JP2019141117A - Pulse wave sensor - Google Patents

Abstract

To provide a compact and accurate sensor.SOLUTION: A pulse wave sensor includes: a first space forming part where a first space is formed of a high rigidity material; a second space forming part where a second space communicating with the first space through a communication hole is formed, in which at least a part of a section opposed to the first space forming part is formed of a flexible material as a contact part with a measurement object, and sections other than the contact part are formed of a high-rigidity material; and a sensor lever attached to the communication hole so as to close the communication hole with a slight gap, which is formed in a cantilever shape from the end of the communication hole to the center. A pulse wave of a measurement object displaces the contact part and generates a pressure difference between the first space and the second space. A sensor lever is deflected by this pressure difference, and on the basis of the deflection, a pulse wave is detected.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a pulse wave sensor.

  Conventionally, this type of pulse wave sensor has been proposed that includes a sensor chip having a pressure detection element, a substrate to which the sensor chip is fixed, and a protective cover for protecting the substrate and the sensor chip (for example, , See Patent Document 1). In this sensor, the outer peripheral surface of the protective cover is formed to have a top surface that is disposed above the pressure detection element in a direction perpendicular to the detection surface of the sensor chip and is parallel to the detection surface. This ensures sufficient durability when mounting for a long time, and suppresses manufacturing costs.

JP 2017-196309 A

  However, although the above-described pulse wave sensor can ensure durability when wearing for a long time, it may give an uncomfortable feeling such as a feeling of pressure at the time of wearing. In order not to give such a sense of incongruity, it is necessary to make the pulse wave sensor small and highly accurate.

  The main object of the pulse wave sensor of the present invention is to provide a small and highly accurate sensor.

  The pulse wave sensor of the present invention employs the following means in order to achieve the main object described above.

The pulse wave sensor of the present invention is
A pulse wave sensor for detecting a pulse wave to be measured,
A first space forming portion that forms the first space with a highly rigid material;
Forming a second space that communicates with the first space by a communication hole, and at least a part of a portion facing the first space forming portion is formed of a flexible material as a contact portion with a measurement target; For the portion other than the contact portion, a second space forming portion formed of a highly rigid material,
A beam-shaped sensor portion attached to the communication hole so as to close the communication hole with a slight gap;
It is a summary to provide.

  In the pulse wave sensor according to the present invention, the first space is formed by the first space forming portion formed of a highly rigid material, and the second space communicating with the first space by the communication hole is formed by the second space forming portion. Form. In the second space forming portion, at least a part of the portion facing the first space forming portion is formed of a flexible material as a contact portion with the measurement object. It is made of a highly rigid material. A beam-shaped sensor portion is attached to the communication hole that communicates the first space and the second space so as to close the communication hole with a slight gap. When the contact portion comes into contact with the measurement target, the contact portion vibrates due to the pulse of the measurement target, and changes the pressure in the second space. Due to the change in the pressure in the second space, a pressure difference is generated between the first space and the second space, and the sensor unit attached to the communication hole is bent. A pulse wave can be detected by detecting the deflection of the sensor portion. Since this pulse wave sensor has a simple structure, it can be made extremely small by using semiconductor technology. It can be made highly accurate. As a result, the sensor can be small and highly accurate.

  In the pulse wave sensor of the present invention, the sensor portion may be formed of a material whose resistance value changes according to deformation at least in the vicinity of one support portion of the beam. If it carries out like this, the resistance value according to the bending of a sensor part can be detected, and it can be set as a more highly accurate sensor.

  In the pulse wave sensor of the present invention, the second space forming portion may be formed in a conical shape or a pyramid shape, and a bottom surface of the conical shape or the pyramid shape may be configured as the contact portion. . In this way, the sensitivity to pulse waves can be increased.

It is a block diagram which shows the outline of a structure of the pulse wave sensor 20 of embodiment. It is explanatory drawing which shows the pulse wave sensor 20 of embodiment by the AA cross section of FIG. It is explanatory drawing which shows an example of the experiment example measured with the pulse wave sensor 20 of embodiment. It is explanatory drawing explaining the attachment position of the pulse wave sensor 20 of embodiment in an experiment example. It is a graph which shows an example of the time change of time difference (DELTA) T. It is a block diagram which shows the outline of a structure of the pulse wave sensor 120 of a modification. It is a block diagram which shows the outline of a structure of the pulse wave sensor 220 of a modification. It is a block diagram which shows the outline of a structure of the pulse wave sensor 320A of a modification. It is a block diagram which shows the outline of a structure of the pulse wave sensor 320B of a modification. It is a block diagram which shows the outline of a structure of the pulse wave sensor 320C of a modification. It is a block diagram which shows the outline of a structure of the pulse wave sensor 320D of a modification. It is a block diagram which shows the outline of a structure of the pulse wave sensor 320E of a modification.

