CN108606801B - PPG technology multispectral skin color calibration and power consumption optimization device and working method - Google Patents
PPG technology multispectral skin color calibration and power consumption optimization device and working method Download PDFInfo
- Publication number
- CN108606801B CN108606801B CN201810479917.2A CN201810479917A CN108606801B CN 108606801 B CN108606801 B CN 108606801B CN 201810479917 A CN201810479917 A CN 201810479917A CN 108606801 B CN108606801 B CN 108606801B
- Authority
- CN
- China
- Prior art keywords
- led
- light
- ppg
- target
- processor
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
- 238000000034 method Methods 0.000 title claims abstract description 26
- 238000005457 optimization Methods 0.000 title claims abstract description 19
- 238000005516 engineering process Methods 0.000 title claims abstract description 15
- 238000001514 detection method Methods 0.000 claims abstract description 59
- 238000004891 communication Methods 0.000 claims abstract description 12
- 238000007689 inspection Methods 0.000 claims description 12
- 125000006850 spacer group Chemical group 0.000 claims description 9
- 230000001133 acceleration Effects 0.000 claims description 7
- 230000007613 environmental effect Effects 0.000 claims description 6
- 238000001228 spectrum Methods 0.000 claims description 4
- 238000012360 testing method Methods 0.000 claims description 4
- 238000005286 illumination Methods 0.000 claims description 3
- 239000000463 material Substances 0.000 claims description 3
- 230000009466 transformation Effects 0.000 claims description 3
- 230000004044 response Effects 0.000 abstract description 3
- 230000001105 regulatory effect Effects 0.000 abstract description 2
- 238000013186 photoplethysmography Methods 0.000 description 40
- 210000001519 tissue Anatomy 0.000 description 20
- 239000008280 blood Substances 0.000 description 9
- 210000004369 blood Anatomy 0.000 description 9
- 230000008859 change Effects 0.000 description 9
- 230000005540 biological transmission Effects 0.000 description 5
- 238000013461 design Methods 0.000 description 5
- 238000010586 diagram Methods 0.000 description 5
- 230000000694 effects Effects 0.000 description 5
- 210000004209 hair Anatomy 0.000 description 5
- 230000010412 perfusion Effects 0.000 description 5
- XVIZMMSINIOIQP-UHFFFAOYSA-N 1,2-dichloro-3-(2-chlorophenyl)benzene Chemical compound ClC1=CC=CC(C=2C(=CC=CC=2)Cl)=C1Cl XVIZMMSINIOIQP-UHFFFAOYSA-N 0.000 description 4
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 4
- 230000008901 benefit Effects 0.000 description 4
- 239000003086 colorant Substances 0.000 description 4
- 230000003287 optical effect Effects 0.000 description 4
- 239000001301 oxygen Substances 0.000 description 4
- 229910052760 oxygen Inorganic materials 0.000 description 4
- 238000012544 monitoring process Methods 0.000 description 3
- 230000009471 action Effects 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 230000003993 interaction Effects 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 230000003595 spectral effect Effects 0.000 description 2
- 238000010521 absorption reaction Methods 0.000 description 1
- 230000006978 adaptation Effects 0.000 description 1
- 238000013459 approach Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000036760 body temperature Effects 0.000 description 1
- 210000000988 bone and bone Anatomy 0.000 description 1
- 230000036471 bradycardia Effects 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 230000003750 conditioning effect Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 210000000624 ear auricle Anatomy 0.000 description 1
- 230000008030 elimination Effects 0.000 description 1
- 238000003379 elimination reaction Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 230000004907 flux Effects 0.000 description 1
- 230000036541 health Effects 0.000 description 1
- 229910052500 inorganic mineral Inorganic materials 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 239000011707 mineral Substances 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 210000003205 muscle Anatomy 0.000 description 1
- 230000035699 permeability Effects 0.000 description 1
- 230000010349 pulsation Effects 0.000 description 1
- 238000002310 reflectometry Methods 0.000 description 1
- 231100000245 skin permeability Toxicity 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Images
Classifications
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B5/00—Measuring for diagnostic purposes; Identification of persons
- A61B5/0059—Measuring for diagnostic purposes; Identification of persons using light, e.g. diagnosis by transillumination, diascopy, fluorescence
- A61B5/0075—Measuring for diagnostic purposes; Identification of persons using light, e.g. diagnosis by transillumination, diascopy, fluorescence by spectroscopy, i.e. measuring spectra, e.g. Raman spectroscopy, infrared absorption spectroscopy
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B5/00—Measuring for diagnostic purposes; Identification of persons
- A61B5/145—Measuring characteristics of blood in vivo, e.g. gas concentration, pH value; Measuring characteristics of body fluids or tissues, e.g. interstitial fluid, cerebral tissue
- A61B5/1455—Measuring characteristics of blood in vivo, e.g. gas concentration, pH value; Measuring characteristics of body fluids or tissues, e.g. interstitial fluid, cerebral tissue using optical sensors, e.g. spectral photometrical oximeters
- A61B5/14551—Measuring characteristics of blood in vivo, e.g. gas concentration, pH value; Measuring characteristics of body fluids or tissues, e.g. interstitial fluid, cerebral tissue using optical sensors, e.g. spectral photometrical oximeters for measuring blood gases
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B5/00—Measuring for diagnostic purposes; Identification of persons
- A61B5/145—Measuring characteristics of blood in vivo, e.g. gas concentration, pH value; Measuring characteristics of body fluids or tissues, e.g. interstitial fluid, cerebral tissue
