Ultrasonic-driven self-powered sweat sensor and performance improvement method thereof

Abstract

The invention discloses an ultrasonic-driven self-powered sweat sensor and a performance improvement method thereof. Belongs to the field of ultrasonic driving and electrochemical sensing and comprises a base station, a glass substrate, a piezoelectric plate, a piezoelectric plate driving power supply, an aluminum electrode, a copper electrode and an electric signal detection unit. A sound pressure field generated by ultrasound in sweat can promote the electrochemical reaction rate of the surface of the electrode, a generated sound flow field can promote the sweat to flow circularly, the concentration polarization effect is weakened while the double electric layers are damaged, the mass transfer rate of the sweat is increased, electric signals generated by the sweat are enhanced, and therefore the sweat can be effectively absorbed. And the performance of the self-powered sweat sensor is improved. Compared with the prior art, the sensitivity of the sweat sensor and the accuracy of a detection result can be improved by adding ultrasound, and a generated electric signal can supply power to the sweat sensor under the amplification action of the ultrasound.

Description

Technical Field

[0001] The present invention belongs to the field of ultrasonic driving and electrochemical sensing, and relates to an ultrasonically driven self-powered sweat sensor and a method for improving its performance; specifically, it relates to a method for improving the performance of a self-powered sweat sensor by promoting mass transfer rate based on an acoustic pressure field and an acoustic flow field. Background Art

[0002] Sweat sensor is an emerging biosensor used to monitor physiological parameters in sweat in real time and analyze the components in sweat to evaluate health status or exercise performance. Sweat contains a variety of electrolytes, metabolites and biomarkers, and changes in the concentration of these components can reflect physiological status. For example, the sodium ion concentration in sweat can be used to infer fluid balance, while the lactate concentration can help evaluate exercise intensity and fatigue.

[0003] The best way to monitor physical health is to use non-invasive and long-term continuous monitoring, which can provide better results than repeatedly taking multiple test samples. Due to the instability of sweat secretion and the low concentration of some components in the metabolites, it is impossible to accurately detect the metabolites in human sweat.

[0004] Long-term continuous detection places high demands on the battery life of sweat sensors; therefore, self-powered sweat sensors are the best solution to the battery life problem, but the concentration and flow of chemical components in sweat are limited, the energy conversion efficiency is low, and usually only a very small current can be generated. Summary of the invention

[0005] In view of the above problems, the purpose of the present invention is to propose an ultrasonically driven self-powered sweat sensor and a performance improvement method thereof, which not only enhances the detection sensitivity of the sweat sensor, but also improves the conversion efficiency of electrical energy.

[0006] The technical solution of the present invention is: the ultrasonic driven self-powered sweat sensor of the present invention comprises a base, a glass substrate and a piezoelectric sheet;

[0007] A circular groove is provided on the base;

[0008] The piezoelectric sheet is bonded to the bottom surface of the glass substrate through epoxy resin and is placed on the circular groove of the base.

[0009] Furthermore, an aluminum electrode and a copper electrode are symmetrically arranged in the glass substrate;

[0010] The aluminum electrode and the copper electrode are connected to an electrical signal detection unit via a wire.

[0011] Furthermore, the aluminum electrode and the copper electrode are not oriented in the same direction as the piezoelectric sheet.

[0012] Furthermore, two ends of the piezoelectric sheet are connected to a piezoelectric sheet driving power source via wires.

[0013] Furthermore, the glass substrate is formed by stacking a round glass with a diameter of 18mm-20mm and a thickness of 1mm-1.5mm and a glass ring with the same outer diameter as the round glass, an inner diameter of 12mm-15mm and a thickness of 1mm-1.5mm.

[0014] Furthermore, the resonance frequency range of the piezoelectric film is 20kHz-200kHz, the operating frequency f is between 103.93kHz-104.83kHz, the operating voltage is about 7.5V-7.7V, and the operating current is 135mA-150mA.

[0015] Furthermore, the diameter of the piezoelectric sheet is the same as that of the glass substrate, and is composed of a ceramic material having a thickness of 1.5 mm to 3 mm and having an inverse piezoelectric effect and two copper sheets bonded together by epoxy resin, forming a sandwich structure.

[0016] Furthermore, the aluminum electrode and the copper electrode are symmetrically bonded to the glass substrate, and one semicircular end thereof is fixedly bonded to the base.

