CN113271116A - Wireless energy supply high-precision signal processing module for wearable sweat sensor - Google Patents
Wireless energy supply high-precision signal processing module for wearable sweat sensor Download PDFInfo
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- CN113271116A CN113271116A CN202110607307.8A CN202110607307A CN113271116A CN 113271116 A CN113271116 A CN 113271116A CN 202110607307 A CN202110607307 A CN 202110607307A CN 113271116 A CN113271116 A CN 113271116A
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/38—Transceivers, i.e. devices in which transmitter and receiver form a structural unit and in which at least one part is used for functions of transmitting and receiving
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J50/00—Circuit arrangements or systems for wireless supply or distribution of electric power
- H02J50/20—Circuit arrangements or systems for wireless supply or distribution of electric power using microwaves or radio frequency waves
- H02J50/27—Circuit arrangements or systems for wireless supply or distribution of electric power using microwaves or radio frequency waves characterised by the type of receiving antennas, e.g. rectennas
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Abstract
The invention discloses a wireless energy supply high-precision signal processing module for a wearable sweat sensor, which comprises a substrate, the sweat sensor, a radio-frequency antenna, a communication circuit, a power supply circuit, a signal processing circuit and an ADC (analog-to-digital converter), wherein the power supply circuit comprises a charge pump circuit, a virtual battery and a voltage stabilizing circuit; the signal processing circuit comprises a voltage following circuit, a programmable gain amplifying circuit and a four-order low-pass filter circuit. The invention can conveniently adjust the gain according to the output signal of the sensor through a program, and meanwhile, the module can also reduce the signal loss and can well remove the interference, thereby effectively improving the measurement data precision of the wearable sweat sensor and facilitating the data receiving and analysis processing of a reader. Meanwhile, a virtual wireless power supply technology is adopted, so that the equipment does not need to be provided with a battery, the size of the equipment is greatly reduced, and the wearing by a user is facilitated.
Description
Technical Field
The invention relates to a signal processing module, in particular to a wireless energy supply high-precision signal processing module for a wearable sweat sensor.
Background
Wearable devices can record data of daily life of a wearer, and the development is rapid in recent years. At present, part of wearable devices can monitor the health condition of a human body, but the functions are too single, most of the wearable devices can only analyze physical signals such as heart rate and blood pressure, and the requirements of monitoring the health of the human body on deeper layers are difficult to meet. Biological fluids of the human body, such as extracellular fluids, interstitial fluids, blood, urine, saliva, and sweat, contain a great deal of information about the health of the human body. Nowadays, blood test has become a routine means for physical examination, because blood contains various proteins, enzymes, carbohydrates, fats, inorganic salts, etc., and abundant information about the health condition of human body can be analyzed by examining the content of related substances in blood. However, the blood test method can only be used as an option for checking the physical condition occasionally, because blood sampling is traumatic to human skin and blood vessel tissue, and blood analysis can be completed only in a laboratory environment, and it is obviously infeasible to obtain the relevant information of the health status of the human body in real time by blood sampling.
Sweat detection provides a noninvasive alternative scheme, and compared with the sweat detection, the sweat detection has the advantages that biological information contained in sweat is rich, the health condition of a human body can be reflected after collection and analysis, and the following sweat markers capable of reflecting the health condition of the human body are as follows:
(1) sodium: by analyzing sodium ions, non-contact injuries such as ion imbalances, disorientation, fatigue and even muscle strain can be predicted and prevented.
(2) Potassium: the lack of potassium ions can cause no strength of the whole body and weakened heartbeat, and the paralysis of respiratory muscles can be caused when the human body is seriously lack of potassium.
(3) Glucose: monitoring blood glucose levels is critical to the prevention or treatment of diabetes. Glucose represents the energy level of the body as a whole, and monitoring glucose concentration can help track the energy expenditure or metabolic rate of the body.
