WO2019031046A1

WO2019031046A1 - Pressure wave measurement device

Info

Publication number: WO2019031046A1
Application number: PCT/JP2018/022040
Authority: WO
Inventors: 智矢宮田
Original assignee: ヤマハ株式会社
Priority date: 2017-08-10
Filing date: 2018-06-08
Publication date: 2019-02-14
Also published as: JP2019033825A

Abstract

In order to make it possible to measure pressure waves with an appropriate amplitude without the need for accurate positioning, a piezoelectric sensor is provided with a piezoelectric sheet and a plurality of signal electrode groups each having a plurality of signal electrodes arranged along one direction on the surface of the piezoelectric sheet. The positions of the plurality of electrodes are such that the plurality of signal electrode groups are alternatingly staggered in the one direction. Consequently, in any of the plurality of signal electrode groups, the facing area between the signal electrodes and an artery that causes pulse waves is large, and a pulse waveform with a large amplitude can be obtained from the signal electrodes.

Description

Device for measuring pressure waves

The present disclosure relates to an apparatus for measuring pressure waves such as pulse waves.

Various devices for measuring pulse waves of a living body such as a human body are provided. Since the pulse wave contains much information indicating the condition of the living body, it is desirable to measure the waveform accurately. Then, the technique which utilizes a piezoelectric sensor for the measurement of a pulse wave is proposed (for example, refer patent document 1).

JP 2004-313409 A JP, 2015-14550, A

In order to accurately measure a pulse wave that is a pressure wave with a piezoelectric sensor, it is necessary to accurately position the piezoelectric sensor so that the piezoelectric sensor accurately opposes the artery that is the source of the pressure wave. . However, such positioning is a cumbersome task.

The piezoelectric sensor disclosed in Patent Document 2 has a configuration in which a ground electrode is stacked on one surface of a long piezoelectric sheet, and a plurality of signal electrodes are stacked on the other surface of the same piezoelectric sheet at an interval. Have. When this piezoelectric sensor is brought into contact with the skin surface in the vicinity of the artery of the subject, any one of the plurality of signal electrodes may face the artery which is the generation source of the pulse wave. It becomes possible to measure

However, depending on the arrangement position of the piezoelectric sensor on the skin surface, the area between the plurality of signal electrodes may face the artery, or part of the signal electrodes may face the artery, but the facing area may be insufficient. In that case, there is a problem that the pulse wave of appropriate amplitude can not be measured.

The present disclosure has been made in view of the above circumstances, and it is an object of the present disclosure to provide a technical means that makes it possible to measure pressure waves of appropriate amplitude without requiring accurate positioning. .

The disclosure includes a piezoelectric sheet and a plurality of signal electrode groups each having a plurality of signal electrodes arranged in one direction on the surface of the piezoelectric sheet, and the positions of the plurality of signal electrodes are the plurality The present invention provides a piezoelectric sensor characterized by being mutually offset in the one direction among the signal electrode groups of
The present disclosure also includes a piezoelectric sheet and a plurality of signal electrode groups each having a plurality of signal electrodes arranged from the first end to the second end of the surface of the piezoelectric sheet, the plurality of signals. The positions of the plurality of signal electrodes of the first signal electrode group which is one of the electrode groups are the plurality of second electrode groups which are different from the first electrode group of the plurality of signal electrode groups. The piezoelectric sensor is closer to the first end than the position of each of the signal electrodes.

According to this disclosure, the positions of the signal electrodes in one direction in each of the signal electrode groups in which the signal electrodes are arranged in one direction are mutually shifted between the signal electrode groups. The area facing the pressure wave source is sufficiently large, and an output voltage waveform of appropriate amplitude can be obtained from the signal electrode. Accordingly, pressure waves of appropriate amplitude can be measured without accurate positioning of the piezoelectric sensor.

It is a top view which shows the structure of the piezoelectric sensor which is 1st Embodiment of this indication. FIG. 2 is a cross-sectional view taken along line II-II of FIG. It is a figure which shows the structure of the pulse-wave measurement apparatus using the same piezoelectric sensor. It is sectional drawing which shows the structure of the piezoelectric sensor which is 2nd Embodiment of this indication.

Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.

First Embodiment
FIG. 1 is a plan view showing the configuration of a piezoelectric sensor 1 according to a first embodiment of the present invention. 2 is a cross-sectional view taken along line II-II of FIG. In the present embodiment, the piezoelectric sensor 1 is used as a pulse wave sensor, with the skin surface area located above the radial artery 8a of the left wrist 8 of the subject as a pressure measurement site. In order to measure the pulse wave, it is preferable that the pressure measurement site be the skin surface area closest to the radial artery 8a.

