Multi-mode backscattering method, smart bracelet, storage medium and program product

Abstract

The invention relates to the technical field of backscatter communication, and discloses a multi-mode backscatter method, a smart bracelet, a storage medium and a program product.The method comprises the steps that base band envelopes of a BLE excitation signal and a ZigBee excitation signal are extracted; identifying a BLE excitation signal and a ZigBee excitation signal from various excitation signals in the environment in combination with a ratio of an alternating current component to a direct current component in the baseband envelope; distinguishing a BLE excitation signal and a ZigBee excitation signal according to a cross-correlation result of the AC component and envelope data of a pre-stored BLE sequence; modulating label information on the BLE excitation signal through phase deviation modulation to generate a BLE backscattering signal; label information is modulated on a ZigBee excitation signal by controlling frequency deviation, and independent modulation irrelevant to the content of the ZigBee excitation signal is achieved. The overall power consumption of the system is reduced, and the coverage range of the system is expanded.

Description

Technical Field

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

[0002] Sweat is an easily accessible biofluid that contains a wealth of physiological indicators. For example, sweat chloride levels can be used to diagnose cystic fibrosis; abnormal sweat concentrations (K + and Na + ) indicates hypokalemia / hyperkalemia, hyponatremia / hypernatremia, muscle cramps or dehydration; lactic acid in sweat is a sensitive marker of blood pressure ischemia; sweat glucose is related to blood glucose metabolism.

[0003] Currently, there have been a lot of works designed multi-biosensor fusion systems. For example, FISA (see Fully integrated wearable sensor arrays for multiplexed in situ perspiration analysis) built a mechanically flexible, 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 for healthcare monitoring, with a communication range of typically tens of meters and power consumption down to tens of microwatts. Unfortunately, existing backscatter systems are designed for single-scenario applications. When the wireless environment fluctuates, system performance degrades dramatically, and when a specific carrier is lost, the system fails completely. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a multimodal backscattering method, a smart bracelet, a storage medium and a program product, which can reduce the power consumption of the system and expand the application scope of the system.

[0006] In order to solve the above technical problems, the present invention adopts the following technical solutions: In a first aspect, the present invention provides a multi-modal backscattering method, using two excitation signals as carriers, specifically comprising: 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.

[0007] In one embodiment, the adopting of a BLE signal having 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.

[0008] In one embodiment, extracting the baseband envelope of the BLE excitation signal and the ZigBee excitation signal by a high-bandwidth rectifier, and identifying 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 includes: 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.

[0009] In one embodiment, the step 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.

[0010] In one embodiment, the method of controlling the frequency offset to modulate the tag information on the ZigBee excitation signal to generate a ZigBee backscatter symbol to achieve independent modulation independent of 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.

[0011] In a second aspect, the present invention provides a smart bracelet, comprising: 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 in any one of the embodiments of the first aspect to generate a BLE backscattering signal and a ZigBee backscattering signal.

[0012] In one embodiment, 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.

[0013] In one of the embodiments, the differential mode technology is used to offset the baseline drift, specifically including: 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.

[0014] In a third aspect, the present invention provides a computer-readable storage medium having a computer program stored thereon, wherein the computer program, when executed by a processor, implements the steps of the method of any one of the embodiments in the first aspect.

[0015] In a fourth aspect, the present invention provides a computer program product, comprising a computer program, which, when executed by a processor, implements the steps of the method of any one of the embodiments in the first aspect.

[0016] Compared with the prior art, the beneficial technical effects of the present invention are: The present invention is based on an ultra-low power backscattering module to achieve the connection between the bracelet and other smart devices, which not only greatly reduces the overall power consumption of the system, but also expands the coverage of the system. Secondly, the multi-source energy harvesting module in the present invention is responsible for converting ambient 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 5.8mW during sweat sensing, 180 pJ / bit for BLE transmission, and 720pJ / bit for ZigBee transmission. Within a distance of 20 meters, the bit error rate of the system is still less than 1%. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 The present invention is a flowchart of a method provided in accordance with an embodiment of the present invention.

[0018] Figure 2 The present invention is a schematic diagram of performing data whitening on a Bluetooth Low Energy (BLE) signal according to an embodiment of the present invention.

[0019] Figure 3It is a schematic diagram of baseband waveforms extracted from different excitation signals according to an embodiment of the present invention.

[0020] Figure 4 A schematic diagram of an average value of the ratio of the AC component to the DC component provided according to an embodiment of the present invention.

[0021] Figure 5 It is a schematic diagram of a cross-correlation result provided according to an embodiment of the present invention.

[0022] Figure 6 It is a schematic diagram of a multi-source energy harvesting module provided according to an embodiment of the present invention.

[0023] Figure 7 Schematic diagram of a differential mode glucose sensor provided according to an embodiment of the present invention.