Sweat, a typical biofluid that can be obtained non-invasively, is potentially more advantageous than saliva in measuring inflammatory biomarkers; sweat has better measurement time continuity than saliva and urine in measuring biomarker concentrations.
Most of the existing wearable sweat detection devices are battery powered, resulting in large size and inconvenient wearing by the user, and short life requiring frequent replacement (e.g., 202010259321.9). Meanwhile, in order to improve the detection accuracy of the wearable sweat detection device, most of manufacturers of wearable sweat detection devices put a lot of effort on the preparation of the sensors themselves, but the design of the signal processing module is slightly considered, for example, the influence caused by signal loss in actual use is not considered. In addition, signals generated by the sweat sensor are weak and signal fluctuation is obvious, most wearable sweat detection devices still amplify the sweat sensor signals only through a simple operational amplifier circuit, amplification gain of the wearable sweat detection devices is not adjustable, and signal interference possibly generated by the surrounding environment cannot be responded. All of the above causes a problem of low accuracy of the sweat detection device.
Disclosure of Invention
The purpose of the invention is as follows: the invention aims to provide a signal processing module which is high in precision, adopts wireless energy supply and is small in size and used for a wearable sweat sensor.
The technical scheme is as follows: the invention discloses a wireless energy supply high-precision signal processing module for a wearable sweat sensor, which comprises a substrate, the sweat sensor, a radio frequency antenna, a communication circuit, a power supply circuit, a signal processing circuit and an ADC (analog-to-digital converter), wherein the power supply circuit comprises a charge pump circuit, a virtual battery and a voltage stabilizing circuit; the signal processing circuit comprises a voltage following circuit, a programmable gain amplifying circuit and a four-order low-pass filter circuit;
the radio frequency antenna is used for sampling data, controlling commands and transmitting electric energy; the charge pump circuit is used for rectifying and boosting electromotive force obtained from the antenna to charge the virtual battery; the virtual battery is used for storing electric energy obtained from the antenna and supplying power to the whole high-precision signal processing module; the voltage stabilizing circuit is used for preventing voltage fluctuation and improving the accuracy of the sweat sensor; the communication circuit is coupled with the sensor unit and the antenna and used for acquiring sampling data from the sensor unit and transmitting detection data through the antenna; the voltage follower circuit is used for improving the loading capacity and reducing the signal loss; the programmable gain amplification circuit is used for amplifying the weak signal of the sweat sensor and inhibiting common-mode interference; the fourth-order low-pass filter circuit is used for inhibiting high-frequency signal noise and eliminating external interference; the analog-to-digital converter ADC is used for converting an analog signal into a digital signal.
Furthermore, the radio frequency antenna is a 16-coil copper loop manufactured on the substrate through an etching technology, and a silver layer covers the surface of the antenna and is used for preventing the antenna from being corroded and improving the energy transmission efficiency.
Further, the resonant frequency of the radio frequency antenna is 13.56MHz, which is the frequency of the communication between the device and the reader
Furthermore, the charge pump circuit is composed of a Schottky diode and a ceramic capacitor, and the boosting multiple is 4 times.
Further, the voltage stabilizing circuit is a zener diode voltage stabilizing circuit.
Further, the voltage follower circuit is composed of an LT1462 dual-channel input operational amplifier, a resistor and a capacitor.
Further, the programmable gain amplifying circuit can select independent gain values as follows:
the independent gain value is determined by the on or off of three MOSFET (metal oxide semiconductor field effect transistor) tubes D1, D2 and D3, wherein R1, R2, R3, R4, R5, R6 and R7 are resistance values; g0 is an independent gain value when all three MOSFET tubes are turned off; g1 is the independent gain value when D1 is turned on and D2 and D3 are turned off; g2 is the independent gain value when D2 is turned on and D1 and D3 are turned off; g3 is the independent gain value when D3 is turned on and D1 and D2 are turned off.
Furthermore, the fourth-order low-pass filter circuit is a fourth-order Butterworth low-pass filter and is composed of an LT1462 dual-channel input operational amplifier, a resistor and a capacitor, and the cutoff frequency is set to be 1 HZ.
