Portable LC wireless intraocular pressure sensor signal acquisition device and application thereof

Abstract

The application belongs to the field of intraocular pressure measurement, and discloses a portable LC wireless intraocular pressure sensor signal acquisition device and application thereof. The device comprises: an intraocular pressure acquisition impedance module for continuously collecting intraocular pressure data signals and generating inductive coupling; a signal conditioning circuit for generating and transmitting amplified sweep signals of different frequencies to the intraocular pressure acquisition impedance module to cause inductive coupling of the intraocular pressure acquisition impedance module, so that the impedance of the intraocular pressure acquisition impedance module changes, and the amplitude ratio and phase difference of the intraocular pressure data signals collected after the impedance changes are detected and analog-to-digital converted; a control circuit for receiving the amplitude ratio and phase difference after analog-to-digital conversion, calculating the impedance real part value, and obtaining the impedance real part curve of the intraocular pressure acquisition impedance module and the resonant frequency at the peak value; and a power supply module for supplying power to the signal conditioning circuit and the control circuit. The application can improve the accuracy and convenience of intraocular pressure measurement.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of intraocular pressure measurement, and more particularly relates to a portable LC wireless intraocular pressure sensor signal acquisition device and application thereof. BACKGROUND

[0002] At present, intraocular pressure is one of the important indicators for diagnosing and monitoring glaucoma diseases. Severe fluctuations in intraocular pressure can worsen glaucoma and lead to serious consequences such as loss of vision. Therefore, it is particularly important to monitor the intraocular pressure of glaucoma patients. However, there is still a lack of an effective continuous intraocular pressure monitoring method. In current clinical diagnosis, single tonometer is used to measure intraocular pressure, which requires multiple measurements on patients at intervals in a day. Although the measurement results are accurate, professional doctors need to continuously operate professional equipment during the measurement process, and the patient needs to be anesthetized, resulting in a complicated, complex, time-consuming and laborious measurement process.

[0003] In order to solve the problems of complex intraocular pressure measurement and non-continuous measurement, domestic and foreign institutions have developed a sensor that can be used for continuous measurement of intraocular pressure. Among them, the LC wireless intraocular pressure sensor has attracted the attention of researchers, and has the advantages of not needing a power supply, small size, high sensitivity, easy to wear, no invasive injury, etc. At the same time, it has derived various types of intraocular pressure sensors such as variable capacitance type and variable inductance type. At present, a vector network analyzer is mostly used to collect the signals of the intraocular pressure sensor. However, the network analyzer is expensive and bulky, and is not convenient to carry. Therefore, it is urgent to design a signal acquisition device that is easy to carry, can continuously detect intraocular pressure signals, has high measurement accuracy and fast response. SUMMARY

[0004] In view of the defects of the prior art, the purpose of the present application is to provide a portable signal acquisition device for LC wireless intraocular pressure sensor to solve the problems of large volume, inconvenience to carry, poor signal measurement accuracy and slow response of the existing continuous intraocular pressure signal acquisition device.

[0005] To achieve the above-mentioned purpose, the present application provides a portable LC wireless intraocular pressure sensor signal acquisition device, comprising:

[0006] An intraocular pressure acquisition impedance module for continuously collecting intraocular pressure data signals and generating inductive coupling;

[0007] A signal conditioning circuit for generating and transmitting amplified sweep signals of different frequencies to the intraocular pressure acquisition impedance module to cause inductive coupling of the intraocular pressure acquisition impedance module, thereby changing the impedance of the intraocular pressure acquisition impedance module; the signal conditioning circuit is also used for detecting the amplitude ratio and phase difference corresponding to the intraocular pressure data signals collected after the impedance change of the intraocular pressure acquisition impedance module, and transmitting the amplitude ratio and the phase difference after analog-to-digital conversion;

[0008] a control circuit configured to receive the amplitude ratio and the phase difference after analog-to-digital conversion, and calculate an impedance real part value based on the amplitude ratio and the phase difference; and further configured to obtain an impedance real part curve of the intraocular pressure acquisition impedance module and a resonance frequency at a peak of the impedance real part curve as an actual intraocular pressure signal value based on the impedance real part value.

[0009] a power supply module configured to supply power to the signal conditioning circuit and the control circuit.

[0010] Further, the intraocular pressure acquisition impedance module comprises an LC wireless intraocular pressure sensor and an excitation unit connected to each other and capable of inductive coupling, wherein the LC wireless intraocular pressure sensor is configured to acquire the intraocular pressure data signal; and the excitation unit is configured to receive the amplified sweep signal and emit the amplified sweep signal in the form of electromagnetic waves to generate inductive coupling with the LC wireless intraocular pressure sensor.

