JP2613635B2 - Pressure pulse wave detector - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an apparatus for detecting a pressure pulse wave generated in an artery of a living body from a plurality of positions on the artery.

2. Description of the Related Art Pressure pulse waves generated from arteries in synchronization with the heartbeat
Various information indicating the state of the circulatory organ, such as the activity state of the heart, the blood pressure value, the degree of arteriosclerosis, etc., is included. In order to detect such a pressure pulse wave, generally, a pressure plate which is pressed against the epidermis of a living body is provided, and the vibration of the bending of the pressure plate is detected at a plurality of positions on the pressure plate in a non-contact manner. Thus, there is provided a pulse wave detection device of a type in which a pressure pulse wave generated from an artery under the epidermis is detected at a plurality of measurement points.

Problems to be Solved by the Invention However, in such a conventional apparatus, in general, a bending state of the pressing plate changes due to thermal expansion of the pressing plate and a main body supporting the pressing plate, and a non-negligible change occurs in an output signal. May be. In particular, when a pressure pulse wave detection device at a relatively low room temperature is attached to a living body, the temperature of the pressure pulse wave detection device rapidly changes to the body temperature of the living body due to the attachment, so the above-mentioned inconvenience is remarkable. Become.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a pressure pulse wave detection device that eliminates the influence of temperature on an output signal representing a pressure pulse wave.

First Means for Solving the Problems To achieve this object, the gist of the first invention is to provide a first pressing plate pressed against the epidermis of a living body,
Pulse wave detection for detecting pressure pulse waves generated from the artery under the epidermis at a plurality of measurement points by detecting the flexural vibration of the first press plate in a plurality of places on the first press plate in a non-contact manner. In the device, the second pressing plate, which has a different coefficient of thermal expansion from the first pressing plate, is pressed against the skin similarly to the first pressing plate, and the bending vibration is detected in a non-contact manner by the first pressing plate. In the vicinity of the first pressing plate and the second pressing plate, based on the difference between the signals detected from the first pressing plate and the second pressing plate due to the difference in the coefficient of thermal expansion between the first pressing plate and the second pressing plate. There is provided a signal correction means for correcting the signal representing the pressure pulse wave so that the influence of the thermal expansion of the first pressing plate is eliminated.

In this way, the first pressing plate has a different coefficient of thermal expansion from that of the first pressing plate and is pressed against the skin similarly to the first pressing plate, and the bending vibration is detected in a non-contact manner. 2 pressing plate is provided, and the first pressing plate and the second
Based on the difference between the signals detected from the pressure plates, the signal representing the pressure pulse wave is corrected so that the influence of the thermal expansion of the first pressure plate is eliminated. The effect of temperature on temperature is eliminated.

Second Means for Solving the Problems The gist of the second invention is that a plurality of first
A common semiconductor substrate on which the pressure-sensitive element is formed, and pressing means for pressing the semiconductor substrate against the epidermis of a living body, and a pressure pulse wave generated from an artery in the epidermis is transmitted by the first pressure-sensitive element. In the pressure pulse wave detecting device of the type for detecting, a second pressure-sensitive element having a temperature change characteristic different from that of the first pressure-sensitive element is provided on the semiconductor substrate, and the first pressure-sensitive element and the second pressure-sensitive element are provided. Based on a difference between signals detected from the first pressure-sensitive element and the second pressure-sensitive element due to different temperature change characteristics of the pressure-sensitive elements, the first
A signal correcting means for correcting the signal representing the pressure pulse wave so as to eliminate the influence of the temperature change of the pressure sensitive element.

In this way, the second pressure-sensitive element having a temperature change characteristic different from that of the first pressure-sensitive element is provided, and the first pressure-sensitive element and the second pressure-sensitive element are provided by the signal correction means. Based on the difference between the signals respectively detected from the second pressure-sensitive elements,
Since the signal representing the pressure pulse wave is corrected so that the influence of the temperature change of the first pressure sensing element is eliminated, the influence of the temperature on the output signal representing the pressure pulse wave is eliminated.

Examples Hereinafter, examples of the present invention will be described in detail with reference to the drawings.

In FIG. 1, a pressure pulse wave detection head 12 is detachably attached to a wrist 10 by a band 14. The pressure pulse wave detection head 12 has a bottomed cylindrical housing 16 and a housing 16.
And a diaphragm 22 that is provided between the housing 16 and the main body 18 to support the main body 18 and form a pressure chamber 20 in the housing 16. When supplied to the pressure chamber 20 via the pressure control valve 26, the main body 18 is pressed onto the radial artery 30 located on the radius 28. In the present embodiment, the diaphragm 22, the housing 16, and the like correspond to a pressing means for pressing the main body 18.