Further, the resolution of the analog-to-digital converter ADC is 12 bits.
Furthermore, the wireless energy supply high-precision signal processing module also comprises a parylene-c coating, the coating covers the power supply circuit, the communication circuit and the signal processing circuit, and the parylene-c coating is mainly used for resisting corrosion, insulating and reducing the friction coefficient.
Further, the substrate can be a standard copper/polyimide flexible electronic layer, the shape of the substrate is similar to that of a standard wound covering, so that the wearing effect of the device is good, the volume of retained sweat can be reduced, and the sweat measuring result is more continuous in time.
Has the advantages that: compared with the prior art, the invention has the following remarkable advantages: the invention can conveniently adjust the gain according to the output signal of the sensor through a program, and meanwhile, the module can also reduce the signal loss and can well remove the interference, thereby effectively improving the measurement data precision of the wearable sweat sensor and facilitating the data receiving and analysis processing of a reader. Meanwhile, a virtual wireless power supply technology is adopted, so that the equipment does not need to be provided with a battery, the size of the equipment is greatly reduced, and the wearing by a user is facilitated.
A voltage stabilizing circuit in the device is used for preventing voltage fluctuation and improving the accuracy of the sweat sensor; the communication circuit is coupled with the sensor unit and the antenna and used for acquiring sampling data from the sensor unit and transmitting detection data through the antenna; the voltage follower circuit is used for improving the loading capacity and reducing the signal loss; the programmable gain amplification circuit is used for amplifying the weak signal of the sweat sensor and inhibiting common-mode interference; the fourth-order low-pass filter circuit is used for suppressing high-frequency signal noise and eliminating external interference.
Drawings
FIG. 1 is a diagram of the hardware architecture of the present invention;
FIG. 2 is a circuit diagram of a charge pump circuit according to an embodiment of the present invention;
FIG. 3 is a schematic diagram of a virtual battery according to the present invention;
FIG. 4 is a schematic diagram of a programmable gain amplifier circuit according to the present invention;
FIG. 5 is a schematic diagram of an antenna structure according to the present invention;
FIG. 6 is a schematic circuit diagram of a voltage follower circuit according to an embodiment of the present invention;
fig. 7 is a schematic circuit diagram of a low-pass filter circuit according to an embodiment of the invention.
Detailed Description
The technical scheme of the invention is further explained by combining the attached drawings.
A functional block diagram of a wireless powered high accuracy signal processing module for a wearable sweat sensor as shown in fig. 1. The device has the advantage of small volume and is convenient to wear, all circuits and antennas of the device are integrated on a standard copper/polyimide flexible electronic layer through reflow soldering, the appearance of the device is similar to that of a standard band-aid, and the device can be directly adhered to the surface of the skin of a human body through a medical-grade adhesive. The paster appearance of this module can closely laminate with human skin to reduce the volume of detaining the sweat, this sweat check out test set of being convenient for carries out the sweat monitoring according to time sequence.
The invention also integrates a sensor unit capable of monitoring other human physiological information, such as a metal microwire made of chromium and gold as a resistance-based temperature sensor. The sensor unit of this module needs to be in direct contact with the skin of the monitored entity for the sensor unit can gather the relevant biological information of the entity, including sodium, potassium plasma concentration and temperature.
The invention comprises the following steps: the antenna comprises a substrate, an antenna and circuit modules, wherein the antenna and the circuit modules are manufactured on the substrate. Referring to fig. 5, in the embodiment of the present application, the antenna is disposed at the edge of the substrate profile, and the operating frequency of the antenna is 13.56 MHZ.
