Multi-modal Backscattering Method, Smart Bracelet, Storage Medium and Program Product

Abstract

The present invention relates to the field of backscatter communication technology, and discloses a multi-modal backscatter method, an intelligent bracelet, a storage medium and a program product. The method includes: extracting the baseband envelopes of BLE excitation signals and ZigBee excitation signals, and identifying the BLE excitation signals and ZigBee excitation signals from various excitation signals in the environment by combining the ratio of the AC component to the DC component in the baseband envelopes; distinguishing the BLE excitation signals and ZigBee excitation signals according to the cross-correlation results between the AC component and the envelope data of the pre-stored BLE sequence; modulating the tag information on the BLE excitation signals through phase shift modulation to generate BLE backscatter signals; and modulating the tag information on the ZigBee excitation signals by controlling the frequency offset to achieve independent modulation independent of the content of the ZigBee excitation signals. The present invention not only reduces the overall power consumption of the system, but also expands the system coverage range.

Description

Technical Field

[0001] The present invention relates to the technical field of backscatter communication, and specifically relates to a multi-modal backscatter method, an intelligent bracelet, a storage medium, and a program product. Background Art

[0002] Sweat is an easily accessible biofluid containing rich physiological indicators. For example, sweat chloride levels can be used for the diagnosis of cystic fibrosis; abnormal sweat concentrations (K + and Na + ) indicate hypokalemia / hyperkalemia, hyponatremia / hypernatremia, muscle cramps, or dehydration; lactate in sweat is a sensitive marker of blood pressure ischemia; sweat glucose is related to blood glucose metabolism.

[0003] Currently, much work has been done to design multi-biosensor fusion systems. For example, FISA (see Fully integrated wearable sensor arrays for multiplexed in situ perspiration analysis) constructs a mechanically flexible and fully integrated sensor array for the measurement and analysis of sweat metabolites. However, the entire system is powered by a rechargeable lithium polymer battery, which is not sustainable and requires regular battery replacement. Current multi-biosensor sweat sensing systems either have a short communication range or limited battery capacity.

[0004] In recent years, backscatter has become one of the most attractive technologies in healthcare monitoring, with a communication range typically reaching dozens of meters and power consumption reducible to dozens of microwatts. Unfortunately, existing backscatter systems are designed for single-scenario applications. When the wireless environment fluctuates, the system performance will drop sharply, and when a specific carrier is lost, the system will completely fail. Summary of the Invention

[0005] To solve the above technical problems, the present invention provides a multi-modal backscatter method, an intelligent bracelet, a storage medium, and a program product, which can reduce the power consumption of the system and expand the application range of the system.

[0006] To solve the above technical problems, the present invention adopts the following technical solutions:

[0007] In a first aspect, the present invention provides a multi-modal backscatter method, using two excitation signals as carriers, specifically including:

[0008] Using a BLE signal with a single-frequency continuous wave as the BLE excitation signal; using a ZigBee signal with random content as the ZigBee excitation signal;

[0009] Extract the baseband envelopes of the BLE excitation signal and the ZigBee excitation signal through a high-bandwidth rectifier, and identify the BLE excitation signal and the ZigBee excitation signal among various excitation signals in the environment by combining the ratio of the AC component to the DC component in the baseband envelope; distinguish the BLE excitation signal and the ZigBee excitation signal according to the cross-correlation result between the AC component and the envelope data of the pre-stored BLE sequence;

[0010] Modulate the tag information on the BLE excitation signal through phase shift modulation to generate a BLE backscatter signal that conforms to the BLE protocol;

[0011] Modulate the tag information on the ZigBee excitation signal by controlling the frequency offset to generate a ZigBee backscatter symbol, realizing independent modulation independent of the content of the ZigBee excitation signal.

[0012] In one embodiment, using a BLE signal with a single-frequency continuous wave as the BLE excitation signal specifically includes:

[0013] The BLE signal modulates bits '0' and '1' with different frequencies, and uses a scrambler to whiten the original bit stream of the BLE signal to obtain the BLE excitation signal.

[0014] In one embodiment, the extracting the baseband envelopes of the BLE excitation signal and the ZigBee excitation signal through a high-bandwidth rectifier, and identifying the BLE excitation signal and the ZigBee excitation signal among various excitation signals in the environment by combining the ratio of the AC component to the DC component in the baseband envelope specifically includes:

[0015] Calculate the DC component of the excitation signal at time p ; where represents the size of the sliding window; represents the th envelope data sampled from the excitation signal, represents the index of the envelope data within the sliding window, ;

[0016] Calculate the AC component of the excitation signal at time p ;

[0017] Calculate the ratio of the AC component to the DC component of the excitation signal at time p ; When meets the set conditions, the corresponding excitation signal is the BLE excitation signal or the ZigBee excitation signal.