[0024] Figure 8 This is a schematic diagram of data flow of a differential mode glucose sensor provided according to an embodiment of the present invention.

[0025] Fig. 9 The diagram is a schematic diagram of a state machine when information modulation is performed on a ZigBee signal according to an embodiment of the present invention. DETAILED DESCRIPTION

[0026] A preferred embodiment of the present invention is described in detail below with reference to the accompanying drawings.

[0027] In view of the limitations of the existing multi-biological sensor fusion system, the present invention has developed a backscatter fusion technology that can simultaneously support multi-excitation backscattering, which not only reduces the overall power consumption but also expands the system coverage.

[0028] like Figure 1 As shown, the present invention provides a multi-mode backscattering method, using two excitation signals as carriers, specifically comprising the following steps: S1: 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.

[0029] S2: extracting the baseband envelope 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 from a variety of excitation signals in the environment based on the ratio of the AC component to the DC component in the baseband envelope; distinguishing the BLE excitation signal and the ZigBee excitation signal based on the cross-correlation result between the AC component and the envelope data of the pre-stored BLE sequence.

[0030] S3: 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.

[0031] S4: The tag information is modulated 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.

[0032] In one embodiment, the step S1 uses a BLE signal with a single-frequency continuous wave as a BLE excitation signal, specifically including: 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.

[0033] In terms of the excitation signal, the backscatter systems in 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 the tag data, and the 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 require redundant encoding to achieve reliable transmission, that is, multiple codewords are used to encode one bit, which significantly reduces the system throughput. For example, the non-single-frequency continuous wave BLE backscatter system uses more than 10 codewords to encode a tag bit, while the ZigBee version uses 8 codewords to encode one bit.

[0034] When single frequency CW excitation is involved, the backscattered signal is generated as follows: ; ; ; represents the excitation signal, Indicates the modulation signal corresponding to the tag data, represents the backscattered signal, represents an imaginary unit; are the amplitudes of the carrier signal and the modulating signal, respectively. are the frequencies of the carrier signal and the modulating signal, respectively. are the phase offsets of the initial signal of the carrier signal and the modulation signal respectively. Among them, and Remains constant during modulation and can be varied and To generate the desired signal, such as WiFi signal, BLE signal, ZigBee signal, LoRa signal, etc. The backscattered signal can be CRC checked, and redundant coding is no longer required to improve reliability. In addition, it only requires one receiver to decode the backscattered signal. However, the use of a single-frequency continuous wave as an excitation signal requires control of the content sent by the transmitter. 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 a carrier when modulating the BLE signal, and uses a non-single-frequency ZigBee signal as a carrier when modulating the ZigBee signal.

[0035] Generate BLE signal based on single frequency continuous wave: BLE signal modulates bit '0' and bit '1' with different frequencies, and the constant bit stream of '0' or '1' generates a single frequency. Figure 2 As 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), the registers are initialized by the channel number. There is a clear mapping between the original bits and the whitened bits, which suggests that reverse engineering can be used to obtain the desired whitened bit stream.

[0036] Modulating BLE signal: The present invention uses phase shift to modulate BLE signal. Specifically, the present invention uses IPS (Instantaneous Phase Shift) modulation technology proposed in IBLE (see Commodity-level BLE backscatter) to modulate BLE signal. BLE receiver uses orthogonal demodulator for signal demodulation, which inspires IBLE to use different phases for backscattering. When it comes to modulating bit '1', the tag transmits the signal with a phase of A square wave controls the RF switch, where Indicates the phase of the previous square wave. When the modulation bit is '0', the tag passes the phase The square wave controls the RF switch.

[0037] In one embodiment, the step S2 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 signals are the BLE excitation signal and the ZigBee excitation signal.

[0038] 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 waveform extracted for different environmental signals is as follows: Figure 3 As shown. Among them, Figure 3 (a), (b), (c), and (d) are the baseband waveforms of BLE signals, ZigBee signals, 802.11b signals, and 802.11n signals, respectively. It can be observed that different environmental signals have different envelopes. The present invention uses the ratio of the AC component to the DC component of the signal to distinguish the environmental signals. The results are shown in Figure 1. Figure 4 As shown in the figure, 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 802.11b and 802.11n signals are above 0.8. This means that the AC / DC value can successfully identify BLE and ZigBee signals from other popular environmental in-band signals. Figure 4 The CDF in represents the probability distribution of the AC / DC value, that is, the cumulative probability of the AC / DC value for different wireless signals.

[0039] In one embodiment, the step S2 of distinguishing the BLE excitation signal from the ZigBee excitation signal according to the cross-correlation result of the AC component and the envelope data of the pre-stored BLE sequence specifically includes: By combining the BLE excitation signal and the ZigBee excitation signal at time p and the envelope data at time p Perform cross-correlation and obtain the cross-correlation result at the i-th envelope data : ; in, represents the total number of time points used to calculate the cross-correlation. Represents a symbolic function.