The circuit modules of the wearable sweat detection device are all powered by the antenna. The antenna can receive and send radio frequency signals, so that the mobile phone can transmit power to the sensor module or communicate with the sensor module in a wireless mode through the NFC function, and communication signals comprise control commands such as adjusting the gain of the amplifying circuit. In some embodiments, the reader receives, via the antenna, communication signals sent by the wearable sweat sensor module, including control commands, detection data of the sensor unit, and identity information of the wearable device, among others. In an embodiment of the application, the workflow of the wearable sweat sensor signal processing module is as follows: the reader device initiates a communication request while the module responds by its own load modulation and inductive coupling with the RFID reader.
The power supply circuit consists of a charge pump, a virtual battery and a voltage stabilizing circuit, wherein the virtual battery is used for storing electric energy and supplying energy to the whole circuit module; the charge pump circuit is used for rectifying and boosting the electromotive force obtained from the antenna to charge the virtual battery; the voltage stabilizing circuit is used for reducing voltage fluctuation and improving the working stability of the module.
The antenna is manufactured on the substrate through an etching process, the number of the antenna turns is 16, the size supplies enough energy for the wearable sweat detection device, and higher communication reliability can be guaranteed. Because the environment that wearable sweat check out test set is located has certain corrosivity, consequently cover a layer of silver as anti-corrosion metal on the antenna surface of preparation on the base plate, this work has improved the energy transmission efficiency of antenna simultaneously.
As shown in fig. 6, the voltage follower circuit mainly comprises LT1462, a resistor and a capacitor, and can effectively avoid signal loss generated when the input impedance of the next stage is smaller due to higher output impedance, and meanwhile, the voltage follower circuit presents a high impedance state to the upper stage circuit and a low impedance state to the next stage circuit, so that the front and rear stage circuits can be isolated, mutual interference is eliminated, and the detection precision of the sweat detection device is improved.
The programmable gain amplification circuit may employ various types of amplification circuits for gain selection. As shown in fig. 4, the programmable gain amplifier circuit of the wearable sweat detection device of the present invention is formed by a resistor, an operational amplifier, a parasitic diode and a MOSFET, and has the advantages of small size and low cost. The user can control the corresponding MOSFET to be conducted through a program, so that the gain required by the user can be flexibly adjusted, and the applicability is wide. User selectable independent gain values are:
the filter circuit may employ various types of circuits for filtering out ripples in the rectified output voltage. As shown in fig. 7, the low-pass digital filter of the wearable sweat detection device of the present invention is a butterworth filter, and the filter is composed of a resistor, an operational amplifier and a capacitor, and has the advantages of small volume and low cost. The cut-off frequency can be designed to be 1HZ by changing relevant parameters of components in the low-pass filter circuit.
Claims (10)
1. A wireless energy supply high-precision signal processing module for a wearable sweat sensor is characterized by comprising a substrate, the sweat sensor, a radio-frequency antenna, a communication circuit, a power supply circuit, a signal processing circuit and an ADC (analog-to-digital converter), wherein the power supply circuit comprises a charge pump circuit, a virtual battery and a voltage stabilizing circuit; the signal processing circuit comprises a voltage following circuit, a programmable gain amplifying circuit and a four-order low-pass filter circuit;
the radio frequency antenna is used for sampling data, controlling commands and transmitting electric energy; the charge pump circuit is used for rectifying and boosting electromotive force obtained from the antenna to charge the virtual battery; the virtual battery is used for storing electric energy obtained from the antenna and supplying power to the whole high-precision signal processing module; the voltage stabilizing circuit is used for preventing voltage fluctuation and improving the accuracy of the sweat sensor; the communication circuit is coupled with the sensor unit and the antenna and used for acquiring sampling data from the sensor unit and transmitting detection data through the antenna; the voltage follower circuit is used for improving the loading capacity and reducing the signal loss; the programmable gain amplification circuit is used for amplifying the weak signal of the sweat sensor and inhibiting common-mode interference; the fourth-order low-pass filter circuit is used for inhibiting high-frequency signal noise and eliminating external interference; the analog-to-digital converter ADC is used for converting an analog signal into a digital signal.