The main body 18 is made of a hard resin, metal, ceramic, or the like, and is made of a highly rigid material having a thickness of, for example, about ten and several mm. As shown in detail in FIGS. The pressing surface 32 has a pair of rectangular recesses 31 and 33, and a plurality of through holes 34 opened in the recess 31 and arranged in a row along the longitudinal direction of the recess 31.
And a plurality of through-holes 35 opened in the recess 33 and arranged in a line along the longitudinal direction of the recess 33.

The pressing surface 32 of the main body 18 has a flexible pressing plate 36 such as a relatively thin metal plate or plastic plate of about 2/100 mm or a relatively thin stainless steel plate plated with gloss. And 37 are stuck. The pressing plates 36 and 37 have different coefficients of thermal expansion β ₁ and β ₂ from each other, and are fixed so as to close the openings of the recesses 31 and 33. In this embodiment, the pressing plate 36 functions as a first pressing plate, and the pressing plate 37 functions as a second pressing plate. Note that the interval between the through holes 34 and 35 corresponds to the interval between the measurement points of the pressure pulse wave, and the radial artery 30
The distance is determined to be sufficiently smaller than the diameter of the radial artery, for example, about 0.1 mm, so that at least three to five measurement points are located within the diameter of the radial artery 30.

A plurality of optical fibers 40a, 40b, 40c
One end of each of them is fitted, and the end faces of these one end are opposed to the pressing plate 36. Further, one ends of a plurality of optical fibers 41a, 41b, 41c,... Are fitted into the through holes 35, and the end surfaces of the one ends are pressed by the pressing plate 37.
It is made to face. The plurality of optical fibers 40a, 4
The ends of 0b, 40c,... And 41a, 41b, 41c,. The other ends of the plurality of optical fibers 40a, 40b, 40c... And 41a, 41b, 41c are fixed to the pressure pulse wave signal output device. The pressure pulse wave signal output device 42 includes the plurality of optical fibers 40a, 40b,
40c... And 41a, 41b, 41c have the same configuration, and therefore, the optical fiber 40a will be described below. As shown in FIG. 4, the pressure pulse wave signal output device 42 includes a laser light source 44 that outputs laser light having the same phase, and a convex lens 46 that converts the light output from the laser light source 44 into parallel light.
And a non-polarizing beam splitter 48 for splitting the beam
A mirror 49 for returning the light reflected by the non-polarizing beam splitter 48, and a convex lens 5 for making the light passing through the non-polarizing beam splitter 48 incident on the other end surface of the optical fiber 40a.
0, and the photosensor 52 for receiving the light extracted by the non-polarizing beam splitter 48 of the propagating through the optical fiber 40a reflected light, pressure pulse wave detection to output the pulse-wave signal SMa ₀ based on the output signal of the photosensor 52 And a circuit 54.

In the pressure pulse wave signal output device 42 configured as described above, the portion of the pressing plate 36 corresponding to the opening of the through hole 34 located at the left end in FIG. 2, that is, faces the distal end surface of the optical fiber 40a. PPW signal SMa ₀ representing the pressure pulse wave that acts on part is adapted to be outputted from the pressure-pulse-wave detection circuit 54. That is, of the laser light output from the laser light source 44, one laser light reflected by the non-polarization beam splitter 48 is reflected by the mirror 49, passes through the non-polarization beam splitter 48, and is received by the photosensor 52. Of the laser light output from the laser light source 44, the other laser light transmitted through the non-polarizing beam splitter 48 is applied to a pressing plate 36 via an optical fiber 40a known as a rod lens, and the pressing plate 36 After being reflected, it is again guided to the optical fiber 40a and returned to the non-polarizing beam splitter 48. Then, the light is reflected by the non-polarizing beam splitter 48 and received by the photosensor 52. Therefore, the laser light received by the photosensor 52 is light reflected by the mirror 49, that is, light reflected by the pressing plate 36, that is, interference light between the measurement light, and in this embodiment, the pressing plate 36 The phase of the interference light is changed by the change in the optical path of the measurement light due to the deflection corresponding to the pressure acting on the interference light. The pressure pulse wave detection circuit 54 sequentially counts the phase change of the interference light corresponding to the minute displacement of the pressing plate 36 at every predetermined small minute unit time, and based on the counted value, the cycle of the pressing plate 36 manner and outputs a pulse wave signal SMa ₀ representing the pressure pulse wave acting.
Figure 5 shows one cycle of the pressure pulse wave represented by the pulse-wave signal SMa _0.