[0011] Still further, the excitation unit is a reading coil wound by enameled wire, and the diameter of the enameled wire is between 0.2 mm and 0.4 mm; preferably, the inner diameter of the reading coil is between 18 mm and 22 mm.

[0012] Further, the signal conditioning circuit comprises a DDS signal generation circuit, a sweep signal amplification circuit and an amplitude and phase detection circuit arranged integrally, wherein:

[0013] the signal input end of the DDS signal generation circuit is connected to the control circuit, and the signal output end of the DDS signal generation circuit is connected to the sweep signal amplification circuit; the control circuit can control the DDS signal generation circuit to generate a sweep signal and transmit the sweep signal to the sweep signal amplification circuit;

[0014] the output end of the sweep signal amplification circuit is connected to the intraocular pressure acquisition impedance module; the sweep signal amplification circuit is configured to amplify and process the sweep signal, and transmit the amplified and processed sweep signal to the intraocular pressure acquisition impedance module to cause inductive coupling of the intraocular pressure acquisition impedance module;

[0015] the signal output end of the amplitude and phase detection circuit is connected to the control circuit, and the signal input end of the amplitude and phase detection circuit is connected to the intraocular pressure acquisition impedance module; the amplitude and phase detection circuit is configured to detect the amplitude ratio and the phase difference, and transmit the voltage value generated after analog-to-digital conversion of the amplitude ratio and the phase difference to the control circuit.

[0016] Still further, the power supply module is connected to the DDS signal generation circuit, the sweep signal amplification circuit and the amplitude and phase detection circuit respectively, and provides different power supply voltages for the three circuits respectively.

[0017] Furthermore, the control circuit includes a main control MCU circuit and an ADC sampling circuit connected to the main control MCU circuit, wherein:

[0018] The ADC sampling circuit is connected to the signal conditioning circuit and is used to convert the amplitude ratio and phase difference after analog-to-digital conversion into digital signals and then transmit them to the main control MCU circuit for calculation and processing.

[0019] Furthermore, the control circuit also includes a data transmission module, which is used to receive the calculation results of the main control MCU circuit and transmit the calculation results to an external terminal to display the corresponding impedance real part curve.

[0020] According to another aspect of the present invention, a method for applying a portable LC wireless intraocular pressure sensor signal acquisition device is also disclosed, the method comprising the following steps:

[0021] S1 continuously receives intraocular pressure data signals;

[0022] S2 generates multiple first sweep signals within a first frequency range to excite the intraocular pressure acquisition impedance module, thereby causing a change in the impedance of the intraocular pressure acquisition impedance module.

[0023] In step S3, the first amplitude ratio and first phase difference of the intraocular pressure data signal acquired by the intraocular pressure acquisition impedance module at each frequency value in step S2 are detected, and the first real part value of the intraocular pressure acquisition impedance module is calculated based on the first amplitude ratio and first phase difference. Then, the first real part curve is obtained based on the first real part value.

[0024] S4 generates multiple second sweep signals in the second frequency range to excite the intraocular pressure acquisition impedance module, thereby causing the impedance of the intraocular pressure acquisition impedance module to change. The second frequency range is centered on the frequency corresponding to the peak value of the first real part curve obtained in step S2.

[0025] In step S5, the second amplitude ratio and the second phase difference of the intraocular pressure data signal acquired by the intraocular pressure acquisition impedance module at each frequency value in step S4 are detected, and the second real part value of the intraocular pressure acquisition impedance module is calculated based on the second amplitude ratio and the second phase difference, and the second real part curve is obtained based on the second real part value.

[0026] S6 performs a moving average filter on the second real part curve to obtain a smooth real part curve;

[0027] S7 performs Lorentz function curve fitting on the smooth real part curve to obtain a fitted curve, and obtains the resonant frequency corresponding to the peak value of the fitted curve as the actual intraocular pressure signal value.

[0028] Furthermore, the first frequency range is from 40MHz to 200MHz, and the first sweep frequency signal is generated according to the first sweep frequency interval.

[0029] Furthermore, the second frequency range is from Fc-800KHz to Fc+800KHz, and the second sweep frequency signal is generated according to the second sweep frequency interval, wherein Fc represents the frequency value corresponding to the peak value of the first real part curve.