[0017] Furthermore, the aluminum electrode and the copper electrode are of the same size and shape, the diameter of the outer semicircle is 5mm-10mm, the end connected to the electrical signal detection unit is 40mm-60mm long, 3mm-5mm wide, and the overall thickness is 0.4mm-0.6mm.

[0018] Furthermore, the method for improving the performance of an ultrasonically driven self-powered sweat sensor has the following operating steps:

[0019] Step (1), placing sweat in a chamber on a glass substrate, the aluminum electrode and the copper electrode are in full contact with the sweat, and the generated electrical signal is transmitted to an electrical signal detection unit through a wire;

[0020] Step (2), turning on the driving power of the piezoelectric sheet, the piezoelectric sheet performs ultrasonic excitation, and forms an acoustic pressure field and an acoustic flow field on the glass substrate, thereby accelerating the mass transfer rate of sweat and amplifying the electrical signal generated by the sweat;

[0021] Step (3), the electrical signal generated at this time is detected by the electrical signal detection unit; at the same time, the amplified electrical signal can also provide energy for the detection unit or other energy-consuming devices.

[0022] The beneficial effects of the present invention are: 1. Ultrasound accelerates the transmission of ions in sweat and the reaction rate on the electrode surface, amplifies the electrical signal generated by sweat, makes the electrical signal easier to be captured by the sweat detection unit, and improves the sensitivity of the sweat sensor; 2. Since ultrasound amplifies the electrical signal generated by sweat, it can provide more electrical energy for the sweat detection unit; 3. Therefore, the device that additionally supplies energy to the detection unit can be appropriately reduced, which can reduce the weight and volume of flexible wearable intelligent detection equipment or micro sensors. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a specific device structure diagram of the present invention;

[0024] Figure 2 is a discharge performance diagram of sweat in an embodiment of the present invention when no ultrasound is applied;

[0025] Figure 3 Discharge performance diagram of sweat when ultrasound is applied in an embodiment of the present invention;

[0026] Figure 4 A diagram of the sensor performance of sweat in an embodiment of the present invention;

[0027] In the figure, 1 is a base, 2 is a glass substrate, 3 is a piezoelectric sheet, 4 is a driving power source for the piezoelectric sheet, 5 is an aluminum electrode, 6 is a copper electrode, and 7 is an electrical signal detection unit. DETAILED DESCRIPTION

[0028] The specific technical scheme of the present invention is further described in detail below with reference to specific examples.

[0029] As shown in the figure, an ultrasonic driven self-powered sweat sensor according to the present invention includes a base 1, a glass substrate 2, a piezoelectric sheet 3, a piezoelectric sheet driving power supply 4, an aluminum electrode 5, a copper electrode 6, and an electrical signal detection unit 7;

[0030] The piezoelectric sheet 3 is bonded to the bottom surface of the glass substrate 2 with epoxy resin and is placed on the circular groove of the base 1 .

[0031] Furthermore, the glass substrate 2 is formed by stacking a round glass with a diameter of 18mm-20mm and a thickness of 1mm-1.5mm and a glass ring with the same outer diameter as the round glass, an inner diameter of 12mm-15mm and a thickness of 1mm-1.5mm.

[0032] Furthermore, the piezoelectric sheet 3 is connected to the piezoelectric sheet driving power source 4 via a wire.

[0033] Furthermore, the resonance frequency range of the piezoelectric sheet 3 is 20kHz-200kHz, the operating frequency f is between 103.93kHz-104.83kHz, the operating voltage is about 7.5V-7.7V, and the operating current is 135mA-150mA.

[0034] Furthermore, the diameter of the piezoelectric sheet 3 is the same as that of the glass substrate 2 , and is composed of a ceramic material having a thickness of 1.5 mm to 3 mm and having an inverse piezoelectric effect and two copper sheets bonded together by epoxy resin, forming a sandwich structure.

[0035] Furthermore, the aluminum electrode 5 and the copper electrode 6 are symmetrically bonded to the glass substrate 2 by double-sided adhesive, and the non-semicircular end is fixed to the base 1 by the same method.

[0036] Furthermore, the aluminum electrode 5 and the copper electrode 6 are connected to an electrical signal detection unit 7 via a wire.

