TWI838258B - Wearable multifunctional sensor device - Google Patents

Abstract

This invention provides a wearable multifunctional sensor device, which comprises a shell, a flexible circuit board, a gas sensor, and at least one of flow sensor. Said shell includes a near side standing wall facing the user, a upper wall extending from a top end of said near side standing wall rearward to the user and formed with a through hole, a distal side standing wall extending downwardly from a distal end of said upper wall that is away from the user, and a lower wall extending forward to the user from a lower end of said distal side standing wall and connecting to an lower end of said near side standing wall. Said flexible circuit board is located inside of said shell, and includes a device setting section disposed in said near side standing wall, and at least one of cantilever beam section extending forward to said distal side standing wall from an top end of said device setting section. Said cantilever beam section formed with an air intake corresponding to the through hole of said upper wall. Said gas sensor disposed in said device setting section. Said at least one of flow sensor disposed in said cantilever beam section, and includes a piezoelectric layer, a top electrode formed on an upper surface of said piezoelectric layer, a bottom electrode formed on a bottom surface of said piezoelectric layer, and an air intake hole penetrating said top electrode and said piezoelectric layer.

Description

Wearable multifunctional sensing device

The present invention relates to a wearable sensing device, and in particular to a wearable multifunctional sensing device.

With the rapid development of industry and civilization, high technology has brought many conveniences to life. However, various pollutions have also emerged with the rapid development, resulting in the air being no longer as clear as before, but filled with pollutants such as PM 2.5 and other harmful substances. Most people have breathed in these invisible but deadly tiny particles without being seen, causing a certain degree of damage to the lungs. Therefore, in order to deal with these invisible threats in the air, wearable devices that can detect the human respiratory health at any time have become the most urgent need at present.

According to research, respiratory flow rate and tidal volume (TV) are closely related to asthma or chronic obstructive pulmonary disease (COPD). These two parameters are currently the most commonly used important indicators for diagnosing lung function. In addition to the two respiratory indicators mentioned above, respiratory temperature has also been found to be an indicator for detecting respiratory diseases. Asthma and COPD are usually accompanied by symptoms of respiratory inflammation, and inflammation will cause the temperature of the air exhaled by the human body to be slightly higher than the normal temperature. Therefore, in order to improve the accuracy of respiratory diagnosis, sensors with both temperature and flow sensing functions are currently being given high attention by the industry.

In addition, lung cancer patients and diabetes patients are often difficult to detect and self-diagnose in the early stages of the disease. Recent studies have shown that patients with the above two diseases have a higher acetone concentration in their exhaled breath than the average person, and as the disease worsens, the acetone concentration in the patient's exhaled breath will be higher. Therefore, as mentioned in the previous paragraph, sensors that simultaneously sense temperature, flow, and gas concentration are more valued by the current industry.

As shown in FIG. 1 , the U.S. Patent Application No. US20140275857A1 (hereinafter referred to as the prior application 1) discloses a wearable device 1, which is suitable for being worn on the nose of a subject (not shown) to monitor the metabolic and cardiopulmonary parameters of the subject. The wearable device 1 includes a surrounding wall 11 configured to seal the nasal cavity of the subject and define a passage 110 connected to the nasal cavity of the subject, a bracket 12 mounted on an inner annular surface 111 of the surrounding wall 11, and a plurality of sensors 13a, 13b, 13c disposed on the bracket 12 at intervals from each other. The sensors 13a, 13b, 13c can be used to measure the subject's physiological parameters, such as temperature, flow, and respiratory gas composition. Among them, the one used to measure temperature can be a thermocouple, the one used to measure flow can be a piezoelectric micro pump, and the one used to measure respiratory gas composition can be an acetone sensor.

Although the wearable device 1 disclosed in the previous case 1 can simultaneously detect multiple physiological parameters of the subject, such as temperature, respiratory gas flow rate, and respiratory gas composition, etc., the sensors 13a, 13b, and 13c of the wearable device 1 are mounted on a bracket 12 fixed on the inner ring surface 111 of the surrounding wall 11. For a piezoelectric micropump that needs to generate an electrical signal difference by the amount of displacement in order to detect the gas flow rate, its sensitivity and accuracy still have room for improvement.

