Blood glucose detection circuit, equipment and system

Abstract

The invention provides a blood glucose detection circuit, device and system. When the blood glucose detection circuit works, a laser emission unit sends light waves with target wavelengths to a detection object; the detection unit detects reflected light and / or transmission light of a detection object and generates a corresponding detection signal; the alternating current signal detection unit obtains an alternating current signal component from the detection signal; the direct-current signal detection unit obtains a direct-current signal component from the detection signal; the collecting and processing unit collects the output signal of the front end to obtain a corresponding target signal, and the target signal comprises blood glucose detection information of a detected object. The alternating current signal detection unit and the direct current signal detection unit are separately arranged, so that separate acquisition of the alternating current signal component and the direct current signal component is realized, the alternating current signal component and the direct current signal component are respectively obtained, and the obtained alternating current signal component and the obtained direct current signal component are more accurate; therefore, the accuracy of the blood glucose detection information of the detected object is guaranteed.

Description

Technical Field

[0001] The present application relates to the technical field of blood glucose detection, and in particular to a blood glucose detection circuit, device and system. Background Art

[0002] Diabetes is a common condition in today's society, and the number of people with diabetes continues to increase. With current medical technology, diabetes cannot be completely cured. Blood sugar control is a key treatment and healthcare tool for people with diabetes and those at high risk for prediabetes. Blood sugar monitoring helps patients understand their blood sugar control status, thereby assessing the effectiveness of their diet, exercise, and medication, and further helping them adjust their lifestyle.

[0003] However, in the current routine medical blood sugar testing process, it is usually necessary to collect the patient's blood or interstitial fluid as a measurement sample, which not only causes pain to the patient, but also easily leads to wound infection, causing secondary damage to the patient.

[0004] Therefore, how to achieve non-invasive blood glucose detection has become a difficult problem that concerns those skilled in the art. Summary of the Invention

[0005] The purpose of this application is to provide a blood glucose detection circuit, device and system to at least partially improve the above-mentioned problems.

[0006] In order to achieve the above objectives, the technical solutions adopted in the embodiments of the present application are as follows:

[0007] In a first aspect, an embodiment of the present application provides a blood glucose detection circuit, the blood glucose detection circuit comprising: a laser emitting unit, a detection unit, an AC signal detection unit, a DC signal detection unit, and an acquisition and processing unit;

[0008] The detection unit is provided corresponding to the laser emitting unit, and the output end of the detection unit is connected to the input end of the AC signal detection unit and the input end of the DC signal detection unit respectively;

[0009] The output end of the AC signal detection unit and the output end of the DC signal detection unit are both connected to the input end of the acquisition and processing unit;

[0010] When the blood sugar detection circuit is working, the laser emitting unit is used to send light waves of target wavelength to the detection object;

[0011] The detection unit is used to detect the reflected light and / or transmitted light of the detection object, generate a corresponding detection signal, and transmit the detection signal to the AC signal detection unit and the DC signal detection unit;

[0012] The AC signal detection unit is used to obtain an AC signal component from the detection signal;

[0013] The DC signal detection unit is used to obtain a DC signal component from the detection signal;

[0014] The acquisition and processing unit is used to acquire the output signal of the AC signal detection unit and the output signal of the DC signal detection unit to obtain a corresponding target signal, wherein the target signal includes the blood glucose detection information of the detection subject.

[0015] In a second aspect, an embodiment of the present application provides a blood glucose detection device, comprising the above-mentioned blood glucose detection circuit.

[0016] In a third aspect, an embodiment of the present application provides a blood glucose detection system, comprising a host computer and the above-mentioned blood glucose detection device, wherein the host computer is communicatively connected to the blood glucose detection device.

[0017] Compared with the existing technology, in the blood glucose detection circuit provided by the present application, the AC signal detection unit and the DC signal detection unit are set separately to realize the separate collection of the AC signal component and the DC signal component, and the AC signal component and the DC signal component are obtained respectively, so that the obtained AC signal component and DC signal component are more accurate, thereby ensuring the accuracy of the blood glucose detection information of the detection object.

[0018] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, preferred embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work.

[0020] Figure 1 This is one of the structural diagrams of the blood glucose detection circuit provided in the embodiment of the present application;

[0021] Figure 2 This is a second structural diagram of the blood glucose detection circuit provided in an embodiment of the present application;

[0022] Figure 3 A schematic structural diagram of an AC signal detection unit provided in an embodiment of the present application;

[0023] Figure 4 This is a structural diagram of a DC signal detection unit provided in an embodiment of the present application.

[0024] In the figure: 10-laser emitting unit; 11-laser emitter; 12-laser driver chip; 20-detection unit; 21-reflective detector; 22-transmissive detector; 23-channel selection switch; 30-AC signal detection unit; 31-first charge amplifier; 32-high-pass filter; 33-first reverse gain amplifier; 34-first low-pass filter; 40-DC signal detection unit; 41-current mirror; 42-second charge amplifier; 43-second reverse gain amplifier; 44-second low-pass filter; 50-acquisition and processing unit; 501-processor; 502-collector; 60-power module; 61-battery; 62-soft start circuit; 63-boost circuit; 64-negative voltage circuit; 65-step-down circuit; 66-voltage regulation circuit; 200-host computer; 300-detection station. DETAILED DESCRIPTION

[0025] To make the objectives, technical solutions, and advantages of the embodiments of the present application more clear, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Generally, the components of the embodiments of the present application described and shown in the drawings herein can be arranged and designed in various different configurations.

[0026] The following describes some embodiments of the present application in detail with reference to the accompanying drawings. In the absence of conflict, the following embodiments and features therein may be combined with each other.

[0027] Current blood glucose monitoring methods lack the ability to achieve both high sensitivity and a high dynamic range, making it impossible to achieve high-precision testing across the entire measurement range. Furthermore, due to differences in the structure of human skin, fat, protein, water content, capillary walls, and other tissues, accuracy requirements may be compromised if the measurement position shifts or the body's condition changes.

[0028] In order to overcome the above problems, the present application embodiment provides a blood glucose detection circuit, please refer to Figure 1 , Figure 1 This is one of the structural schematic diagrams of the blood glucose detection circuit provided in the embodiment of the present application.