[0040] if If the value is less than 0.8 and the cross-correlation result is greater than or equal to 0.7, the excitation signal is a BLE excitation signal; if If the value is less than 0.8 and the cross-correlation result is less than 0.7, the excitation signal is a ZigBee excitation signal.

[0041] Since the distribution of AC / DC values ​​of BLE signal and ZigBee signal is close, the present invention uses envelope characteristics to further identify the two signals. Specifically, the envelope of BLE signal is different, which provides an opportunity for signal identification. The present invention takes a pre-stored BLE sequence envelope data S(p) and the excitation signal A(p) for cross-correlation. When cross-correlating, the DC component D(p) is not included because D(p) can be regarded as a constant signal, and the cross-correlation of D(p) contributes little to data packet identification.

[0042] The cross-correlation calculation can be easily performed using the low-power programmable logic gate array AGLN250V2-VQ100I. The cross-correlation result R(i) of 2000 packets is shown in the figure. Figure 5 As shown in the figure. 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 result of the BLE signal is stably higher than 0.7.

[0043] The AC / DC value and the cross-correlation result are combined 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, the current signal is determined to be 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, the current signal is determined to be a ZigBee signal.

[0044] In one embodiment, the step S4 modulates the tag information on the ZigBee excitation signal by controlling the frequency offset to generate the ZigBee backscatter symbol, which can achieve independent modulation independent of the content of the ZigBee excitation signal, specifically including: 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 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.

[0045] The present invention uses a single-frequency continuous wave as a carrier when modulating a BLE signal, and uses a non-single-frequency ZigBee signal as a carrier when modulating a ZigBee signal. Specifically, the present invention uses a commercial ZigBee device as a transmitter to send a ZigBee signal with random content. To this end, the present invention designs a new ZigBee backscatter modulation scheme based on the physical layer characteristics of the ZigBee signal. The technical details of the backscatter of the ZigBee signal will be introduced below.

[0046] Modulate ZigBee signals. In existing ZigBee backscatter systems that use non-single-frequency continuous waves as excitation signals, the tags are unaware of both the excitation signal and the reflected signal. Therefore, the tag cannot freely manipulate the reflected signal, resulting in the data packet failing the CRC check and being discarded by the receiver. In addition, since data decoding depends on the excitation signal, the backscatter system requires additional receivers, which increases deployment costs. Although some existing technologies (such as BumbleBee) control the sign of the reflected chip by introducing a dominant phase offset to cover the low-speed excitation signal (such as BLE4 with a phase offset less than π / 4), it cannot effectively modulate the high-speed ZigBee signal with a phase offset of π / 2 in the ZigBee network, which poses a challenge to the deployment of the ZigBee network.

[0047] The present invention proposes a new ZigBee backscatter modulation method, which enables the tag to use the ZigBee signal in the environment as a carrier, and only one receiver is needed 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 mode of chip '1' is a phase shift of +π / 2, while the modulation mode of chip '0' is a phase shift of −π / 2.

[0048] In a commercial ZigBee receiver, the signal is first sampled by an analog-to-digital converter to obtain discrete in-phase and quadrature (IQ) values. Subsequently, an intermediate frequency channel filter is used to remove out-of-band noise. After that, 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 a code chip '1'; if it is less than 0, it is determined as a code chip '0'. The final output will be compared with the symbol corresponding to 32 consecutive code chips, and the target symbol will be demodulated using the minimum Hamming distance method.

[0049] The ZigBee receiver demodulates the chip into '1' or '0' according to the sign of the phase offset. Specifically, when the phase offset is positive, such as , and The value of is demodulated as chip '1'. Further, when the phase offset is negative, such as , and The value of is 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 sign of the backscatter chip? Taking the modulation chip '1' as an example, the concept of the present invention is as follows. The modulation chip '1' corresponds to a shift in the frequency domain from the center frequency Likewise, chip '0' corresponds to a frequency offset from the center frequency Since the phase shift is the integral of the frequency shift, By introducing a frequency offset (in ), the chip '0' or '1' can be modulated as a positive frequency offset. This will become a positive phase offset. Therefore, no matter whether the excitation code is '1' or '0', it can be modulated into a code '1'. Therefore, the modulation result is driven by the tag and has nothing to do with the content of the stimulus ZigBee. The state machine of the tag modulation is as follows Fig. 9 shown.

[0050] It should be understood that, although the steps in the flowcharts of the accompanying drawings of the specification are displayed in sequence as indicated by the arrows, these steps are not necessarily executed in sequence in the order indicated by the arrows. Unless otherwise specified herein, there is no strict order restriction on the execution of these steps, and these steps can be executed in other orders. Moreover, at least a part of the steps in the flowcharts 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 time, but can be executed at different times, and the execution order of these steps or stages is not necessarily sequential, but can be executed in turn or alternately with other steps or at least a part of the steps or stages in other steps.