- A61B5/1455—Measuring characteristics of blood in vivo, e.g. gas concentration, pH value; Measuring characteristics of body fluids or tissues, e.g. interstitial fluid, cerebral tissue using optical sensors, e.g. spectral photometrical oximeters
- A61B5/14551—Measuring characteristics of blood in vivo, e.g. gas concentration, pH value; Measuring characteristics of body fluids or tissues, e.g. interstitial fluid, cerebral tissue using optical sensors, e.g. spectral photometrical oximeters for measuring blood gases
- A61B5/14552—Details of sensors specially adapted therefor
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B5/00—Measuring for diagnostic purposes; Identification of persons
- A61B5/72—Signal processing specially adapted for physiological signals or for diagnostic purposes
- A61B5/7203—Signal processing specially adapted for physiological signals or for diagnostic purposes for noise prevention, reduction or removal
Abstract
The invention discloses a multi-spectral skin color calibration and power consumption optimization device based on PPG technology, which comprises a detection device body; the detection device body comprises an LED, a PD and a processor; the LED and the PD are arranged on the same side of the detection device body facing the target to be detected; the processor is connected with the LED in a control mode through the LED time sequence controller and the LED driver in sequence; the PD is in communication connection with the processor through the transconductance amplifier, the band-pass filter and the analog-to-digital converter in sequence; compared with the traditional method, the method solves two problems: firstly, the skin complexion is calibrated by using bicolor light, and the problem that dark skin cannot be collected smoothly is solved by using light with longer wavelength such as infrared light, so that the device can adapt to more user groups, and the user experience is obviously improved; and secondly, a method for dynamically adjusting and regulating PPG detection parameters is provided, so that the PPG detection parameters enter a working response state at the highest speed, and data are acquired by adopting the optimal performance-power ratio, so that the cruising ability of the detection device is obviously improved.
Description
Technical Field
The invention relates to the field of wearable equipment, in particular to a device for multi-spectral skin color calibration and power consumption optimization of a PPG (photoplethysmography) technology and a working method.
Background
The use of the PPG technique to detect blood oxygen saturation is a common vital sign signal detection function in medical devices, and is now widely used. PPG detection techniques mainly have two types from the viewpoint of sensor layout: one is the classic transmission detection technique used on medical instruments, and the other is the reflection detection technique used on current wearable products. The transmission refers to that a Light Emitting Diode (LED) and a Photodiode (PD) are arranged on the opposite side of the tissue, light transmitted through the tissue is absorbed by the tissue or a blood part, and a detected PPG signal regularly changes along with pulsation; by reflective, it is meant that the LED and PD are on the same side, and thus the PD detects light absorbed and emitted by the tissue portion. The transmission type detection technology is generally used for detecting the blood oxygen saturation, the sensor is placed at a position with good permeability such as a nail or an earlobe, and the positions have more capillaries, thin skin cuticle, light skin color and less hairs, so the transmission type detection technology is generally used for occasions with high requirements on signal quality, such as medical equipment. The reflective detection technology is not unique relative to a transmission detection light path, most of light is scattered and lost, so that the signal quality is relatively poor, but the reflective detection has great placement flexibility, is widely applied to the current wearable product and has extremely high market value.
As an application based on the principle of photodetection, the reflective PPG technique itself has significant advantages:
1. non-invasive detection methods, which do not require electrodes;
2. because the photoelectric absorption or reflection condition of local tissues is analyzed, the detection can be realized on one hand, and the user experience is better;
but the disadvantages are also very evident:
1. the photoelectric detection is greatly influenced by the body surface environment of a human body, such as the conditions of black skin, more hair, tattoo and the like; for example, black can absorb most of the light intensity, hair can emit light, tattoos change tissue properties; therefore, it is difficult to detect PPG under certain conditions, let alone applications that require multiple waveform details such as blood oxygen saturation;
2. the discontent of partial users (such as black skin, fur, tattoo and the like) is easily caused, and the misunderstanding of the equipment distinguishing to the customers is caused; since the principle of detection is not understood by every customer and the equipment provider may also be difficult to interpret clearly with the customer, especially for common consumer products;
3. the volume tracing wave is easy to be interfered by the outside, so that the waveform distortion is serious, and the identification effect is influenced; most obvious are ambient light interference, light leakage interference of the device itself and interference caused by user motion;
in the design of portable small-volume systems, particularly wearable health detection equipment, due to the diversity of use environments and the dispersion of user groups, product designs with higher reliability and robustness are required to ensure the consistency of products, and the requirements on the product designs are high.