[0029] The blood glucose detection circuit includes: a laser emitting unit 10 , a detection unit 20 , an AC signal detection unit 30 , a DC signal detection unit 40 and an acquisition and processing unit 50 .

[0030] The detection unit 20 is provided corresponding to the laser emitting unit 10 , and the output end of the detection unit 20 is connected to the input end of the AC signal detection unit 30 and the input end of the DC signal detection unit 40 respectively.

[0031] The output end of the AC signal detection unit 30 and the output end of the DC signal detection unit 40 are both connected to the input end of the acquisition and processing unit 50 .

[0032] The acquisition and processing unit 50 has two input terminals, namely a first input terminal and a second input terminal. The output terminal of the AC signal detection unit 30 is connected to the first input terminal of the acquisition and processing unit 50, and the output terminal of the DC signal detection unit 40 is connected to the second input terminal of the acquisition and processing unit 50.

[0033] When the blood sugar detection circuit is working, the laser emitting unit 10 is used to send light waves of the target wavelength to the detection object.

[0034] The laser emitting unit 10 is used to send light waves of a target wavelength to the detection object according to the acquired target instruction.

[0035] Different target instructions correspond to different target wavelengths. The laser emission band of the laser emitting unit 10 includes at least one wavelength that does not absorb glucose molecules at all and one wavelength that absorbs glucose with an intensity greater than a preset intensity (strong absorption).

[0036] It should be noted that by changing the target instruction, the wavelength and / or intensity of the light wave (laser) emitted by the laser emitting unit 10 can be controlled, so that the corresponding signals of the test object at different wavelengths / or intensities can be collected, and then a comprehensive comparison and analysis can be performed to obtain more accurate blood glucose test results.

[0037] It should also be noted that the target instruction can be automatically generated by the laser emitting unit 10 (such as the laser driver chip 12 below) according to a preset working cycle, or it can be transmitted to the laser emitting unit 10 by the acquisition and processing unit 50.

[0038] The detection unit 20 is used to detect reflected light and / or transmitted light of the detection object, generate corresponding detection signals, and transmit the detection signals to the AC signal detection unit 30 and the DC signal detection unit 40 .

[0039] The AC signal detection unit 30 is used to obtain an AC signal component from the detection signal.

[0040] The DC signal detection unit 40 is used to obtain a DC signal component from the detection signal.

[0041] It should be noted that in the present application, the detection signal is processed separately by the AC signal detection unit 30 and the DC signal detection unit 40, so that the AC signal component and the DC signal component can be obtained respectively, making the obtained AC signal component and DC signal component more accurate.

[0042] The acquisition processing unit 50 is used to acquire the output signal of the AC signal detection unit 30 and the output signal of the DC signal detection unit 40 to obtain a corresponding target signal. The target signal includes blood glucose detection information of the detection subject.

[0043] The target signal includes a first target signal obtained by collecting the output signal of the AC signal detection unit 30 and a second target signal obtained by collecting the output signal of the DC signal detection unit 40 .

[0044] The acquisition and processing unit 50 can perform calculations and analysis based on the target signal to obtain the blood glucose detection information of the detection object, and can also send the target signal to the host computer 200 described below. The host computer 200 can be, but is not limited to, a mobile phone, a laptop computer, a server, etc. The host computer 200 performs calculations and analysis on the target signal to obtain the blood glucose detection information of the detection object. The host computer 200 can also transmit the obtained blood glucose detection information of the detection object to the acquisition and processing unit 50, and the acquisition and processing unit 50 can control the display unit (not shown) to display the blood glucose detection information.

[0045] In the blood glucose detection circuit provided by the present application, the AC signal detection unit 30 and the DC signal detection unit 40 are set separately to realize the separate collection of the AC signal component and the DC signal component, and the AC signal component and the DC signal component are obtained respectively, so that the obtained AC signal component and DC signal component are more accurate, thereby ensuring the accuracy of the blood glucose detection information of the detection object.

[0046] about Figure 1 The structure of each unit in the blood glucose detection circuit shown in FIG. 1 is an optional embodiment of the present application, please refer to FIG. Figure 2 , Figure 2 This is the second structural diagram of the blood glucose detection circuit provided in an embodiment of the present application.

[0047] like Figure 2 As shown, the laser emitting unit 10 includes a laser emitter 11 and a laser driving chip 12 electrically connected to the laser emitter 11 .

[0048] The laser emitter 11 can be an edge-emitting laser or a vertical cavity surface-emitting laser. The laser emitting unit 10 can include N groups of laser emitters 11, where N is greater than or equal to 2, and the number of laser emitters 11 in each group is greater than or equal to 1. The laser emitters 11 in each group emit lasers of different wavelengths, that is, the N groups of laser emitters 11 can emit light waves (lasers) of N wavelengths. It should be noted that in the same time period, only one group of laser emitters 11 is in operation and emits light waves of only one wavelength.

[0049] After obtaining the target instruction, the corresponding target wavelength is determined, and then the laser emitter 11 corresponding to the target wavelength can be determined, and the laser emitter 11 corresponding to the target wavelength is controlled to work and transmit the light wave corresponding to the target wavelength.

[0050] In an optional embodiment, after obtaining the target instruction, the corresponding target intensity can also be determined, and then the laser driver chip 12 can adjust the output power of the laser emitting unit 10 to adjust the light wave intensity of the laser emitter 11 corresponding to the target wavelength.

[0051] The detection object is located on the optical path of the laser emitting unit 10, for example Figure 2 The light waves emitted by the laser emitting unit 10 can irradiate the detection object in the detection station 300.

[0052] It should be noted that the detection objects in this application can be but are not limited to the earlobe, the base between the index finger and thumb, the fingertips, lips, arms, the second or third joints of the fingers, the abdomen and the wrist.

[0053] Please continue to refer to Figure 2 The detection unit 20 includes a reflective detector 21 , a transmissive detector 22 and a channel selection switch 23 .