As described above, the pressure pulse wave signals SMa ₀ , SMb ₀ , SMC ₀ ... Representing the pressure pulse waves at each measurement point located on the radial artery 30
. And SMa ₁ , SMb ₁ , SMc ₁ ... are pressure pulse wave signal output devices
It is supplied to the control device 56 from the control device 56.
Processes the input signal in accordance with a pre-stored program, and automatically removes the effects associated with temperature changes to create accurate pulse wave signals. That is, since the pressing plates 36 and 37 are disposed close to each other and are pressed under the same pressing condition, first, in step S1 of FIG. 6, the pressure pulse wave based on the reflected light from the pressing plate 36 Among the signals, for example, the maximum signal SMC ₀ and the maximum signal SMC ₁ among the pressure pulse wave signals based on the reflected light from the pressing plate 37 are read, and in step S2, the signals SMC ₀ and SMC ₁ are read. Is calculated. This difference signal ΔSM
Is calculated, for example, by comparing the maximum peak values or the minimum peak values. This difference signal ΔSM is
The magnitude (ratio) of the difference signal ΔSM is caused by the difference between the thermal expansion coefficients β ₁ and β ₂ of the pressing plates 36 and 37.
Is related to the temperature of the pulse wave sensor 12. Therefore, in the present embodiment, the relationship between the magnitude of the difference signal ΔSM and the correction constant K of the pulse wave signal is experimentally determined and stored in advance so that the influence of the thermal expansion of the pressing plate 36 is eliminated. In step S3, a correction constant K is obtained from the relationship shown in FIG. 7, for example, based on the actual difference signal ΔSM. In step S4, for example, each data point value of the pulse wave signal SMC ₀ is sequentially multiplied by the correction constant K,
The corrected pulse wave signal SMC ₀ is obtained. Other pulse wave signals SMa ₀ ,
SMb ₀ ··· is also corrected, respectively, if necessary in the same way.

Pulse wave signals SMa ₀ , SMb ₀ , SMC ₀ corrected in this way
.. Have the effects of temperature removed, and the control device 56 displays, for example, the pulse wave shape shown in FIG. 1988
No. 293424), a pressure pulse wave at a measurement point which is not affected by the tension of the arterial tube wall is selected to continuously monitor the blood pressure value, or, as disclosed in Japanese Patent Application No. 63-87720.
As described in Japanese Patent Application Laid-Open No. 1-259836, the arterial stiffness is measured based on the pressure pulse wave obtained while changing the pressing force of the main body 18, and the result is output to an output device (not shown). Output.

As described above, in the present embodiment, pressing is performed under the same pressing condition using the pressing plates 36 and 37 having different thermal expansion coefficients from each other, and the pulse wave signals obtained from the reflected lights of the pressing plates 36 and 37, respectively. A difference signal ΔSM is calculated, and a correction value K is calculated based on the difference signal ΔSM from a relationship obtained in advance,
Since the pulse wave signal is corrected using the correction value K, a pulse wave signal from which the influence of temperature has been removed can be automatically obtained.
Therefore, a highly accurate pulse wave shape can be displayed, or highly accurate measurement can be performed based on the corrected pulse wave signal.

Further, according to the present embodiment, the temperature detecting element and the circuit need not be provided in the pressure pulse wave sensor 12 as compared with the case where the temperature sensor is provided, and thus there is an advantage that the size and cost are reduced.

Next, another embodiment of the present invention will be described. In the following embodiments, the same reference numerals are given to portions common to the above description, and the description will be omitted.

In FIG. 8, the main body 18 of the pulse wave sensor 12 of this embodiment is provided with a row of optical fibers 40a, 40b, 40c,. A small pressing plate 60 having a coefficient of thermal expansion β ₃ different from the coefficient of thermal expansion β ₁ is disposed adjacent to the end of the pressing plate 36. In the present embodiment, the small pressing plate 60 functions as a second pressing plate. Since the pressure pulse wave generated from the radial artery 30 is almost insensitive to the small pressing plate 60 and is disposed exclusively at a position sensitive to the pressing force by the pressure pulse wave sensor 12, the small pressing plate 60 Pulse signal SM obtained based on the reflected light from
determining a difference signal DerutaSM ₁ and pulse wave signals SMa obtained based on the reflected light from the end of the k and the pressing plate 36, to determine the correction constant K on the basis of previously obtained relation to the difference signal DerutaSM ₁ ,
The correction can be made in the same manner as in the above-described embodiment. Thereby, the same effect as that of the above-described embodiment can be obtained.