[0018] In one embodiment, the distinguishing the BLE excitation signal and the ZigBee excitation signal according to the cross-correlation result between the AC component and the envelope data of the pre-stored BLE sequence specifically includes:

[0019] By cross-correlating the AC components of the BLE excitation signal and the ZigBee excitation signal at time p with the envelope data of the pre-stored BLE sequence at time p to obtain the cross-correlation result at the i-th envelope data :

[0020] ;

[0021] wherein represents the total number of time points used for calculating the cross-correlation; by the value of and the cross-correlation result to distinguish between the BLE excitation signal and the ZigBee excitation signal represents the sign function

[0022] In one embodiment, the tag information is modulated on the ZigBee excitation signal by controlling the frequency offset to generate a ZigBee backscatter symbol, realizing independent modulation independent of the content of the ZigBee excitation signal, specifically including:

[0023] When modulating the chip '1' in the tag information, the corresponding chip in the ZigBee excitation signal is driven by the tag to perform frequency offset from the center frequency is the set frequency offset value

[0024] When modulating the chip '0' in the tag information, the corresponding chip in the ZigBee excitation signal is driven by the tag to perform frequency offset from the center frequency

[0025] In a second aspect, the present invention provides a smart bracelet, including:

[0026] A multi-source energy harvesting module, including a solar panel, a thermoelectric generator, and a radio frequency rectifier, isolates each energy source through a diode and is connected to a power management chip to realize the collaborative collection of light energy, thermal energy, and radio frequency energy;

[0027] A multi-biochemical sweat sensing module, integrating a six-channel electrode array, is used to detect the component information in sweat and adopts a differential mode technique to cancel the baseline drift; the component information includes the concentrations of glucose, lactic acid, sodium ions, potassium ions, hydrogen ions, and chloride ions;

[0028] A backscatter module is used to identify BLE excitation signals and ZigBee excitation signals in the environment, and modulate the component information as tag information in the BLE excitation signal and ZigBee excitation signal through the multimodal backscatter method in any one of the first aspects to generate a BLE backscatter signal and a ZigBee backscatter signal.

[0029] In one embodiment, the electrode array includes a glucose sensing electrode for measuring glucose concentration and covered with glucose oxidase, a lactate sensing electrode for measuring lactate concentration and covered with lactate oxidase, a control electrode covered with bovine serum albumin, ion-selective electrodes for measuring sodium ion concentration, potassium ion concentration, hydrogen ion concentration and chloride ion concentration respectively, and a reference electrode combined with a polyvinyl butyral coating.

[0030] In one embodiment, the differential mode technology is adopted to cancel the baseline drift, which specifically includes: both the glucose sensing electrode and the lactate sensing electrode are current-type sensors; the current signal output by the current-type sensor includes a target molecule concentration signal, an interference signal and a drift signal, and the signal output by the control electrode includes an interference signal and a drift signal; based on the output of the current-type sensor and the output of the control electrode, kinetic differential operation is performed to cancel the baseline drift.

[0031] In a third aspect, the present invention provides a computer-readable storage medium, on which a computer program is stored, and when the computer program is executed by a processor, the steps of the method in any one of the first aspects are implemented.

[0032] In a fourth aspect, the present invention provides a computer program product, including a computer program, and when the computer program is executed by a processor, the steps of the method in any one of the first aspects are implemented.

[0033] Compared with the prior art, the beneficial technical effects of the present invention are:

[0034] Based on the ultra-low-power backscatter module, the present invention realizes the connection between the bracelet and other intelligent devices, which not only greatly reduces the overall power consumption of the system, but also expands the system coverage. Secondly, the multi-source energy harvesting module in the present invention is responsible for converting environmental radio frequency, light and heat into electrical energy for system maintenance. Finally, the present invention designs a multi-biochemical sweat sensing module for measuring biochemical markers in sweat. The prototype of the present invention is made on a flexible printed circuit board. Experiments show that the present invention consumes 5.8 mW during sweat sensing, 180 pJ / bit for BLE transmission, and 720 pJ / bit for ZigBee transmission. Within a distance of 20 meters, the bit error rate of the system is still lower than 1%. Description of the Drawings

[0035] Figure 1 Schematic diagram of the method flow provided according to an embodiment of the present invention.