[0054] The reflective detector 21 uses a photodetector with low dark current, large target area and high sensitivity to detect light reflected from the detection object. The transmissive detector 22 uses a photodetector with low dark current, large target area and high sensitivity to detect light that passes through the detection object.

[0055] The channel selection switch 23 may be a high-speed, low-loss, multi-channel, bidirectional programmable analog switch, with an on-resistance of 5Ω and a switching response time of less than 5ns.

[0056] The reflective detector 21 is disposed on the side or around the laser emitting unit 10 , and the reflective detector 21 and the laser emitting unit 10 are located on the same side relative to the detection object.

[0057] The transmissive detector 22 is disposed on the light-emitting path of the laser emitting unit 10 , and the transmissive detector 22 and the laser emitting unit 10 are located on opposite sides relative to the detection object.

[0058] The channel selection switch 23 is provided with a first end, a second end and a third end. The first end and the second end of the channel selection switch 23 serve as the input end of the channel selection switch 23, and the third end of the channel selection switch 23 serves as the output end of the detection unit 20, which are respectively connected to the input end of the AC signal detection unit 30 and the input end of the DC signal detection unit 40.

[0059] The output end of the reflective detector 21 is connected to a first end of the channel selection switch 23 , and the output end of the transmissive detector 22 is connected to a second end of the channel selection switch 23 .

[0060] The channel selection switch 23 is used to switch the conduction state.

[0061] The conducting state includes a first state in which the first terminal and the third terminal of the channel selection switch 23 are conducting with each other and a second state in which the second terminal and the third terminal of the channel selection switch 23 are conducting with each other.

[0062] The channel selection switch 23 is used to switch the conduction state according to a preset interval.

[0063] It should be noted that in some optional scenarios, the channel selection switch 23 can maintain the first state or the second state for a long time according to the switching instruction until the switching instruction changes, which can be input by the user or issued by the acquisition and processing unit 50. It should be noted that when the channel selection switch 23 is in the first state, the reflective detector 21 is in operation, and the detection signal transmitted by the reflective detector 21 can be obtained. The detection object can be selected from the arm, the second or third joint of the finger, the abdomen, and the wrist. When the channel selection switch 23 is in the second state, the transmissive detector 22 is in operation, and the detection signal transmitted by the transmissive detector 22 can be obtained. The detection object can be selected from the earlobe, the base between the index finger and the thumb, the fingertips, the lips, etc.

[0064] Of course, the channel selector switch 23 can also frequently switch between the first state and the second state at preset periodic intervals based on received switching instructions. In this case, the reflective detector 21 and the transmissive detector 22 operate simultaneously, with the detection signals transmitted from the reflective detector 21 and the detection signals transmitted from the transmissive detector 22 being sampled at fixed periodic intervals. It should be noted that the switching frequency of the channel selector switch 23 is typically above 10 kHz, and the switching time is extremely short. Therefore, it can be considered as synchronous detection of the two signals. In this detection mode, the detection signals transmitted from the reflective detector 21 and the detection signals transmitted from the transmissive detector 22 are synchronously detected in a time-sharing manner.

[0065] It should also be noted that, in some optional embodiments, the detection unit 20 includes only one of the reflective detector 21 or the transmissive detector 22, and the channel selection switch 23 may not be provided to obtain a single form of detection signal (transmissive form or reflective form).

[0066] Please continue to refer to Figure 2 The AC signal detection unit 30 includes a first charge amplifier 31 , a high-pass filter 32 , a first reverse gain amplifier 33 , and a first low-pass filter 34 , which are cascaded in sequence.

[0067] An input end of the first charge amplifier 31 serves as an input end of the AC signal detection unit 30 and is connected to an output end of the detection unit 20 .

[0068] The output end of the first low-pass filter 34 serves as the output end of the AC signal detection unit 30 and is connected to the input end of the acquisition and processing unit 50 .

[0069] The first charge amplifier 31 is used to convert the detection signal into a reverse voltage signal.

[0070] The high-pass filter 32 is used to filter out the DC signal component in the output signal of the first charge amplifier 31 and retain the AC signal component.

[0071] The first reverse gain amplifier 33 is used to amplify the AC signal component output by the high-pass filter 32 and convert it into a forward amplified signal.

[0072] The first low-pass filter 34 is used to filter out interference signals from the forward amplified signal output by the first reverse gain amplifier 33. It should be noted that the AC signal detection unit 30 is also called the AC Sense Circuit. Because the optical non-invasive real-time human blood glucose signal is extremely small and has a low signal frequency, the detection signal output by the detection unit 20 needs to be converted into a voltage signal for amplification and filtering.

[0073] Please refer to Figure 3 , Figure 3 Schematic diagram of the structure of the AC signal detection unit provided in an embodiment of the present application. The first charge amplifier 31 includes a first operational amplifier U1, a first resistor R1, a second resistor R2 and a first capacitor C1.

[0074] The first operational amplifier U1 can be a low-noise precision operational amplifier. It can be a CMOS operational amplifier with an input bias current less than 50fA and an equivalent noise current less than 0.1fA / √Hz. The first operational amplifier U1 is used to convert the detection signal (a small photocurrent signal, PPG_In shown in the figure) into a voltage signal and amplify it.

[0075] A non-inverting input terminal of the first operational amplifier U1 is connected to one end of the first resistor R1 , and the other end of the first resistor R1 is grounded.

[0076] One end of the second resistor R2 and one end of the first capacitor C1 are connected to the output end of the first operational amplifier U1 , and the other end of the second resistor R2 and the other end of the first capacitor C1 are connected to the inverting input end of the first operational amplifier U1 .

[0077] The inverting input terminal of the first operational amplifier U1 serves as the input terminal of the first charge amplifier 31 , and the output terminal of the first operational amplifier U1 serves as the output terminal of the first charge amplifier 31 .

[0078] The high-pass filter 32 includes a third resistor R3 and a second capacitor C2. One end of the third resistor R3 is grounded, and one end of the second capacitor C2 serves as the input end of the high-pass filter 32 and is connected to the output end of the first charge amplifier 31. The other end of the third resistor R3 is connected to the other end of the second capacitor C2, and a terminal is led out at the connection point to serve as the output end of the high-pass filter 32.