[0030] Compared with the prior art, the above technical solutions conceived by this invention have the following main advantages:

[0031] 1. The portable LC wireless intraocular pressure sensor signal acquisition device of the present invention includes a signal conditioning circuit, and an intraocular pressure acquisition impedance module, a control circuit, and a power supply module respectively connected to the signal conditioning circuit. The intraocular pressure acquisition impedance module can undergo inductive coupling. Based on the principle of inductive coupling, the intraocular pressure acquisition impedance module is regarded as a new impedance. An excitation signal is given by transmitting a sweep frequency signal through the signal conditioning circuit, thereby detecting the amplitude ratio and phase difference of the signal of the intraocular pressure acquisition impedance module at different frequencies. Then, the control circuit performs analog-to-digital conversion, and calculates the real part of the impedance based on the amplitude ratio and phase difference after analog-to-digital conversion. The real part of the impedance can also be used to obtain the real part curve of the impedance. The resonant frequency at the real part curve of the impedance is the actual resonant frequency of the intraocular pressure sensor. Thus, the intraocular pressure signal is extracted in a simple way. Moreover, the signal acquisition device has a simple structure, high integration, easy operation, and high acquisition accuracy.

[0032] 2. The signal conditioning circuit of the portable LC wireless intraocular pressure sensor signal acquisition device of the present invention mainly includes a DDS signal generation circuit, a sweep frequency signal amplification circuit, and an amplitude and phase detection circuit. It effectively separates the digital part and the analog part, avoids the problem of signal crosstalk, improves the stability of the signal acquisition device, and effectively reduces the area of ​​the circuit board, making it more portable.

[0033] 3. The measurement cycle of the portable LC wireless intraocular pressure sensor signal acquisition device of the present invention is shorter than that of other devices. Since the real part of the impedance curve is a variation of the Lorentz function, after fitting the acquired curve with the Lorentz function curve, the peak value of the curve can be located more accurately. The frequency corresponding to the peak value is found in the fitted curve, which is the resonant frequency of the LC wireless intraocular pressure sensor. The entire data processing cycle is at most 1.2s, which meets the requirements of real-time and fast intraocular pressure measurement.

[0034] 4. The signal acquisition device of the present invention is also equipped with a data transmission module, which can transmit signal data to an external display device in real time via wired or wireless means for display, so that users can intuitively view the change process of intraocular pressure signal in real time. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the overall modular structure of the portable LC wireless intraocular pressure sensor signal acquisition device provided in an embodiment of the present invention;

[0036] Figure 2 This is a schematic diagram of the power supply structure in the portable LC wireless intraocular pressure sensor signal acquisition device provided in an embodiment of the present invention;

[0037] Figure 3 This is a simplified electrical model diagram of the readout coil and the LC wireless intraocular pressure sensor in the portable LC wireless intraocular pressure sensor signal acquisition device provided in the embodiments of the present invention;

[0038] Figure 4 This is a schematic diagram of the amplitude and phase detection circuit in the portable LC wireless intraocular pressure sensor signal acquisition device provided in an embodiment of the present invention;

[0039] Figure 5 This is a flowchart of the program data processing in the portable LC wireless intraocular pressure sensor signal acquisition device provided in an embodiment of the present invention.

[0040] In the diagram: 1-sine wave sweep signal, 2-equivalent resistance of the readout coil, 3-readout coil, 4-LC wireless intraocular pressure sensor, 5-simplified coupling circuit of the readout coil and intraocular pressure sensor, 6-equivalent circuit of the coupling circuit. Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0042] In the description of this invention, it should be understood that the terms "center," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0043] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0044] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0045] like Figure 1 As shown, this embodiment of the invention provides a portable LC wireless intraocular pressure sensor signal acquisition device, including a signal conditioning circuit, and an intraocular pressure acquisition impedance module, a control circuit, and a power supply module respectively connected to the signal conditioning circuit, wherein:

[0046] The intraocular pressure acquisition impedance module is used to continuously acquire intraocular pressure data signals and generate inductive coupling;

[0047] The signal conditioning circuit generates sweep signals of different frequencies, amplifies and transmits the sweep signals to the intraocular pressure acquisition impedance module, causing inductive coupling in the intraocular pressure acquisition impedance module and thus changing its impedance. The signal conditioning circuit also detects the amplitude ratio and phase difference of the intraocular pressure data signal after the impedance of the intraocular pressure acquisition impedance module changes, and converts the amplitude ratio and phase difference into voltage values ​​through analog-to-digital conversion and transmits them to the control circuit.

