention is not limited to the configurations of the above-described embodiments, and various modifications and combinations are possible within the technical scope of the invention. For example, Embodiments 1 to 3 and each modified example can be combined.

1, 1A, 1B, 1C, 10A, 10B, 10C, 10D, 20, 20A, 20B, 20C, 30 blood vessel diameter sensor, 2 pulser receiver, 3 controller, 4 indicator, 11 substrate, 12, 12A, 12B, 12a, 12b, 12c, 12d, 12e, 12f, 12g ultrasonic element, 13 substance, 14 flexible film, 15 backing, 16, 16A flexible sheet, 17 connector, 18 opening, 19 display device, 100, 100A vessel diameter measuring device, 120 acoustic lens.

Claims (16)

A blood vessel diameter sensor that is attached to the epidermis of a human body,
a flexible substrate;
a plurality of ultrasonic elements arranged in a row in the lateral direction on the substrate,
The plurality of ultrasonic elements transmit ultrasonic waves and receive reflected signals from the measurement object,
The transmitting/receiving surface of the ultrasonic wave formed by the plurality of ultrasonic elements is concave, and even when the ultrasonic wave transmitting/receiving surface is attached to a non-flat portion of the human body, the transmitting/receiving surface is in close contact with the attached portion. blood vessel diameter sensor. 2. The blood vessel diameter sensor according to claim 1, wherein the lateral cross-sectional shape of the transmitting/receiving surface is concave toward the substrate. 3. The blood vessel diameter sensor according to claim 1 , wherein the plurality of ultrasonic elements are arranged with a gap therebetween. 4. The blood vessel diameter sensor according to claim 3 , wherein said gap is filled with a material having flexibility. The blood vessel diameter sensor according to any one of claims 1 to 4 , further comprising a flexible membrane arranged on the transmitting/receiving surface. The blood vessel diameter sensor according to any one of claims 1 to 5 , further comprising a backing arranged between the substrate and the plurality of ultrasonic elements. The blood vessel according to any one of claims 1 to 6 , wherein the surfaces forming the transmitting/receiving surfaces of the plurality of ultrasonic elements have a vertical cross-sectional shape that is concave toward the substrate. diameter sensor. The blood vessel diameter sensor according to any one of claims 1 to 6 , further comprising an acoustic lens arranged on the transmitting/receiving surface. The vertical length of the plurality of ultrasonic elements is 0.2 to 2.0 mm, and the pitch of the plurality of ultrasonic elements in the horizontal direction is 0.04 to 4.0 mm. Item 9. The blood vessel diameter sensor according to any one of items 1 to 8 . a plurality of said substrates;
the plurality of ultrasonic elements arranged on each of the plurality of substrates;
The blood vessel diameter according to any one of claims 1 to 9 , characterized by comprising either a flexible sheet in which a plurality of said substrates are arranged in a row or a connecting portion that connects a plurality of said substrates. sensor. a blood vessel diameter sensor according to any one of claims 1 to 9 ;
a pulser receiver that transmits a drive signal to the blood vessel diameter sensor and receives a reflected signal from the blood vessel diameter sensor;
a control device that controls driving of the blood vessel diameter sensor by the pulser receiver and obtains a blood vessel diameter based on the reflected signal received by the pulser receiver; A blood vessel diameter measuring device characterized by driving a plurality of matching ultrasonic elements simultaneously or with a time lag. The control device sequentially drives a group consisting of a plurality of adjacent ultrasonic elements among the plurality of ultrasonic elements, and determines the group that receives the strongest reflected signal,
12. The blood vessel diameter measuring apparatus according to claim 11 , wherein a plurality of said ultrasonic elements included in said determined group are driven. comprising two blood vessel diameter sensors arranged in a row;
The control device is
estimating the position of the blood vessel based on the position where one of the two blood vessel diameter sensors received the strongest reflected signal and the position where the other of the two blood vessel diameter sensors received the strongest reflected signal;
13. The blood vessel diameter measuring device according to claim 12 , wherein an angle of running of said blood vessel with respect to said two blood vessel diameter sensors is obtained. 14. The blood vessel diameter measurement device according to claim 13 , further comprising a display device for displaying the estimated position of the blood vessel. comprising two blood vessel diameter sensors arranged in a row;
The control device is
Obtaining the pulse wave propagation time in each of the two blood vessel diameter sensors from the change in the blood vessel diameter measured by the two blood vessel diameter sensors,
13. The blood vessel diameter measurement according to claim 11 or 12, wherein the hardness and blood pressure of the blood vessel are obtained from the difference in propagation time of the pulse wave in the two blood vessel diameter sensors and the distance between the two blood vessel diameter sensors. Device. comprising two blood vessel diameter sensors arranged in a row;
The two blood vessel diameter sensors are arranged at an angle with respect to the blood vessel, one transmitting the ultrasonic waves and the other receiving the reflected signals,
13. The blood vessel diameter measuring apparatus according to claim 11, wherein the controller measures the blood flow velocity in the blood vessel from Doppler frequency shift of reflected signals from red blood cells moving in the blood vessel.

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