From the above description, it can be seen that improving the structure of the wearable multifunctional sensing device to enhance the sensitivity and accuracy of detecting gas flow is a topic that needs to be broken through by relevant technical personnel in the technical field to which this case belongs.

Therefore, the purpose of the present invention is to provide a wearable multifunctional sensing device that can improve the sensitivity and accuracy of detecting gas flow.

Therefore, the wearable multifunctional sensing device of the present invention is suitable for being worn under the nostrils of a user, and comprises an outer shell, a flexible circuit board, a gas sensor, and at least one flow sensor. The outer shell comprises a proximal wall facing the user, a top wall extending from a top end of the proximal wall away from the user and provided with at least one air inlet, a distal wall extending downward from a distal end of the top wall away from the user, and a bottom wall extending from a bottom end of the distal wall toward the user to connect to a bottom end of the proximal wall. The flexible circuit board is located in the outer shell and includes a component setting area arranged on the proximal vertical wall, and at least one cantilever beam area extending from a top end of the component setting area toward the distal vertical wall, and the cantilever beam area is provided with a through hole corresponding to the air inlet of the top wall. The at least one gas sensor is arranged in the component setting area. The flow sensor is arranged in the cantilever beam area and includes a piezoelectric layer, an upper electrode formed on an upper surface of the piezoelectric layer, a lower electrode formed on a lower surface of the piezoelectric layer, and a gas through hole penetrating the upper electrode and the piezoelectric layer.

The effect of the present invention is that when the exhaled airflow of the user flows through the gas through-hole of the flow sensor from above, the cantilever beam area of the flexible circuit board can provide sufficient strain to the piezoelectric layer to generate a corresponding piezoelectric signal, thereby improving the sensitivity of the detection signal.

Referring to FIG. 2 , FIG. 3 and FIG. 4 , an embodiment of the wearable multifunctional sensing device of the present invention is suitable for being worn below the nostrils of a user 9 as shown in FIG. 11 . The wearable multifunctional sensing device of the embodiment of the present invention comprises a housing 2, a flexible circuit board 3, a gas sensor 4, two flow sensors 5, two temperature sensors 6, and two plugs 7.

Please refer to Figures 2, 3, 4 and 11 together. The housing 2 includes a proximal wall 21 facing the philtrum of the user 9, a top wall 22 extending from a top end of the proximal wall 21 away from the user 9 and provided with two air inlets 220 spaced apart from each other, a distal wall 23 extending downward from a distal end of the top wall 22 away from the user 9, a bottom wall 24 extending from a bottom end of the distal wall 23 toward the user 9 to connect with a bottom end of the proximal wall 21, and two protrusions 25. The bottom wall 24 of the housing 2 is provided with two air outlets 240 penetrating one upper surface and one lower surface thereof. Each convex block 25 protrudes from the top wall 22 and forms a circumference of the corresponding air inlet 220 toward the nostril of the user 9, and each convex block 25 forms a channel (not shown) communicating with the corresponding air inlet 220. In this embodiment of the present invention, the proximal wall 21, the top wall 22, the distal wall 23 and the bottom wall 24 jointly define two pairs of signal output ports 20 connected to the left and right sides of the nose of the user 9. Each plug body 7 is sleeved on the corresponding convex block 25 and is provided with an air inlet channel 70 communicating with the corresponding air inlet 220. In this embodiment of the present invention, each plug body 7 is made of silicone.

The flexible circuit board 3 is located in the housing 2 and includes a component placement area 31 disposed on the proximal wall 21 and two cantilever beam areas 32 spaced apart from each other and extending from a top end of the component placement area 31 toward the distal wall 23. Each cantilever beam area 32 is provided with a through hole 320 corresponding to each air inlet 220 of the top wall 22.