[0048] The control circuit is used to calculate the real part of the impedance based on the amplitude ratio and phase difference, and to obtain the real part impedance curve of the intraocular pressure acquisition impedance module based on the real part impedance. It is also used to obtain the resonant frequency at the peak of the real part impedance curve as the actual intraocular pressure signal value.

[0049] The power supply module is used to supply power to the signal conditioning circuit and the control circuit.

[0050] In a preferred embodiment, the intraocular pressure acquisition impedance module includes an LC wireless intraocular pressure sensor and an excitation unit that are interconnected and inductively coupled. The LC wireless intraocular pressure sensor is used to acquire intraocular pressure data signals. The excitation unit is used to receive an amplified sweep signal and transmit the amplified sweep signal in the form of electromagnetic waves to excite the intraocular pressure acquisition impedance module.

[0051] In a more preferred embodiment, the excitation unit is a reading coil wound with enameled wire, and the wire diameter of the enameled wire is between 0.2mm and 0.4mm, such as 0.2mm, 0.3mm, 0.4mm, etc.; preferably, the inner diameter of the reading coil is 18mm-22mm, such as 18mm, 19mm, 20mm, 21mm, 22mm, etc.

[0052] In a preferred embodiment, the signal conditioning circuit includes an integrated DDS signal generation circuit, a swept-frequency signal amplification circuit, and an amplitude and phase detection circuit, wherein:

[0053] The signal input terminal of the DDS signal generating circuit is connected to the control circuit, and its signal output terminal is connected to the sweep frequency signal amplification circuit. The control circuit can control the DDS signal generating circuit to generate a sweep frequency signal and transmit the sweep frequency signal to the sweep frequency signal amplification circuit.

[0054] The output of the sweep frequency signal amplification circuit is connected to the intraocular pressure acquisition impedance module. The sweep frequency signal amplification circuit is used to amplify and process the sweep frequency signal and transmit the amplified sweep frequency signal to the intraocular pressure acquisition impedance module so that the intraocular pressure acquisition impedance module undergoes inductive coupling, thereby enabling the detection of the resonant frequency of the wireless intraocular pressure sensor.

[0055] The signal output terminal of the amplitude and phase detection circuit is connected to the control circuit, and its signal input terminal is connected to the intraocular pressure acquisition impedance module. The amplitude and phase detection circuit is used to detect the amplitude ratio and the phase difference, and converts the amplitude ratio and the phase difference into an analog-to-digital value to generate a voltage value that is transmitted to the control circuit. Specifically, the signal input and output terminals of the amplitude and phase detection circuit are connected to the aforementioned reading coil using an IPEX type coaxial cable.

[0056] The working principle of the aforementioned intraocular pressure acquisition impedance module is as follows:

[0057] like Figure 3 The diagram shows a simplified electrical model of the reading coil and the LC wireless intraocular pressure sensor in the portable LC wireless intraocular pressure sensor signal acquisition device provided in this embodiment of the invention. The reading coil 1 and the LC wireless intraocular pressure sensor 2 are inductively coupled, and their equivalent model is the simplified coupling circuit 5. The reading coil 1 is equivalent to an inductor L1 and a resistor R1 connected in series, and the LC wireless intraocular pressure sensor 2 is equivalent to an inductor L2, a resistor R2, and a capacitor C2 connected in series. The equivalent impedance calculated by formula (1) is:

[0058]

[0059] In the formula, f is the operating frequency of the circuit. s The resonant frequency of the LC wireless intraocular pressure sensor is represented by its value. Q is the quality factor of the LC wireless intraocular pressure sensor, and its value is... , k is the coupling coefficient between the readout coil and the LC wireless intraocular pressure sensor; the calculated impedance Z in The frequency corresponding to the maximum real part is the resonant frequency f of the LC wireless intraocular pressure sensor. s .

[0060] In a more preferred embodiment, the power supply module is connected to the DDS signal generation circuit, the sweep frequency signal amplification circuit, and the amplitude and phase detection circuit respectively, and provides different power supply voltages to the three respectively. The multi-channel power supply prevents crosstalk between power supplies and improves the stability of the power supply.

[0061] In a preferred embodiment, the control circuit includes a main control MCU circuit and an ADC sampling circuit connected to the main control MCU circuit, wherein:

[0062] The ADC sampling circuit is connected to the signal conditioning circuit and is used to convert the voltage value generated by the amplitude ratio and phase difference after analog-to-digital conversion into a digital signal and then transmit it to the main control MCU circuit for calculation and processing.