[0079] The high-pass filter 32 in the present application solution can be a first-order RC high-pass filter (1st order RC High Pass Fitter) with a cutoff frequency of 0.159 Hz, which is used to isolate the AC / DC mixed signal output by the first charge amplifier 31 from DC and retain only the AC signal component.

[0080] It should be noted that the high-pass filter 32 needs to filter out the DC signal and retain the heart rate signal, playing the role of passing AC and blocking DC. The heart rate is usually between 0.5Hz and 4Hz. The high-pass filter 32 needs to filter out the DC signal while ensuring that the lowest heart rate signal passes. The frequency corresponding to the -3dB point in the amplitude-frequency characteristic curve of the high-pass filter 32 is the cutoff frequency. Therefore, in the design of the first-order RC high-pass filter here, it is necessary to ensure that the cutoff frequency is less than 0.5Hz and leave a margin. The cutoff frequency f of the high-pass filter 32 c The calculation formula is as follows:

[0081]

[0082] Here we select R = 1MΩ, C = 1uF, and substitute it into the formula to calculate the cutoff frequency f c =0.159Hz.

[0083] The first inverse gain amplifier 33 includes a fourth resistor R4 , a fifth resistor R5 , a sixth adjustable resistor R6 , a third capacitor C3 , and a second operational amplifier U2 .

[0084] It should be noted that the first reverse gain amplifier 33 is a second-stage reverse gain adjustable proportional amplifier circuit. The second operational amplifier U2 can be a low-noise precision operational amplifier with an input offset voltage Vos < 100uV. It is used to reversely linearly amplify the AC signal output by the high-pass filter 32. The amplification gain coefficient can be adjusted according to the strength of the AC signal.

[0085] One end of the fourth resistor R4 is connected to the non-inverting input terminal of the second operational amplifier U2 , and the other end of the fourth resistor R4 is grounded.

[0086] One end of the fifth resistor R5 serves as the input end of the first reverse gain amplifier 33 and is connected to the output end of the high-pass filter 32 . The other end of the fifth resistor R5 is connected to the inverting input end of the second operational amplifier U2 .

[0087] Two ends of the third capacitor C3 are respectively connected to the inverting input terminal and the output terminal of the second operational amplifier U2.

[0088] A first end of the sixth adjustable resistor R6 is connected to the inverting input terminal of the second operational amplifier U2 , a second end of the sixth adjustable resistor R6 is connected to the output terminal of the second operational amplifier U2 , and a third end of the sixth adjustable resistor R6 is grounded.

[0089] It should be noted that the resistance of the sixth adjustable resistor R6 is adjustable, so that the amplification gain coefficient of the first reverse gain amplifier 33 can be adjusted to achieve the purpose of improving the detection dynamic range and sensitivity of the blood glucose detection circuit.

[0090] The sixth adjustable resistor R6 can be, but is not limited to, any one of a programmable digital potentiometer, a programmable sliding resistor, and a programmable function potentiometer.

[0091] The control end of the sixth adjustable resistor R6 is connected to the acquisition processing unit 50 , and the acquisition processing unit 50 can send an adjustment instruction to the sixth adjustable resistor R6 to change the resistance value of the sixth adjustable resistor R6 .

[0092] The output end of the second operational amplifier U2 serves as the output end of the first reverse gain amplifier 33 and is connected to the input end of the first low-pass filter 34 .

[0093] Please continue to refer to Figure 3 In an optional implementation, the first low-pass filter 34 includes a seventh resistor R7, an eighth resistor R8, a ninth resistor R9, a third operational amplifier U3, a fourth capacitor C4, and a fifth capacitor C5.

[0094] One end of the seventh resistor R7 serves as the input end of the first low-pass filter 34, the other end of the seventh resistor R7 is connected to one end of the eighth resistor R8, the other end of the eighth resistor R8 is connected to the non-inverting input end of the third operational amplifier U3, one end of the fourth capacitor C4 is grounded, and the other end of the fourth capacitor C4 is connected between the eighth resistor R8 and the non-inverting input end of the third operational amplifier U3.

[0095] One end of the fifth capacitor C5 is connected to the inverting input terminal of the third operational amplifier U3, the other end of the fifth capacitor C5 is connected between the seventh resistor R7 and the eighth resistor R8, one end of the ninth resistor R9 is connected to the output terminal of the third operational amplifier U3, the output terminal of the third operational amplifier U3 is also connected between the fifth capacitor C5 and the inverting input terminal of the third operational amplifier U3, and the other end of the ninth resistor R9 serves as the output terminal of the first low-pass filter 34 (shown as AC_Out in the figure).

[0096] The first low-pass filter 34 may be a second-order Butterworth low-pass filter with a cutoff frequency higher than twice the maximum heart rate (e.g., 9 Hz). The first low-pass filter 34 is configured to filter the portion of the mixed frequency signal output by the first reverse gain amplifier 33 that is higher than the human PPG signal (approximately between 0.5 and 4 Hz).

[0097] In the AC signal detection unit 30 of the present application, the detection signal is converted into a reverse voltage signal through a first charge amplifier 31, and then filtered out by a high-pass filter 32 to remove the DC signal component, retaining only the AC signal component containing blood glucose information, and then amplified and converted into a forward amplified signal by a first reverse gain amplifier 33 with adjustable amplification gain, and finally output after filtering out the interference signal by a first low-pass filter 34.

[0098] The AC signal detection unit 30 can use a first-order RC high-pass filter with a cutoff frequency of 0.01-0.3Hz as the high-pass filter 32 to block DC current from the signal amplified by the first charge amplifier 31. It should be noted that the AC signal component in the detection signal contains a negative voltage component after the DC bias is removed. Therefore, the first operational amplifier U1, the second operational amplifier U2, and the third operational amplifier U3 in the AC signal detection unit 30 are all powered by dual power supplies. As shown in the figure, the boost voltage VCC and the negative voltage VEE are applied to the two ends of the operational amplifier, respectively.