Referring to FIG. 5 , the gas sensor 4 is disposed in the component placement area 31 of the flexible circuit board 3. The gas sensor 4 includes an interdigitated electrode 41 disposed on the component placement area 31 of the flexible circuit board 3, and a gas sensing layer 42 formed on the interdigitated electrode 41. Preferably, the gas sensing layer 42 is composed of a material mixed with tin oxide powder and graphene powder. Specifically, the embodiment of the present invention first applies a lithography process and an etching process to a chromium/aluminum multilayer film plated on a front surface of a polyimide film to obtain the interdigitated electrode 41 on the front surface of the polyimide film. Next, tin oxide powder and graphene powder are synthesized by hydrothermal method and then ground to refine the powder. The refined tin oxide powder and graphene powder are immersed in alcohol to form a mixed solution. The mixed solution is then coated on the interdigitated electrode 41 by drop casting to obtain the gas sensing layer 42 and complete the gas sensor 4 of the embodiment. Finally, a double-sided tape is attached to the back side of the polyimide film, and the gas sensor 4 with the double-sided tape attached is attached to the component setting area 31 of the flexible circuit board 3.

Please refer to FIG. 4 and FIG. 6 , each flow sensor 5 is disposed on the corresponding cantilever beam area 32, and includes a piezoelectric layer 51, an upper electrode 52 formed on an upper surface of the corresponding piezoelectric layer 51, a lower electrode 53 formed on a lower surface of the corresponding piezoelectric layer 51, and a gas through hole 50 penetrating the corresponding upper electrode 52 and the piezoelectric layer 51. Each temperature sensor 6 is disposed on the lower surface of the corresponding piezoelectric layer 51 and surrounds the corresponding lower electrode 53. Preferably, the gas through hole 50 of each flow sensor 5 is defined by a predetermined pattern, and each predetermined pattern has a connecting hole 501 located at a center of each piezoelectric layer 51 and each upper electrode 52, and a plurality of fan-shaped holes 502 radially extending outward from each corresponding connecting hole 501 and arranged at intervals. The lower electrode 53 of each flow sensor 5 has a plurality of fan-shaped areas 531 arranged at intervals on the lower surface of each corresponding piezoelectric layer 51 and corresponding to each two adjacent fan-shaped holes 502 of the corresponding predetermined pattern, a plurality of connecting areas 532 connecting each corresponding two adjacent fan-shaped areas 531, and an output area 533 connecting one of the corresponding fan-shaped areas 531. More preferably, the piezoelectric layer 51 of each flow sensor 5 is made of barium titanium oxide (BaTiO ₃ ).

It should be noted that the main function of the design of the connecting hole 501 and the fan-shaped hole 502 of the air intake through hole 50 of each flow sensor 5 is to first gather the intake gas introduced from above at each connecting hole 501, and then make the intake gas further move toward each fan-shaped hole 502 and gather. In this way, users with low breathing volume can gather their intake volume through the above design, thereby increasing the electrical signal detected by each flow sensor 5.

Specifically, the embodiment of the present invention first uses a titanium plate having an air intake hole 50 of the predetermined pattern as the upper electrode 52 of each flow sensor 5, and synthesizes the piezoelectric layer (BaTiO ₃ ) 51 and another piezoelectric layer 54 attached to a lower surface and an upper surface of each titanium plate (upper electrode 52) by a hydrothermal method, and then covers the lower surface of the piezoelectric layer 51 with a mask (not shown) to sputter-plate a patterned aluminum (Al) layer, so that each patterned aluminum layer becomes the corresponding lower electrode 53 and temperature sensor 6, thereby manufacturing each corresponding flow sensor 5. Finally, each flow sensor 5 and the corresponding cantilever beam area 32 are combined via a double-sided adhesive attached to an upper surface of the corresponding cantilever beam area 32. As can be seen from the above description, in this embodiment of the present invention, each temperature sensor 6 is a thermistor made of Al.

Preferably, in order to collect the gas volume that passes downward from each air inlet 220 of the top wall 22 shown in FIG. 4 through the air inlet through hole 50 of each corresponding flow sensor 5 to the bottom of each corresponding flow sensor 5, the housing 2 further includes a gas collecting wall 26 as shown in FIG. 3. The gas collecting wall 26 of the housing 2 protrudes toward the top wall 22 from a circumference of the upper surface of the bottom wall 24 where the two air outlets 240 are provided, so as to be located below the two flow sensors 5. Specifically, the gas collecting wall 26 has two surrounding sections that partially surround the corresponding air outlets 240, and a connecting section that is located between the surrounding sections and connects the surrounding sections.