[0063] Specifically, the main control MCU circuit uses the following formula for calculation:

[0064] R renl =coS(phS)×mng×R ref -R ref (2)

[0065] In the formula, mag is the signal amplitude ratio, phs is the signal phase difference, and R ref The reference resistor value;

[0066] It can also be based on the maximum real part R of the impedance real The corresponding real part curve is obtained, and after smoothing the real part curve, Lorentz function curve fitting is performed to accurately locate the peak value of the corresponding real part curve.

[0067] In a more preferred embodiment, the control circuit further includes a data transmission module. The data transmission module is used to receive the calculation results of the main control MCU circuit and transmit the calculation results to an external terminal to display the corresponding impedance real part curve. Specifically, the data transmission module includes a serial port to USB circuit and a wireless Bluetooth module. The serial port to USB circuit is used to realize the connection between the main control MCU circuit and the external host computer, and the wireless Bluetooth module is used to realize the connection between the main control MCU circuit and external mobile communication terminals such as mobile phones.

[0068] More specifically, the main control MCU circuit, serial-to-USB circuit, and ADC sampling circuit are integrated on a single circuit board as the core board (top board), used for data processing, calculation, and communication. The remaining circuits, namely the DDS signal generation circuit, sweep frequency signal amplification circuit, and amplitude and phase detection circuit, are integrated on another circuit board as the signal conditioning circuit (bottom board), used for signal generation, amplification, and detection. The top and bottom boards are connected by pin headers to form a stacked structure, further reducing the area of ​​the circuit board. The power supply module is a power management circuit that provides power through a lithium battery. This power management circuit is also integrated on the bottom board and connected to the DDS signal generation circuit, sweep frequency signal amplification circuit, and amplitude and phase detection circuit, respectively.

[0069] Another embodiment of the present invention discloses an application method of a portable LC wireless intraocular pressure sensor signal acquisition device, the application method comprising the following steps:

[0070] S1 continuously receives intraocular pressure data signals;

[0071] S2 generates multiple first sweep frequency signals within the first frequency range, amplifies and processes them to excite the intraocular pressure acquisition impedance module, thereby causing a change in the impedance of the intraocular pressure acquisition impedance module.

[0072] In step S3, the first amplitude ratio and the first phase difference of the intraocular pressure data signal acquired by the intraocular pressure acquisition impedance module at each frequency value in step S2 are detected. The first real part value of the intraocular pressure acquisition impedance module is calculated based on the first amplitude ratio and the first phase difference. Then, the first real part curve is obtained based on the first real part value.

[0073] S4 generates multiple second sweep frequency signals in the second frequency range, amplifies and processes them to excite the intraocular pressure acquisition impedance module, thereby causing the impedance of the intraocular pressure acquisition impedance module to change.

[0074] S5 detects the second amplitude ratio and the second phase difference of the intraocular pressure data signal acquired by the intraocular pressure acquisition impedance module at each frequency value in step S4, and calculates the second real part value of the intraocular pressure acquisition impedance module based on the second amplitude ratio and the second phase difference. The second real part curve is obtained based on the second real part value, and the second frequency range is centered on the frequency corresponding to the peak value of the first real part curve obtained in step S2.

[0075] S6 performs a moving average filter on the second real part curve to obtain a smooth real part curve.

[0076] S7 performs Lorentz function curve fitting on the smooth real part curve to obtain the fitted curve, and obtains the resonant frequency corresponding to the peak value of the fitted curve as the actual intraocular pressure signal value.

[0077] In a more preferred embodiment, the first frequency range is 40MHz to 200MHz, and the first sweep frequency signal is generated according to the first sweep frequency interval.

[0078] In a more preferred embodiment, the second frequency range is from Fc-800KHz to Fc+800KHz, and a second sweep frequency signal is generated according to a second sweep frequency interval, wherein Fc represents the frequency value corresponding to the peak value of the first real part curve, so that the obtained amplitude ratio curve and phase difference curve are more refined.

[0079] To better illustrate the implementation details of the present invention, the following embodiments are provided to further illustrate the present invention. It should be understood that the following embodiments are only preferred implementation methods and are not intended to limit the scope of protection of the present invention in any way.

[0080] Example 1

[0081] like Figure 1 As shown, the portable LC wireless intraocular pressure sensor signal acquisition device provided in this embodiment mainly includes the following parts: core board circuit, signal conditioning circuit, lithium battery, lithium battery charging circuit and reading coil.