[0036] Figure 2 Schematic diagram of data whitening for Low Energy Bluetooth (BLE) signals provided according to an embodiment of the present invention.

[0037] Figure 3 Schematic diagram of baseband waveforms extracted for different excitation signals provided according to an embodiment of the present invention.

[0038] Figure 4 Schematic diagram of the average value of the ratio of the alternating current component to the direct current component provided according to an embodiment of the present invention.

[0039] Figure 5 Schematic diagram of the cross - correlation result provided according to an embodiment of the present invention.

[0040] Figure 6 Schematic diagram of a multi - source energy harvesting module provided according to an embodiment of the present invention.

[0041] Figure 7 Schematic diagram of the principle of a differential - mode glucose sensor provided according to an embodiment of the present invention.

[0042] Figure 8 Schematic diagram of the data flow of a differential - mode glucose sensor provided according to an embodiment of the present invention.

[0043] Figure 9 Schematic diagram of the state machine when information modulation is performed on ZigBee signals provided according to an embodiment of the present invention. Detailed implementation manners

[0044] The following provides a detailed description of a preferred implementation manner of the present invention in conjunction with the accompanying drawings.

[0045] In view of the limitations existing in the existing multi - biosensor fusion system, the present invention has developed a backscatter fusion technology, which can support multi - excitation backscatter simultaneously, not only reducing the overall power consumption but also expanding the system coverage.

[0046] As Figure 1 shown, the present invention provides a multi - modal backscatter method, using two excitation signals as carriers, specifically including the following steps:

[0047] S1: Use a BLE signal with a single - frequency continuous wave as the BLE excitation signal; use a ZigBee signal with random content as the ZigBee excitation signal.

[0048] S2: Extract the baseband envelopes of the BLE excitation signal and the ZigBee excitation signal through a high-bandwidth rectifier, and identify the BLE excitation signal and the ZigBee excitation signal among various excitation signals in the environment by combining the ratio of the AC component to the DC component in the baseband envelope; distinguish the BLE excitation signal and the ZigBee excitation signal according to the cross-correlation result between the AC component and the envelope data of the pre-stored BLE sequence.

[0049] S3: Modulate the tag information on the BLE excitation signal through phase-offset modulation to generate a BLE backscatter signal that complies with the BLE protocol.

[0050] S4: Modulate the tag information on the ZigBee excitation signal by controlling the frequency offset to generate a ZigBee backscatter symbol, which can achieve independent modulation independent of the content of the ZigBee excitation signal.

[0051] In one embodiment, using a BLE signal with a single-frequency continuous wave as the BLE excitation signal in step S1 specifically includes:

[0052] The BLE signal modulates bit '0' and bit '1' with different frequencies, and uses a scrambler to whiten the original bit stream of the BLE signal to obtain the BLE excitation signal.

[0053] In terms of excitation signals, the backscatter systems of the prior art can be divided into two categories: non-single-frequency continuous wave backscatter systems and single-frequency continuous wave-based backscatter systems. Traditional non-single-frequency continuous wave backscatter systems usually use codeword conversion to modulate tag data, and codeword conversion converts the excitation codeword into other valid codewords from the same codebook. Without decoding the excitation codeword, the backscattered data packet usually causes a cyclic redundancy check (CRC) error. In addition, these backscatter systems also need to perform redundant coding to achieve reliable transmission, that is, use multiple codewords to encode one bit, significantly reducing the system throughput. For example, the non-single-frequency continuous wave BLE backscatter system uses more than 10 codewords to encode one tag bit, while the ZigBee version uses 8 codewords to encode one bit.

[0054] When it comes to single-frequency continuous wave excitation, the generation method of the backscatter signal is as follows:

[0055] ;

[0056] ;

[0057] ;

[0058] represents the excitation signal represents the modulation signal corresponding to the tag data, represents the backscattered signal, represents the imaginary unit; are the amplitudes of the carrier signal and the modulation signal respectively, are the frequencies of the carrier signal and the modulation signal respectively, are the initial signal of the carrier signal and the phase offset of the modulation signal respectively. Among them, and remain constant during modulation and can be changed and to generate desired signals such as WiFi signals, BLE signals, ZigBee signals, LoRa signals, etc. The backscattered signal can perform CRC checks and no longer requires redundant coding to improve reliability. In addition, it only requires one receiver to decode the backscattered signal. However, using a single-frequency continuous wave as the excitation signal requires controlling what the transmitter sends. Therefore, in order to enable the backscattering system and the bracelet of the present invention to have a wider range of application scenarios, the present invention uses a single-frequency continuous wave as the carrier when modulating the BLE signal, and uses a non-single-frequency ZigBee signal as the carrier when modulating the ZigBee signal.