In addition, the power consumption is also an important index for measuring the products, and is directly related to the experience problem of users, especially in the continuous heart rate monitoring occasions such as fitness, running, marathon, sleep monitoring and the like, which need continuous heart rate detection while keeping low power consumption, so that how to quickly find appropriate parameters to optimize the power consumption and change the parameters adaptively according to the change of the environment is a problem that needs to be considered in product design, and from the system perspective, the following problems exist:
1. the Perfusion Index (PI) of human tissue, PI being the ratio of the effective AC component of the signal to the DC offset, is very much affected by the ambient temperature and attitude, and we generally expect that larger PI values are better. It is easy to understand that the blood-gas interaction of the body becomes better after the temperature is high or the body moves to be preheated, namely the alternating PPG signal becomes better; in addition, changes in posture can also cause perfusion changes in blood, such as hand throwing, sitting, standing up, etc.; the parameters set once are difficult to adapt to the change of the environment, for example, running is started in the case of high indoor temperature, the original parameters are difficult to adapt after the running is finished, or the signals are good after the human body is heated after running, so that the parameters are required to be adaptively adjusted to ensure that the lowest power consumption is used on the premise of acquiring the signals;
2. the inconsistency of system devices is mainly reflected in the inconsistency between the current of the LED and the emitted light intensity and errors in the optical design of equipment, which can indirectly cause the inconsistency of the light intensity and influence the detection result;
3. many people use direct current indicators of signals to determine the strength of the signals, and the debugging method is fast but mainly has two problems: firstly, the magnitude of a direct current signal is irrelevant to the perfusion index PI of the signal, and the direct current is possibly very high but the alternating current is very poor; secondly, because the relation between the LED light intensity and the driving current is not linear and the deviation between devices is large, only the size of a direct current signal is not beneficial to power consumption optimization;
4. the alternating current part is used for determining and optimizing parameters, although the parameters are reasonable, the speed is too slow, the alternating current change frequency is consistent with the pulse rate of the human body, the time of at least 5 seconds is required for obtaining more than three pulse waves in consideration of the condition of too slow heart rate, the time is unacceptable, and the action of a user can greatly interfere the detection effect in the period.
In summary, the PPG detection currently applied to wearable consumer products still has the problems of compatibility with different skin colors, cruising ability, and the like. Therefore, a PPG technique multi-spectral skin color calibration and power consumption optimization device which can adapt to various skin colors and effectively optimize power consumption is needed to be invented.
Disclosure of Invention
The purpose of the invention is as follows: in order to overcome the defects in the prior art, the invention provides the device for calibrating the multispectral skin color and optimizing the power consumption of the PPG technology, which can adapt to various skin colors and effectively optimize the power consumption.
The technical scheme is as follows: in order to achieve the purpose, the device for calibrating the multispectral skin color and optimizing the power consumption of the PPG technology comprises a detection device body; the detection device body comprises an LED, a PD and a processor; the LED and the PD are arranged on one side of the detection device body facing the target to be detected; the processor is connected with the LED in a control mode through the LED time sequence controller and the LED driver in sequence; and the PD is in communication connection with the processor through the transconductance amplifier, the band-pass filter and the analog-to-digital converter in sequence.
Furthermore, the detection device body also comprises a PCB and an upper cover plate; the LED and the PD are arranged on the PCB; the upper cover plate is arranged between the skin of the target to be detected and the LED and the PD; antireflection films are plated on two surfaces of the upper cover plate;
a spacer is arranged between the LED and the PD; the isolating piece is made of opaque materials; the height of the isolating piece is equal to the distance between the upper cover plate and the PCB.
Further, the LED includes a first light emitting unit and a second light emitting unit; a green LED is arranged in the first light-emitting unit; and a red light LED and an infrared light LED are compositely arranged in the second light-emitting unit.
Furthermore, the processor is also in communication connection with the acceleration sensor and the Bluetooth module respectively; the processor is in communication connection with the temperature sensor; the temperature sensor is arranged on one side of the detection device body facing the target to be detected and is in contact with the skin of the target to be detected.
A method for multi-spectral skin color calibration and power consumption optimization of PPG technology comprises the following steps: comprises the following steps;
step one, initializing the configuration of a circuit, and setting a PPG time sequence;
step two, removing the influence of dark current; turning off the LED, testing the dark current of the PD under the condition of no illumination and storing the dark current, and subtracting the value from the detected data;
removing the influence of ambient light; turning off the LED in the first and fourth detection periods and turning on the LED in the second and third detection periods; importing corresponding detection data of four periods of PD, then removing the environmental light data AL which is X1+ X4 and removing the environmental light data X which is X2+ X3-X1-X4; wherein X1 denotes the inspection data of the first cycle, X2 denotes the inspection data of the second cycle, X3 denotes the inspection data of the third cycle, and X4 denotes the inspection data of the fourth cycle;
step four, acquiring and drawing a CTR curve by using a multispectral scanning target;
judging whether the target is a human tissue according to the relation between the CTR curve threshold and the CTR ratio among the multiple spectra; if the human body tissue is judged not to be the human body tissue, the target type can be further identified; if the skin color type is judged to be the human tissue, further marking the skin color type, and calling a corresponding light-emitting unit for subsequent detection;
step six, measuring the CTR (current transformation ratio) and Noise of the target tissueCircuit；
CTR＝IPD/ILED；IPDIs the current value, I, read by the photodiode PDLEDIs the magnitude of the set LED driving current;
step seven, assuming parameter SNRAC(signal-to-noise ratio of AC part) and PI (perfusion index), calculating the current I required by the LEDLED；
step eight, starting to operate the circuit;
step nine, obtaining the PI value and the SNR in real time in the operation processACAnd feeding the obtained values back to the circuit to continuously optimize the PI value and the SNR AC value until the PI value and the SNR AC value are stable.