[0082] The core board circuit is mainly composed of digital circuits. Specifically: the serial-to-USB circuit processes the acquired signals digitally and outputs them to an external computer for visualization; the main control MCU circuit uses an STM32G4 chip, primarily used to control the DDS chip to generate sweep signals, perform data calculations, and control the entire signal acquisition device; the Bluetooth module is used for wireless communication with a mobile phone, facilitating the viewing of the real-time signal curves of the LC wireless intraocular pressure sensor; and the ADC sampling circuit converts the analog signals from the signal conditioning circuit into digital signals, which are then output to the main control MCU circuit for processing and calculation.

[0083] The signal conditioning circuit is mainly an analog circuit, including: the DDS signal generation circuit uses the AD9959 direct digital frequency synthesizer chip to generate sine wave signals of different frequencies in sequence; specifically, it can generate sine wave sweep signals from 40MHz to 200MHz; the sweep signal amplification circuit amplifies the sine wave sweep signal from the DDS signal generation circuit to increase the radiated power, and the amplified sweep signal is transmitted to the readout coil; the amplitude and phase detection circuit uses the AD8302 integrated chip to receive two sine wave signals of the same frequency from the load (i.e., the readout coil), compares the amplitude and phase of the two signals, and converts the amplitude ratio and phase difference into analog outputs according to a certain proportional relationship.

[0084] The power management circuit, lithium battery, and lithium battery charging circuit serve as the power supply modules for the entire signal acquisition device. The lithium battery is a 3000mAh 3.7V lithium battery. The power management circuit converts the supply voltage of the lithium battery into the voltage required by each module, providing power to the three circuit modules of the signal conditioning circuit. The lithium battery charging circuit uses a TP5100 power management chip to charge the lithium battery.

[0085] The aforementioned reading coil is made of enameled wire. In this embodiment, a coil with a wire diameter of 0.3mm, an inner diameter of 20mm, and 2 turns is preferably used. Simulation results show that this type of coil has the best signal extraction effect.

[0086] Figure 2 This is a schematic diagram of the power supply structure in the portable LC wireless intraocular pressure sensor signal acquisition device provided in this embodiment of the invention. Since the device requires different power supply voltages, the power management circuit needs to generate multiple voltages. Therefore, the DC-DC boost circuit uses a boost circuit to boost 3.7V to 5V to power the sweep frequency signal amplification circuit, amplitude and phase detection circuit, and core board circuit. The three LDOs step down output 3.3V and 1.8V respectively to power the DDS signal generation circuit. Multiple power supplies prevent crosstalk between power supplies and improve power supply stability.

[0087] Combination Figure 3 As can be seen from the working principle of the aforementioned intraocular pressure acquisition impedance module, when the intraocular pressure changes, the intraocular pressure sensor attached to the cornea will also deform accordingly, and the parameters such as the diameter of its internal inductance will change, resulting in a change in the resonant frequency of the LC wireless intraocular pressure sensor. The intraocular pressure corresponds one-to-one with the resonant frequency. By inputting sinusoidal signals of different frequencies, the real part of the impedance is continuously measured. When the real part of the impedance is the largest, the frequency of the corresponding signal is the resonant frequency. The amplitude and phase detection circuit can detect the voltage signal at the two ends of the reading coil, that is, the voltage signal between point 1 and point 2 in the figure, and obtain the amplitude ratio mag and the phase difference phs. The main control circuit is equipped with a curve fitting algorithm and a data filtering method, which can calculate the maximum value of the real part of the impedance R through the aforementioned formula (2). real Then, based on the maximum real part R of the impedance real The corresponding real part curve is obtained, and after smoothing the real part curve, Lorentz function curve fitting is performed to accurately locate the peak value of the corresponding real part curve.

[0088] Figure 4This is a schematic diagram of the amplitude and phase detection circuit in the portable LC wireless intraocular pressure sensor signal acquisition device provided in this embodiment of the invention. The amplitude and phase detection circuit uses the AD8302 integrated chip, requiring only a few external components to realize amplitude and phase detection of two AC input signals, with an input signal frequency range of up to 2.7GHz; Figure 4 As shown, the input voltage signals come from... Figure 3 Points 1 and 2 in the circuit, the peak-to-peak value of the signal at point 1 is V. pp 1. The peak-to-peak value of the signal at point 2 is V. pp2 Both signals have the same frequency and a phase difference of Δθ; the two AC signals are input to the AD8302 amplitude and phase detection circuit, which outputs two analog voltage signals V. phs and V mag Both have the same relationship with phase difference and amplitude ratio, respectively. Figure 4 The curves shown on the right side of the AD8302 amplitude and phase detection circuit represent the relationship between phase and amplitude. Therefore, by measuring the voltage output of the amplitude and phase detection circuit, the phase difference and amplitude ratio can be quickly obtained, and thus the corresponding impedance real part curve can be obtained.