In FIG. 9, the main body 18 of the pressure pulse wave detecting head 12 includes a frame-shaped frame 62 to which a ceramic substrate 61 is fixed, and a semiconductor substrate 64 fixed to the ceramic substrate 61. On one surface of the semiconductor substrate 64, recesses 66a, 66b,.
By providing j at a plurality of locations along a straight line, a locally thin portion is formed. In these thin portions, a pressure-sensitive resistor whose resistance value changes in response to strain by a known semiconductor technology, a pressure-sensitive diode or a pressure-sensitive transistor whose current in a PN junction changes in response to strain are formed. Thus, a plurality of pressure-sensitive elements 68a, 68b,... 68j are formed at intervals of, for example, 0.3 mm. Recesses 66a, 66b,
.. 66j are filled with soft silicone rubber 70a, 70b,... 70j functioning as a pressure transmission medium, and when the semiconductor substrate 64 is pressed against the skin, a pressure pulse generated from the radial artery 30 Waves are sensed at the pressure sensitive elements 68a, 68b, ... 68j. While conductor wiring (not shown) is provided on the ceramic substrate 61, the wiring with the wiring on the semiconductor substrate 64 is bonded via a wire (not shown),
A signal representing a pressure pulse wave is output from the pressure-sensitive elements 68a, 68b,... 68j to the control device 56 via these wires and conductor wiring.

In this embodiment, for example, the pressure-sensitive element 68j is provided with a different temperature characteristic as compared with the other pressure-sensitive elements 68a, 68b,. That is, the thickness of the pressure-sensitive element 68j and / or the coefficient of thermal expansion of the silicon rubber 70j filled in the recess 66j is changed as compared with those of the others, so that the output signal of the pressure-sensitive element 68j becomes temperature-dependent. The change received by the change is made different. For this reason, the control device 56 calculates a difference signal ΔSM between the output signal of the pressure-sensitive element 68a and the output signal of the pressure-sensitive element 68j, for example. A correction constant K is calculated based on the signal ΔSM, and the signals output from the pressure-sensitive elements 68a, 68b,... Are respectively corrected by the correction constant K, as in the embodiment of FIG. Therefore, also in this embodiment, the same effects as in the above-described embodiment can be obtained. In addition,
Two rows of pressure-sensitive elements may be provided on the semiconductor substrate 64 so that the temperature characteristics of the pressure-sensitive elements in one row are different from those in the other row. In this case, correction is made in the same manner as in the embodiment of FIG.

As described above, the present invention has been described with reference to the drawings showing one embodiment, but the present invention can be applied to other aspects.

For example, in the above-described embodiment, it has been described that the pressure pulse wave generated from the radial artery 30 is detected.
The pressure pulse wave sensor 12 may be pressed by another artery to detect a pressure pulse wave generated from another artery.

Further, in the above-described pressing plates 36 and 37, between the portions corresponding to the through holes 34 and 35, a plurality of slits penetrate in the thickness direction of the pressing plates 36 and 37, and the pressing plates 36 and 37 In a state where 37 is pressed against the epidermis of the living body, in a direction substantially parallel to the radial artery 30, that is, in the width direction of the pressing plates 36 and 37, a predetermined distance is kept from the edge so as not to impair the durability of the pressing plates 36 and 37. Thus, it may be formed along the width direction. This way, the radial artery
In a state where the pressing plates 36 and 37 flex and vibrate in response to the pulsation of 30, each portion corresponding to the through hole 34, that is, the pressing plate
Since the respective vibration detection points on 36 and 37 are separated from each other by the slits, the vibrations detected at the detection points are preferably prevented from interfering with each other.

Further, the main body 18 in the above-described embodiment is provided with a diaphragm.
It is designed to be driven in the pressing direction by 22,
In addition, a driving device for moving in a direction intersecting with the radial artery 30 or a rocking positioning device for positioning a rocking position around one axis parallel to the radial artery 30 may be provided.

In the above-described embodiment, one optical fiber 40a, 40b, 40c,... Is provided for each pressure pulse wave measurement point, but a single bundle of optical fibers is provided. May be.

