JP2017169648A - Biological sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a biological sensor capable of measuring a respiratory movement waveform, a respiratory sound waveform, a cardiac sound waveform, and an electrocardiographic waveform by a compact and simple configuration.SOLUTION: A biological sensor 100 includes a piezoelectric element 21 for converting vibration to voltage, a pair of electrocardiographic electrodes 31 and 32 for detecting an electric signal generated by a living body, and a vibration transmission plate 11 for transmitting the vibration generated by the living body to the piezoelectric element 21. The piezoelectric element 21, and the pair of electrocardiographic electrodes 31 and 32 are provided to the vibration transmission plate 11, and conductive adhesive gels 315 and 325 are applied to one of the surfaces of the pair of electrocardiographic electrodes 31 and 32.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a biosensor including an electrocardiogram electrode and a piezoelectric element to be worn on a living body chest, and more specifically, for monitoring a subject's electrocardiogram signal and respiratory motion signal for a long time. The present invention relates to a biosensor.

  Respiration monitoring under sedation can have serious consequences, and respiratory monitoring is strongly recommended, but conventional methods for monitoring respiratory rate include methods such as impedance methods, cabometers, and airflow acoustic signal measurement methods. It is used. However, since the impedance method detects respiratory motion by impedance change between electrodes, monitoring of the respiratory rate is relatively easy, but reliability is low. The capnometer directly detects the carbon dioxide concentration in exhaled air and inhaled air, so it has high reliability. However, the capnometer needs to be worn to restrain a living body such as a nasal cannula or a mask, and requires a carbon dioxide detector. An apparatus for measuring the respiratory rate based on an airflow acoustic signal is expensive although it is considered to be comfortable and reliable.

  It is also possible to monitor heart rate and blood saturated oxygen concentration with a small pulse oximeter and detect respiratory failure due to a decrease in the blood saturated oxygen concentration. Since there is a delay of several tens of seconds until the oxygen saturation concentration is lowered, there is a risk that a rapid treatment is delayed. Respiration monitoring by these conventional methods has limitations in terms of reliability, patient tolerance, and economy, and a new respiratory monitoring monitoring that overcomes these demands is desired.

  In addition, ECG is also monitored under sedation, but a monitoring device must be added to monitor the breathing while wearing these devices, ensuring a sufficient surgical field when used during surgery. It may be difficult to do this, and there is a problem that device management becomes more complicated. For these reasons, a device that is capable of measuring a plurality of pieces of biological information with a small size and a sense of restraint with high accuracy is desired.

  Conventionally, devices disclosed in Patent Documents 1 and 2 are known as devices that measure biological data such as a heart rate and a respiration rate to be measured in an unconstrained state.

  According to Patent Document 1, the vibration waveform is detected by a piezoelectric element mounted on the vibration transmission plate using a vibration transmission plate, and the vibration waveform is separated and extracted into a respiratory motion, a heartbeat and a heart sound by a filter circuit. It is possible to do.

  According to Patent Literature 2, an electrocardiogram waveform, respiratory motion, and heart rate can be measured using a pair of electrocardiographic electrodes and an electromagnetic coil. The respiratory motion and the heart rate give a high-frequency signal to the electromagnetic coil, and a change in the distance between the electromagnetic coil and the living body surface is regarded as a change in strong vibration frequency.

Japanese Patent No. 4899117 JP 2001-299712 A

  However, according to the technique described in Patent Document 1, it is possible to monitor the heart rate from the heart sound waveform, but what kind of heart failure has occurred from the heart sound waveform has a knowledge of how to see the heart sound related to heart disease. Because there are few, it is difficult to specify the type of heart disease from the electrocardiogram as in the electrocardiogram. In respiratory function monitoring, body movements other than respiratory movements are also measured, so that respiratory movements may not be measured accurately.

  In the method described in Patent Document 2, the measurement of respiratory motion is limited only to a part with a large variation in the surface of the living body such as the abdomen, and cannot be applied to a part with a small variation in the surface of the living body such as the chest. In addition, since the capacitance between the surface of the living body and the electromagnetic coil is measured, if the potential of the living body greatly fluctuates due to the use of an electric knife, the respiratory motion and heart rate cannot be measured correctly due to the influence of noise. There is a case.

