TW201010671A - Respiratory monitoring system - Google Patents

Abstract

Disclosed is a respiratory monitoring system including a pyroelectric sensor and a computer system. The pyroelectric sensor includes a housing having a surface configured for receiving the respiratory airflow of a user, a substrate disposed in the housing, and two sensing electrodes respectively disposed on the top surface and the bottom surface of the substrate. The top surface and bottom surface of the substrate are parallel to the airflow-receiving surface of the housing. The sensing electrodes produce a plurality of voltage values which vary as a function of the temperature difference between the top surface and bottom surface of the substrate. The computer system is electrically connected to the pyroelectric sensor to calculate out the user's respiratory air volumetric rate according to the area of the airflow-receiving surface of the housing and the voltage values, and calculate out the user's respiratory rate according to the variation period of the voltage values.

Description

201010671 IX. Description of the Invention: [Technical Field] The present invention relates to a respiratory monitoring system, and more particularly to a respiratory monitoring system capable of simultaneously monitoring a respiratory rate and a respiratory flow velocity. [Prior Art] Breathing is the main gas exchange mechanism of the human body. Once the mechanism of the exchange of gas has a problem, it will affect normal life, and serious people may be fatal. ❿ Therefore, monitoring of breathing is an important indicator of the normal maintenance of life phenomena, especially for some patients with symptoms of sleep apnea. These patients often stop breathing when they are unconsciously, resulting in insufficient oxygen supply to the human body. In severe cases, sudden death may occur. In addition, for asthma patients, monitoring of breathing is also quite important. If the asthma is not treated immediately, it often happens unfortunately. More than 12 million people in the United States suffer from sleep apnea, a condition that is often interrupted by breathing. If we can respond to these situations in the first place, it will greatly reduce the damage 因此. Therefore, it is necessary to monitor the breathing of the human body. SUMMARY OF THE INVENTION Accordingly, one aspect of the present invention is to provide a respiratory monitoring system for monitoring a respiratory rate of breathing using a helium and a flow i of a respiratory airflow. To achieve the above object, embodiments of the present invention provide a respiratory monitoring system, which includes at least a focal electrical sensor and a computer system. The detector includes at least a housing, a substrate and at least two sensing electrodes, wherein the housing has a surface for receiving a breathing air flow of the user, and the substrate is in a pure position. The substrate has a top surface and a bottom surface, the top surface and the bottom surface being parallel to the surface of the housing, and the sensing electrodes being located on the top surface and the bottom surface, respectively. These sensing electrodes can generate a plurality of voltage values based on temperature changes of the top and bottom surfaces. The computer system is electrically connected to the focal inductance detector to calculate the flow rate of the user's respiratory airflow according to the surface area and the voltage value of the casing, and calculate the breathing rate of the user according to the period of change of the voltage value. According to another embodiment of the invention, the respiratory monitoring system further comprises a charge beta amplifier, a filter and a signal amplifier. The charge amplifier is electrically connected to the focal inductor to eliminate the time constant effect of the focal inductor and the signal transmission line. The waver is electrically connected to the charge amplifier to filter out the noise of the output signal of the focus sensor. The signal amplifier is electrically connected between the computer system and the signal amplifier to amplify the signal output from the focal inductor. [Embodiment] Referring to both the drawings and FIG. 2, the figure is a functional block diagram of a respiratory monitoring system 100 according to an embodiment of the present invention, and FIG. 2 is a diagram showing an embodiment of the present invention. An example of the internal structure of the focal length detector 11〇. The respiratory monitoring system 100 includes a focal electrical sensor, a computer system 120, and a mask-type carrier 130. The mask type carrying device 13 is configured to carry the focal electrical detector 110' to place the focal electrical detector 110 under the user's nostril. Thus, the pyroelectric detector 11 can output an electronic signal according to the temperature change of the respiratory airflow. To the computer system 120, the computer system 12 uses these electronic signals to calculate the user's breathing rate and the flow rate of the respiratory airflow. The computer system 120 includes a data capture module 120a. This data 7 201010671 operation module 120a converts the format of the electronic signal into a format acceptable to the computer system 12 . In this embodiment, the focal electrical detector 110 is a piezoelectric ceramic, and the material thereof may include lead bismuth (PZ), lead titanate (ρτ) or lead stearate (ΡΖΤ). The pyroelectricity of the piezoelectric ceramic is applied only for sensing. For example, a focus sensor suitable for use in the present invention is a sensor commercially available from Pro_Wave Electronics Model 400ER080, which is provided with a piezoelectric ceramic diaphragm under the housing. In a particular embodiment, the focal electrical detector 110 has a housing, 112, a substrate 114 and signal output pins 116 & and 116b. The substrate 114 has sensing electrodes 114a, 114b, a top surface 114c and a bottom surface 114d, wherein the top surface mc and the bottom surface 114d are parallel to the housing surface 112a, and the sensing electrodes 114 & and 114b are located on the top surface 114c and The bottom surface 114d is parallel to each other. The casing surface 112a is perpendicular to the traveling direction of the breathing airflow fa so that the temperature of the breathing airflow Fa is transmitted to the internal sensing electrodes 114a and 114b through the body surface H2a. When the casing surface U2a is subjected to the impact of the breathing airflow Fa, the sensing electrodes 114a and 114b sense the temperature change and output voltage signals from the signal output pins 116a and 116b due to the pyroelectric effect. For temperature conduction, the sensing electrode 114a is located at the upwind and the sensing electrode 114b is located at the downwind, so the sensing electrode 114a will sense a temperature change in preference to the sensing electrode 114b. In the following, how to use the respiratory monitoring system 1 to measure the user's breathing rate and the flow rate of breathing gas will be explained. First, for an ideal piezoelectric ceramic, its constitutive equation can be expressed as follows: (1)