Has the advantages that: the invention discloses a device for multi-spectral skin color calibration and power consumption optimization of a PPG (photoplethysmography) technology, which comprises a detection device body; the detection device body comprises an LED, a PD and a processor; the LED and the PD are arranged on one side of the detection device body facing the target to be detected; the processor is connected with the LED in a control mode through the LED time sequence controller and the LED driver in sequence; the PD is in communication connection with the processor through the transconductance amplifier, the band-pass filter and the analog-to-digital converter in sequence; compared with the traditional method, the method solves two problems: firstly, the skin complexion is calibrated by using bicolor light, and the problem that dark skin cannot be collected smoothly is solved by using light with longer wavelength such as infrared light, so that the device can adapt to more user groups, and the user experience is obviously improved; and secondly, a method for dynamically adjusting and regulating PPG detection parameters is provided, so that the PPG detection parameters enter a working response state at the highest speed, and data are acquired by adopting the optimal performance-power ratio, so that the cruising ability of the detection device is obviously improved.
Drawings
FIG. 1 is a diagram of the overall architecture of a skin tone calibration and power consumption optimization apparatus;
fig. 2 is a schematic diagram of a PPG sensor layout;
figure 3 is a schematic diagram of PPG signal composition;
FIG. 4 is a schematic representation of ambient light detection cancellation;
FIG. 5 is a plot of the CTR of the skin for different spectral scans;
fig. 6 is a flow chart of a multispectral skin color calibration and power consumption optimization method.
Detailed Description
The present invention will be further described with reference to the accompanying drawings.
A multi-spectral skin color calibration and power consumption optimization device of PPG technology comprises a detection device body 13; the detection device body 13 comprises an LED14, a PD15 and a processor 9; the LED14 and the PD15 are arranged on the same side of the detection device body 13 facing the target 1 to be detected; the processor 9 is connected with the LED14 in a control mode through the LED time sequence controller 3 and the LED driver 2 in sequence; the PD15 is in communication connection with the processor 9 through the transconductance amplifier 4, the band-pass filter 5 and the analog-to-digital converter 6 in sequence.
The detection device body 13 further comprises a PCB 16 and an upper cover plate 17; the LED14 and the PD15 are mounted on the PCB 16; the upper cover plate 17 is arranged between the skin of the target 1 to be detected and the LEDs 14 and PD 15; antireflection coatings are plated on two surfaces of the upper cover plate 17, so that light reflection on the upper surface and the lower surface can be effectively reduced.
A spacer 19 is arranged between the LED14 and the PD 15; the isolating piece 19 is made of opaque materials; the height of the spacer 19 is equal to the distance between the upper cover plate 17 and the PCB board 16.
The LED14 includes a first light emitting unit 141 and a second light emitting unit 142; a green light LED is disposed in the first light emitting unit 141; the second light emitting unit 142 is provided with a red light LED and an infrared light LED.
The processor 9 is also in communication connection with the acceleration sensor 10 and the Bluetooth module 11 respectively; the processor 9 is in communication connection with the temperature sensor 8; the temperature sensor 8 is arranged on one side of the detection device body 13 facing the target 1 to be detected and is contacted with the skin of the target 1 to be detected;
the core LED drive 2, the LED time sequence control 3, the transconductance amplifier 4, the band-pass filter 5, the digital-to-analog converter 6 and the state machine logic control 7 of the PPG acquisition circuit can be completed by an integrated chip AFE4405 of TI company, and the chip is a highly integrated chip aiming at the PPG acquisition circuit and only needs to pass through I2The register can be configured to start PPG signal acquisition by connecting the C or SPI interface with the processor, and the PPG signal is directly output to the processor through the digital interface, so that the PPG signal acquisition is very convenient; the processor 9 and the bluetooth module 11 may select a BLE5.0 SOC chip nRF52840 of Nordic corporation or a bluetooth SOC chip CC2640 of TI corporation; the temperature sensor 8 can be selected from a chip-level temperature monitoring scheme ADT7420 of ADI company; the acceleration sensor 10 can be selected from an LIS3DH chip and a triaxial acceleration sensor chip of ST company;
as shown in fig. 1, a transconductance amplifier 4, a band-pass filter 5, a digital-to-analog converter 6, an LED driver 2, an LED timing controller 3, and a state machine logic controller 7 together form a signal conditioning part; the state machine logic controller 7 is responsible for coordinating the work of each unit, if a discrete device circuit is used, the discrete device circuit is generally born by the processor 9, the LED time sequence control 3 drives the LED by the LED drive 2 according to the programmed time sequence, the LED drive 2 is generally multi-path, a plurality of LEDs can be driven simultaneously, and only one path is listed for simplicity; the light emitting diode emits light to a target 1 to be detected, meanwhile, the photodiode detects that an optical signal returned from a tissue is converted into a current signal, then the current is converted into a voltage signal through the transconductance amplifier 4, and the voltage signal is converted into a digital signal through the band-pass filter 5 and then sent to the digital-to-analog converter 6; in order to cooperate with PPG signal acquisition, the device integrates a temperature sensor 8 and an acceleration sensor 10 at the same time, wherein the temperature sensor 8 does not detect the body temperature but acquires the temperature of the body surface, is used for calibrating the temperature during PPG signal acquisition and is used for other algorithms such as algorithm compensation during acquisition of electrodermal activity; the acceleration sensor 10 is used for knowing whether the current state is in a motion state, and the motion can cause the judgment of the influence of the larger DC drift of the PPG signal; in addition, the device is integrated with a bluetooth module 11 for communication with other devices.