[0051] The present invention also provides a smart bracelet, comprising: 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 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; The backscatter module is used to identify the BLE excitation signal and the ZigBee excitation signal in the environment, and modulate the component information as tag information in the BLE excitation signal and the ZigBee excitation signal through a multimodal backscatter method to generate a BLE backscatter signal and a ZigBee backscatter signal.

[0052] The smart bracelet corresponds to the role of the tag in the backscatter system.

[0053] The present invention uses solar panels, thermoelectric generators (TEGs), and radio frequency rectifiers to collect multi-source energy from light, heat, and radio frequency (RF) signals. If these collection modules are directly connected to a power management chip (the present invention can use the TIBQ25570 chip), the thermoelectric generator, which has a much smaller resistance than other components, will act as a load and consume most of the energy. Therefore, the present invention uses the unidirectional conductivity of the diode to isolate these collection devices. Figure 6 As shown, each harvesting module is connected to the BQ25570 chip through a low voltage dropout Schottky diode. The equivalent resistance of the rectifier and the thermoelectric generator is high, so most of the energy can be effectively obtained through the BQ25570. Figure 6 In the figure, Vout represents the output voltage of the chip, and Vcap represents the voltage stored in the capacitor.

[0054] In one embodiment, 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.

[0055] 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 ion (K + ), hydrogen ion (H + ) and chloride ions (Cl - ), which selectively convert the concentration of the corresponding components into electrical signals. Glucose oxidase, lactate oxidase and bovine serum albumin (BSA) are modified on the three working electrodes respectively. The carbon electrode is used as the counter electrode and the Ag / AgCl electrode acts as the reference electrode. The BSA-covered working electrode is used here as the control electrode to offset drift and interference. Na + , K + , H + and Cl - The measurements are obtained with an ion selective electrode in combination with a polyvinyl butyral (PVB) coated reference electrode for level determination.

[0056] In one of the embodiments, the differential mode technology is used to offset the baseline drift, specifically including: 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.

[0057] Specifically, in electrochemical systems, even if there is no target electrochemical reaction, the generated current or voltage signal may drift over time, which may be caused by environmental influences, human motion, or instrument artifacts, and is known as "baseline drift". Wearable biochemical sensors are affected by baseline drift, especially when long-term measurements are performed 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.

[0058] The present invention adopts a differential measurement method to offset baseline drift and noise. The following takes the measurement of glucose concentration as an example, and the measurement of lactic acid concentration adopts the same principle. The schematic diagram of the differential mode glucose sensor is shown in FIG. Figure 7 As shown, Figure 7 middle represents the current generated by the sensing electrode covered with glucose oxidase (GOx), which originates from the oxidation reaction of glucose and represents a signal related to the glucose concentration; represents the current generated by the control electrode covered with bovine serum albumin (BSA), which serves as a reference signal and is not affected by glucose and is used to correct the interference of environmental factors; represents the voltage signal generated by the sensing electrode covered with glucose oxidase (GOx), which, after conversion by an operational amplifier, represents the current signal generated by glucose oxidation; represents the voltage signal generated by the control electrode covered with bovine serum albumin (BSA), which is used as the 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 by glucose oxidase (GOx) and a control electrode covered by bovine serum albumin (BSA). BSA was chosen as a control for GOx for two reasons: first, BSA is an inertial protein commonly used in electrochemical biosensors and has no catalytic activity towards glucose. Second, it is fairly stable and easy to obtain. The block diagram of the differential mode glucose sensor is shown in Figure 8 As shown, both the GOx-covered sensing electrode and the BSA-covered control electrode respond to the baseband drift caused by environmental influences ( ), respond to noise caused by various biomolecules ( ), biomolecules including small electrolytes, metabolites, hormones and large proteins in human sweat, but only the GOx-covered sensing electrode responded to glucose ( ). The interference signal and drift signal generated by the differential mode glucose sensor can be offset by the following signal processing circuit and kinetic differential measurement.

[0059] The signal processing path for each electrode is implemented by analog circuits. The circuits are 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). In order to obtain information about the concentrations of glucose and lactate, 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, the inverter then 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) of -3dB and 1Hz frequency to minimize noise and interference in the measurement.

[0060] In H + , Cl - , K + 、Na + In the measurement path, the signal generated is the voltage difference between their corresponding ion selective electrodes (ISE) and the reference electrode coated with PVB, and the present invention directly measures this voltage difference. Each of their signal processing paths includes: two voltage buffers of the ion selective electrode and the reference electrode combined with the polyvinyl butyral coating, a differential amplifier and an analog-to-digital converter, and a low-pass filter to suppress noise and interference.

[0061] 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.

[0062] 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.

[0063] 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.

[0064] 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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