[0099] In an optional embodiment, the AC signal detection unit 30 does not include a DC bias, and the acquisition and processing unit 50 cannot directly sample the output signal of the AC signal detection unit 30. A voltage boosting unit (not shown in the figure) can be added between the AC signal detection unit 30 and the acquisition and processing unit 50 to perform sampling preprocessing, and the acquisition and processing unit 50 samples the preprocessed signal.

[0100] It should be noted that the AC signal component representing blood glucose concentration in the human body's detection signal (also known as the PPG signal) is detected by the AC signal detection unit 30. Interference signals from other tissues, muscles, capillary walls, water, protein, fat, and other sources exist synchronously in the PPG signal in the form of DC signals. Although the DC signal does not contain blood glucose information, it fully records human tissue information and is crucial for locating the blood glucose signal sampling site and determining valid sampling values. Therefore, a DC signal detection unit 40 (also known as the DC sense circuit) is required to detect the DC signal.

[0101] Please continue to refer to Figure 2 The DC signal detection unit 40 includes a current mirror 41 , a second charge amplifier 42 , a second reverse gain amplifier 43 , and a second low-pass filter 44 , which are cascaded in sequence.

[0102] An input end of the current mirror 41 serves as an input end of the DC signal detection unit 40 and is connected to an output end of the detection unit 20 .

[0103] The output end of the second low-pass filter 44 serves as the output end of the DC signal detection unit 40 and is connected to the input end of the acquisition and processing unit 50 .

[0104] The current mirror 41 is used to output a mirror current of the detection signal.

[0105] The second charge amplifier 42 is used to convert the mirror current output by the current mirror 41 into a reverse voltage signal.

[0106] The second reverse gain amplifier 43 is used to convert the reverse voltage signal output by the second charge amplifier 42 into a forward amplified signal.

[0107] The second low-pass filter 44 is used to filter out the AC signal component in the output signal of the second reverse gain amplifier 43 and retain the DC signal component.

[0108] The current mirror 41 can be a high-precision, wide-range (3nA to 3mA) linear current mirror for outputting a 1:1 mirror image of the detection signal (photocurrent signal). It should be noted that the current mirror 41 can be used to isolate the DC signal detection unit 40 from the AC signal detection unit 30, preventing them from interfering with each other.

[0109] like Figure 4As shown, the DC signal detection unit 40 also includes a tenth resistor R10, an eleventh resistor R11, a sixth capacitor C6, a seventh capacitor C7, an eighth capacitor C8 and a fourteenth capacitor C14, one end of the tenth resistor R10 is connected to one end of the fourteenth capacitor C14, the other end of the fourteenth capacitor C14 is grounded, the other end of the tenth resistor R10 is connected to the current input terminal (INPT) of the current mirror 41, one end of the eleventh resistor R11 is connected to the input current range limit pin (RLIM) of the current mirror 41, the other end of the eleventh resistor R11 is connected to the power pin (VPOS) of the current mirror 41, the power pin is connected to the input power supply of the current mirror 41 (which can be an external power supply or an internal power supply in the blood glucose detection circuit), one end of the seventh capacitor C7 and one end of the eighth capacitor C8 are grounded, and the other end of the seventh capacitor C7 and the other end of the eighth capacitor C8 are connected to the power pin.

[0110] One end of the sixth capacitor C6 is grounded, and the other end of the sixth capacitor C6 is connected to a reference voltage pin (SREF) of the current mirror 41 and a voltage setting pin (VSET) of the current mirror 41 , respectively.

[0111] The tenth resistor R10 is used to isolate the interference of the ground signal on the detection signal.

[0112] It should be noted that the sixth capacitor C6 can be used as a filter capacitor. When using SREF to set the input voltage (SREF = VSET), a capacitor should be placed between SREF and ground to filter out SREF noise and improve the power supply's frequency rejection. The sixth capacitor C6 can be selected as 2.2nF. Combined with the 20kΩ output resistor of SREF (internal to the pin), it can produce a frequency rejection of approximately 3kHz.

[0113] The tenth resistor R10 and the fourteenth capacitor C14 may together form an RC series input compensation circuit to provide necessary high frequency compensation at the INPT pin.

[0114] The seventh capacitor C7 and the eighth capacitor C8 can be used as decoupling capacitors to filter and decouple the external input power.

[0115] The eleventh resistor R11 can be used as a current limiting resistor. VPOS is connected to RLIM by the eleventh resistor R11 to limit the input current of INPT. The formula is as follows:

[0116]

[0117] Among them, I LIM Indicates the input current of INPT, VCC indicates the external power supply voltage, R LIMIt represents the internal resistance of the RLIM pin. Therefore, by adjusting the resistance value of the eleventh resistor R11, the input current range of INPT can be limited.

[0118] Please continue to refer to Figure 4 In an optional implementation, the second charge amplifier 42 includes a twelfth resistor R12, a thirteenth resistor R13, a ninth capacitor C9, and a fourth operational amplifier U4.

[0119] The non-inverting input terminal of the fourth operational amplifier U4 is connected to the reference voltage, one end of the twelfth resistor R12 is grounded, and the other end of the twelfth resistor R12 is connected to the non-inverting input terminal of the fourth operational amplifier U4.

[0120] Two ends of the thirteenth resistor R13 are respectively connected to the output terminal and the inverting input terminal of the fourth operational amplifier U4.

[0121] Two ends of the ninth capacitor C9 are respectively connected to the output terminal and the inverting input terminal of the fourth operational amplifier U4.

[0122] The output end of the fourth operational amplifier U4 serves as the output end of the second charge amplifier 42 and is connected to the input end of the second inverse gain amplifier 43 .

[0123] An inverting input terminal of the fourth operational amplifier U4 serves as an input terminal of the second charge amplifier 42 and is connected to an output terminal (IOUT) of the current mirror 41 .

[0124] The fourth operational amplifier U4 can be a low-noise precision operational amplifier, such as a CMOS operational amplifier with an input bias current less than 50fA and an equivalent noise current less than 0.1fA / √Hz. The second charge amplifier 42 is used to convert the tiny photocurrent signal output by the current mirror 41 into a voltage signal and amplify it.