Before the embodiment of the present invention is actually used, a charge integration amplifier 81 as shown in FIG. 7 , a plurality of passive components (five resistors 82 and one capacitor 83 as shown in FIG. 7 ), two four-input terminal blocks 84 respectively located at the signal output ports 20 of the housing 2, and a circuit diagram 85 for signal connection of the gas sensor 4, each flow sensor 5, each temperature sensor 6, the passive components and each four-input terminal block 84 are further arranged on a surface of the component arrangement area 31 of the flexible circuit board 3 so as to enable the electronic signals of the gas sensor 4, each flow sensor 5 and each temperature sensor 6 to be output externally. Taking the flow sensor 5 and the temperature sensor 6 on the left side of FIG. 7 as an example, the flow sensor 5 uses one of the circuits of the circuit pattern 85 to connect the output area 533 of the lower electrode 53 of the flow sensor 5 to the charge integration amplifier 81 and one of the resistors 82. The electrical signal of the charge integration amplifier 81 is then sequentially transmitted to the resistor 82 on the left side and the four-input terminal block 84 on the left side. The signal of the temperature sensor 6 on the left side is also connected to the four-input terminal block 84 on the left side through the circuit pattern 85. Finally, the four-input terminal block 84 on the left side connects the electrical signals of the flow sensor 5 and the temperature sensor 6 on the left side to an external analysis device through four single-core wires (not shown).

In the embodiment of the present invention, the flexible circuit board 3 is explained by taking the circuit pattern 85 arranged on the surface of the component setting area 31 so that the electrical signals of the gas sensor 4, each flow sensor 5 and each temperature sensor 6 are transmitted to the external analysis equipment via a single core wire, but the present invention is not limited thereto. It should be additionally explained that the flexible circuit board 3 of the present invention can also replace the circuit pattern 85 by an internal connection line (not shown) buried in the component setting area 31 and a plurality of contacts (not shown) connected to the internal connection line and exposed on the surface of the component setting area 31, and the charge integration amplifier 81, the passive components, a measurement module (not shown) and a wireless transmission module (not shown) are combined on the contacts by surface mounting technology (SMT). In this way, the measured electrical signal can be transmitted to an external device through wireless communication.

In order to confirm the performance of each flow sensor 5, each temperature sensor 6 and gas sensor 4 of the embodiment of the present invention, before the aforementioned components are assembled to the flexible circuit board 3, the applicant also simulates and tests their electrical properties respectively. The detailed simulation test means and test results are briefly stated as follows.

The simulation detection method of each flow sensor 5 is to use a bi-directional positive pressure ventilator (BMC RESmart BPAP system T-25T) to produce a regular breathing pressure, and cooperate with a laser displacement meter for calibration. In detail, an outlet of the bi-directional positive pressure ventilator is connected to a three-way pipe so that its regular breathing pressure is divided into two branches, and the two branches are connected to the top of each flow sensor 5 and a commercially available Omrom D6f flow meter respectively by two rubber tubes with inner and outer diameters of 4 mm and 6 mm, and the laser displacement meter is set up below each flow sensor 5. It should be noted that the signals of each flow sensor 5 are first captured by the charge integration amplifier 81 shown in FIG7 and then connected to the NI-USB signal acquisition (DAQ) card purchased from National Instrument, and finally transmitted to the Labview program in the computer 86 shown in FIG11 for analysis. In addition, the commercially available Omrom D6f flow meter and the laser displacement meter also use the DAQ card to capture signals.

As shown in FIG8 , it can be seen that the flow sensor 5 can be observed through the simulation detection means described in the previous section, and the start time and end time of the breathing corresponding to the signal of the flow sensor (i.e., the element signal of the blue curve) and the signal of the laser displacement meter (yellow curve) can all correspond to each other.