Di=[dijk]TXjk+[Kij]x>TEj+[pi]x ^ T, 8 201010671 where D is the generated charge density; d is the piezoelectric modulus at a fixed temperature τ; Κ is a fixed pressureχ And the dielectric tensor at temperature τ; Ε is the electric field strength; ρ is the pyroelectric coefficient at a fixed pressure: j, j, k represents the direction. In the present embodiment, since the effect of the electric field is small relative to other factors, Equation (1) can be rewritten as follows:

Di=[dijk]TXjk +[Ρΐ]χΔΤ, (7)

Then, since the crust surface 112a is perpendicular to the traveling direction of the respiratory airflow Fa, the momentum of the breathing gas can be expressed by the following equation: J = Jpu2dA = pii2 JdA = P^A = pq^/a (3) where J is The momentum of the respiratory airflow Fa before impacting the piezoelectric ceramic; p is the gas density of the respiratory airflow; u is the velocity of the respiratory airflow in the horizontal direction; a is the area of the shell surface 11〇; 込 is the flow rate (volumetricfl〇wrate) due to the respiratory airflow Fa impacts the piezoelectric ceramic and does not have any velocity in the horizontal direction, so the pressure 壳体 of the casing surface 112a can be expressed by the following equation: X=3/A= pQ2v/A (4) Equation (1) Combine with (4) to get the following equation:

Dj=Qs/A=p ΔΤ+d pQl/A2 (5) where Qs is the generated charge; ΔΤ is the temperature difference caused by breathing. Appropriate selection of piezoelectric ceramics according to the resonant frequency reduces the effect of the piezoelectric effect on the charge density D, for example, selecting a piezoelectric ceramic whose resonant frequency is much larger than the human respiratory frequency. When the contribution of the piezoelectric effect to the charge density D is much smaller than the contribution of the pyroelectric effect, equation (5) can be described as follows:

Qs=Ap ΔΤ (6) 9 201010671 In the respiration, the temperature difference ΔΤ of the respiratory airflow is caused by exhalation and inhalation, while the sensing electrodes l14a and U4b are located at the upwind and the downwind, respectively. The temperature change is sensed, so the voltage signal v<)ut output by the signal output pins 116& and 116b can be described as follows according to equation (6): d(T} m dt v~ dt ^out — Rl^Ap where rl Is the input impedance; <τ> is the average temperature sensed by the electrode; 丨u stands for