[0125] Please continue to refer to Figure 4 In an optional embodiment, the second reverse gain amplifier 43 includes a fourteenth resistor R14, a fifteenth resistor R15, a sixteenth resistor R16, a seventeenth resistor R17, a tenth capacitor C10, an eleventh capacitor C11 and a fifth operational amplifier U5.

[0126] One end of the fourteenth resistor R14 is connected to the non-inverting input terminal of the fifth operational amplifier U5 , and the other end of the fourteenth resistor R14 is connected to the reference voltage.

[0127] One end of the fifteenth resistor R15 and one end of the tenth capacitor C10 are grounded, and the other ends of the fifteenth resistor R15 and the other ends of the tenth capacitor C10 are connected between the fourteenth resistor R14 and the non-inverting input terminal of the fifth operational amplifier U5.

[0128] One end of the sixteenth resistor R16 serves as the input end of the second inverse gain amplifier 43 and is connected to the output end of the second charge amplifier 42 . The other end of the sixteenth resistor R16 is connected to the inverting input end of the fifth operational amplifier U5 .

[0129] Two ends of the seventeenth resistor R17 are respectively connected to the output terminal and the inverting input terminal of the fifth operational amplifier U5.

[0130] Two ends of the eleventh capacitor C11 are respectively connected to the output terminal and the inverting input terminal of the fifth operational amplifier U5 .

[0131] The output end of the fifth operational amplifier U5 serves as the output end of the second reverse gain amplifier 43 and is connected to the input end of the second low-pass filter 44 .

[0132] The second reverse gain amplifier 43 can be a second-stage reverse gain fixed-ratio amplifier circuit. A low-noise precision operational amplifier with an input offset voltage Vos < 100 μV can be used as the fifth operational amplifier U5. The second reverse gain amplifier 43 is used to reversely linearly amplify the signal output by the second charge amplifier 42, with a fixed amplification gain coefficient.

[0133] Please continue to refer to Figure 4 In an optional implementation, the second low-pass filter 44 includes an eighteenth resistor R18, a nineteenth resistor R19, a twentieth resistor R20, a sixth operational amplifier U6, a twelfth capacitor C12, and a thirteenth capacitor C13.

[0134] One end of the eighteenth resistor R18 serves as the input end of the second low-pass filter 44, the other end of the eighteenth resistor R18 is connected to one end of the nineteenth resistor R19, the other end of the nineteenth resistor R19 is connected to the non-inverting input end of the sixth operational amplifier U6, one end of the twelfth capacitor C12 is grounded, and the other end of the twelfth capacitor C12 is connected between the nineteenth resistor R19 and the non-inverting input end of the sixth operational amplifier U6.

[0135] One end of the thirteenth capacitor C13 is connected to the inverting input terminal of the sixth operational amplifier U6, the other end of the thirteenth capacitor C13 is connected between the eighteenth resistor R18 and the nineteenth resistor R19, one end of the twentieth resistor R20 is connected to the output terminal of the sixth operational amplifier U6, the output terminal of the sixth operational amplifier U6 is also connected between the thirteenth capacitor C13 and the inverting input terminal of the sixth operational amplifier U6, and the other end of the twentieth resistor R20 serves as the output terminal of the second low-pass filter 44 (shown as DC_Out in the figure).

[0136] The second low-pass filter 44 can be a second-order Butterworth low-pass filter with a cutoff frequency lower than the heart rate (e.g., 0.159 Hz). The second low-pass filter 44 is used to filter the AC signal component in the mixed frequency signal output by the second reverse gain amplifier 43, retaining only the DC signal component.

[0137] In the DC signal detection unit 40 of the present application, the detection signal first passes through the current mirror 41, outputting a 1:1 mirror current. The current mirror 41 effectively isolates the input current from the mirror current, preventing the post-processing circuit from interfering with the original signal. This effectively isolates the DC signal detection unit 40 from the AC signal detection unit 30. The mirror current is converted by a second charge amplifier 42 into a reverse voltage signal with a biased reference voltage (Vref), which is then amplified by a second reverse gain amplifier 43 to a forward amplified signal. Finally, the AC signal component is filtered out by a second low-pass filter 44 before being output.

[0138] The DC signal detection unit 40 retains only the DC signal at its input and maintains the weak measured signal as a positive voltage signal by synchronously providing a fixed DC bias Vref at the non-inverting input of the two-stage amplifier op amp. The output of the DC signal detection unit 40 can be directly sampled.

[0139] Regarding the structure of the acquisition and processing unit 50, the present application embodiment also provides an optional implementation method, please continue to refer to Figure 2 The acquisition and processing unit 50 includes a processor 501 and a collector 502 connected to the processor 501 .

[0140] like Figure 2 As shown, the collector 502 is connected to the output end of the AC signal detection unit 30 and the output end of the DC signal detection unit 40 respectively, and is used to sample the output signal of the AC signal detection unit 30 and the output signal of the DC signal detection unit 40 to obtain the corresponding target signal and transmit the target signal to the processor 501.

[0141] The processor 501 may be a microprocessor unit (also known as an MCU) with a communication module (which may be a wireless communication module such as Bluetooth or WiFi). The processor 501 may control various components in the blood glucose detection circuit, such as the collector 502, the laser driver chip 12, the channel selection switch 23, and the sixth adjustable resistor R6 in the first reverse gain amplifier 33.

[0142] Processor 501 controls collector 502. It samples at a specified frequency, collects the sampled digital signals, and performs preprocessing to obtain the target signal. Processor 501 can transmit the target signal to host computer 200 via a wireless communication module or a wired communication module. Processor 501 can be a low-power MCU equipped with an ARM Cortex-M0 processor and Bluetooth functionality.

[0143] The collector 502 is an analog signal sampling circuit (ADC) and may adopt a 24-bit resolution single-phase single-ended ADC for high-precision sampling of the output signal of the AC signal detection unit 30 and the output signal of the DC signal detection unit 40 .

[0144] Please continue to refer to Figure 2 The power module 60 includes a battery 61 , a soft start circuit 62 , a boost circuit 63 , a negative voltage circuit 64 , a buck circuit 65 and a voltage regulating circuit 66 .