[0059] Generating BLE signals based on a single-frequency continuous wave: The BLE signal modulates bits '0' and '1' with different frequencies, and a constant bit stream of '0' or '1' generates a single frequency. As Figure 2 shown, the BLE signal uses a scrambler to avoid constant '0' and '1' in the original bit stream. In a preferred embodiment, the scrambler uses a linear feedback shift register (e.g., ), to ensure that the encoded bit stream is as random as possible (i.e., data whitening), and the register is initialized by the channel number. There is an obvious mapping between the original bits and the whitened bits, which indicates that reverse engineering can be used to obtain the desired whitened bit stream.

[0060] Modulating the BLE signal: The present invention uses phase offset to modulate the BLE signal. Specifically, the present invention adopts the IPS (instantaneous phase shift) modulation technique proposed in IBLE (see Commodity-level BLE backscatter) to modulate the BLE signal. The BLE receiver uses an orthogonal demodulator for signal demodulation, which inspires IBLE to use different phases for backscattering. When it comes to modulating bit '1', the tag controls the radio frequency (RF) switch through a square wave with a phase of , where represents the phase of the previous square wave. When modulating bit '0', the tag controls the RF switch through a square wave with a phase of .

[0061] In one embodiment, the step of extracting the baseband envelopes of the BLE excitation signal and the ZigBee excitation signal through a high-bandwidth rectifier in step S2, and identifying the BLE excitation signal and the ZigBee excitation signal from various excitation signals in the environment by combining the ratio of the AC component to the DC component in the baseband envelope specifically includes:

[0062] Calculate the DC component of the excitation signal at time p ; where represents the size of the sliding window; represents the th envelope data of the sampled excitation signal, represents the index of the envelope data within the sliding window, ;

[0063] Calculate the AC component of the excitation signal at time p ;

[0064] Calculate the ratio of the AC component to the DC component of the excitation signal at time p ; When meets the set conditions, the corresponding excitation signals are the BLE excitation signal and the ZigBee excitation signal.

[0065] Specifically, the backscatter system of the present invention needs to identify BLE signals and ZigBee signals. In a preferred embodiment, the present invention uses a high-bandwidth rectifier to directly extract the baseband envelope of the excitation signal. The baseband waveforms extracted for different environmental signals are as Figure 3 shown. Among them, Figure 3 in (a), (b), (c), and (d) are the baseband waveforms of the BLE signal, ZigBee signal, 802.11b signal, and 802.11n signal respectively. It can be observed that different environmental signals have different envelopes. The present invention uses the ratio of the alternating current (AC) component to the direct current (DC) component of the signal to distinguish environmental signals, and the results are as Figure 4 shown. For ZigBee signals, 99.8% of the data is below 0.02; for BLE signals, more than 99.8% of the data is distributed between 0.03 and 0.05, and the AC / DC values of the 802.11b signal and 802.11n signal are higher than 0.8. This means that the AC / DC value can successfully identify BLE signals and ZigBee signals from other popular in-band environmental signals. Figure 4 The CDF in

[0066] In one embodiment, differentiating the BLE excitation signal and the ZigBee excitation signal according to the cross - correlation result between the AC component and the envelope data of the pre - stored BLE sequence in step S2 specifically includes:

[0067] By performing cross - correlation on the AC component of the BLE excitation signal and the ZigBee excitation signal at time p and the envelope data at time p to obtain the cross - correlation result at the i - th envelope data :

[0068] ;

[0069] wherein, represents the total number of time points used for calculating the cross - correlation, represents the sign function.

[0070] If is less than 0.8 and the cross - correlation result is greater than or equal to 0.7, the excitation signal is the BLE excitation signal; if is less than 0.8 and the cross - correlation result is less than 0.7, the excitation signal is the ZigBee excitation signal.

[0071] Since the AC / DC value distributions of the BLE signal and the ZigBee signal are similar, the present invention uses the envelope characteristics to further identify these two signals. Specifically, the envelopes of the BLE signals are different, which provides an opportunity for signal identification. The present invention performs cross - correlation on the envelope data S(p) of a pre - stored BLE sequence and the excitation signal A(p). When performing cross - correlation, the DC component D(p) is not included because D(p) can be regarded as a constant signal and the contribution of the cross - correlation of D(p) to the data packet identification is small.