[0037] Furthermore, the aluminum electrode 5 and the copper electrode 6 are of the same size and shape, the diameter of the outer semicircle is 5mm-10mm, the end connected to the electrical signal detection unit 7 is 40mm-60mm long, 3mm-5mm wide, and the overall thickness is 0.4mm-0.6mm.

[0038] Furthermore, the ultrasonic driven self-powered sweat sensor and the method for improving its performance are operated as follows:

[0039] (1) placing sweat in a chamber on a glass substrate 2, the aluminum electrode 5 and the copper electrode 6 are in full contact with the sweat, and the generated electrical signal is transmitted to the electrical signal detection unit 7 through a wire;

[0040] (2) Turn on the piezoelectric film driving power supply 4, the piezoelectric film 3 is ultrasonically excited, and an acoustic pressure field and an acoustic flow field are formed on the glass substrate 2, which accelerates the mass transfer rate of sweat and amplifies the electrical signal generated by the sweat;

[0041] (3) The electrical signal generated at this time is more easily detected by the electrical signal detection unit 7 due to the amplification effect of ultrasound;

[0042] At the same time, the amplified electrical signal can also provide energy for the detection unit or other energy-consuming devices.

[0043] Furthermore, the acoustic pressure field generated by ultrasound in sweat can promote the electrochemical reaction rate on the electrode surface, and the acoustic flow field generated promotes the circulation of sweat, which weakens the concentration polarization effect while destroying the double electric layer, accelerates the mass transfer rate of sweat, and amplifies the electrical signal generated by sweat, making it easy to be recognized by the electrical signal detection unit 7 and providing electrical energy for the detection unit;

[0044] Furthermore, the main components for implementing the above method are a sweat detection unit for detecting electrical signals and a device capable of generating ultrasound (including but not limited to a buzzer, a piezoelectric sheet 3, and a Langevin vibrator).

[0045] Furthermore, the electrical signals generated by sweat can be amplified by various ultrasonic excitation methods and vibration modes.

[0046] Furthermore, the application of ultrasound technology has a dual improvement effect, which not only improves the sensitivity of the sweat sensor and the accuracy of the detection results, but also improves the output power of the self-powered sweat sensor.

[0047] Furthermore, the ultrasonic driving power source drives the piezoelectric sheet to perform ultrasonic vibration (the piezoelectric sheet 3 and the glass substrate 3 are bonded with epoxy resin), thereby generating an ultrasonic sound field on the glass substrate 3 containing the sweat;

[0048] The aluminum electrode 5 and the copper electrode 6 are respectively attached to both sides of the glass substrate 2, and are partially immersed in the sweat. The exposed parts are connected to the electrical signal detection unit 7, which not only provides the electrical signal for detection but also supplies energy for it.

[0049] Ultrasonic vibration generates an acoustic pressure field in sweat, which accelerates the electrochemical reaction rate on the surface of the aluminum electrode 5 and the copper electrode 6, and the generated acoustic flow field accelerates the transmission rate of ions. Therefore, ultrasound has an amplifying effect on the electrical signal generated by sweat, which is easy to be detected by the electrical signal detection unit and improves the efficiency of electrical energy conversion.

[0050] The peak value of electrical energy provided by sweat is about 2 microwatts. After applying ultrasound, the peak value of electrical energy can reach about 12 microwatts, which is 6 times the original peak value. It will fluctuate due to the different composition and concentration of metabolites in sweat.

[0051] When the load is 0.1 V, the current value is about 18 microamperes. After applying ultrasound, the current value is about 80 microamperes, which can be more easily recognized by the electrical signal detection unit 7.

[0052] In an embodiment,

[0053] The resonant frequency of the piezoelectric piece 3 is 104.5kHz, the operating frequency f=104.83kHz, the operating voltage is 7.7V (effective value), and the operating current is 150mA;

[0054] The driving power supply of the piezoelectric piece 3 sends an electrical signal from a signal generator to a power amplifier for amplifying the power of the electrical signal, which is used to drive the piezoelectric piece 3 , and an oscilloscope displays the working voltage value and working current value of the piezoelectric piece 3 .

[0055] The glass substrate 2 is formed by stacking a round glass with a diameter of 20 mm and a thickness of 1 mm and a glass ring with an outer diameter of 20 mm, an inner diameter of 15 mm and a thickness of 1 mm, and is used to hold the object to be detected.