In the above-described embodiment, the pressure pulse wave is detected based on the phase difference of the interference light. However, the pressure pulse wave is detected based on a change in the amount of reflected light generated in association with the bending of the pressing plate 36. You may make it. In this case, a bundle of optical fibers composed of, for example, one or more irradiation optical fibers and a light receiving optical fiber bundled around its periphery is used for each pressure pulse wave measurement point. When the reflected light guided by the optical fiber is received by the optical sensor, a pressure pulse wave signal is output. The light source at this time may be a light source such as an LED or a lamp as long as the light output is constant.

In the above-described embodiment, the pressure pulse wave is detected based on the phase difference of the interference light. However, the phase difference due to the Doppler shift may be detected using optical heterodyne. That is, a laser light source that outputs laser light of two orthogonal frequencies is used, the two-frequency laser light is separated into two optical paths of measurement light and reference light, the optical path of the reference light is fixed, and the optical path of the measurement light is In addition to the optical path reflected by the pressing plate, a measurement beat signal is created by combining the reflected measurement light and the reference light, and a reference beat signal is created by combining two orthogonal frequencies immediately after being output from the laser light source. And outputs a pressure pulse wave signal based on the shift between the measured beat signal and the reference beat signal.

Further, in the above-described embodiment, the light source and the light receiving element are provided separately from the pressure pulse wave detection head 12, but may be provided integrally. In such a case, for example, a microlens array in which a plurality of lenses are arranged in a line at an interval of 100β by an electron beam exposure technique, or a plurality of light emitting units and light receiving units are formed on a semiconductor chip at an interval of 100μ, respectively. The LED array and the light receiving element array are stacked above the pressing plate 36 at an appropriate interval.

The above is merely an embodiment of the present invention, and the present invention can be variously modified without departing from the spirit thereof.

[Brief description of the drawings]

FIG. 1 is a diagram showing a system configuration of one embodiment of the present invention. 2 and 3 are a partially cutaway perspective view and a side sectional view showing the main body of the pressure pulse wave detecting head of the embodiment of FIG. FIG. 4 is a diagram for explaining in detail the configuration of the pressure pulse wave signal output device of the embodiment of FIG. FIG. 5 is a diagram showing an example of a pulse wave signal output from the apparatus of FIG. FIG. 6 is a flowchart for explaining the operation of the embodiment of FIG. FIG. 7 is a diagram showing the relationship used in the description of the flowchart of FIG. 8th
The figure shows another embodiment of the present invention. Fig. 9
FIG. 7 is a diagram showing a part of another embodiment of the present invention. 12: pressure pulse wave detection sensor 16: housing 22: diaphragm 30: radial artery (artery) 36: pressing plate (first pressing plate) 37: pressing plate (second pressing plate) 60: small pressing plate (second pressing plate) 64: semiconductor substrate 68a, b,...: Pressure-sensitive element (first pressure-sensitive element) 68j: pressure-sensitive element (second pressure-sensitive element)

Claims (2)

(57) [Claims] A first pressing plate which is pressed against the epidermis of a living body, wherein a flexural vibration of the first pressing plate is detected at a plurality of positions on the first pressing plate in a non-contact manner, whereby the subcutaneous skin is detected. In a pressure pulse wave detection device that detects a pressure pulse wave generated from an artery at a plurality of measurement points, the pressure pulse wave has a coefficient of thermal expansion different from that of the first pressing plate. A second pressing plate, which is pressed and whose bending vibration is detected in a non-contact manner, is provided in the vicinity of the first pressing plate, and the second pressing plate is deformed due to a difference in thermal expansion coefficient between the first pressing plate and the second pressing plate. Signal correction means for correcting the signal representing the pressure pulse wave based on the difference between the signals detected from the first pressing plate and the signal detected from the second pressing plate so as to eliminate the influence of the thermal expansion of the first pressing plate. A pressure pulse wave detection device, comprising: 2. A pressure pulse wave generated from an artery in the epidermis, comprising: a common semiconductor substrate on which a plurality of first pressure-sensitive elements are formed; and pressing means for pressing the semiconductor substrate against the epidermis of a living body. Pressure pulse wave detecting device of the type detecting the pressure by the first pressure-sensitive element, wherein a second temperature change characteristic different from that of the first pressure-sensitive element
A pressure-sensitive element provided on the semiconductor substrate;
Based on a difference between signals detected from the first pressure-sensitive element and the second pressure-sensitive element due to different temperature change characteristics of the pressure-sensitive element and the second pressure-sensitive element. A pressure pulse wave detection device, comprising: a signal correction unit for correcting a signal representing the pressure pulse wave so that the influence of a temperature change of the pressure sensing element is eliminated.