  An object of the present invention is to provide a biosensor capable of measuring a respiratory motion waveform, a respiratory sound waveform, a cardiac sound waveform, and an electrocardiographic waveform with a small and simple configuration.

  In order to achieve the above-described object, the present invention provides a piezoelectric element that converts vibration into a voltage, a pair of electrocardiographic electrodes that detect an electrical signal emitted by a living body, and a vibration that transmits vibration generated by the living body to the piezoelectric element. A transmission plate, wherein the piezoelectric element and the pair of electrocardiographic electrodes are provided on the vibration transmission plate, and a conductive adhesive is provided on one surface of the pair of electrocardiographic electrodes. It is a biological sensor.

  The vibration transmission plate has a longitudinal direction, and includes a pair of engagement mechanisms for engaging the pair of electrocardiographic electrodes at both ends of the longitudinal direction, and the piezoelectric element is the longitudinal direction of the vibration transmission plate You may make it provide in the center part.

  The vibration transmission plate may be flexible and insulating.

  The pair of engagement mechanisms may be metal plates in which a hole is formed in the center and a plurality of slits are formed radially from the hole.

  The biosensor of the present invention detects an electrocardiogram waveform with a pair of electrocardiographic electrodes provided at both ends of a vibration transmission plate, and at the same time uses a piezoelectric element provided substantially at the center of the vibration transmission plate to It becomes possible to detect surface vibration. The detected vibration waveform can be separated and extracted into a respiratory motion waveform, a heart sound waveform, and a respiratory sound waveform depending on the frequency band. Thereby, in the monitoring of the respiratory function, not only the respiratory motion but also the respiratory sound waveform can be monitored, so that the respiratory function can be monitored with high reliability by the double monitoring. Also in monitoring of cardiac function, it becomes possible to perform dual monitoring of an electrocardiogram waveform and a cardiac sound waveform, so that it is possible to monitor cardiac function with higher reliability. In addition, each ECG electrode can be easily attached and detached by the engagement mechanism, and by using a commercially available ECG pad, it is cheap and hygienic without having to clean and sterilize the used ECG electrode. Can be used.

The figure which shows the biosensor 100 affixed on a biological body Perspective view of biosensor 100 Exploded perspective view of biosensor 100 Sectional drawing of the biosensor 100 cut | disconnected by the cut surface which passes the center of the width direction of the vibration transmission board 11 and orthogonal to the width direction of the vibration transmission board 11 The figure which shows the hardware constitutions of the biosignal monitoring unit 51 The flowchart which shows the flow of the process by the biological signal monitoring unit 51.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. First, the biosensor 100 according to the embodiment of the present invention will be described with reference to FIGS.

  As shown in FIGS. 1 and 2, the biosensor 100 includes a disc-shaped piezoelectric element 21 that converts vibration into voltage, a longitudinal direction (= up and down direction on the paper surface in FIG. 1), and a width direction orthogonal to the longitudinal direction ( = A flexible and insulating vibration transmission plate 11 that transmits vibration generated by a living body to the piezoelectric element 21 and both ends of the vibration transmission plate 11 in the longitudinal direction. A pair of engagement mechanisms 311 and 321, a pair of electrocardiogram electrodes 31 and 32 that are engaged by the pair of engagement mechanisms 311 and 321 and detect an electrical signal generated by a living body, both surfaces of the piezoelectric element 21, and a pair of hearts And a film electric wire 41 that bundles a plurality of conductor patterns electrically connected to the electric electrodes 31 and 32. The piezoelectric element 21 is provided at the center in the longitudinal direction of the vibration transmission plate 11.

  As shown in FIG. 1, the biosensor 100 is affixed to the body surface of the chest of a living body. Desirably, the biosensor 100 is affixed to the body surface on the sternum of a living body. The sternum, which does not seem to be deformed by the respiratory motion, is actually slightly deformed by the respiratory motion. The vibration transmission plate 11 transmits vibration generated by deformation of the sternum to the piezoelectric element 21. In other words, the piezoelectric element 21 converts the distortion of the vibration transmitting plate 11 caused by the vibration generated by the living body into a voltage.