[0145] The battery 61 is connected to the soft start circuit 62 , the soft start circuit 62 is connected to the boost circuit 63 and the buck circuit 65 respectively, the boost circuit 63 is connected to the negative voltage circuit 64 , and the buck circuit 65 is connected to the voltage regulating circuit 66 .

[0146] The power module 60 is used to provide stable single-ended and dual-ended power supply voltages to the AC signal detection unit 30, and to provide stable single-ended and dual-ended power supply voltages (not shown) to the DC signal detection unit 40. The power module 60 is also used to provide a stable power supply voltage and load-adjustable power supply to the laser driver chip 12, and to provide a stable power supply voltage and a precise sampling reference voltage (RefV) to the acquisition and processing unit 50.

[0147] Among them, the battery 61 can be a lithium battery or button battery with an output voltage of 3.7-4.2V. The slow-start circuit 62 can use a Mosfet with a load current >500mA and an on-resistance <10mΩ, which is used for the power pulse slow-start function in the case of power-on or hot plug. The boost circuit 63 can use a boost chip (Boost) with low noise, efficiency >85% and adjustable output function, which is used to boost the stable voltage output by the slow-start circuit 62 to 5V, providing a stable "+5V" power supply to the entire system. The negative voltage circuit 64 can have a low quiescent current and an integrated built-in adjustable negative voltage regulator chip, which is used to provide a negative voltage output equivalent to the output of the boost circuit 63, providing a stable "-5V" power supply to the entire system, such as VEE. The step-down circuit 65 can utilize a low-noise, >90% efficiency Buck converter chip with integrated peak current control mode to step down the regulated voltage output by the soft-start circuit 62 to 3.3V, providing a stable "+3.3V" power supply for the entire system. The voltage regulator circuit 66 can utilize a synchronous step-down DC / DC converter with a load current >1A, high conversion efficiency, and adjustable output to convert the input voltage of the step-down circuit 65 into an adjustable voltage source ranging from 0.6V to 3.3V. In actual use, this voltage can be adjusted according to load changes in the laser transmitter 11.

[0148] It should be noted that the processor 501 can also control the power module 60 in the blood glucose detection circuit, including but not limited to controlling the power module 60 to enable so that the power module 60 follows the instruction to output a power voltage of a specified amplitude.

[0149] It should be noted that the blood glucose detection circuit provided in the embodiment of the present application can not only be used to detect blood glucose, but also can detect other indicator information.

[0150] An embodiment of the present application also provides a blood glucose detection device, which includes the above-mentioned blood glucose detection circuit.

[0151] The blood glucose detection device can be, but is not limited to, a portable wearable device, such as a smart watch, a smart bracelet, and a smart headset.

[0152] The embodiment of the present application also provides a blood glucose detection system, including a host computer 200 and the above-mentioned blood glucose detection device, and the host computer 200 is communicatively connected to the blood glucose detection device.

[0153] In summary, the embodiments of the present application provide a blood glucose detection circuit, device, and system. The blood glucose detection circuit includes: a laser emitting unit, a detection unit, an AC signal detection unit, a DC signal detection unit, and an acquisition and processing unit; the detection unit is arranged corresponding to the laser emitting unit, and the output end of the detection unit is connected to the input end of the AC signal detection unit and the input end of the DC signal detection unit respectively; the output end of the AC signal detection unit and the output end of the DC signal detection unit are both connected to the input end of the acquisition and processing unit; when the blood glucose detection circuit is working, the laser emitting unit is used to send a light wave of a target wavelength to the detection object; the detection unit is used to detect the reflected light and / or transmitted light of the detection object, generate a corresponding detection signal, and transmit the detection signal to the AC signal detection unit and the DC signal detection unit; the AC signal detection unit is used to obtain the AC signal component from the detection signal; the DC signal detection unit is used to obtain the DC signal component from the detection signal; the acquisition and processing unit is used to collect the output signal of the AC signal detection unit and the output signal of the DC signal detection unit to obtain the corresponding target signal, and the target signal includes the blood glucose detection information of the detection object. In the blood glucose detection circuit provided by the present application, the AC signal detection unit and the DC signal detection unit are set separately to realize the separate collection of the AC signal component and the DC signal component, and the AC signal component and the DC signal component are obtained respectively, so that the obtained AC signal component and the DC signal component are more accurate, thereby ensuring the accuracy of the blood glucose detection information of the detection object.

[0154] The above description is merely a preferred embodiment of the present application and is not intended to limit the present application. Various modifications and variations are possible for those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application.

[0155] It will be apparent to those skilled in the art that the present application is not limited to the details of the exemplary embodiments described above and that the present application can be implemented in other specific forms without departing from the spirit or essential characteristics of the present application. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the present application is defined by the appended claims, not the foregoing description, and all variations within the meaning and range of equivalents of the claims are intended to be included therein. Any reference sign in a claim should not be construed as limiting the claim to which it relates.

Claims

1. A blood glucose detection circuit, characterized in that: The blood glucose detection circuit includes: a laser emitting unit, a detection unit, an AC signal detection unit, a DC signal detection unit and an acquisition and processing unit; The detection unit is provided corresponding to the laser emitting unit, and the output end of the detection unit is connected to the input end of the AC signal detection unit and the input end of the DC signal detection unit respectively; The output end of the AC signal detection unit and the output end of the DC signal detection unit are both connected to the input end of the acquisition and processing unit; When the blood sugar detection circuit is working, the laser emitting unit is used to send light waves of target wavelength to the detection object; The detection unit is used to detect the reflected light and / or transmitted light of the detection object, generate a corresponding detection signal, and transmit the detection signal to the AC signal detection unit and the DC signal detection unit; The AC signal detection unit is used to obtain an AC signal component from the detection signal; The DC signal detection unit is used to obtain a DC signal component from the detection signal; The acquisition and processing unit is used to acquire the output signal of the AC signal detection unit and the output signal of the DC signal detection unit to obtain a corresponding target signal, wherein the target signal includes the blood glucose detection information of the detection subject.

