JPH082352B2 - Pulse wave detector - Google Patents

Description

TECHNICAL FIELD The present invention relates to a pulse wave detecting device, and more particularly to a device for detecting a pulse wave at a plurality of positions on a body surface in a direction intersecting a blood vessel.

2. Description of the Related Art A pressure wave or vibration of a blood vessel wall that is generated with the pulsation of the heart and propagates in a blood vessel is generally called a pulse wave. From this pulse wave, various medical information such as the motion state of the heart can be obtained. It is known to be obtained. Then, as a device for detecting such a pulse wave, a pressure sensor for detecting the pressure vibration of the pulse wave generated from the blood vessel in the human body by being pressed against the body surface of the human body, and the blood vessel on the body surface. Plural units are arranged in the intersecting direction, and the pulse wave is detected based on the electric signal output from the pressure sensor pressed directly above the blood vessel, for example, the optimum position for detecting the pulse wave in the intersecting direction. There are things I tried to do.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention By the way, in order to detect a pulse wave more accurately, it is desirable that the pressure sensor is arranged as finely as possible in a direction intersecting with a blood vessel. Since a gauge is used and is pressed against the body surface with a contact surface having a size equal to or larger than the diameter of the blood vessel, the pressure sensor cannot be arranged extremely finely.

Means for Solving the Problems The present invention has been made in the background of the above circumstances, and an object of the present invention is to miniaturize the pressure sensor in order to improve the detection accuracy of the pulse wave, and at a minute interval. It is to be able to arrange.

And in order to achieve such an object, the present invention is arranged in a direction intersecting with blood vessels on the body surface of the human body,
In a pulse wave detection device equipped with a plurality of pressure sensors that respectively detect pressure vibrations of a pulse wave generated from a blood vessel when pressed against the body surface, a thin wall is formed by forming a plurality of recesses on the surface of a semiconductor substrate. And the piezoelectric transducers that output electric signals corresponding to the pressure vibrations of the pulse wave are transmitted to the thin wall portions via the body surface and are formed in the thin wall portions. The pressure sensor is configured by the piezoelectric conversion element.

In this pulse wave detecting device, a plurality of recesses are formed on the surface of the semiconductor substrate to provide a thin portion, and the thin portion has a pressure sensitive diode, a pressure sensitive transistor, or a semiconductor strain gauge. Since a piezoelectric conversion element such as is formed by impurity diffusion and used as a pressure sensor, the pressure sensor can be downsized and can be formed at extremely small intervals. Therefore, by arranging the semiconductor substrate in which the small piezoelectric conversion elements are formed at minute intervals so that the arrangement direction of the piezoelectric conversion elements is the direction intersecting with the blood vessel, the pulse wave in the direction intersecting with the blood vessel is maximized. It is possible to detect finely and improve the accuracy of detecting the pulse wave.

In the case where the semiconductor substrate is pressed with the recess side facing the body surface, in order to transmit the pressure vibration from the body surface to the thin portion, for example, a rubber that acts like a fluid is used. A filler or the like will be embedded in the recess.

Further, in accurately detecting the pressure vibration of the pulse wave, the thickness of the thin portion where the piezoelectric conversion element is formed is different depending on the type of the semiconductor substrate or the piezoelectric conversion element, for example, 15
About μm is desirable.

Embodiment Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings.

In FIG. 1, reference numeral 10 denotes a hollow main body having an opening 12 at the lower end, and the opening 12 is detachably attached to a wrist 18 by a band 16 in a state of facing the body surface 14 of a human body. The main body 10 includes an annular side wall member 20 and a lid member 24 fixed to the upper end of the side wall member 20 with the outer peripheral edge portion of the diaphragm 22 sandwiched therebetween, and the inner peripheral edge portion of the diaphragm 22 is fixed to the pressing member 26. ing. The diaphragm 22 is made of an elastically deformable material such as rubber, and the pressing member 26 is held movably in the main body 10 via the diaphragm 22. Further, an airtight pressure chamber 28 is formed by the diaphragm 22 between the main body 10 and the pressing member 26, so that pressure air is supplied from the pressure air supply source 30 via the pressure regulating valve 32. Has become.