The analog detection method for each temperature sensor (i.e., each thermistor) 6 is to use an impedance analyzer (WAYNE KERR 6500B) 87 as shown in FIG. 11 to measure its impedance value at different temperatures; wherein, a voltage of 0.01 V is set to reduce the charge accumulation effect of each temperature sensor 6 during measurement, and a frequency of 10 kHz is set to reduce the effect of capacitance change and inductance change on resistance. For the calibration of each temperature sensor 6, a K-type thermocouple is used, and the DAQ card is also used to capture the signal. In actual simulation testing, the K-type thermocouple and each temperature sensor 6 are contacted with the surface of a heater (hot plate, not shown) to ensure that the actual heating conditions of the two are consistent. Specifically, the heater heats and cools the K-type thermocouple and each temperature sensor 6 three times (36°C, 38°C, 40°C), and the signal captured by the DAQ card is transmitted to the computer 86.

As shown in FIG. 9a, FIG. 9b and FIG. 9c, it can be observed that the impedance value change curve and the resistance value change curve of each temperature sensor 6 and the K-type thermocouple under different heating and cooling conditions are almost consistent with the temperature change curve actually measured by the K-type thermocouple through the simulation detection means described in the previous paragraph.

The analog detection method of the gas sensor 4 is to use an acetone sensing chamber customized by the applicant to create an environment in which the acetone gas concentration in the chamber can be adjusted. Specifically, the environment in which the acetone gas concentration in the chamber can be adjusted is to use a pump to evacuate the chamber to create a power source for the air flow, and then use a flow controller to adjust the ratio of the acetone gas flow rate entering the chamber to the atmospheric flow rate to create a total gas flow rate of a target acetone concentration in the environment.

As shown in FIG. 10 , the gas sensor 4 can be observed through the simulation detection method described in the previous paragraph. Under the conditions of different acetone concentrations (100 ppm, 500 ppm and 2500 ppm), the response of the gas sensor 4 increases with the increase of acetone concentration, and the response of the same acetone concentration is similar.

The applicant further wears the wearable multifunctional sensing device of the embodiment of the present invention on the user 9 (see FIG. 11 ) for detection. Specifically, each plug 7 of the wearable multifunctional sensing device of the embodiment of the present invention is placed in each nostril of the user 9, and the electrical signal of the left flow sensor 5 located at the left cantilever beam area 32 of the flexible circuit board 3 (see FIG. 7 ) is connected to the DAQ capture card (not shown) through the left four-input terminal block 84 via two single-core signal lines, and then transmitted to the LavView program in the computer 86 for analysis. Furthermore, the electrical signals of the gas sensor 4 located in the component setting area 31 of the flexible circuit board 3 and the right-side temperature sensor (i.e., thermistor) 6 located in the right-side cantilever beam area 32 are connected to the DAQ capture card (not shown) and the impedance analyzer 87 through four single-core signal connections via the right-side four-input terminal block 84, and then transmitted to the LavView program in the computer 86 for analysis.

It should be noted that the user 9 did not have nasal congestion during the test, so the exhaled and inhaled volumes of the left and right nasal cavities during the breathing process should not be much different, and are explained together here. As shown in FIG. 12a, the temperature of the gas exhaled by the user 9 is about 35°C, and the voltage values corresponding to the exhalation and inhalation of the gas flow curve (orange curve) also correspond to the temperature values corresponding to the exhalation and inhalation of the gas temperature curve (blue curve). This shows that the left side flow sensor 5 of the embodiment of the present invention is disposed on the left side cantilever beam area 32 of the flexible circuit board 3, so that when the exhaled gas of the user 9 flows downward from the top of the left side flow sensor 5 through its gas through hole 50, the left side cantilever beam area 32 can be used to generate a swing to provide sufficient displacement to the piezoelectric layer 51, thereby improving the sensitivity of the left side flow sensor 5. As shown in FIG. 12b, the acetone concentration detected in the exhaled gas of the user 9 in the early stage (45 seconds) is greater than 1 ppm.