[0072] Using the low - power programmable logic gate array AGLN250V2 - VQ100I, the calculation of the cross - correlation can be easily performed. The cross - correlation results R(i) of 2000 data packets are as Figure 5 shown. The sampling rate is set to 20 MS / s, and the BLE template sequence length is set to 128 samples. It can be seen that the cross - correlation results of the BLE signals are stably higher than 0.7.

[0073] Combining the AC / DC value and the cross - correlation result for signal identification: if the AC / DC value of the current signal is below 0.8 and the cross - correlation result is above 0.7, it is determined that the current signal is a BLE signal; if the AC / DC value of the current signal is below 0.8 and the cross - correlation result is below 0.7, it is determined that the current signal is a ZigBee signal.

[0074] In one embodiment, in step S4, modulating the tag information on the ZigBee excitation signal by controlling the frequency offset to generate a ZigBee backscatter symbol can achieve independent modulation independent of the content of the ZigBee excitation signal, specifically including:

[0075] When modulating the chip '1' in the tag information, drive the corresponding chip in the ZigBee excitation signal by the tag to perform a frequency offset from the center frequency;

[0076] When modulating the chip '0' in the tag information, drive the corresponding chip in the ZigBee excitation signal by the tag to perform a frequency offset from the center frequency.

[0077] The present invention uses a single - frequency continuous wave as the carrier when modulating the BLE signal, and uses a non - single - frequency ZigBee signal as the carrier when modulating the ZigBee signal. Specifically, the present invention uses a commercial ZigBee device as the transmitter to send ZigBee signals with random content. For this reason, the present invention designs a new ZigBee backscatter modulation scheme according to the physical layer characteristics of the ZigBee signal. The technical details of the backscatter of the ZigBee signal will be introduced below.

[0078] Modulating the ZigBee signal. In the existing ZigBee backscatter system using a non - single - frequency continuous wave as the excitation signal, the tag is unknown about both the excitation signal and the reflected signal. Therefore, the tag cannot freely control the reflected signal, resulting in the data packet being unable to pass the CRC check and being discarded by the receiver. In addition, since data decoding depends on the excitation signal, the backscatter system requires an additional receiver, thus increasing the deployment cost. Although some existing technologies (such as BumbleBee) control the symbols of the reflection chip by introducing a dominant phase offset to cover low - speed excitation signals (for example, BLE4 with a phase offset less than π / 4), it cannot effectively modulate high - speed ZigBee signals with a phase offset of π / 2 in the ZigBee network, which poses a challenge to the deployment of the ZigBee network.

[0079] The present invention proposes a new ZigBee backscatter modulation method, enabling the tag to use the ZigBee signal in the environment as the carrier and only requiring one receiver to obtain the tag data. According to the IEEE802.15.4 standard followed by the ZigBee physical layer, every 4 bits of data are mapped to 1 symbol, each symbol consists of 32 chips, and the chip rate is 2.0Mchip / s. The modulation method for chip '1' is a phase offset of +π / 2, while the modulation method for chip '0' is a phase offset of -π / 2.

[0080] In a commercial ZigBee receiver, the signal is first sampled by an analog-to-digital converter to obtain discrete in-phase quadrature (IQ) values. Subsequently, an intermediate frequency channel filter is used to remove out-of-band noise. Then, the system calculates the phase difference and inputs the phase difference for binarization: if the phase difference is greater than 0, it is determined as chip '1'; if it is less than 0, it is determined as chip '0'. The final output will be compared with the symbols corresponding to 32 consecutive chips, and the minimum Hamming distance method is used to demodulate the target symbol.

[0081] The ZigBee receiver demodulates the chips into '1' or '0' according to the sign of the phase offset. Specifically, when the phase offset is positive, such as , and the values are demodulated as chip '1'. Further, when the phase offset is negative, such as , and the values are demodulated as chip '0'. Based on this understanding, a natural question arises: can the modulation be manipulated to include a larger phase offset to control the symbols of the backscatter chip? Taking the modulation of chip '1' as an example, the concept of the present invention is as follows. The modulation of chip '1' corresponds to a frequency offset of from the center frequency in the frequency domain. Similarly, chip '0' corresponds to a frequency offset of from the center frequency. Since the phase offset is the integral of the frequency offset, that is . By introducing a frequency offset (denoted by ), chip '0' or '1' can be modulated to a positive frequency offset. After the accumulation of time , this will become a positive phase offset. Therefore, regardless of whether the excitation chip is '1' or '0', it can be modulated to chip '1'. Thus, the modulation result is driven by the tag and is independent of the content of the excitation ZigBee. The state machine of tag modulation is as shown in Figure 9 .