2. The wireless-powered high-accuracy signal processing module for a wearable sweat sensor of claim 1 wherein the rf antenna is a 16-turn copper coil loop fabricated on a substrate by etching techniques, and the antenna surface is covered with a silver layer.
3. The wirelessly powered high accuracy signal processing module for a wearable sweat sensor of claim 2 where the radio frequency antenna has a resonant frequency of 13.56 MHZ.
4. The wirelessly powered high accuracy signal processing module for a wearable sweat sensor of claim 1 where the charge pump circuit is comprised of a schottky diode and a ceramic capacitor with a 4 x boost.
5. The wireless-powered high-accuracy signal processing module for a wearable sweat sensor of claim 1 where the voltage regulator circuit is a zener diode voltage regulator circuit.
6. The wirelessly powered high accuracy signal processing module for a wearable sweat sensor of claim 1 where the voltage follower circuit is comprised of LT1462 dual channel input operational amplifier, resistor and capacitor.
7. The wirelessly powered high accuracy signal processing module for a wearable sweat sensor of claim 1 where the programmable gain amplification circuit can select independent gain values of:
the independent gain value is determined by the on or off of three MOSFET (metal oxide semiconductor field effect transistor) tubes D1, D2 and D3, wherein R1, R2, R3, R4, R5, R6 and R7 are resistance values; g0 is an independent gain value when all three MOSFET tubes are turned off; g1 is the independent gain value when D1 is turned on and D2 and D3 are turned off; g2 is the independent gain value when D2 is turned on and D1 and D3 are turned off; g3 is the independent gain value when D3 is turned on and D1 and D2 are turned off.
8. The wireless-powered high-accuracy signal processing module for a wearable sweat sensor of claim 1 where the fourth order low-pass filter circuit is a fourth order butterworth low-pass filter consisting of an LT1462 dual channel input operational amplifier, a resistor and a capacitor, with a cutoff frequency of 1 HZ.
9. The wirelessly powered high accuracy signal processing module for a wearable sweat sensor of claim 1 where the analog to digital converter ADC has a resolution of 12 bits.
10. The wirelessly powered high accuracy signal processing module for a wearable sweat sensor of claim 1 further comprising a parylene-c coating over the power supply circuitry, communication circuitry and signal processing circuitry.
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| CN202110607307.8A CN113271116B (en) | 2021-06-01 | 2021-06-01 | Wireless energy supply high-precision signal processing module for wearable sweat sensor |
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| CN202110607307.8A CN113271116B (en) | 2021-06-01 | 2021-06-01 | Wireless energy supply high-precision signal processing module for wearable sweat sensor |
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN106943138A (en) * | 2017-03-13 | 2017-07-14 | 韦佳伶 | Signal conditioner, ECG detection device and signal condition method |
| US20200107758A1 (en) * | 2018-10-09 | 2020-04-09 | General Electric Company | Wearable sweat sensing systems and methods thereof |
| CN111323828A (en) * | 2020-04-02 | 2020-06-23 | 中国海洋大学 | Program-controlled gain type ocean electric field signal acquisition method, system, device and application |
| CN111671437A (en) * | 2020-07-21 | 2020-09-18 | 香港纺织及成衣研发中心有限公司 | Wearable sweat detection system and method and wearable equipment |
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- 2021-06-01 CN CN202110607307.8A patent/CN113271116B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106943138A (en) * | 2017-03-13 | 2017-07-14 | 韦佳伶 | Signal conditioner, ECG detection device and signal condition method |
| US20200107758A1 (en) * | 2018-10-09 | 2020-04-09 | General Electric Company | Wearable sweat sensing systems and methods thereof |
| CN111323828A (en) * | 2020-04-02 | 2020-06-23 | 中国海洋大学 | Program-controlled gain type ocean electric field signal acquisition method, system, device and application |
| CN111671437A (en) * | 2020-07-21 | 2020-09-18 | 香港纺织及成衣研发中心有限公司 | Wearable sweat detection system and method and wearable equipment |
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