CN111887827A

CN111887827A - Multispectral PPG equipment based on Bayer filter and application thereof

Info

Publication number: CN111887827A
Application number: CN202010862731.2A
Authority: CN
Inventors: 姜红; 王文锦; 刘明
Original assignee: Zhongshan Hospital Fudan University
Current assignee: Zhongshan Hospital Fudan University
Priority date: 2020-08-25
Filing date: 2020-08-25
Publication date: 2020-11-06

Abstract

The invention provides multispectral PPG equipment based on a Bayer filter, which is characterized by comprising the following components: the light source equipment is only used for emitting single-beam broadband white light, and the single-beam broadband white light emitted by the light source equipment is emitted into the skin of a human body; the Bayer filter is used for decomposing broadband white light reflected or transmitted from the skin into a plurality of beams of light with narrow band, and the band is increased or switched by adding or changing the color mode of the Bayer filter so as to meet the specific requirement of the multispectral PPG on the band; and an optical sensor for receiving the plurality of beams of light of the narrow band wavelength band emitted from the bayer filter. The multispectral PPG equipment based on the Bayer filter adopts a single light source mode, and single-beam white light is decomposed into different wave bands by using a filter array. According to the specific requirement of the wave bands, the wave bands can be added or switched by adding or changing the color mode of the filter, so that the flexibility and the freedom degree of multispectral monitoring are greatly increased.

Description

Multispectral PPG equipment based on Bayer filter and application thereof

Technical Field

The invention relates to a photoplethysmography (PPG) device and to the use of such a device.

Background

Photoplethysmography (PPG) has been used in wearable professional medical devices (e.g. finger oximeter) to monitor physiological indicators such as heart rate, respiratory rate, and blood oxygen saturation. The basic function of Multi-spectrum photoelectric volume pulse waves (Multi-wavelet PPG) is particularly important, and pulse wave signals (PPG) under different wave bands can be monitored simultaneously. The pulse wave energy of different wave bands reflects different human physiological characteristics, such as the heart rate signal of a green wave band is strongest; the infrared band is most sensitive to changes in blood oxygen (blood oxygen saturation). The phase difference between signals of different wave bands (such as blue light and infrared light) can calculate the Pulse transit time (Pulse transit time) and the blood pressure. Therefore, the PPG signal can be simultaneously taken under a plurality of wave bands (visible light and infrared light), and the PPG signal acquisition method has important medical significance and application value. Furthermore, multispectral PPG (visible and infrared) not only increases the measurable physiological signals, but also the robustness of single signal monitoring, such as by signal processing methods of multi-channel fusion noise reduction.

At present, the relatively mature wearable physiological monitoring products on the market are mostly of two types: (1) ECG: the heart rate, heart rate variability, is monitored purely by ECG, but the blood oxygen saturation cannot be monitored (in principle not allowed). Thus, the ECG has a limitation in the number of physiological indicators that can be monitored. (2) PPG (e.g. finger oximeter, sports bracelet): heart rate was monitored by the green band, and blood oxygen saturation was monitored by both red and infrared bands. PPG signals are susceptible to motion interference and ambient light interference.

As shown in fig. 1, the currently existing multi-spectral PPG device comprises light sources 1 corresponding to the number of wavelength bands, for example, 4 light sources 1 as shown in fig. 1, corresponding to 4 beams of light of different wavelength bands, and the spectra of the 4 beams of light of different wavelength bands are shown in fig. 2. The 4 beams of light with different wave bands are input into the human skin 2, reflected (or projected) from the human skin 2, and then received by the optical sensor 3. If an additional wave band needs to be added to the existing multispectral PPG equipment or the existing wave band needs to be changed, a light source needs to be added or modified, optical hardware and a chip need to be redesigned, and the acquisition mode of a multichannel signal needs to be redesigned. Meanwhile, the volume of the device is increased along with the increase of the number of the light sources, so that the miniaturization and portable application are more difficult. Moreover, each addition or modification of a spectral band entails a consumption of labor, material and time costs.