[0082] It should be understood that although the steps in the flowchart of the accompanying drawings of the specification are shown in sequence according to the indication of the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless there is a clear indication in this article, the execution of these steps has no strict order limit, and these steps can be executed in other orders. Moreover, at least a part of the steps in the flowchart of the accompanying drawings of the specification may include multiple steps or multiple stages, and these steps or stages are not necessarily executed at the same moment, but can be executed at different moments, and the execution order of these steps or stages is not necessarily sequential, but can be executed alternately or alternately with at least a part of other steps or steps or stages in other steps.

[0083] The present invention also provides a smart bracelet, comprising:

[0084] A multi-source energy harvesting module, including a solar panel, a thermoelectric generator, and a radio frequency rectifier, isolates each energy source through a diode and is connected to a power management chip to achieve the collaborative collection of light, heat, and radio frequency energy;

[0085] A multi-biochemical sweat sensing module, integrating a six-channel electrode array, is used to detect the component information in sweat and adopts a differential mode technique to cancel baseline drift; the component information includes the concentrations of glucose, lactic acid, sodium ions, potassium ions, hydrogen ions, and chloride ions;

[0086] A backscatter module, used to identify BLE excitation signals and ZigBee excitation signals in the environment, and through a multi-modal backscatter method, modulates the component information as tag information in the BLE excitation signal and the ZigBee excitation signal to generate a BLE backscatter signal and a ZigBee backscatter signal.

[0087] The smart bracelet corresponds to the role of a tag in the backscatter system.

[0088] The present invention uses a solar panel, a thermoelectric generator (TEG), and a radio frequency rectifier to collect multi-source energy of light, heat, and radio frequency (RF) signals. If these harvesting modules are directly connected to a power management chip (the present invention can use the TIBQ25570 chip), the thermoelectric generator with a much smaller resistance than other components will act as a load and consume most of the energy. Therefore, the present invention uses the one-way conductivity of a diode to isolate these harvesting devices. As Figure 6 shown, each harvesting module is connected to the BQ25570 chip through a low-dropout Schottky diode. The equivalent resistances of the rectifier and the thermoelectric generator are both very high, so most of the energy can be effectively obtained through the BQ25570. Figure 6 Among them, Vout represents the output voltage of the chip, and Vcap represents the voltage stored in the capacitor.

[0089] In one embodiment, the electrode array includes a glucose sensing electrode for measuring glucose concentration and covered with glucose oxidase, a lactic acid sensing electrode for measuring lactic acid concentration and covered with lactic acid oxidase, a control electrode covered with bovine serum albumin, ion-selective electrodes for measuring sodium ion concentration, potassium ion concentration, hydrogen ion concentration, and chloride ion concentration respectively, and a reference electrode combined with a polyvinyl butyral coating.

[0090] Specifically, the present invention uses a customized multi-biochemical sensor and a signal processing circuit for sweat sensing. The multi-biochemical sensor adopts a six-channel electrode array structure to detect glucose, lactic acid, sodium ions (Na + ), potassium ions (K+ ), hydrogen ions (H + ), and chloride ions (Cl - ). These electrodes selectively convert the concentration of the corresponding components into electrical signals. Glucose oxidase, lactate oxidase, and bovine serum albumin (BSA) are respectively modified on three working electrodes. The carbon electrode serves as the counter electrode, and the Ag / AgCl electrode acts as the reference electrode. Here, the working electrode covered with BSA is used as the control electrode to offset drift and interference. Na + , K + , H + , and Cl - measurement values are obtained based on ion-selective electrodes and combined with a reference electrode coated with polyvinyl butyral (PVB) for horizontal determination.

[0091] In one embodiment, the differential mode technique is adopted to offset baseline drift, specifically including: both the glucose sensing electrode and the lactate sensing electrode are current-type sensors; the current signals output by the current-type sensors include target molecule concentration signals, interference signals, and drift signals, and the signals output by the control electrode include interference signals and drift signals; based on the output of the current-type sensors and the output of the control electrode, kinetic differential operations are performed to offset baseline drift.

[0092] Specifically, in an electrochemical system, even without a target electrochemical reaction, the generated current or voltage signals may drift over time, which may be caused by environmental influences, human movement, or instrument artifacts, and is called "baseline drift". Wearable biochemical sensors are affected by baseline drift, especially in the case of long-term measurements in complex systems, making it difficult to accurately estimate the concentration of target molecules in sweat. Various methods have been proposed in the prior art to overcome this problem, including dual reporting methods, filtering techniques, and compensation algorithms, but the mechanism of baseline drift is still unclear.