The sensing electrode 114a at the upwind and 丨D represent the sensing electrode 114b at the downwind. Regarding the measurement of the flow rate of the respiratory airflow Fa, since the input impedance R1 area A and the coefficient p are constant, the voltage signal 乂(10) is proportional to the flow velocity of the respiratory gas flow, and the flow rate of the air flow is the flow velocity multiplied by the area A. Therefore, in this embodiment, a calibration is first performed to measure the relationship between the voltage signal vout and the flow fan. For example, when the calibration operation is performed to know that the voltage signal is 〇5 volts, the flow rate is 3 〇 cm/sec, and then the computer system 12 自动 can automatically calculate the voltage signal according to the correspondence 乂 1 volt, the flow rate is 6 Centimes/second. Regarding the measurement of the respiratory rate, since the respiratory cycle is formed by the inspiratory cycle, the pause cycle, and the expiratory cycle, and the temperature change of the respiratory action also changes corresponding to the three cycles, therefore, it is only necessary to calculate the voltage signal ¥ The change cycle can be used to obtain the time required for breathing once, and then converted into a rate. For example, using the computer system 12〇 to make the voltage signal V()ut into a waveform diagram, and then calculating the difference between the two adjacent peaks, the time required for breathing once can be obtained. Please refer to FIG. 3 and FIG. 4 at the same time. FIG. 3 is a functional block diagram of a respiratory monitoring system 200 according to an embodiment of the present invention, and FIG. 4 is a diagram showing a charge according to an embodiment of the present invention. A schematic diagram of the circuit of amplifier 210. The respiratory monitoring system 200 is similar to the respiratory monitoring system 1 〇〇, but differs in that the respiratory monitoring system 200 further includes a charge amplifier 210, a filter 220, and a signal amplifier 230. The charge amplifier 210 is electrically coupled to the focal inductor 110' to eliminate the time constant effect of the focal inductor and the signal transmission line. The filter 220 is electrically connected to the charge amplifier 210 to filter out the noise of the voltage signal Vout. The signal amplifier 230 is electrically connected between the computer system 12 and the signal amplifier 230 to amplify the voltage signal v. ^. The charge amplifier 210 includes an input capacitor 212, an operational amplifier 214, and a feedback circuit 216. The feedback circuit 216 includes a feedback capacitor 216a and a feedback resistor 216b connected in parallel with each other, and one end of the focal inductor 110 and the input capacitor 212. One end is electrically connected to the negative terminal of the operational amplifier 214, and the other end of the focal inductor 110, the other end of the input capacitor 212, and the positive terminal of the operational amplifier 214 are electrically connected to the ground reference potential. The feedback circuit 216 is electrically connected between the output terminal and the negative terminal of the operational amplifier 214 to feedback the output signal of the operational amplifier 214. By appropriately designing the values of the feedback capacitor 216a and the feedback resistor 216b, the time constant effect of the focal inductor and the signal transmission line can be eliminated. Referring to FIG. 5, the system of the respiratory monitoring system according to an embodiment of the present invention is shown. 300 functional block diagram. The respiratory monitoring system 3 is similar to the respiratory monitoring system 100' but differs in that the respiratory monitoring system 3 uses the ear-worn carrying device 310 to carry the focal electrical detector 11'. Since the ear-worn carrying device 310 is worn in a manner that is easier than the mask-type carrying device 13, the respiratory monitoring system 300 is more convenient to use than the respiratory monitoring system 1 201010671. Although the present invention has been disclosed in the above embodiments, it is not intended to limit the present invention, and the present invention can be modified and retouched without departing from the spirit and scope of the present invention. The scope is subject to the definition of the scope of the patent application attached. BRIEF DESCRIPTION OF THE DRAWINGS The above and other objects, features, and advantages of the present invention will become more apparent from the following description. : Fig. 1 is a functional block diagram showing a respiratory monitoring system not according to an embodiment of the present invention. Fig. 2 is a schematic view showing the internal structure of a focal electrical detector according to an embodiment of the present invention. Figure 3 is a functional block diagram showing a respiratory monitoring system in accordance with an embodiment of the present invention. ® Fig. 4 is a circuit diagram showing a charge amplifier according to an embodiment of the present invention. Figure 5 is a functional block diagram showing a respiratory monitoring system in accordance with an embodiment of the present invention. . [Main component symbol description] 110 : focal electrical detector 114 : substrate 114b : sensing electrode 100 : respiratory monitoring system 112 : housing 艎 • 114a : sensing electrode 12 201010671 114c : top surface ' 116a : signal output pin 120 : computer system 130: mask type carrier device 210 · charge amplifier 214: operational amplifier 216a: feedback capacitor 230: signal amplifier 〇 310: ear-mounted carrier 114d: bottom surface 116b: signal output pin 120a: data capture Device 200: Respiratory Monitoring System 212: Input Capacitor 216: Feedback Circuit 216b: Feedback Resistor 220: Filter 300: Respiratory Monitoring System