[0089] Example 2

[0090] Combination Figure 5 This is a flowchart of the program data processing in the portable LC wireless intraocular pressure sensor signal acquisition device provided in this embodiment.

[0091] The S1 signal acquisition device continuously receives intraocular pressure data collected by the LC wireless intraocular pressure sensor;

[0092] S2 then performs a wide-range frequency sweep. The device generates a first frequency sweep signal with an interval of 0.4MHz from 40MHz to 200MHz to excite the intraocular pressure acquisition impedance module, thereby causing the impedance of the intraocular pressure acquisition impedance module to change and obtain the magnitude of the real part of the impedance at each frequency point. The wide-range frequency sweep can quickly locate the approximate position of the peak value of the real part of the impedance.

[0093] S3 detects the first amplitude ratio and the first phase difference of the intraocular pressure data signal collected by the intraocular pressure acquisition impedance module at each frequency value in the previous step, and substitutes the first amplitude ratio and the first phase difference into formula (2) to calculate the first real part value of the intraocular pressure acquisition impedance module, and then obtains the first real part curve based on the first real part value;

[0094] S4 uses the frequency of the peak value of the real part of the impedance obtained by wide-range frequency sweep as the center frequency Fc, and generates a second frequency sweep signal from Fc-800KHz to Fc+800KHz with an interval of 4KHz, in order to perform narrow-range frequency sweep to excite the intraocular pressure acquisition impedance module, thereby causing the impedance of the intraocular pressure acquisition impedance module to change again.

[0095] In step S5, the second amplitude ratio and second phase difference corresponding to the intraocular pressure data signal acquired by the intraocular pressure acquisition impedance module at each frequency value in step S4 are detected. The second real part value is obtained through the same calculation steps as the previous steps, and the second real part curve is fitted based on the second real part value, thereby obtaining a more refined phase difference curve and amplitude ratio curve, and the resolution can be improved to 4KHz.

[0096] S6 performs a sliding mean filter on the second real part curve, setting the sliding window to 3 to remove spikes with large deviations in the curve; since the second real part curve is a variation of the Lorentz function, after fitting the acquired curve with the Lorentz function curve, the peak value of the second real part curve can be located more accurately; the frequency at which the peak value is found from the fitted curve is the resonant frequency of the LC infinite intraocular pressure sensor.

[0097] In summary, the portable LC wireless intraocular pressure sensor signal acquisition device disclosed in this invention has a data processing cycle of 1.2s, which meets the real-time requirements of intraocular pressure measurement. Based on the principle of measuring amplitude ratio and phase difference, it consists of a core board circuit, a signal conditioning circuit, a lithium battery, a lithium battery charging circuit, and a reading coil. It has a high degree of structural integration, is compact and portable, and the entire circuit board can be manufactured to a size of 60mm*36mm. Its internal software is equipped with data filtering and curve fitting algorithms, which have high peak extraction accuracy and fast measurement speed. The signal acquisition device also has a built-in Bluetooth module, which can easily transmit the data waveform wirelessly to a mobile phone for real-time display. The signal acquisition device can also be integrated with the reading coil into glasses, and together with the LC wireless intraocular pressure sensor, it can quickly and conveniently measure changes in intraocular pressure, making it suitable for various complex situations.