[0093] In the present invention, a differential measurement method is adopted to offset baseline drift and noise. Taking the measurement of glucose concentration as an example below, the measurement of lactate concentration uses the same principle. The schematic diagram of the differential mode glucose sensor is as Figure 7 shown, Figure 7 in represents the current generated by the sensing electrode covered with glucose oxidase (GOx), originating from the oxidation reaction of glucose, representing the signal related to the glucose concentration; represents the current generated by the control electrode covered with bovine serum albumin (BSA), serving as a reference signal, not affected by glucose, and used to correct the interference of environmental factors; represents the voltage signal generated by the sensing electrode covered with glucose oxidase (GOx), which, after being converted by an operational amplifier, represents the current signal generated by the oxidation of glucose; Represents the voltage signal generated by the control electrode covered with bovine serum albumin (BSA), which serves as a reference voltage to eliminate the influence of non-glucose factors on the measurement; V out1 Represents the output of the differential-mode glucose sensor. The electrode array of the differential-mode glucose sensor consists of two different working electrodes, including a sensing electrode covered with glucose oxidase (GOx) and a control electrode covered with bovine serum albumin (BSA). There are two reasons for choosing BSA as the control for GOx: First, BSA is a commonly used inertial protein in electrochemical biosensors and has no catalytic activity towards glucose. Second, it is quite stable and easily obtainable. The block diagram of the differential-mode glucose sensor is as shown in Figure 8 shown. Both the GOx-covered sensing electrode and the BSA-covered control electrode will respond to the baseband drift caused by environmental influences ( ), respond to the noise caused by various biomolecules ( ), and the biomolecules include small electrolytes, metabolites, and hormones and large proteins in human sweat, but only the GOx-covered sensing electrode responds to glucose ( ). The interference signals and drift signals generated by the differential-mode glucose sensor can be cancelled through the following signal processing circuit and kinetic differential measurement.

[0094] The signal processing path for each electrode is implemented by an analog circuit. The circuit is configured to ensure that the analog output of each path is finely resolved while remaining within the input voltage range of the analog-to-digital converter (ADC). To obtain information about the glucose and lactate concentrations, the present invention tests the reverse current from the glucose sensing electrode and the lactate sensing electrode to the Ag / AgCl electrode. In the signal processing path, the present invention first uses a transimpedance amplifier (TIA) to convert the current into a voltage signal. Since a reverse current is generated, the output voltage of the transimpedance amplifier is negative. Therefore, an inverter subsequently converts the negative voltage into a positive voltage, which can be accepted by the analog-to-digital converter and used for all glucose, lactate, and control paths. The last part of each signal processing path is a unity-gain low-pass filter (LPF) with -3 dB and a frequency of 1 Hz to minimize the noise and interference in the measurement.

[0095] In the measurement paths of H + , Cl - , K + , Na + , the signal generated is the voltage difference between their corresponding ion-selective electrode (ISE) and the reference electrode coated with PVB, and the present invention directly measures this voltage difference. Each of their signal processing paths sequentially includes: two voltage buffers for the ion-selective electrode and the reference electrode combined with a polyvinyl butyral coating, a differential amplifier and an analog-to-digital converter, and a low-pass filter for suppressing noise and interference.

[0096] The present invention also provides a computer-readable storage medium including instructions, such as a memory including instructions, and the above instructions can be executed by a processor to perform the above method. The storage medium can be a computer-readable storage medium, for example, the computer-readable storage medium can be a ROM, a random access memory (RAM), a CD-ROM, a magnetic tape, a floppy disk, an optical data storage device, etc.

[0097] The present invention also provides a computer program product, comprising a computer program, wherein the computer program implements the steps of the above method when executed by a processor.

[0098] It is obvious to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims are included in the present invention, and any reference numerals in the claims should not be regarded as limiting the claims involved.

[0099] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A multi-modal backscattering method, using two excitation signals as carriers, characterized in that: Specifically include: A BLE signal with a single-frequency continuous wave is used as a BLE excitation signal; a ZigBee signal with random content is used as a ZigBee excitation signal; The baseband envelopes of the BLE excitation signal and the ZigBee excitation signal are extracted by a high-bandwidth rectifier, and the BLE excitation signal and the ZigBee excitation signal are identified from a variety of excitation signals in the environment by combining the ratio of the AC component to the DC component in the baseband envelope; the BLE excitation signal and the ZigBee excitation signal are distinguished based on the cross-correlation result of the AC component and the envelope data of the pre-stored BLE sequence; The tag information is modulated on the BLE excitation signal through phase shift modulation to generate a BLE backscatter signal that complies with the BLE protocol; By controlling the frequency offset, the tag information is modulated on the ZigBee excitation signal to generate ZigBee backscatter symbols, achieving independent modulation independent of the content of the ZigBee excitation signal.