[0056] The diameter of the piezoelectric sheet 3 is 20 mm, which is the same as the diameter of the glass substrate 2 , and the thickness is 2 mm. Copper sheets with a thickness of 0.5 mm are attached to the upper and lower surfaces.

[0057] The aluminum electrode 5 and the copper electrode 6 are of the same size and shape. The diameter of the outer semicircle is 10 mm, the end connected to the electrical signal detection unit is 50 mm long and 5 mm wide, and the overall thickness is 0.6 mm.

[0058] The electrical signal detection unit 7 is undertaken by the electrochemical workstation to collect and record the electrical signals generated by the metabolites.

[0059] The present invention proposes a method for improving the performance of a self-powered sensor by promoting mass transfer rate based on acoustic pressure field and acoustic flow field. The method is an ultrasound-based electrochemical detection method, which utilizes ultrasound to generate acoustic pressure field and acoustic flow field in sweat to increase the mass transfer rate.

Claims

1. An ultrasonically driven self-powered sweat sensor, characterized in that: It comprises a base (1), a glass substrate (2) and a piezoelectric piece (3); A circular groove is provided on the base (1); The piezoelectric piece (3) is bonded to the bottom surface of the glass substrate (2) via epoxy resin and is placed on the circular groove of the base (1).

2. The ultrasonically driven self-powered sweat sensor according to claim 1, characterized in that: An aluminum electrode (5) and a copper electrode (6) are symmetrically arranged in the glass substrate (2); The aluminum electrode (5) and the copper electrode (6) are connected to an electrical signal detection unit (7) via a wire.

3. The ultrasonically driven self-powered sweat sensor according to claim 2, characterized in that: The aluminum electrode (5) and the copper electrode (6) are not oriented in the same direction as the piezoelectric sheet (3).

4. The ultrasonically driven self-powered sweat sensor according to claim 1, characterized in that: Both ends of the piezoelectric sheet (3) are connected to a piezoelectric sheet driving power source (4) via wires.

5. The ultrasonically driven self-powered sweat sensor according to claim 1, characterized in that: The glass substrate (2) is formed by stacking a round glass with a diameter of 18mm-20mm and a thickness of 1mm-1.5mm and a glass ring with the same outer diameter as the round glass, an inner diameter of 12mm-15mm and a thickness of 1mm-1.5mm.

6. The ultrasonically driven self-powered sweat sensor according to claim 1, characterized in that: The resonant frequency range of the piezoelectric piece (3) is 20kHz-200kHz, the operating frequency f is between 103.93kHz-104.83kHz, the operating voltage is about 7.5V-7.7V, and the operating current is 135mA-150mA.

7. The ultrasonically driven self-powered sweat sensor according to claim 1, characterized in that: The diameter of the piezoelectric sheet (3) is the same as that of the glass substrate (2), and is composed of a ceramic material having a thickness ranging from 1.5 mm to 3 mm and having an inverse piezoelectric effect and two copper sheets bonded together by epoxy resin, forming a sandwich structure.

8. The ultrasonically driven self-powered sweat sensor according to claim 2, characterized in that: The aluminum electrode (5) and the copper electrode (6) are symmetrically bonded to the glass substrate (2), and one semicircular end thereof is fixedly bonded to the base (1).

9. The ultrasonically driven self-powered sweat sensor according to claim 8, characterized in that: The aluminum electrode (5) and the copper electrode (6) have the same size and shape, the diameter of the outer semicircle is 5mm-10mm, the end connected to the electrical signal detection unit (7) is 40mm-60mm long and 3mm-5mm wide, and the overall thickness is 0.4mm-0.6mm.

10. The method for improving the performance of an ultrasonically driven self-powered sweat sensor according to any one of claims 1 to 9, wherein: The steps are as follows: Step (1), placing sweat in a chamber on a glass substrate (2), allowing the aluminum electrode (5) and the copper electrode (6) to fully contact the sweat, and transmitting the generated electrical signal to an electrical signal detection unit (7) via a wire; Step (2), turning on the piezoelectric piece driving power supply (4), the piezoelectric piece (3) is ultrasonically excited, and an acoustic pressure field and an acoustic flow field are formed on the glass substrate (2), thereby accelerating the mass transfer rate of sweat and amplifying the electrical signal generated by the sweat; Step (3), the electrical signal generated at this time is detected by the electrical signal detection unit (7); at the same time, the amplified electrical signal can also provide energy for the detection unit or other energy-consuming devices.

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