  Since the body surface on the sternum has a substantially flat shape regardless of gender, even the plate-like vibration transmission plate 11 can be securely attached. Further, since the body surface on the sternum of the living body is a part close to the heart and trachea, it is possible to accurately detect a vibration signal of the living body caused by heart sounds, breathing sounds, and the like. In addition, the biosensor 100 attached to the body surface of the chest of a living body does not get in the way even in an operation performed by incising the abdomen. In addition, the biological sensor 100 attached to the body surface of the chest of a living body is unlikely to erroneously detect abdominal movements other than breathing (for example, physical skin deformation such as abdominal deformation or body position change due to surgery). Therefore, monitoring of respiratory function is not hindered.

  The size of the vibration transmitting plate 11 is preferably within the size of the sternum of a living body. In the embodiment of the present invention, the longitudinal dimension of the vibration transmission plate 11 is 110 mm, and the width dimension of the vibration transmission plate 11 is 30 mm. These dimensions are for general adults, and it is desirable for children and newborns to shorten the longitudinal dimension of the vibration transmitting plate 11 in accordance with the size of the sternum. When the longitudinal dimension of the vibration transmitting plate 11 is 80 mm or more, the detection performance of the biological signal is good.

  Moreover, as a material of the vibration transmission plate 11, an elastic plastic having an appropriate restoring property is used. The thickness of the vibration transmitting plate 11 is a low frequency band of 0.5 Hz or less, which is characteristic of thorax respiratory motion, a frequency band of 20-100 Hz, which is characteristic of heart sounds, and a frequency of 100-400 Hz, which is characteristic of respiratory sounds. It is necessary to set the thickness to an appropriate thickness that can detect all of the frequency bands, and 0.3 mm to 2.0 mm is desirable. In the embodiment of the present invention, the material of the vibration transmission plate 11 is a composite material of a glass epoxy plate and vinyl chloride resin (PVC), and the thickness of the vibration transmission plate 11 is 1.0 mm.

  As shown in FIGS. 3 and 4, the vibration transmission plate 11 includes a substrate 111 on which the piezoelectric element 21 is placed and a cover plate 112 bonded to the substrate 111. A pair of engagement mechanisms 311 and 321 and a copper foil conductor pattern 15 (151, 152, 153, 154, 211) are formed on the substrate 111. Both surfaces of the piezoelectric element 21 are electrically connected to the film electric wire 41 through conductor patterns 151, 152, and 211. The pair of electrocardiographic electrodes 31 and 32 are electrically connected to the film electric wire 41 via the conductor patterns 153 and 154. The film wire 41 is electrically connected to the biological signal measuring device 1 described later.

  The cover plate 112 is pressure-bonded to the substrate 111 with the piezoelectric element 21, the pair of engagement mechanisms 311 and 321, and the conductor patterns 151, 152, 153, 154, and 211 interposed therebetween. A circular hole is formed in the cover plate 112 at a position facing the pair of engagement mechanisms 311 and 321 formed in the vibration transmission plate 11.

  In order for the piezoelectric element 21 to efficiently convert the vibration of the living body into an electric signal, it is desirable that the substrate 111 and the cover plate 112 are closely attached without any gap. In the embodiment of the present invention, the covering plate 112 is heated to be softened, and is deformed and brought into close contact with the shape of the piezoelectric element 21 for pressure bonding. Therefore, the material of the covering plate 112 is preferably a plastic having thermoplasticity, for example, polyethylene (PE), polypropylene (PP), vinyl chloride resin (PVC), polystyrene (PS), ABS resin (ABS), polyethylene. Tephthalate (PET), acrylic resin (PMMA), polycarbonate (PC), or polyamide (PA) is desirable. In the embodiment of the present invention, a vinyl chloride resin (PVC) having a thickness of 0.5 mm, which is inexpensive and excellent in workability, is used as the material of the covering plate 112. Thermoplastic plastics have the property of shrinking in the rolling direction at the time of manufacture when heated (above the glass transition point of the polymer molecule), and therefore annealed before heating and pressure-bonding the cover plate 112. Is desirable.