The pressing member 26 includes an annular side wall member 36, a lid member 38 fixed to the upper end of the side wall member 36 with the inner peripheral edge of the diaphragm 22 sandwiched therebetween, and a pressing plate disposed at the lower end of the side wall member 36. It consists of 40 and. As shown in FIG. 2, the pressing plate 40 is formed by forming a large number of pressure sensitive diodes 44 on the upper surface of a semiconductor chip 42 made of single crystal silicon or the like by impurity diffusion or the like, and changes in pressure at the joint portion. The electric signals corresponding to the above are extracted from between the common terminal 46 and the individual terminals 48. Multiple pressure sensitive diodes 44
In the state where the main body 10 is attached to the wrist 18, the arteries 50 are formed at regular intervals in a direction intersecting the radial artery 50 whose pulse wave is to be detected at a substantially right angle.
The width dimension and the interval in the direction substantially perpendicular to are within a range in which at least three pressure-sensitive diodes 44 are directly above the radial artery 50, that is, directly above the radial artery 50 and approximately the same diameter as the diameter of the artery 50. It is defined to be located inside. The shape of the pressure sensitive diode 44 and the length dimension in the direction parallel to the artery 50 are appropriately set.

In addition, the pressure sensitive diode which is the lower surface 52 of the pressing plate 40
In the portion corresponding to 44, a recess is formed in each and a rubber filler 54 is embedded therein. The rubber filler 54 is filled in the recess so that the lower surface 52 is flat without applying a load to the pressure sensitive diode 44, and the body surface 14 immediately above the artery 50 and in the vicinity thereof is covered with the pressing plate 40. While being pressed flat by the lower surface 52, the pressure vibration of the pulse wave generated from the radial artery 50 is transmitted to the pressure sensitive diode 44 via the rubber filler 54. The portion of the semiconductor chip 42 provided with the recess, that is, the thin portion where the pressure sensitive diode 44 is formed has an extremely thin thickness of, for example, about 15 μm, and the pressure vibration is transmitted through the rubber filler 54. As a result, a pressure fluctuation occurs at the junction of the pressure sensitive diode 44, and the electric signal corresponding to the pressure fluctuation is output from the pressure sensitive diode 44 as a pulse wave signal SM. In this embodiment, the semiconductor chip 42 corresponds to a semiconductor substrate and the pressure sensitive diode 44 corresponds to a piezoelectric conversion element, that is, a pressure sensor.

The pressing plate 40 is fixed to the lower end opening of the container-shaped holding member 56 made of an insulating material disposed inside the side wall member 36 so that electrical leakage from the semiconductor chip 42 is prevented. It has become. Further, the empty space 58 surrounded by the holding member 56 and the pressing plate 40 is open to the atmosphere via the rubber tube 60, and the pressure inside the empty space 58 fluctuates due to body temperature and the like, The pulse wave signal SM output from the piezoelectric diode 44 is prevented from changing.

The pulse wave signal SM output from the pressure sensitive diode 44 is supplied to the control device 62. The control device 62 is composed of a microcomputer or the like, detects the pulse wave of the artery 50 based on the supplied pulse wave signal SM, and outputs the display signal SS to the display / recording device 64 to output the pulse wave. Is displayed and recorded, and a drive signal SD is output to the pressure regulating valve 32 to control the pressure value of the pressure air supplied into the pressure chamber 28.

 Hereinafter, the operation of the present embodiment will be described.

First, when the start switch (not shown) is operated in a state where the body 10 is attached to the wrist 18 by the band 16 so that the pressing plate 40 of the pressing member 26 covers the area directly above the radial artery 50, the drive signal SD is output. As a result, pressure air having a predetermined constant pressure is supplied into the pressure chamber 28. As a result, the pressing member 26 moves the body surface 14 relative to the body 10.
The lower surface 52 of the pressing plate 40 is pressed against the body surface 14 by being moved in the direction toward. Then, when the lower surface 52 is pressed against the body surface 14 in this manner, the pressure vibration of the pulse wave generated from the artery 50 is transmitted to the pressure sensitive diode 44, and the pulse wave signal SM corresponding to the pressure vibration is output. Like The constant pressure is set to a level at which the pressure oscillation of the pulse wave can be detected by the pressure sensitive diode 44.

Subsequently, the pressure regulating valve 32 is controlled based on the pulse wave signal SM output from the pressure sensitive diode 44, so that the pressure of the pressure air supplied into the pressure chamber 28 can detect the pulse wave. The pressure member 26 is adjusted so as to be pressed against the body surface 14 with an optimum pressing force, for example, based on the amplitude and signal intensity of the supplied pulse wave vibration SM. Then, in that state, a large number of pulse wave signals supplied from each pressure sensitive diode 44.
The pulse wave signal SM output from the pressure sensitive diode 44 pressed to the optimum position for detecting the pulse wave is selected from the SMs based on the amplitude, signal strength, and the like. In this example,
Since at least three pressure-sensitive diodes 44 are pressed right above the artery 50, the pulse wave in the direction intersecting with the artery 50 is detected very finely.
Among the pressure-sensitive diodes 44 pressed right above, the pulse wave signal SM output from the pressure-sensitive diode 44 pressed to the central portion, which is not affected by the tension of the tube wall of the artery 50, is selected.