Disclosure of Invention

The technical problem to be solved by the invention is as follows: the optical configuration (multiple independent light sources) of the conventional multispectral PPG is not suitable for multi-band expansion and selection, and the light sources are usually additionally added or modified according to the specific requirements of the monitoring signal, and the existing multi-light source mode limits the freedom of research, development and application.

In order to solve the above technical problem, an aspect of the present invention provides a multispectral PPG device based on a bayer filter, including:

the light source equipment is only used for emitting single-beam broadband white light, and the single-beam broadband white light emitted by the light source equipment is emitted into the skin of a human body;

the Bayer filter is used for decomposing broadband white light reflected or transmitted from the skin into a plurality of beams of light with narrow band, and the band is increased or switched by adding or changing the color mode of the Bayer filter so as to meet the specific requirement of the multispectral PPG on the band;

and an optical sensor for receiving the plurality of beams of light of the narrow band wavelength band emitted from the bayer filter.

Preferably, the continuous wave band of the single-beam broadband white light is 450nm-950 nm.

Preferably, the bayer filter is a color filter array arranged over a grid of pixels of the light sensing element.

Another technical solution of the present invention is to provide an application of the above-mentioned multispectral PPG device based on bayer filter, which is characterized in that the multispectral PPG device is applied to a wearable device that is portable.

Another aspect of the present invention provides an application of the above-mentioned bayer-filter-based multispectral PPG apparatus, wherein the bayer-filter-based multispectral PPG apparatus is used alone to monitor a plurality of physiological signals.

Another aspect of the present invention provides a use of the above-mentioned bayer-filter-based multispectral PPG apparatus, wherein the bayer-filter-based multispectral PPG apparatus is used with ECG and/or EEG to monitor a plurality of physiological signals.

The multispectral PPG equipment based on the Bayer filter adopts a single light source mode, and single-beam white light is decomposed into different wave bands by using a filter array. According to the specific requirement of the wave bands, the wave bands can be added or switched by adding or changing the color mode of the filter, so that the flexibility and the freedom degree of multispectral monitoring are greatly increased. In actual research and application, the invention can meet different requirements of manufacturers and users on wave bands, and the modification of the filter is more convenient and simpler than that of a light source, thereby reducing the cost of manpower, material resources and time. The technical scheme provided by the invention belongs to optical hardware architecture innovation, is easy to detect whether the optical hardware architecture is used in a product, and has practical application and protection values.

Drawings

Fig. 1 is a schematic diagram of a currently existing multi-spectral PPG device;

fig. 2 is a schematic diagram of a light source spectrum of a currently existing multi-spectral PPG device;

fig. 3 is a schematic structural diagram of a multi-spectral PPG device based on a bayer filter according to the present invention;

FIG. 4 is a schematic spectrum diagram of a single broadband white light used in the present invention;

fig. 5 and 6 illustrate that the color pattern of the bayer filter can be changed or added to arbitrarily divide the broad band white band into different narrow bands to meet the requirement of the multi-spectral PPG on the number of bands and the specific band setting.

Detailed Description

The invention will be further illustrated with reference to the following specific examples. It should be understood that these examples are for illustrative purposes only and are not intended to limit the scope of the present invention. Further, it should be understood that various changes or modifications of the present invention may be made by those skilled in the art after reading the teaching of the present invention, and such equivalents may fall within the scope of the present invention as defined in the appended claims.

The invention aims to replace the multi-light source monitoring mode of the existing multi-spectral PPG and improve the degree of freedom and flexibility of increasing or modifying wave bands. The invention divides single-beam broadband white light into a plurality of narrow-band wave bands through a Bayer filter, and synchronously measures PPG under the separated wave bands. The wavelength band is increased or replaced only by changing the color mode of the Bayer filter without adding or modifying a light source like the traditional method, so that the manpower, material resources and time cost in research and development are saved.

As shown in fig. 3, specifically, the present invention is mainly composed of the following three modules: a light source 4, a bayer filter 5 and an optical sensor 3.

Light source 1: unlike the conventional approach of using multiple independent (narrow-band) light sources as shown in fig. 1, the present invention uses a single-beam broadband white light source 4, as shown in fig. 4, which emits light in a continuous wavelength band of 450nm to 950nm (visible and infrared).