  In an embodiment of the present invention, the material of the substrate 111 is a 0.3 mm glass epoxy printed circuit board (PCB). Conductive patterns 151, 152, 153, 154, and 211 for connecting the components are formed in advance on the substrate 111 by attaching a copper foil having a thickness of 18 μm and performing an etching process. Thus, when the vibration transmission plate 11 is formed by thermocompression bonding, the piezoelectric element 21 and the pair of engagement mechanisms 311 and 321 placed on the substrate 111 and the conductor patterns 151, 152, 153, 154, and 211 are arranged. Due to the difference in the coefficient of thermal expansion of each component, it is possible to minimize the occurrence of defects such as tearing due to local stress concentration in the heating-cooling process.

  In the embodiment of the present invention, a hot melt sheet 103 having a thickness of 50 μm is used as an adhesive in thermocompression bonding of the substrate 111 and the cover plate 112. The material of the hot melt sheet 103 is desirably a polyester system that is in a molten state at about 80 ° C. or higher and has high adhesiveness and flexibility. By heating for 1 to 3 minutes at a temperature of 90 to 120 ° C. at the time of thermocompression bonding, it is possible to reliably perform pressure bonding without peeling in a normal use range. Due to the difference in thermal expansion coefficient between the substrate 111 and the cover plate 112, warpage occurs in the cooling process, but the vibration transmission plate 11 is cooled after cooling and molded in a state opposite to the slightly warped direction. Can be made flat.

  In order to attach the biosensor 100 to the body surface of the electrocardiographic electrodes 31 and 32, the adhesive is a low-polarization voltage and stable silver-silver chloride electrode and a highly conductive material as an adhesive. Adhesive gels 315 and 325 are applied to transmit weak electromotive force of the myocardium from the body surface. By directly attaching the surfaces of the electrocardiographic electrodes 31 and 32 to which the conductive adhesive gels 315 and 325 are applied to the epidermis immediately above the sternum of the living body's chest, the electrocardiographic waveform and the vibration waveform on the living body surface are combined into a single biosensor. 100 enables simultaneous detection. The adhesive is not limited to the conductive adhesive gels 315 and 325 but may be a conductive adhesive seal.

  Each of the pair of engagement mechanisms 311 and 321 has an insertion opening in which a circular hole is formed in the center of a donut-shaped metal plate, and a plurality of slits are formed radially with respect to the hole. Cylindrical protrusions 313 and 323 are formed on the surfaces of the electrocardiographic electrodes 31 and 32 facing the substrate 111. The protrusions 313 and 323 are formed with grooves that go around the side surfaces. The electrocardiographic electrodes 31 and 32 are locked to the engaging mechanisms 311 and 321 by inserting the projections 313 and 323 of the electrocardiographic electrodes 31 and 32 into the insertion ports of the respective engaging mechanisms 311 and 321. The insertion openings of the engagement mechanisms 311 and 321 become leaf springs by slits and fit into the grooves of the protrusions 313 and 323. Therefore, since the projections 313 and 323 of the electrocardiographic electrodes 31 and 32 are securely locked without shifting the engaging portion in normal use, the electrocardiographic signals of the electrocardiographic electrodes 31 and 32 are conducted without contact failure. At the same time, the vibration of the body surface is transmitted to the piezoelectric element 21 via the vibration transmitting plate 11.

  Although the electrocardiographic pads 314 and 324 of the electrocardiographic electrodes 31 and 32 are in contact with the body surface S by the adhesive conductive adhesive gels 315 and 325, the vibration of the body surface S causes the conductive adhesive gels 315 and 325 to Attenuate somewhat. However, in the embodiment of the present invention, in the frequency range “0.1 to 1 kHz” necessary for detecting various biological signals described later, since it has a high signal / noise ratio (= S / N ratio), It is possible to detect a biological signal with high accuracy.