As shown in FIG. 2, the piezoelectric sensor 1 has a thin film-like piezoelectric sheet 10. On one surface of the piezoelectric sheet 10, a thin film ground electrode 11G is stacked over the entire surface. Further, on the other surface of the piezoelectric sheet 10, three signal electrode groups 11SA1, 11SA2 and 11SA3 each composed of a plurality of rectangular thin film signal electrodes 11S are stacked. That is, all of the three signal electrode groups 11SA1, 11SA2, and 11SA3 are disposed on the other surface of the piezoelectric sheet 10. These signal electrode groups are arranged in one layer where the distance from the skin surface of the left wrist 8 of the subject to be measured which is a pressure measurement site is substantially the same. The other surface of the piezoelectric sheet 10 on which all of the three signal electrode groups 11SA1, 11SA2 and 11SA3 are arranged is on the skin surface of the wrist 8 which is an example of a pressure-side measurement site than one surface of the piezoelectric sheet 10. It is a near face.

In the present embodiment, each signal electrode 11S provided in each signal electrode group is arranged in one direction perpendicular to the radial artery 8a. In addition, the width D of the first signal electrode group 11SA1 in the arrangement direction of each signal electrode 11S, the width D of the second signal electrode group 11SA2 in the arrangement direction of each signal electrode 11S, and the third signal electrode group 11SA3. The widths D of the signal electrodes 11S in the arrangement direction are equal to one another. The width D of this signal electrode is about the same as the diameter of the radial artery 8a which is a pulse wave generation source, and is about 3 mm. Further, an interval B between the signal electrodes 11S in the first signal electrode group 11SA1, an interval B between the signal electrodes 11S in the second signal electrode group 11SA2, and an interval between the signal electrodes 11S in the third signal electrode group 11SA3. B are equal to one another. The interval B is about a fraction of the width D. That is, the distance B between the signal electrodes 11S is smaller than the width D in the direction in which the signal electrodes 11S are arranged. Further, as apparent from FIG. 1, the width of the piezoelectric sheet 10 in the arranging direction of the signal electrodes 11S, that is, the size of the piezoelectric sheet 10 in the horizontal direction in FIG. 1 is the width of the radial artery 8a in the arranging direction, that is, It is larger than the size of the radial artery 8a in the left and right direction of FIG. Further, the distance B between the signal electrodes 11S is smaller than the width of the radial artery 8a.

Further, in the present embodiment, the positions in the direction in which the signal electrodes 11S are arranged in the respective signal electrode groups are mutually shifted between the signal electrode groups. Specifically, the position of each signal electrode 11S in the second signal electrode group 11SA2 is in the arranging direction (rightward in FIG. 1) with respect to the position of each signal electrode 11S in the first signal electrode group 11SA1. It has shifted by a predetermined length. Then, each signal electrode 11S in the third signal electrode group 11SA3 is offset from the position of each signal electrode 11S in the second signal electrode group 11SA2 by a predetermined length in the alignment direction (right direction in FIG. 1) . As shown in FIG. 1, the position of each signal electrode 11S in the second signal electrode group 11SA2 is the distance B between the signal electrodes 11S with respect to the position of each signal electrode 11S in the first signal electrode group 11SA1. It is offset to the right of FIG. 1 by a smaller length than that. The position of each signal electrode 11S in the third signal electrode group 11SA3 is smaller than the distance B between the signal electrodes 11S with respect to each signal electrode 11S in the first signal electrode group 11SA2, as shown in FIG. It is shifted to the right of.
The position of the signal electrode 11S with respect to the piezoelectric sheet 10 can also be expressed as follows. Assuming that the left end of the piezoelectric sheet 10 in the drawing is the sheet left end 10A (an example of the first end) and the right end of the piezoelectric sheet 10 is the sheet right end 10B (the example of the second end) as shown in FIG. The signal electrodes 11S of the electrode groups 11SA1, 11SA2 and 11SA3 are arranged in a direction from the sheet left end 10A to the sheet right end 10B. The position of each signal electrode 11S in the first signal electrode group 11SA1 is closer to the left end 10A of the sheet than the position of each signal electrode 11S in the second signal electrode group 11SA2. Similarly, the position of each signal electrode 11S in the second signal electrode group 11SA2 is closer to the left end 10B of the sheet than the position of each signal electrode 11S in the third signal electrode group 11SA3.