As shown in fig. 2, which is a schematic diagram of a layout of a PPG sensor, this structure has a photodiode in the middle, generally at least one photodiode, and LED diodes, generally at least one LED of two colors, preferably at least two LEDs, 1 being a green LED, 2 being a red LED, 3 being an infrared LED, because the combination of red and infrared light is a classic arrangement for measuring blood oxygen saturation, it is recommended that a two-in-one LED device is used to save space on a board, the left and right LEDs are symmetrical and on a straight line with PD, the LEDs of the same suffix are driven at the same time and the different suffixes are driven in time; because red and infrared light are more permeable to human tissue than green light, their corresponding required LED-to-PD distance is also greater; depending on the size of the conventional wearable device, the distance of LED1 to PD is set by experience here to be twice the distance of LED2/3 to PD; namely, the distance from the center of the LED1 to the edge of the middle PD effective photosensitive area is 2-4mm, and the distance from the center of the LED2/3 to the middle PD effective edge is 4-8 mm; the PD and the LED area need to be separated by the spacer 19, so that the light emitted by the LED can be effectively reduced from being reflected to the PD by the upper cover plate 17, the reflected path is reflected back to the internal PD by the inner surface of the upper cover plate through the light path a shown in fig. 2 or the light path B is reflected back to the internal PD by the outer surface of the upper cover plate, and the light intensity of the reflected path is much higher than that of a normal signal (the light path C) coming back from human tissues, so that the height of the spacer 19 is equal to the distance between the upper cover plate 17 and the PCB 16, that is, the spacer 19 is raised to fill the air gap between the upper cover plate 17 and the PCB 16, which can eliminate the error introduced by the light path a, and the error introduced by the light path B can be eliminated by reducing the thickness of the upper cover plate and.
The light source with two or more wavelengths is used for testing, and the following advantages are mainly achieved:
1) the device is used for overcoming the problem that a single-wavelength light source is absorbed under different skin conditions, for example, very black skin can absorb most of green light, and the effect of using red light or infrared light is better;
2) to overcome the influence of hair reflection, the distance between the LED and the PD needs to be increased in principle to reduce the influence of hair reflection. Because the wavelength of the red light and the infrared light is longer, the distance between the LED and the PD is required to be enlarged for self detection so as to obtain a better detection effect;
3) only the direct current component of the signal is used instead of the alternating current component, and the method is fast and stable;
4) the data proportion and the amplitude of different targets under different spectral irradiation can be obtained through multispectral scanning, so that different objects can be distinguished, for example, whether the equipment is worn on a hand, or placed on a table, sleeved on a mineral water bottle or even worn on a hand of a teddy bear, and the like;
5) because green light is relatively excellent in superficial reflectivity of most skins, wearing devices such as bracelets and the like on the market at present mostly adopt green light as a detection light source to obtain the best power consumption performance, once the wearing devices reach a dark environment, the green light is particularly dazzling, and the actions such as sleeping of a user are interfered; the multispectral detection has the advantage that infrared light invisible to human eyes can be used for detection at night, so that interference to users is effectively avoided.
As shown in fig. 3, the PPG signal is a schematic diagram, and the PPG signal mainly includes an ac component and a dc component, and the ac component reflects the blood-gas interaction in blood or the change of blood flux. The direct current component consists of three parts, namely, error from the equipment, namely ambient light and light reflected by internal structures; second, the transmitted light of venous blood; and thirdly, light reflected by muscles and bones. The latter two are the tissue's own DC signal, and the spacer 19 in fig. 2 above can effectively eliminate internal structural reflections, but ambient light induced error elimination requires the use of the method of fig. 4.