2. The blood glucose detection circuit according to claim 1, wherein: The detection unit includes a reflective detector, a transmissive detector and a channel selection switch; The reflective detector is arranged on the side or around the laser emitting unit, and the reflective detector and the laser emitting unit are on the same side relative to the detection object; The transmission detector and the laser emitting unit are located on opposite sides of the detection object; The channel selection switch is provided with a first end, a second end and a third end, the first end and the second end of the channel selection switch serve as input ends of the channel selection switch, and the third end of the channel selection switch serves as an output end of the detection unit; The output end of the reflective detector is connected to the first end of the channel selection switch, and the output end of the transmissive detector is connected to the second end of the channel selection switch; The channel selection switch is used to switch the conduction state of the reflective detector and the transmissive detector respectively connected to the third end, wherein the conduction state includes a first state in which the first end of the channel selection switch is conductively connected to the third end and a second state in which the second end of the channel selection switch is conductively connected to the third end.

3. The blood glucose detection circuit according to claim 1, wherein: The AC signal detection unit includes a first charge amplifier, a high-pass filter, a first reverse gain amplifier, and a first low-pass filter connected in cascade sequence; The input end of the first charge amplifier serves as the input end of the AC signal detection unit; The output end of the first low-pass filter serves as the output end of the AC signal detection unit; The first charge amplifier is used to convert the detection signal into a reverse voltage signal; The high-pass filter is used to filter out the DC signal component in the output signal of the first charge amplifier and retain the AC signal component; The first reverse gain amplifier is used to amplify the AC signal component output by the high-pass filter and convert it into a forward amplified signal; The first low-pass filter is used to filter out interference signals in the forward amplified signal output by the first reverse gain amplifier.

4. The blood glucose detection circuit according to claim 3, wherein: The first charge amplifier includes a first operational amplifier, a first resistor, a second resistor and a first capacitor; The non-inverting input terminal of the first operational amplifier is connected to one end of the first resistor, and the other end of the first resistor is grounded; One end of the second resistor and one end of the first capacitor are both connected to the output terminal of the first operational amplifier, and the other end of the second resistor and the other end of the first capacitor are both connected to the inverting input terminal of the first operational amplifier; The inverting input terminal of the first operational amplifier serves as the input terminal of the first charge amplifier, and the output terminal of the first operational amplifier serves as the output terminal of the first charge amplifier.

5. The blood glucose detection circuit according to claim 3, wherein: The first reverse gain amplifier includes a fourth resistor, a fifth resistor, a sixth adjustable resistor, a third capacitor and a second operational amplifier; One end of the fourth resistor is connected to the non-inverting input terminal of the second operational amplifier, and the other end of the fourth resistor is grounded; One end of the fifth resistor serves as the input end of the first reverse gain amplifier, and the other end of the fifth resistor is connected to the inverting input end of the second operational amplifier; Two ends of the third capacitor are respectively connected to the inverting input terminal and the output terminal of the second operational amplifier; A first end of the sixth adjustable resistor is connected to the inverting input terminal of the second operational amplifier, a second end of the sixth adjustable resistor is connected to the output terminal of the second operational amplifier, and a third end of the sixth adjustable resistor is grounded; The output end of the second operational amplifier serves as the output end of the first reverse gain amplifier.

6. The blood glucose detection circuit according to claim 1, wherein: The DC signal detection unit includes a current mirror, a second charge amplifier, a second reverse gain amplifier and a second low-pass filter which are cascaded in sequence; The input end of the current mirror serves as the input end of the DC signal detection unit; The output end of the second low-pass filter serves as the output end of the DC signal detection unit; The current mirror is used to output a mirror current of the detection signal; The second charge amplifier is used to convert the mirror current output by the current mirror into a reverse voltage signal; The second reverse gain amplifier is used to convert the reverse voltage signal output by the second charge amplifier into a forward amplified signal; The second low-pass filter is used to filter out the AC signal component in the output signal of the second reverse gain amplifier.

7. The blood glucose detection circuit according to claim 6, wherein: The second charge amplifier includes a twelfth resistor, a thirteenth resistor, a ninth capacitor, and a fourth operational amplifier; The non-inverting input terminal of the fourth operational amplifier is connected to a reference voltage, one end of the twelfth resistor is grounded, and the other end of the twelfth resistor is connected to the non-inverting input terminal of the fourth operational amplifier; Two ends of the thirteenth resistor are respectively connected to the output terminal and the inverting input terminal of the fourth operational amplifier; Two ends of the ninth capacitor are respectively connected to the output terminal and the inverting input terminal of the fourth operational amplifier; The output end of the fourth operational amplifier serves as the output end of the second charge amplifier; The inverting input terminal of the fourth operational amplifier serves as the input terminal of the second charge amplifier.

8. The blood glucose detection circuit according to claim 6, wherein: The second reverse gain amplifier includes a fourteenth resistor, a fifteenth resistor, a sixteenth resistor, a seventeenth resistor, a tenth capacitor, an eleventh capacitor and a fifth operational amplifier; One end of the fourteenth resistor is connected to the non-inverting input terminal of the fifth operational amplifier, and the other end of the fourteenth resistor is connected to the reference voltage; One end of the fifteenth resistor and one end of the tenth capacitor are grounded, and the other end of the fifteenth resistor and the other end of the tenth capacitor are both connected between the fourteenth resistor and the non-inverting input terminal of the fifth operational amplifier; One end of the sixteenth resistor serves as the input end of the second reverse gain amplifier, and the other end of the sixteenth resistor is connected to the inverting input end of the fifth operational amplifier; Two ends of the seventeenth resistor are respectively connected to the output terminal and the inverting input terminal of the fifth operational amplifier; The two ends of the eleventh capacitor are respectively connected to the output terminal and the inverting input terminal of the fifth operational amplifier; The output end of the fifth operational amplifier serves as the output end of the second reverse gain amplifier.

9. A blood sugar detection device, characterized in that: The invention comprises the blood glucose detection circuit according to any one of claims 1 to 8.

10. A blood sugar detection system, characterized in that: It comprises a host computer and the blood glucose detection device according to claim 9, wherein the host computer is communicatively connected with the blood glucose detection device.

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