[0098] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An application method of a portable LC wireless intraocular pressure sensor signal acquisition device, characterized in that, The signal acquisition device includes an intraocular pressure acquisition impedance module, a signal conditioning circuit, a control circuit, and a power supply module for supplying power to the signal conditioning circuit and the control circuit. Application methods include: S1 continuously acquires intraocular pressure data signals using the intraocular pressure acquisition impedance module; S2 uses the signal conditioning circuit to generate multiple first sweep frequency signals in a first frequency range of 40MHz to 200MHz. The first sweep frequency signals are generated by scanning according to the first sweep frequency interval, and after amplification, they excite the intraocular pressure acquisition impedance module so that the intraocular pressure acquisition impedance module undergoes inductive coupling, thereby causing its impedance to change. The signal conditioning circuit described in S3 includes an AD8302 integrated chip. The AD8302 chip is used to detect the first amplitude ratio and the first phase difference of the intraocular pressure data signal, and the first real part value of the intraocular pressure acquisition impedance module is calculated based on the first amplitude ratio and the first phase difference. The calculation formula is as follows: R real =cos(phs)×mag×R ref R ref Where Rreal is the maximum real part of the impedance, phs is the signal phase difference, mag is the signal amplitude ratio, and Rref is the reference resistance value; Then, the first real part curve is obtained based on the first real part value; S4 utilizes the signal conditioning circuit to generate multiple second sweep frequency signals within the second frequency range from Fc-800KHz to Fc+800KHz according to the second sweep frequency interval. After the second sweep frequency signals are amplified and processed, they excite the intraocular pressure acquisition impedance module, thereby causing the impedance of the intraocular pressure acquisition impedance module to change. The second frequency range is centered on the frequency corresponding to the peak value of the first real part curve obtained in step S2, and Fc represents the frequency value corresponding to the peak value of the first real part curve. S5 uses the control circuit to receive the second amplitude ratio and the second phase difference corresponding to each frequency value in step S4, and calculates the second real part value of the intraocular pressure acquisition impedance module based on the second amplitude ratio and the second phase difference, and obtains the second real part curve based on the second real part value; S6 uses the control circuit to perform a sliding mean filter on the second real part curve to obtain a smooth real part curve; S7 uses the control circuit to perform Lorentz function curve fitting on the smooth real part curve to obtain the fitted curve, and obtains the resonant frequency corresponding to the peak value of the fitted curve, which is used as the actual intraocular pressure signal value.

2. The application method as described in claim 1, characterized in that, The intraocular pressure acquisition impedance module includes an LC wireless intraocular pressure sensor and an excitation unit that are interconnected and inductively coupled. The LC wireless intraocular pressure sensor is used to acquire the intraocular pressure data signal. The excitation unit is used to receive an amplified sweep frequency signal and transmit the amplified sweep frequency signal in the form of electromagnetic waves to generate inductive coupling with the LC wireless intraocular pressure sensor.

3. The application method as described in claim 2, characterized in that, The excitation unit is a reading coil made of enameled wire, and the wire diameter of the enameled wire is between 0.2mm and 0.4mm; the inner diameter of the reading coil is 18mm-22mm.

4. The application method as described in claim 1, characterized in that, The signal conditioning circuit includes an integrated DDS signal generation circuit, a swept-frequency signal amplification circuit, and an amplitude and phase detection circuit, wherein: The signal input terminal of the DDS signal generating circuit is connected to the control circuit, and its signal output terminal is connected to the sweep frequency signal amplification circuit. The control circuit can control the DDS signal generating circuit to generate a sweep frequency signal and transmit the sweep frequency signal to the sweep frequency signal amplification circuit. The output of the sweep frequency signal amplification circuit is connected to the intraocular pressure acquisition impedance module. The sweep frequency signal amplification circuit is used to amplify and process the sweep frequency signal and transmit the amplified sweep frequency signal to the intraocular pressure acquisition impedance module so that the intraocular pressure acquisition impedance module is inductively coupled. The signal output terminal of the amplitude and phase detection circuit is connected to the control circuit, and its signal input terminal is connected to the intraocular pressure acquisition impedance module. The amplitude and phase detection circuit is used to detect the amplitude ratio and phase difference, and converts the amplitude ratio and phase difference into an analog-to-digital value to generate a voltage value that is transmitted to the control circuit.

5. The application method as described in claim 4, characterized in that, The DDS signal generation circuit, the frequency sweep signal amplification circuit, and the amplitude and phase detection circuit are also connected to the power supply module, which provides different power supply voltages to the three components respectively.

6. The application method as described in claim 1, characterized in that, The control circuit includes a main control MCU circuit and an ADC sampling circuit connected to the main control MCU circuit, wherein: The ADC sampling circuit is connected to the signal conditioning circuit and is used to convert the amplitude ratio and phase difference of the analog-to-digital conversion into digital signals, which are then transmitted to the main control MCU circuit for calculation and processing.

7. The application method as described in claim 6, characterized in that, The control circuit also includes a data transmission module, which is used to receive the calculation results of the main control MCU circuit and transmit the calculation results to an external terminal to display the corresponding impedance real part curve.

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