A method for multi-spectral skin color calibration and power consumption optimization of PPG technology comprises the following steps: comprises the following steps;
step one, initializing the configuration of a circuit, and setting a PPG time sequence;
step two, removing the influence of dark current; turning off the LED, testing the dark current of the PD under the condition of no illumination and storing the dark current, and subtracting the value from the detected data;
removing the influence of ambient light; as shown in fig. 4, the LED is turned off in the first and fourth sensing periods and turned on in the second and third sensing periods; importing corresponding detection data of four periods of PD, then removing the environmental light data AL which is X1+ X4 and removing the environmental light data X which is X2+ X3-X1-X4; wherein X1 denotes the inspection data of the first cycle, X2 denotes the inspection data of the second cycle, X3 denotes the inspection data of the third cycle, and X4 denotes the inspection data of the fourth cycle;
step four, after the errors causing the direct current DC part of the PPG signal are eliminated, a CTR curve can be drawn by using a multispectral scanning target; fig. 5 shows an example of CTR curves of different spectrum scanning skins, where the CTR value is related to the efficiency of optical mechanisms and optical devices and the object to be tested, and it can be seen that green light is almost absorbed by black skin and infrared light has obvious change, so that the two are combined to help determine the skin color type and whether the target is other objects outside the human body, and the specific implementation is to obtain the determination rules of different targets according to experiments; the simple decision logic is as follows:
because the green and infrared LEDs are at different distances from the PD, if the target is a fixed reflective surface such as a desktop, the CTR produced by the green light being closer to the PD is much greater than the infrared; if the target is a human body, the darker the skin color, the larger the difference in CTR measured for both lights;
because the wavelengths of the green light and the infrared light are different and the distances between the green light and the infrared light and the PD are different, whether the equipment is far away from or close to a target can be detected by utilizing the characteristic, the signal change is reflected that the infrared light changes at a long distance, and the green light changes violently only when the green light reaches a certain distance;
the calibrated skin color is generally not used for informing a user so as to avoid misunderstanding, but can be used for guiding equipment to make corresponding adjustment; for example:
1) the equipment is facilitated to quickly optimize parameter configuration; if the target is found to reflect very little signal, it is likely that dark skin requires increased emitted light intensity; if the target is found to be strongly reflected back, which is likely to be of the hair-reflecting or skin-permeable type, the emitted light intensity needs to be reduced;
2) if the device knows the skin color condition of the user, measures can be actively taken to avoid misunderstanding of the user, such as skin color discrimination, differential treatment and other problems;
3) for some specific users, we can give the variation trend of skin permeability, which can reflect the variation of skin complexion or internal tissues of the users;
judging whether the target is a human tissue according to the relation between the CTR curve threshold and the CTR ratio among the multiple spectra; if the human body tissue is judged not to be the human body tissue, the target type can be further identified; if the skin color type is judged to be the human tissue, further marking the skin color type, and calling a corresponding light-emitting unit for subsequent detection;
step six, measuring the CTR (current transformation ratio) and Noise of the target tissueCircuitCTR and NoiseCircuitThe signal can be directly acquired;
CTR＝IPD/ILED；IPDis the current value, I, read by the photodiode PDLEDIs the magnitude of the set LED driving current;
step (ii) ofSeventhly, a parameter SNR is assumedAC(signal-to-noise ratio of AC part) and PI (perfusion index), calculating the current I required by the LEDLED；
Step eight, starting to operate the circuit;
step nine, obtaining the PI value and the SNR in real time in the operation processACAnd feeding the obtained values back to the circuit to continuously optimize the PI value and the SNR AC value until the PI value and the SNR AC value are stable.
Therefore, a SNR is assumed in step sevenACBecause direct on-line measurement is inefficient and time consuming, requiring at least several valid PPG waveforms, which severely slows down the response time of the entire device and does not give timely feedback to the user; while the SNR is presetACIs the simplest approach because all PPG-related algorithms are concerned with SNRACTherefore, we naturally know the lowest SNR that the algorithm can accept in the algorithm development processACThe value is, and the algorithm experience value is directly taken as if the value is the same; for PI, it is a time-varying value, the difficulty of on-line measurement and SNRACSimilarly, a worst value can be firstly selected to ensure that the algorithm works, for example, the PI of our target population is 0.05% -3%, the worst value can be directly selected at the initial stage, and the algorithm can quickly find the ILEDAnd then calculating PI and SNR synchronously with the increase of the number of samplesACThen the true PI and SNR are determinedACSubstituting the formula of solving the current ILED to obtain the optimal configuration; the method is an automatic parameter optimization method, which can quickly determine parameters and dynamically adjust the parameters according to the change of the environment, so that the equipment always collects data with the optimal parameters and the lowest power consumption.
The above description is only of the preferred embodiments of the present invention, and it should be noted that: it will be apparent to those skilled in the art that various modifications and adaptations can be made without departing from the principles of the invention and these are intended to be within the scope of the invention.
Claims (5)
1. A method for multi-spectral skin color calibration and power consumption optimization of PPG technology comprises the following steps: comprises the following steps;
step one, initializing the configuration of a circuit, and setting a PPG time sequence;
step two, removing the influence of dark current; turning off the LED, testing the dark current of the PD under the condition of no illumination and storing the dark current, and subtracting the value from the detected data;
removing the influence of ambient light; turning off the LED (14) during the first and fourth sensing periods and turning on the LED during the second and third sensing periods; importing corresponding detection data of four periods of PD, then removing the environmental light data AL which is X1+ X4 and removing the environmental light data X which is X2+ X3-X1-X4; wherein X1 denotes the inspection data of the first cycle, X2 denotes the inspection data of the second cycle, X3 denotes the inspection data of the third cycle, and X4 denotes the inspection data of the fourth cycle;
step four, acquiring and drawing a CTR curve by using a multispectral scanning target;
judging whether the target is a human tissue according to the relation between the CTR curve threshold and the CTR ratio among the multiple spectra; if the human body tissue is judged not to be the human body tissue, the target type can be further identified; if the skin color type is judged to be the human tissue, further marking the skin color type, and calling a corresponding light-emitting unit for subsequent detection;
step six, measuring the CTR (current transformation ratio) and Noise of the target tissueCircuit；
CTR＝IPD/ILED；IPDIs the current value, I, read by the photodiode PDLEDIs the magnitude of the set LED driving current;
step seven, assuming parameter SNRAC(signal-to-noise ratio of AC part) and PI (fill index), calculate the power required by the LEDStream ILED；
step eight, starting to operate the circuit;
step nine, obtaining the PI value and the SNR in real time in the operation processACFeeding the obtained value back to the circuit to continuously optimize the PI value and the SNRACUntil the value stabilizes.
