Multi-spectral skin color calibration and power consumption optimization device and working method of PPG technology

Abstract

The invention discloses a multi-spectral skin color calibration and power consumption optimization device based on a PPG technology. The device comprises a detection device body, the detection devicebody comprises an LED, a PD and a processor, the LED and the PD are disposed on the same side, facing a target to be detected, of the detection device body, the processor is sequentially in controlling connection with the LED through an LED timing controller and an LED driver, and the PD is sequentially in communication connection with the processor through a transconductance amplifier, a band pass filter and an analog-to-digital converter; compared with a traditional method, a working method of the device achieves two major purposes that one, two-color light is used for calibrating skin colors, light with a longer wavelength such as infrared light is used for overcoming the problem that dark skin cannot be collected smoothly, so that the device adapts to more user groups, and user feelings are significantly improved; two, a method of dynamically adjusting PPG detection parameters is proposed, so that a working response state is entered at the fastest speed, the data is collected by using the best performance-to-power ratio, and the capability of prolonging runtime of a detection device is significantly improved.

Description

technical field [0001] The invention relates to the field of wearable devices, in particular to a PPG technology multi-spectral skin color calibration and power consumption optimization device and a working method. Background technique [0002] The use of plethysmography wave PPG technology to detect blood oxygen saturation has been a commonly used vital sign signal detection function in medical devices, and it has been widely used. There are two main types of PPG detection technology in terms of sensor layout: one is the classic transmission detection technology used in medical instruments, and the other is the reflection detection technology currently used in wearable products. The so-called transmission means that the light emitting diode (LED) and photodiode (PD) are on the opposite side of the tissue, the light transmitted through the tissue is partially absorbed by the tissue or blood, and the detected PPG signal changes regularly with the pulsation; the so-called Ref...

AI Technical Summary

Problems solved by technology

[0007] 1. Photoelectric detection is greatly affected by the environment of the human body surface, such as dark skin, more hair, and tattoos; for example, black will absorb most of the light intensity, hair will emit light, and tattoos change the tissue characteristics; therefore, It is still difficult to detect PPG under certain conditions, let alone applications that require more waveform details such as blood oxygen saturation;

[0008] 2. It is easy to cause dissatisfaction among some users (such as dark skin, hairiness and tattoos, etc.), and cause misunderstandings that the equipment treats customers differently; because not every customer understands the principle of detection, and it may be difficult for equipment providers to explain clearly to customers , especially general consumer products;

[0009] 3. The plethysmography wave is susceptible to external interference, which leads to severe waveform distortion and affects the recognition effect; the most obvious is the interference of ambient light, light leakage interference of its own equipment, and interference caused by user movement;

It is easy to understand that the body's blood-gas interaction becomes better after the temperature is high or the body is warmed up after exercise, that is, the exchange PPG signal at this time becomes better; in addition, changes in posture will also cause changes in blood perfusion, such as shaking hands, sitting down , standing up, etc.; then the parameters set at one time are difficult to adapt to changes in the environment. For example, if you start running in a place where the indoor temperature is high, it is difficult to adapt the original parameters when the weather is cold after you go out, or after warming up after running. The signal will also become better, which requires adaptive adjustment of parameters to ensure the lowest power consumption under the premise of collecting the signal;

[0013] 2. The inconsistency of system components is mainly reflected in the inconsistency between the current of the LED and the emitted light intensity and the error in the optical design of the equipment, which will indirectly lead to the inconsistency of the light intensity and affect the test results;

[0014] 3. Many people use the DC index of the signal to determine the strength of the signal. This debugging method is very fast but there are two main problems: 1. The size of the DC signal has nothing to do with the perfusion index PI of the signal. It is possible that the DC signal is high but the AC signal Very poor; Second, because the relationship between LED light intensity and driving current is not linear and the deviation between devices is large, only looking at the magnitude of the DC signal is not conducive to power consumption optimization;

[0015] 4. It is reasonable to use the communication part to determine and optimize the parameters, but the speed is too slow. Since the change frequency of the communication is consistent with the pulse rate of the human body, it takes at least 5 seconds to obtain more than three pulse waves considering the slow heart rate. , which is unacceptable, and the user's actions during this period will greatly interfere with the detection effect

[0016] To sum up, the PPG detection currently applied to wearable consumer products still has problems such as compatibility with different skin colors and battery life.

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