  Next, the form for implementing this invention is demonstrated. FIG. 1 is a configuration diagram showing an outline of the configuration of the pulse wave sensor 20 of the embodiment. FIG. 2 is an explanatory diagram illustrating the pulse wave sensor 20 according to the embodiment along the AA cross section of FIG. 1. FIG. 1 is an explanatory diagram showing the pulse wave sensor 20 of the embodiment by a BB cross section of FIG.

  As shown in the figure, the pulse wave sensor 20 according to the embodiment includes a first housing member 22, a second housing member 24, a membrane member 28, a sensor chip 40, and cables 48a and 48b. In FIG. 1, the lower end (the lower surface of the membrane member 28) is brought into contact with the measurement object to detect the pulse wave.

  The first housing member 22 is formed in a cylindrical shape with one end (upper end in FIG. 1) closed and the other end (lower end in FIG. 1) opened by a highly rigid material (for example, reinforced plastic). Yes. The second housing member 24 is made of a highly rigid material (for example, reinforced plastic) as in the first housing member 22 and has a communication hole 25 in the center, and the lower end (lower end in FIG. 1) has a mortar shape ( It is formed as a disk-shaped member formed in a conical shape. A first space 26 is formed by the first housing member 22 and the second housing member 24.

  The film member 28 is formed as a thin film of a material (for example, resin such as polyimide) having flexibility as a film when the film is formed. A second space 30 is formed by the film member 28 and the second housing member 24. The first space 26 and the second space 30 communicate with each other through a communication hole 25 formed in the second housing member 24 and are sealed as a whole. As described above, since the pulse wave is detected by bringing the lower surface of the membrane member 28 into contact with the measurement object, the membrane member 28 forms a contact portion.

  The sensor chip 40 is basically formed as a thin plate substrate made of silicon, and has a cantilever sensor lever 42 including a substantially rectangular head portion 44a and two leg portions 44b that support the head portion 44a. Is formed. As shown in FIG. 2, two U-shaped slight gaps 46a and 46b are formed at the boundary portion of the sensor lever 42, and the first space 26 and the second space 30 are formed by the gaps 46a and 46b. Communicate. The two legs 44b of the sensor lever 42 are formed by piezoresistors whose resistance values change with respect to deformation. For example, the two legs 44b can be configured by laminating a piezoresistive layer on a silicon layer. When a pressure difference is generated between the first space 26 and the second space 30, the sensor lever 42 bends in a smaller pressure direction. At this time, the degree of bending of the two leg portions 44b changes, and thereby the resistance value of the piezoresistive layer of the two leg portions 44b changes. Therefore, the change in resistance value is output as a detection signal. For the signal detection, for example, a Wheatstone bridge configured with the two legs 44b of the sensor lever 42 as one of the resistors can be used. Such a sensor lever 42 can be manufactured with extremely high accuracy by using a semiconductor manufacturing technique.

  FIG. 3 is an explanatory diagram illustrating an example of an experiment measured by the pulse wave sensor 20 according to the embodiment. In this experimental example, as shown in FIG. 4, the pulse wave sensor 20 of the embodiment is attached to the wrist of the left hand and the tip of the index finger. In the pulse wave sensor 20 used in this experiment, the first housing member 22 has an outer diameter of 12 mm, an inner diameter of 10 mm, a length of 1.5 mm, and an inner height of 1 mm. Regarding the second housing member 24, the diameter was 12 mm, the diameter of the communication hole 25 was 1.5 mm, the length of the communication hole was 0.5 mm, and the diameter of the bottom of the mortar shape was 8 mm. About the sensor chip 40, the length of length and width was 1.5 mm, and thickness was 0.3 mm. As the sensor lever 42, the width of the head 44a is 100 μm, the length from the base of the two legs 44b to the end of the head 44a is 125 μm, and the thickness is 0.3 μm. The first housing member 22 and the second housing member 24 were formed by Full cure 720 using a 3D printer. In FIG. 3, the vertical axis represents resistance strain (resistance value change amount ΔR: ΔR / R with respect to the resistance value R). In FIG. 3, the solid line is a signal detected by the pulse wave sensor 20 attached to the wrist, and the alternate long and short dash line is a signal detected by the pulse wave sensor 20 attached to the tip of the index finger. ΔT is the time difference between the peaks of the two signals. As shown in the figure, the signal from the pulse wave sensor 20 attached to the tip of the index finger shows a delay of the time difference ΔT and the signal attenuation with respect to the signal from the pulse wave sensor 20 attached to the wrist. FIG. 5 is a graph showing an example of the time change of the time difference ΔT. As shown in the figure, it can be seen that the time difference ΔT slightly varies with the passage of time (change in state).