2. An optimization device based on the method for PPG technology multispectral skin color calibration and power consumption optimization of claim 1, characterized in that: comprises a detection device body (13); the detection device body (13) comprises an LED (14), a PD (15) and a processor (9); the LED (14) and the PD (15) are arranged on one side, facing the target (1) to be detected, of the detection device body (13); the processor (9) is connected with the LED (14) in a control mode through the LED time sequence controller (3) and the LED driver (2) in sequence; the PD (15) is in communication connection with the processor (9) through the transconductance amplifier (4), the band-pass filter (5) and the analog-to-digital converter (6) in sequence.
3. The optimization device of claim 2, wherein: the detection device body (13) further comprises a PCB (printed circuit board) 16 and an upper cover plate (17); the LED (14) and the PD (15) are mounted on a PCB (16); the upper cover plate (17) is arranged between the skin of the target (1) to be detected and the LED (14) and the PD (15); antireflection films are plated on two surfaces of the upper cover plate (17);
a spacer (19) is arranged between the LED (14) and the PD (15); the isolating piece (19) is made of opaque materials; the height of the spacer (19) is equal to the distance between the upper cover plate (17) and the PCB (16).
4. The optimization device of claim 2, wherein: the LED (14) comprises a first light emitting unit (141) and a second light emitting unit (142); a green LED is arranged in the first light-emitting unit (141); and a red light LED and an infrared light LED are compositely arranged in the second light-emitting unit (142).
5. The optimization device of claim 2, wherein: the processor (9) is also in communication connection with the acceleration sensor (10) and the Bluetooth module (11) respectively; the processor (9) is in communication connection with the temperature sensor (8); the temperature sensor (8) is arranged on one side, facing the target (1) to be detected, of the detection device body (13) and is in contact with the skin of the target (1) to be detected.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810479917.2A CN108606801B (en) | 2018-05-18 | 2018-05-18 | PPG technology multispectral skin color calibration and power consumption optimization device and working method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810479917.2A CN108606801B (en) | 2018-05-18 | 2018-05-18 | PPG technology multispectral skin color calibration and power consumption optimization device and working method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN108606801A CN108606801A (en) | 2018-10-02 |
| CN108606801B true CN108606801B (en) | 2021-03-05 |
Family
ID=63663502
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201810479917.2A Active CN108606801B (en) | 2018-05-18 | 2018-05-18 | PPG technology multispectral skin color calibration and power consumption optimization device and working method |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN108606801B (en) |
Families Citing this family (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR102649997B1 (en) * | 2019-03-18 | 2024-03-22 | 삼성전자주식회사 | Electronic device and method for operating thereof |
| EP3946028A1 (en) * | 2019-03-28 | 2022-02-09 | Aktiia SA | Ppg sensor having a high signal to noise ratio |
| CN110192867B (en) * | 2019-06-25 | 2022-03-25 | 深圳市蓝瑞格生物医疗科技有限公司 | Method and system for improving measurement precision of measurement system |
| US11141103B2 (en) * | 2019-07-25 | 2021-10-12 | Mediatek Inc. | Vital-sign detection system and control method therefor |
| CN112806972B (en) * | 2019-11-18 | 2023-04-07 | Oppo广东移动通信有限公司 | PPG measuring circuit and method, and wearable electronic device |
| CN111093487B (en) * | 2019-11-29 | 2023-02-17 | 深圳市汇顶科技股份有限公司 | Self-adaptive biological feature detection method and device and electronic equipment |
| CN113545757A (en) * | 2020-04-26 | 2021-10-26 | 广东小天才科技有限公司 | Core temperature measuring method and device, terminal and storage medium |
| CN114271783B (en) * | 2020-09-27 | 2024-01-30 | 北京小米移动软件有限公司 | Skin detection device, method and terminal |
| CN114366043A (en) * | 2020-10-15 | 2022-04-19 | Oppo广东移动通信有限公司 | PPG sensor, PPG testing method, electronic device and wearable device |
| CN112168171A (en) * | 2020-10-16 | 2021-01-05 | 北京中科心研科技有限公司 | Skin complexion detection method and device based on wearable pulse signals |
| CN116763271A (en) * | 2021-12-30 | 2023-09-19 | 荣耀终端有限公司 | PPG control method and device and electronic equipment |
Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101120878A (en) * | 2006-08-10 | 2008-02-13 | 三星电子株式会社 | Living body measurement apparatus |
| CN201033073Y (en) * | 2007-02-07 | 2008-03-12 | 深圳市科瑞康实业有限公司 | Sphygmus blood oxygen test apparatus |
| CN203647348U (en) * | 2013-12-09 | 2014-06-18 | 上海德尔格医疗器械有限公司 | Oxygen saturation detecting instrument |
| CN104224143A (en) * | 2014-09-28 | 2014-12-24 | 成都金海鼎盛科技有限公司 | Ultralow-power-consumption PPG (Photo Plethysmo Graphy) signal acqusition circuit and acqusition method |
| CN104411231A (en) * | 2012-06-29 | 2015-03-11 | 株式会社东芝 | Health management support device, method and program |