2. A multimodal backscattering method according to claim 1, characterized in that: The method of using a BLE signal with a single-frequency continuous wave as a BLE excitation signal specifically includes: The BLE signal modulates bit '0' and bit '1' with different frequencies, and uses a scrambler to perform data whitening on the original bit stream of the BLE signal to obtain a BLE excitation signal.

3. A multimodal backscattering method according to claim 1, characterized in that: The method extracts the baseband envelopes of the BLE excitation signal and the ZigBee excitation signal by a high-bandwidth rectifier, and identifies the BLE excitation signal and the ZigBee excitation signal from a variety of excitation signals in the environment by combining the ratio of the AC component to the DC component in the baseband envelope, specifically including: Calculate the DC component of the excitation signal at time p ;in Indicates the size of the sliding window; Indicates the sampling of the excitation signal Envelope data, represents the index of the envelope data within the sliding window, ; Calculate the AC component of the excitation signal at time p ; Calculate the ratio of the AC component to the DC component of the excitation signal at time p ;when When the set conditions are met, the corresponding excitation signal is a BLE excitation signal or a ZigBee excitation signal.

4. A multimodal backscattering method according to claim 3, characterized in that: The method of distinguishing the BLE excitation signal from the ZigBee excitation signal according to the cross-correlation result between the AC component and the envelope data of the pre-stored BLE sequence specifically includes: By taking the AC components of the BLE excitation signal and the ZigBee excitation signal at time p The envelope data of the pre-stored BLE sequence at time p Perform cross-correlation and obtain the cross-correlation result at the i-th envelope data : ； in, Indicates the total number of time points used when calculating the cross-correlation; The BLE excitation signal and the ZigBee excitation signal are distinguished by the value and the cross-correlation result. Represents a symbolic function.

5. A multi-modal backscattering method according to claim 1, characterized in that: The method of modulating the tag information on the ZigBee excitation signal by controlling the frequency offset to generate a ZigBee backscatter symbol and realize independent modulation irrelevant to the content of the ZigBee excitation signal specifically includes: When the code chip in the modulated tag information is '1', the corresponding code chip in the ZigBee excitation signal is driven by the tag to change from the center frequency to The frequency offset of is the set frequency offset value; When the chip '0' in the modulated tag information is used, the corresponding chip in the ZigBee excitation signal is driven by the tag to rotate from the center frequency frequency offset.

6. A smart bracelet, characterized in that: include: Multi-source energy harvesting module, including solar panels, thermoelectric generators and RF rectifiers, isolating each energy source through diodes and connected to a power management chip to achieve the coordinated collection of light, heat and RF energy; The multi-biochemical sweat sensor module integrates a six-channel electrode array to detect the composition information in sweat, using differential mode technology to offset baseline drift; the composition information includes the concentration of glucose, lactate, sodium ion, potassium ion, hydrogen ion and chloride ion; A backscattering module is used to identify BLE excitation signals and ZigBee excitation signals in the environment, and modulate the component information as tag information in the BLE excitation signal and the ZigBee excitation signal through the multimodal backscattering method as described in any one of claims 1 to 5 to generate a BLE backscattering signal and a ZigBee backscattering signal.

7. The smart bracelet according to claim 6, characterized in that: The electrode array includes a glucose sensing electrode for measuring glucose concentration and covered by glucose oxidase, a lactate sensing electrode for measuring lactate concentration and covered by lactate oxidase, a control electrode covered by bovine serum albumin, ion selective electrodes for measuring sodium ion concentration, potassium ion concentration, hydrogen ion concentration and chloride ion concentration, respectively, and a reference electrode combined with a polyvinyl butyral coating.

8. The smart bracelet according to claim 7, characterized in that: The differential mode technology used to offset the baseline drift specifically includes: the glucose sensing electrode and the lactate sensing electrode are both current sensors; the current signal output by the current sensor includes a target molecule concentration signal, an interference signal and a drift signal, and the signal output by the control electrode includes an interference signal and a drift signal; a kinetic differential operation is performed based on the output of the current sensor and the output of the control electrode to offset the baseline drift.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 5 are implemented.

10. A computer program product, comprising a computer program, characterized in that When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 5 are implemented.

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