In the example shown in FIG. 2, the surface of the piezoelectric sensor 1 on the side of the first to third signal electrode groups 11SA1 to 11SA3 is attached by gel 19 to the skin surface area above the radial artery 8a. Note that which surface of the piezoelectric sensor 1 is attached to the skin surface is optional, and the surface on the ground electrode 11G side may be attached to the skin surface by the gel 19.

The piezoelectric sheet 10 is formed of a piezoelectric material that converts pressure into voltage, is stressed by a pulse wave from a subject, and generates a potential difference according to the acceleration of the stress change.

The piezoelectric material forming the piezoelectric sheet 10 may be, for example, an inorganic material such as lead zirconate titanate, but is preferably a polymeric piezoelectric material having flexibility so as to be in close contact with the surface of a living body. .

Examples of the polymer piezoelectric material include polyvinylidene fluoride (PVDF), vinylidene fluoride-trifluorinated ethylene copolymer (P (VDF / TrFE)), and vinylidene cyanide-vinyl acetate copolymer (P (VDCN /). And the like.

Further, as the piezoelectric sheet 10, a large number of flat pores are formed in, for example, polytetrafluoroethylene (PTFE), polypropylene (PP), polyethylene (PE), polyethylene terephthalate (PET) or the like which does not have piezoelectric characteristics, for example, corona discharge It is also possible to use one to which a piezoelectric property is imparted by polarizing and charging the flat pores facing each other.

The lower limit of the average thickness of the piezoelectric sheet 10 is preferably 10 μm, and more preferably 50 μm. On the other hand, the upper limit of the average thickness of the

piezoelectric sheets

10L and 10U is preferably 500 μm, more preferably 200 μm. If the average thickness of the piezoelectric sheet 10 is less than the lower limit, the strength of the piezoelectric sheet 10 may be insufficient. Conversely, when the average thickness of the piezoelectric sheet 10 exceeds the upper limit, the deformability of the piezoelectric sheet 10 may be reduced, and the detection sensitivity may be insufficient.

The material of the signal electrode 11S and the ground electrode 11G may be any one having conductivity, and examples thereof include metals such as aluminum, copper and nickel, and carbon.

The average thickness of the signal electrode 11S and the ground electrode 11G is not particularly limited, and may be, for example, 0.1 μm or more and 30 μm or less, although it depends on the lamination method. If the average thickness of the signal electrode 11S and the ground electrode 11G is less than the lower limit, the strength of the signal electrode 11S and the ground electrode 11G may be insufficient. Conversely, when the average thickness of the signal electrode 11S and the ground electrode 11G exceeds the upper limit, transmission of vibration to the piezoelectric sheet 10 may be inhibited.

The method of laminating the signal electrode 11S and the ground electrode 11G on the piezoelectric sheet 10 is not particularly limited, and examples thereof include vapor deposition of metal, printing of a carbon conductive ink, and coating and drying of silver paste.

FIG. 3 is a view showing the configuration of a pulse wave measurement device 100 using the piezoelectric sensor 1. In this pulse wave measuring device 100, the ground electrode 11G of the piezoelectric sensor 1 is grounded, and each signal electrode 11S in the first to third signal electrode groups 11SA1 to 11SA3 is connected to the plurality of impedance conversion devices 2 respectively. It is connected to the amplifier 3. The plurality of impedance conversion devices 2 are devices that perform impedance conversion to eliminate mismatch between the output impedance of each signal electrode 11S of the piezoelectric sensor 1 and each input impedance of the plurality of amplifiers 3. The plurality of amplifiers 3 amplify the output voltage of each signal electrode 11S of the piezoelectric sensor 1 supplied through the plurality of impedance conversion devices 2 and supply the amplified voltage to the measurement control device 4. Output voltage waveforms of the plurality of amplifiers 3 indicate pulse waveforms (pressure waveforms) detected by the signal electrodes 11S of the piezoelectric sensor 1. The measurement control device 4 selects an appropriate one of these pulse waveforms, for example, the pulse waveform with the largest amplitude, and supplies it to the pulse wave processing device 4. The pulse wave processing device 4 is a device having a function of displaying a pulse waveform, such as an oscilloscope, and a waveform analysis function of obtaining parameters of the pulse wave such as a pulse rate.
The above is the configuration of the pulse wave measurement device 100.