| CN107260150A (en) * | 2016-04-05 | 2017-10-20 | 硅实验室公司 | Optical arrangement for energy-conservation, low noise photoplethysmographic sensor module |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6912413B2 (en) * | 2002-09-13 | 2005-06-28 | Ge Healthcare Finland Oy | Pulse oximeter |
| US20130012785A1 (en) * | 2011-07-07 | 2013-01-10 | Lombardi Daniel J | Method and apparatus for enabling continuous data acquisition across multiple stages of care |
-
2018
- 2018-05-18 CN CN201810479917.2A patent/CN108606801B/en active Active
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101120878A (en) * | 2006-08-10 | 2008-02-13 | 三星电子株式会社 | Living body measurement apparatus |
| CN201033073Y (en) * | 2007-02-07 | 2008-03-12 | 深圳市科瑞康实业有限公司 | Sphygmus blood oxygen test apparatus |
| CN104411231A (en) * | 2012-06-29 | 2015-03-11 | 株式会社东芝 | Health management support device, method and program |
| CN203647348U (en) * | 2013-12-09 | 2014-06-18 | 上海德尔格医疗器械有限公司 | Oxygen saturation detecting instrument |
| CN104224143A (en) * | 2014-09-28 | 2014-12-24 | 成都金海鼎盛科技有限公司 | Ultralow-power-consumption PPG (Photo Plethysmo Graphy) signal acqusition circuit and acqusition method |
| CN107260150A (en) * | 2016-04-05 | 2017-10-20 | 硅实验室公司 | Optical arrangement for energy-conservation, low noise photoplethysmographic sensor module |
Also Published As
| Publication number | Publication date |
|---|---|
| CN108606801A (en) | 2018-10-02 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN108606801B (en) | PPG technology multispectral skin color calibration and power consumption optimization device and working method | |
| JP6501760B2 (en) | Portable pulse measuring device | |
| US10881310B2 (en) | Motion artifact mitigation methods and devices for pulse photoplethysmography | |
| CN104968259B (en) | System and method for the vital sign information for determining object | |
| EP3380002B1 (en) | Wearable device and system for acquiring physiological information of a subject | |
| RU2664600C2 (en) | Marker with light-emitting area for use in determining information on vital signs | |
| TWI608826B (en) | Optical sensing device and measurement method thereof | |
| TW201517875A (en) | Method and apparatus for determining SpO2 of a subject from an optical measurement | |
| CN109645972A (en) | It is a kind of for measuring the array arrangement circuit of heart rate and blood oxygen | |
| US20220354389A1 (en) | Sensor device for optical measurement of biological properties | |
| US11564630B2 (en) | Systems and methods for low power pulse oximetry | |
| US10582887B2 (en) | Blood oxygenation sensor with LED current modulation | |
| US20180333088A1 (en) | Pulse Oximetry Capturing Technique | |
| CN104605838A (en) | Heart rate detection method and device | |
| CN112272538A (en) | System and method for determining at least one vital sign of a subject | |
| KR102326554B1 (en) | System and Method for Improving of Plethysmography Pulsatile Blood Signal in Blood Glucose Measurement using Skin Color Sensor | |
| WO2016108056A1 (en) | A ppg-based physiological sensing system with a spatio-temporal sampling approach towards identifying and removing motion artifacts from optical signals | |
| WO2018206014A1 (en) | Dual optical path sensor module | |
| CN209932708U (en) | Array arrangement circuit for measuring heart rate and blood oxygen | |
| WO2016111696A1 (en) | A ppg-based physiological sensing system with a spatio-temporal sampling approach towards identifying and removing motion artifacts from optical signals | |
| KR20170064906A (en) | Apparatus and method for measuring bio-signal | |
| CN111991005A (en) | Hand-held type sublingual blood oxygen saturation measuring device | |
| TW201511735A (en) | A PPG-based physiological sensing system with a spatio-temporal sampling approach towards identifying and removing motion artifacts from optical signals | |
| CN111150384A (en) | Wearable device | |
| TWI827427B (en) | A wearable device and a method for selecting and interpreting light intensity data values applicable thereto |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant | ||
| TR01 | Transfer of patent right |
Effective date of registration: 20211207 Address after: 350000 office building 09, floor 11, 2, Taihe City Plaza (phase I), No. 6, Banzhong Road, Xindian Town, Jin'an District, Fuzhou City, Fujian Province Patentee after: Fujian haomagic Electronic Technology Co.,Ltd. Address before: No.809 Qianhu Road, Wuxi City, Jiangsu Province Patentee before: WUXI INSTITUTE OF COMMERCE |
|
| TR01 | Transfer of patent right | ||
| CP01 | Change in the name or title of a patent holder |
Address after: 350000 office building 09, floor 11, 2, Taihe City Plaza (phase I), No. 6, Banzhong Road, Xindian Town, Jin'an District, Fuzhou City, Fujian Province Patentee after: Fujian Shouzhong'an Intelligent Technology Co.,Ltd. Address before: 350000 office building 09, floor 11, 2, Taihe City Plaza (phase I), No. 6, Banzhong Road, Xindian Town, Jin'an District, Fuzhou City, Fujian Province Patentee before: Fujian haomagic Electronic Technology Co.,Ltd. |
|
| CP01 | Change in the name or title of a patent holder |