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Claims (1)

201010671 X. Patent application park: 1. A respiratory monitoring system for monitoring a respiratory airflow of a user, wherein the respiratory monitoring system comprises: a focal electrical detector comprising a respiratory airflow receiving surface, wherein the focal The electrical detector generates a plurality of voltage signals according to the temperature change of the respiratory airflow; and a power system is electrically connected to the focal electrical detector, wherein the computer system is based on the area of the respiratory airflow receiving surface and the voltage signals The flow rate of the respiratory airflow is calculated, and the beer suction rate of the user is calculated according to a change period of the voltage signals. 2. The respiratory monitoring system of claim 1, wherein the focal electrical sensor comprises: a housing having a housing surface as the respiratory airflow receiving surface; a substrate disposed in the housing Wherein the substrate has a top surface and a bottom surface 'the top surface and the bottom surface are parallel to the housing surface; and at least two sensing electrodes are respectively located on the top surface and the bottom surface to be according to the top surface And the temperature change of the bottom surface to generate the voltage signals. 3. The respiratory monitoring system of claim 2, further comprising a charge amplifier electrically coupled between the focal electrical detector and the computer system to eliminate the time constant effect of the focal electrical detector. 4_ The respiratory monitoring system of claim 2, wherein the 201010671 includes a filter electrically connected between the amplifier and the computer system to filter out noise of the voltage signals. 5. The respiratory monitoring system of claim 3, further comprising a signal amplifier electrically coupled between the filter and the computer system to amplify the voltage signals. 6. The respiratory monitoring system of claim 2, wherein the charge amplifier comprises at least: an operational amplifier having a positive terminal, a negative terminal, and an output terminal, wherein the positive terminal is coupled to a ground reference a voltage, the negative terminal is electrically connected to the focal inductor; a feedback circuit electrically connected between the negative terminal and the output terminal, wherein the feedback circuit comprises at least a feedback capacitor and a feedback resistor; And an input capacitor, wherein one end of the feedback capacitor is electrically connected to the negative terminal, and the other end of the input capacitor is electrically connected to the ground reference voltage. 7. The respiratory monitoring system of claim 1, further comprising a carrying device configured to be disposed on the face of the user and carrying the focal electrical sensor to cause the respiratory flow of the focal electrical sensor The receiving surface is substantially perpendicular to the direction of travel of the respiratory airflow. 8. The respiratory monitoring system of claim 6, wherein the carrying device is a mask-type carrying device. The respiratory monitoring system of claim 6, wherein the carrying device is an ear-worn carrying device. The respiratory monitoring system of claim 1, wherein the computer system further comprises a data capture module for converting the format of the voltage signals into a format acceptable to the computer system. In the respiratory monitoring described in item 1 of the patent application scope, the frequency of the vibration of the focal inductance detector is substantially greater than the human respiratory rate. 'its