  In the pulse wave sensor 20 of the embodiment described above, the sensor chip 40 is attached so as to close the communication hole 25 between the first space 26 and the second space 30, and the resistance value of the sensor chip 40 changes with respect to deformation 2. The sensor lever 42 which consists of the one leg part 44b and the head part 44a, and bends according to a pressure difference between the 1st space 26 and the 2nd space 30 is formed. Since the membrane member 28 that constitutes the second space 30 and constitutes the abutting portion that abuts the measurement object has flexibility, the membrane member 28 is displaced by the pulse wave, and the pressure of the second space 30 is changed, A pressure difference is generated between the first space 26 and the second space 30. The sensor lever 42 is bent by this pressure difference, and the resistance values of the two leg portions 44b are changed. By detecting this, the pulse wave can be detected. Since the sensor lever 42 can be formed using a semiconductor manufacturing technique, the detection accuracy can be extremely increased, and the size can be reduced. As a result, the sensor can be small and highly accurate. Moreover, since the bottom of the second housing member 24 is formed in a mortar shape (conical shape), even a slight pulse wave can be detected with high sensitivity.

  In the pulse wave sensor 20 of the embodiment, the cantilever-shaped sensor lever 42 including the substantially rectangular head 44a and the two legs 44b that support the head 44a is used. And it is good also as a double-supported beam-like sensor part which consists of two leg parts which pinch | interpose this head. In this case, one or both of the two legs may be formed by a piezoresistor whose resistance value changes with deformation.

  In the pulse wave sensor 20 of the embodiment, the bottom of the second housing member 24 is formed in a mortar shape (conical shape). However, as shown in the second housing member 124 of the pulse wave sensor 120 of the modified example of FIG. 6, the inside may be hollowed out in a cylindrical shape from the bottom.

  In the pulse wave sensor 20 of the embodiment, the bottom of the second housing member 24 is formed in a mortar shape (conical shape). However, as shown in the pulse wave sensor 220 of the modification of FIG. 7, it may not have a mortar-shaped (conical) portion. In this case, if the first housing member 222 and the second housing member 224 are formed to have a size enough to form the communication hole, both the first space 226 and the second space 230 are reduced, and the entire sensor is It can be made extremely small.

  In the pulse wave sensor 20 of the embodiment, the whole is formed in a cylindrical shape. However, it may be formed in a prismatic shape as a whole. In this case, the bottom of the second housing member may be formed in a pyramid shape.

  In the pulse wave sensor 20 of the embodiment, the lower surface (contact surface) of the film member 28 is flat, but the entire lower surface is similar to the film member 28A included in the pulse wave sensor 320A of the modified example illustrated in FIG. It is good also as a smooth convex shape. In addition, a cylindrical (or rectangular) rib 28b may be formed at the center of the lower surface as in the film member 28B provided in the pulse wave sensor 320B of the modified example illustrated in FIG. A plurality of cylindrical (or rectangular) ribs 28c are formed in a lattice (or zigzag) pattern on the lower surface as in the film member 28C provided in the pulse wave sensor 320C of the modified example illustrated in FIG. Also good. The shapes of the ribs 28b and 28c of the pulse wave sensors 320B and 320C of the modified example illustrated in FIGS. 9 and 10 are the film members 28D and 28E of the pulse wave sensors 320D and 320E of the modified example illustrated in FIGS. Like the ribs 28d and 28e formed in the above, the side surfaces may be formed so as to be drawn by convex arcs.

  As mentioned above, although the form for implementing this invention was demonstrated using the Example, this invention is not limited at all to such an Example, In the range which does not deviate from the summary of this invention, it is with various forms. Of course, it can be implemented.

  The present invention is applicable to the pulse wave sensor manufacturing industry.

  20, 120, 220, 320A to 320E Pulse wave sensor, 22, 222 First housing member, 24, 124, 224 Second housing member, 25 communication hole, 26, 226 First space, 28, 28A to 28E Membrane Member, 28b-28e rib, 30, 230 2nd space, 40 sensor chip, 42 sensor lever, 44a head, 44b leg, 48a, 48b cable.

Claims (3)

A pulse wave sensor for detecting a pulse wave to be measured,
A first space forming portion that forms the first space with a highly rigid material;
Forming a second space that communicates with the first space by a communication hole, and at least a part of a portion facing the first space forming portion is formed of a flexible material as a contact portion with a measurement target; For the portion other than the contact portion, a second space forming portion formed of a highly rigid material,
A beam-shaped sensor portion attached to the communication hole so as to close the communication hole with a slight gap;
A pulse wave sensor. The pulse wave sensor according to claim 1,
The sensor part is formed of a material whose resistance value changes according to deformation at least in the vicinity of one support part of the beam.
Pulse wave sensor. The pulse wave sensor according to claim 1 or 2,
The second space forming portion is formed in a conical shape or a pyramid shape, and the bottom surface of the conical shape or the pyramid shape is configured as the contact portion.
Pulse wave sensor.