Bayer filter 5: on the optical receiver side, a bayer filter 5 decomposes the broadband white light reflected (or transmitted) from the human skin 2 into a plurality of light of narrow band wavelength bands, and then sends it to the optical sensor 3. The bayer filter 5 is a color filter array like a mosaic, arranged on a pixel grid of the light sensing element. Imaging devices using single-chip digital photosensitive elements, such as cameras, have been widely used to generate color images. When white light enters the bayer filter 5, the white light is divided into different narrow-band lights by a color filter array preset on the bayer filter 5, and then enters the photosensitive element. The color filter array of a common RGB camera is RGGB (50% green, 25% red, 25% blue). According to the physiological signal (heart rate, blood oxygen or blood pressure) to be monitored, the present invention can change or add the color pattern of the filter to meet the requirement of the multispectral PPG on the wavelength band (number and location), as shown in fig. 5 and 6. For example: under the monitoring of blood oxygen saturation, red light and infrared light are required, the invention can change the Bayer pattern of RGGB into R-IR1-IR2-IR3, namely a red channel (650nm), a first infrared channel (750nm), a second infrared channel (900nm) and a third infrared channel (940 nm).

The optical sensor 3: this section employs an array of optical sensors, similar to conventional optical sensors.

The invention radically changes the multispectral optical processing structure, and makes the modification or increase of the multispectral PPG wave band more convenient and easier. The invention adopts Bayer filter to divide single-beam broadband white light after incidence on skin into a plurality of narrow-band wave bands for multi-band PPG monitoring. Only the color mode of the Bayer filter is changed for replacing or increasing the wave band, so that the flexibility and the degree of freedom of the equipment can be greatly improved. Compared with the traditional multispectral PPG equipment, the invention can complete the resetting of the spectrum only by changing the filter without adding a light source or modifying a hardware structure. And the time cost and the technical cost for modifying the filter are low, so that the method is widely used for the camera technology. The invention can support multi-band PPG signal monitoring, and the selection of specific bands can be determined by practical application and specific requirements. The monitored multispectral PPG signal can be used for calculating a plurality of physiological indexes, such as heart rate, heart rate variability, respiratory rate, blood oxygen saturation, blood pressure change/blood pressure and the like, and continuous, noninvasive and dynamic physiological monitoring is realized. The invention can be used for professional medical equipment and health products, and can be applied to disease prediction (such as new coronary pneumonia), chronic disease management (such as sleep apnea syndrome (obstructive, central nervous system and mixed), cardiovascular diseases), intensive care, old people, neonates and the like through dynamic monitoring of physiological indexes such as heart rate, respiration, blood oxygen, blood pressure and the like.

Specifically, the technical scheme provided by the invention is suitable for the following scenes:

professional medical equipment: long-term continuous physiological monitoring and reporting is performed for certain types of patients, such as cardiovascular disease, cardiopulmonary dysfunction/rehabilitation, sleep apnea syndrome (obstructive, central nervous, mixed), Intensive Care Unit (ICU), cardiopathy unit (CCU), postoperative care, and the like.

Household healthcare equipment: providing physiological monitoring for a special population or under a specific scene, such as the elderly, the infants, the snorers, the chronic disease monitoring or the population with related requirements.

Claims

1. A bayer filter based multi-spectral PPG device, comprising:

2. The bayer filter based multi-spectral PPG apparatus of claim 1, wherein the single broadband white light has a continuous band of 450nm to 950 nm.

3. The bayer filter based multi-spectral PPG apparatus of claim 1, wherein the bayer filter is a color filter array arranged over a grid of pixels of the light sensing element.

4. Use of the bayer filter based multi-spectral PPG device of claim 1 in a portable wearable device.

5. Use of the bayer filter based multi-spectral PPG device of claim 1 for monitoring a plurality of physiological signals alone, wherein the bayer filter based multi-spectral PPG device of claim 1 is used for monitoring a plurality of physiological signals.

6. Use of the bayer filter based multi-spectral PPG device of claim 1 in conjunction with ECG and/or EEG to monitor a plurality of physiological signals.