As can be seen from the above detailed description of the present invention, each flow sensor 5 of the embodiment of the present invention can not only improve the sensitivity of its detection signal through its corresponding cantilever beam area 32, but also the design of the connecting hole 501 and the fan-shaped hole 502 of the air intake hole 50 of each flow sensor 5 can also enable users with low breathing volume to collect their intake volume through the aforementioned design, thereby improving the electrical signal detected by each flow sensor 5.

In summary, the wearable multifunctional sensing device of the present invention can enhance the detection signal sensitivity of the corresponding flow sensor 5 through each cantilever beam area 32 of the flexible circuit board 3. In addition, the connecting hole 501 and the fan-shaped hole 502 of the air intake hole 50 of each flow sensor 5 can also enable users with lower breathing volume to collect their intake volume to enhance the electrical signal detected by each flow sensor 5, so that the purpose of the present invention can be achieved.

However, the above is only an embodiment of the present invention and should not be used to limit the scope of implementation of the present invention. All simple equivalent changes and modifications made according to the scope of the patent application of the present invention and the content of the patent specification are still within the scope of the present patent.

2: Housing 20: Signal output port 21: Near side wall 22: Top wall 220: Air inlet 23: Far side wall 24: Bottom wall 240: Air outlet 25: Bump 26: Gas collecting wall 3: Flexible circuit board 31: Component placement area 32: Cantilever beam area 320: Through hole 4: Gas sensor 41: Interdigitated electrode 42: Gas sensing layer 5: Flow sensor 50: Air inlet hole 501: Connecting hole 502: Fan-shaped hole 51: Piezoelectric layer 52: Upper electrode 53: Lower electrode 531: Fan-shaped area 532: Connection area 533: Output area 54: Another piezoelectric layer 6: Temperature sensor 7: Plug 70: Air intake channel 81: Charge integration amplifier 82: Resistor 83: Capacitor 84: Four-input terminal block 85: Circuit diagram 86: Computer 87: Impedance analyzer 9: User

Other features and functions of the present invention will be clearly presented in the implementation method with reference to the drawings, in which: Figure 1 is a three-dimensional diagram illustrating the wearable device disclosed in the early publication number US20140275857A1 of the United States invention patent; Figure 2 is a three-dimensional assembly diagram illustrating an embodiment of the wearable multifunctional sensing device of the present invention; Figure 3 is a partial cross-sectional view illustrating the detailed structure of a housing of the embodiment of the present invention and its relative position relationship with two flow sensors; Figure 4 is a partial three-dimensional exploded view illustrating the housing of the embodiment of the present invention, a flexible circuit board, the flow sensors, a gas sensor, two temperature sensors and two plugs before assembly; Figure 5 is a partial three-dimensional exploded view, illustrating the detailed structure of the gas sensor of the embodiment of the present invention; Figure 6 is a partial three-dimensional exploded view, illustrating the detailed structure and relative position of each flow sensor and its corresponding temperature sensor of the embodiment of the present invention; Figure 7 is a partial three-dimensional assembly view, illustrating the circuit relationship of the flexible circuit board of the embodiment of the present invention electrically connected to a charge integration amplifier, a complex resistor and a capacitor; Figure 8 is a voltage and displacement versus time relationship diagram, illustrating the electrical signals simulated by each flow sensor of the embodiment of the present invention through a dual positive pressure ventilator, a laser displacement meter and a flow meter before assembly; Figure 9 is a graph showing the relationship between resistance value, electrical impedance value and temperature over time, illustrating the electrical signals simulated by each temperature sensor of the embodiment of the present invention through a heating plate, a thermocouple and an impedance analyzer before assembly. Figure 9a illustrates the electrical impedance value of each temperature sensor in response to time changes under different temperature conditions, Figure 9b illustrates the resistance value of each temperature sensor in response to time changes under different temperature conditions, and Figure 9c illustrates the temperature in response to time changes under different temperature conditions actually measured by the thermocouple; Figure 10 is a graph showing the relationship between response and time, illustrating the simulated response of the gas sensor of the embodiment of the present invention through an acetone sensing chamber under different acetone concentrations before assembly; FIG11 is a schematic diagram illustrating the state of the embodiment of the present invention during actual use/testing; FIG12a is a temperature and voltage versus time relationship diagram illustrating the actual use/testing results of the right temperature sensor and the left flow sensor of the embodiment of the present invention; and FIG12b is a acetone concentration and voltage versus time relationship diagram illustrating the actual use/testing results of the gas sensor and the left flow sensor of the embodiment of the present invention.