Next, the operation of this embodiment will be described. The measurer applies gel 19 to one surface of the piezoelectric sensor 1 and affixes the piezoelectric sensor 1 to the skin surface area near the radial artery 8a as shown in FIG. In the example shown in FIG. 1, the middle signal electrode 11S of each of the first to third signal electrode groups 11SA1 to 11SA3 faces the radial artery 8a.

When blood flows to the radial artery 8a, the radial artery 8a repeats expansion and contraction by the pulse that sends out the blood flow, and vibration in a direction perpendicular to the skin surface in a region facing the radial artery 8a on the skin surface of the left wrist 8 Occurs. The component of the pressure generated in the skin surface area in the thickness direction of the piezoelectric sheet 10 propagates to the area of the piezoelectric sheet 10 facing the skin surface area. As a result, in the piezoelectric sheet 10, a voltage corresponding to the pressure is generated between the signal electrode 11S and the ground electrode 11G sandwiching the region where the pressure is propagated. More specifically, in the piezoelectric sheet 10, a pressure applied to a region facing the signal electrode 11S and to which a pressure wave from the skin surface propagates generates a voltage in the signal electrode 11S.

In the example shown in FIG. 1, since the area of the signal electrode 11S in the middle of the first signal electrode group 11SA1 among the signal electrodes 11S is the largest facing the radial artery 8a, the output voltage waveform obtained from this signal electrode 11S Amplitude is the largest. Therefore, the measurement control device 4 selects the pulse waveform having the largest amplitude and supplies it to the pulse wave processing device 4.

As described above, according to the present embodiment, since the positions of the signal electrodes are mutually shifted between the plurality of signal electrode groups, the signal electrodes of any of the signal electrode groups face the artery that is the generation source of the pulse wave. The area is sufficiently large, and a pulse wave of appropriate amplitude can be obtained from the signal electrode. Therefore, according to the present embodiment, it is possible to measure a pulse wave of appropriate amplitude without performing accurate positioning of the piezoelectric sensor.

Second Embodiment
FIG. 4 is a cross-sectional view showing the configuration of a piezoelectric sensor 1A according to a second embodiment of the present disclosure. The piezoelectric sensor 1A includes two thin film piezoelectric sheets 10L (an example of a first piezoelectric sheet) and 10U (an example of a second piezoelectric sheet). A thin film ground electrode 11G is sandwiched between the

piezoelectric sheets

10L and 10U. The ground electrode 11G is attached to the entire surface of the

piezoelectric sheets

10L and 10U. Then, on the surface of the piezoelectric sheet 10L opposite to the ground electrode 11G, a first signal electrode group 11LA including a plurality of rectangular thin film signal electrodes 11L arranged at equal intervals is disposed. Further, on the surface of the piezoelectric sheet 10U opposite to the ground electrode 11G, a second signal electrode group 11UA including a plurality of rectangular thin film signal electrodes 11U arranged at equal intervals is disposed. That is, in the present embodiment, the first signal electrode group 11LA and the second signal electrode group 11UA are a plurality of layers (in this case, different in distance from the skin surface of the left wrist of the person to be measured) They are arranged in two layers.

In the present embodiment, the width D in the direction of arrangement of the signal electrodes 11L in the first signal electrode group 11LA and the width D in the direction of arrangement of the signal electrodes 11U in the second signal electrode group 11UA are equal to each other. Further, the distance between the signal electrodes 11L in the first signal electrode group 11LA is also the same as the width D, and the distance between the signal electrodes 11U in the second signal electrode group 11UA is also the same as the width D. As apparent from FIG. 4, the widths of the

piezoelectric sheets

10L and 10U in the arranging direction of the

signal electrodes

11L and 11U, that is, the sizes of the

piezoelectric sheets

10L and 10U in the lateral direction of FIG. The width 8a is larger than the size of the radial artery 8a in the lateral direction of FIG. The width D in the direction in which the

signal electrodes

11L and 11U are aligned is smaller than the width of the radial artery 8a. Furthermore, the interval between the

signal electrodes

11L and 11U in the alignment direction is smaller than the width of the radial artery 8a.