Thereafter, the selected pulse wave signal SM is continuously read and the display signal SS is output, whereby the pulse wave represented by the pulse wave signal SM is displayed / recorded on the display / recording device 64.

Here, the pulse wave detection device of the present embodiment is the semiconductor chip 42
In order to form a large number of pressure-sensitive diodes 44 on the back surface and to form a recess on the back surface thereof to reduce the thickness of the semiconductor chip 42, and to transmit the pressure vibration from the body surface 14 into the recess. By embedding the rubber filler 54 of, because the pressure oscillation of the pulse wave is detected by the pressure sensitive diode 44, it becomes possible to detect the pulse wave in the direction intersecting with the artery 50 at an extremely small interval. It was. This makes it possible to detect three or more pressure-sensitive diodes 44 just above the artery 50 to detect a pulse wave. For example, the central portion directly above the artery 50 and less affected by the tension of the vessel wall. By selecting the pulse wave signal SM output from the pressure sensitive diode 44, the pulse wave can be detected with high accuracy.

Although one embodiment of the present invention has been described in detail with reference to the drawings, the present invention can be implemented in other modes.

For example, although the pressure-sensitive diode 44 is formed as the piezoelectric conversion element in the above-described embodiment, a semiconductor strain gauge or a pressure-sensitive transistor may be formed. It is also possible to configure one pressure sensor with two or four pressure sensitive diodes and output a pulse wave signal by a bridge circuit or the like.

Further, although a large number of pressure-sensitive diodes 44 are arranged in the above-mentioned embodiment, for example, when the pressing member 26 can be forcibly moved in a direction intersecting the artery 50 by an actuator, a relatively small number of pressure-sensitive diodes are detected. The provision of the piezo-electric diode 44 is sufficient.

Further, the three pressure-sensitive diodes 44 are used, and the pressing member 26 is arranged so that the pressure-sensitive diode 44 at the center thereof is located substantially in the center just above the artery 50 based on the amplitude and signal strength of the pulse wave signal SM. Move the pressure sensitive diode 44 in its center
Alternatively, the pulse wave may be detected based on the pulse wave signal SM output from the pulse wave signal SM.

Further, although the pressure sensitive diodes 44 are arranged in a line on the semiconductor chip 42, the width dimension and the interval of the pressure sensitive diodes 44 can be increased if the pressure sensitive diodes 44 are arranged in two lines by shifting by 1/2 pitch. On the other hand, if the intervals are the same, the resolution is doubled, and it becomes possible to detect a more detailed pulse wave. Also, according to the same idea,
It is also possible to provide the pressure sensitive diodes 44 in three or more rows.

Further, although the pressure sensitive diodes 44 are arranged in a direction intersecting the artery 50 at a substantially right angle in the above-described embodiment, they may be arranged so as to intersect the artery 50 at an angle. Even in that case, the space between the pressure-sensitive diodes 44 in the direction perpendicular to the artery 50 is narrowed, so that the pressure-sensitive diodes 44 are separated by 2 as described above.
The same effect as when providing more than one row is obtained.

Further, in the above-described embodiment, the pulse wave detection device for detecting the pulse wave from the radial artery 50 has been described, but the present invention is similarly applied to the case of detecting the pulse wave from another artery such as the carotid artery, or the vein. obtain.

Although not illustrated one by one, the present invention can be carried out in variously modified and improved modes based on the knowledge of those skilled in the art without departing from the spirit thereof.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view showing a main part of a pulse wave detecting device according to one embodiment of the present invention. FIG. 2 is a partially cutaway perspective view for explaining a plurality of pressure sensors provided in the apparatus of FIG. 14: Body surface 42: Semiconductor chip (semiconductor substrate) 44: Pressure-sensitive diode (pressure sensor) 50: Radial artery (blood vessel) 54: Rubber filler SM: Pulse wave signal (electrical signal)

Claims (2)

[Claims] 1. A plurality of pressure sensors arranged on a body surface of a human body in a direction intersecting with a blood vessel, each of which detects a pressure vibration of a pulse wave generated from the blood vessel when pressed against the body surface. In the pulse wave detecting device, a plurality of recesses are formed on the surface of the semiconductor substrate to provide a thin portion, and the pressure vibration of the pulse wave is transmitted to the thin portion via the body surface to cause the pressure vibration. 2. A pulse wave detecting device characterized in that piezoelectric conversion elements for outputting an electric signal corresponding to are formed in the thin portions, respectively, and the pressure sensor is constituted by the piezoelectric conversion elements. 2. The semiconductor substrate is pressed with the recess side facing the body surface, and a rubber filler for transmitting the pressure signal is embedded in the recess. The pulse wave detection device according to item 1.