21: Near side wall

22: Top wall

220: Air intake

23: Far side wall

24: Bottom wall

240: Air outlet

25: Bump

3: Flexible circuit board

31: Component setting area

32: Cantilever beam area

320: Perforation

4: Gas sensor

5: Flow sensor

6: Temperature sensor

7: Plug body

70: Air intake duct

Claims (9)

A wearable multifunctional sensing device, suitable for being worn under a user's nostrils, comprises: an outer shell, comprising a proximal wall facing the user, a top wall extending from a top end of the proximal wall away from the user and provided with at least one air inlet, a distal wall extending downward from a distal end of the top wall and away from the user, and a bottom wall extending from a bottom end of the distal wall toward the user to connect with a bottom end of the proximal wall; a flexible circuit board, located in the outer shell and comprising a component installation area arranged on the proximal wall, and at least one cantilever beam area extending from a top end of the component installation area toward the distal wall, the cantilever beam area being provided with a through hole corresponding to the air inlet of the top wall; A gas sensor disposed in the element setting area; and At least one flow sensor disposed in the cantilever beam area and comprising a piezoelectric layer, an upper electrode formed on an upper surface of the piezoelectric layer, a lower electrode formed on a lower surface of the piezoelectric layer, and a gas through hole penetrating the upper electrode and the piezoelectric layer. A wearable multifunctional sensing device as described in claim 1, wherein the top wall of the outer shell is provided with two air inlets; the flexible circuit board includes two cantilever beam areas spaced apart from each other, and the wearable multifunctional sensing device includes two flow sensors. A wearable multifunctional sensing device as described in claim 2, wherein the gas through hole of each flow sensor is defined by a predetermined pattern, each predetermined pattern having a connecting hole located at a center of each piezoelectric layer and each upper electrode, and a plurality of fan-shaped holes extending radially outward from each corresponding connecting hole and arranged at intervals from each other; the lower electrode of each flow sensor has a plurality of fan-shaped areas spaced apart from each other on the lower surface of each corresponding piezoelectric layer and corresponding to each corresponding predetermined pattern, a plurality of connecting areas connecting each corresponding two adjacent fan-shaped areas, and an output area connected to one of the corresponding fan-shaped areas. A wearable multifunctional sensing device as described in claim 3, wherein the piezoelectric layer of each flow sensor is made of barium titanium oxide. The wearable multifunctional sensing device as described in claim 2 further includes two temperature sensors, each of which is disposed on the lower surface of the corresponding piezoelectric layer and surrounds the corresponding lower electrode. A wearable multifunctional sensing device as described in claim 2, wherein the gas sensor includes an interdigitated electrode disposed on a component placement area of the flexible circuit board, and a gas sensing layer formed on the interdigitated electrode. In the wearable multifunctional sensing device as described in claim 6, the gas sensing layer is composed of a material mixed with tin oxide powder and graphene powder. The wearable multifunctional sensing device as described in claim 2 further includes two plug bodies, and the outer shell also includes two protrusions, each of which protrudes toward the nostrils of the user from its top wall and is formed with a circumference of its corresponding air inlet, and each of the protrusions is formed with a channel connected to the corresponding air inlet, and each of the plug bodies is mounted on the corresponding protrusion and is provided with an air inlet channel connected to the corresponding air inlet. A wearable multifunctional sensing device as described in claim 2, wherein the outer shell further includes an air collecting wall, and the bottom wall of the outer shell is provided with two air outlets penetrating an upper surface and a lower surface thereof, and the air collecting wall of the outer shell protrudes toward the top wall from the upper surface of the bottom wall and a periphery where the two air outlets are provided, so as to be located below the two flow sensors.