  5 and 6 show the hardware configuration of the biological signal monitoring unit 51 using the biological sensor 100 and the processing flow. The biological signals converted into electrical signals by the piezoelectric element 21 and the pair of electrocardiographic electrodes 31 and 32 are amplified by the biological signal detection unit 521 and digitally converted by the AD conversion unit 522. The digitized electrocardiogram data is subjected to filtering processing by the calculation unit 53, and the electrocardiogram waveform 551 is displayed on the display unit 55. Similarly, the vibration signal of the body surface is digitally converted by the AD conversion unit 522, bandpass filtering by the frequency band is performed by the calculation unit 53, and separated and extracted into a respiratory motion waveform 553, a heart sound waveform 552, and a respiratory sound waveform 554, respectively. Displayed on the display unit 55. The computing unit 53 also performs normal / abnormal judgment of the electrocardiogram waveform 551, the respiratory motion waveform 553, the heart sound waveform 552, and the respiratory sound waveform 554, and displays a warning on the display unit 55 when an abnormality occurs. The control unit 54 changes display settings for various biological signal waveforms on the display unit 55 of the biological signal monitoring unit 51 or changes settings for normal / abnormal determination.

  The electrocardiogram waveform 551, the respiratory motion waveform 553, the cardiac sound waveform 552, and the respiratory sound waveform 554 are recorded as time series data together with the normal / abnormal determination history. The time-series data can be transmitted directly to a personal computer or tablet terminal via a wired LAN, wireless LAN, or Bluetooth (registered trademark) communication that is wireless communication by the transmission unit 56, and clouded via the personal computer or tablet terminal. It can also be sent to a server and monitored remotely.

DESCRIPTION OF SYMBOLS 100 Biosensor 103 Hot melt seal 11 Vibration transmission plate 111 Substrate 112 Cover plate 15 Conductor pattern 151 Conductor pattern for piezoelectric element cathode 152 Conductor pattern for anode of piezoelectric element 153 Electrocardiogram electrode conductor pattern (head side)
154 ECG electrode conductor pattern (abdominal side)
211 Conductor pattern (jumper)
21 Piezoelectric element 31 ECG electrode (head side)
311 Engagement electrode plate (head side)
313 ECG electrode engaging part (head side)
314 Electrode pad (head side)
315 Conductive adhesive gel (head side)
32 ECG electrodes (abdominal side)
321 Engaging electrode plate (abdomen side)
323 ECG electrode engaging part (abdominal side)
324 electrode pad (abdominal side)
325 conductive adhesive gel (abdomen side)
41 Film Electric Wire 51 Biological Signal Monitoring Unit 52 Biological Signal Processing Unit 521 Biological Signal Detection Unit 522 AD Conversion Unit 53 Calculation Unit 54 Control Unit 55 Display Unit 551 Electrocardiogram Waveform 552 Cardiac Sound Waveform 553 Respiration Motion Waveform 554 Respiration Sound Waveform 56 Transmitting Unit 57 Storage unit S Body surface (skin)

Claims (4)

A piezoelectric element that converts vibration into voltage;
A pair of electrocardiographic electrodes for detecting an electrical signal emitted by the living body;
A vibration transmission plate for transmitting vibration generated by the living body to the piezoelectric element;
With
The piezoelectric element and the pair of electrocardiographic electrodes are provided on the vibration transmission plate,
A biosensor comprising a conductive adhesive on one surface of the pair of electrocardiographic electrodes. The vibration transmission plate has a longitudinal direction, and includes a pair of engagement mechanisms that engage the pair of electrocardiographic electrodes at both ends of the longitudinal direction,
The biosensor according to claim 1, wherein the piezoelectric element is provided at a central portion in the longitudinal direction of the vibration transmission plate. The biosensor according to claim 1, wherein the vibration transmission plate has flexibility and insulation. The biosensor according to claim 2, wherein the pair of engagement mechanisms are metal plates in which a hole is formed in the center and a plurality of slits are formed radially from the hole.

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