In the present embodiment, the positions of the

signal electrodes

11L and 11U are mutually offset between the first and second signal electrode groups 11LA and 11UA. Specifically, the position of each signal electrode 11U in the second signal electrode group 11UA deviates by one signal electrode along the alignment direction with respect to the position of each signal electrode 11L in the first signal electrode group 11LA. ing. Then, each signal electrode 11U in the second signal electrode group 11UA faces the area of the gap between the two adjacent signal electrodes 11L in the first signal electrode group 11LA or the area next to the signal electrode 11L. .
Further, the positions of the

signal electrodes

11L and 11U with respect to the

piezoelectric sheets

10L and 10U can also be expressed as follows. As shown in FIG. 4, the left ends of the

piezoelectric sheets

10L and 10U in the drawing are the sheet left ends 10LA and 10UA (an example of the first end), and the right ends of the

piezoelectric sheets

10L and 10U are the sheet right ends 10LB and 10UB (the second end In one example, the

signal electrodes

11L and 11U of the signal electrode groups 11LA and 11UA are arranged in the direction from the sheet left end 10LA and 10UA toward the sheet right end 10LB and 10UB. The position of each signal electrode 11L in the first signal electrode group 11LA is closer to the left end 10LA of the sheet by one signal electrode than the position of each signal electrode 11U in the second signal electrode group 11UA.

In the present embodiment, it is necessary to propagate a pulse wave generated on the skin surface of the subject to both of the

piezoelectric sheets

10L and 10U. For this reason, it is preferable that the thicknesses of the

piezoelectric sheets

10L and 10U be thinner than the average of the thicknesses of the piezoelectric sheets in the first embodiment. The thicknesses of the signal electrode and the ground electrode are the same.

In the present embodiment, since the

piezoelectric sheets

10L and 10U are sufficiently thin, the vertical pressure vibration generated on the skin surface propagates through the

piezoelectric sheets

10L and 10U with a sufficient amplitude. Therefore, even when either the signal electrode 11L of the first signal electrode group 11LA or the signal electrode 11U of the second signal electrode group 11UA faces the radial artery 8a, an output voltage waveform with sufficient amplitude from the signal electrode Is obtained. Therefore, the same effect as that of the first embodiment can be obtained also in the present embodiment.

Other Embodiments
As mentioned above, although each embodiment of this indication was described, other embodiments can be considered to this indication. For example:

(1) In each of the above embodiments, the piezoelectric sensor according to the present disclosure is applied to a device for measuring a radial artery wave, but the piezoelectric sensor according to the disclosure is a pulse wave other than the radial artery wave or a pressure wave other than the pulse wave. It is applicable also to the pressure wave measuring device to measure.

(2) In the first embodiment, the three signal electrode groups 11SA1 to 11SA3 are disposed on the surface of the piezoelectric sheet 10. However, two signal electrode groups or four or more signal electrode groups may be disposed. Also, how many signal electrodes are provided in one signal electrode group is optional.

(3) In the first embodiment, the signal electrode 11S having the same width as the diameter of the radial artery 8a which is a pulse wave generation source is used, but the signal electrode having a width shorter than the diameter of the radial artery 8a 11S may be closely arranged on the piezoelectric sheet 10 at a sufficiently short interval. Specifically, when the diameter of the radial artery 8a is 3 mm, the width of the signal electrode 11S is 1/2 or less of this diameter, for example, 1.5 mm, and the signal electrodes 11S are piezoelectric sheets at an interval of 0.2 mm, for example. To be densely arranged. In this case, in each of the signal electrode groups 11SA1 to 11SA3, two to three signal electrodes 11S arranged in a direction crossing the radial artery 8a face the radial artery 8a, and output voltage waveforms with large amplitude are obtained from these signal electrodes. Be In this case, the measurement control device 4 may combine the pulse waveforms supplied to the pulse wave processing device 5 according to the following procedure.

(3-1) The amplitudes of the output voltage waveforms obtained from all the signal electrodes 11S are compared, and the signal electrode 11S which is the generation source of the output voltage waveform having the maximum amplitude is selected.

(3-2) The signal electrode group to which the selected signal electrode 11S belongs is selected, and in the signal electrode group, the signal electrode 11S generating the output voltage waveform having the second largest amplitude next to the maximum amplitude is selected.

(3-3) The output voltage waveform of the maximum amplitude and the output voltage waveform of the second order amplitude are added, and the pulse waveform supplied to the pulse wave processing device 5 is synthesized.

Note that the width of the signal electrode 11S is further narrowed to make the three or more signal electrodes 11S face the radial artery 8a, and the pulse supplied to the pulse wave processing device 5 using the output voltage waveform of the three or more signal electrodes 11S. The waveforms may be synthesized.

(4) In the second embodiment, the distance between the signal electrodes in each signal electrode group is made shorter than the width of the signal electrode, and each signal electrode 11U in the second signal electrode group 11UA is the first signal electrode group 11LA. Each signal electrode may be disposed so as to partially overlap with the signal electrode 11L in FIG.

(5) In the second embodiment, the arrangement positions of the first signal electrode group 11LA, the ground electrode 11G, and the second signal electrode group UA are arbitrary. A first signal electrode group 11LA is interposed between the

piezoelectric sheets

10L and 10U, and a ground electrode 11G is disposed on the surface of the piezoelectric sheet 10L opposite to the first signal electrode group LA, and a first signal in the piezoelectric sheet 10U The second signal electrode group 11UA may be disposed on the surface opposite to the electrode group LA.

(6) In the piezoelectric sensor 1A of the second embodiment, the signal electrode groups are arranged in two layers different in distance from the pressure measurement site. However, the signal electrode groups may be arranged in three or more layers.

100: pulse

wave measuring device

1, 1A: piezoelectric sensor, 10, 10L, 10U: piezoelectric sheet, 11LA, 11SA1: first signal electrode group, 11UA, 11SA2: second signal electrode group, 11SA3: third signal electrode group, 11S, 11L, 11U: signal electrode, 11G: ground electrode, 19: gel, 2: impedance conversion device, 3: amplifier, 4: measurement control device, 5: Pulse wave processing device, 8: Left wrist, 8a: Radial artery.

Claims

Piezoelectric sheet,
And a plurality of signal electrode groups each having a plurality of signal electrodes arranged in one direction on the surface of the piezoelectric sheet,
The piezoelectric sensor, wherein the positions of the plurality of signal electrodes are mutually offset in the one direction among the plurality of signal electrode groups.
The size in one direction of the piezoelectric sheet is larger than the width in one direction of the artery to be measured,
The piezoelectric sensor according to claim 1, wherein the plurality of signal electrodes are spaced apart from each other in the one direction at a separation distance smaller than a width in the one direction of the artery.
The first signal electrode group and the second signal electrode group which are two adjacent ones of the plurality of signal electrode groups are mutually offset in the one direction at a distance smaller than the separation distance. Piezoelectric sensor described in.
4. The device according to claim 1, wherein the plurality of signal electrodes are spaced apart from each other in the one direction at a separation distance smaller than a width of each of the plurality of signal electrodes in the one direction. Piezoelectric sensor.
The piezoelectric sensor according to any one of claims 1 to 4, wherein the plurality of signal electrode groups are arranged in one layer whose distance from the pressure measurement site is substantially the same.
The piezoelectric sensor according to any one of claims 1 to 4, wherein all of the plurality of signal electrode groups are disposed on one of two faces of one piezoelectric sheet.
The piezoelectric sensor according to any one of claims 1 to 4, wherein all of the plurality of signal electrode groups are disposed on a surface closer to a pressure measurement site of two surfaces of one piezoelectric sheet.
The piezoelectric sensor according to any one of claims 1 to 4, wherein the plurality of signal electrode groups are respectively disposed in a plurality of layers having different distances from the pressure measurement site.
The piezoelectric sheets are two piezoelectric sheets on which at least one of the plurality of signal electrode groups is disposed,
A first signal electrode group which is at least one of the plurality of signal electrode groups is disposed on a surface of a first piezoelectric sheet which is one of the two piezoelectric sheets, and one of the plurality of signal electrode groups is disposed. A second signal electrode group different from the first signal electrode group is disposed on the surface of a second piezoelectric sheet different from the first piezoelectric sheet of the two piezoelectric sheets,
The position of each of the plurality of signal electrodes of the first electrode group and the position of each of the plurality of signal electrode groups of the second electrode group are mutually offset in the one direction. Piezoelectric sensor.
Piezoelectric sheet,
A plurality of signal electrode groups each having a plurality of signal electrodes arranged in a direction from the first end to the second end of the surface of the piezoelectric sheet;
The position of each of the plurality of signal electrodes of the first signal electrode group which is one of the plurality of signal electrode groups is a second electrode different from the first electrode group of the plurality of signal electrode groups The piezoelectric sensor closer to the first end than the position of each of the plurality of signal electrodes in a group.
The piezoelectric sensor according to any one of claims 1 to 10.
And a measurement control unit configured to select a signal electrode that can obtain a pressure wave with the largest amplitude among the signal electrodes included in the plurality of sets of signal electrode groups.
A piezoelectric sensor according to any one of claims 1 to 10, comprising:
The pulse wave measurement device in which a plurality of signal electrodes included in the signal electrode group are aligned in a direction perpendicular to an artery.