CN117503079B - Blood sugar monitoring silicon optical chip - Google Patents

Abstract

The invention provides a blood sugar monitoring silicon optical chip, which comprises: an infrared photonic circuit, a visible light circuit, a signal transmission circuit and an ASIC chip; the infrared photonic circuit and the visible light circuit are connected with the ASIC chip through the signal transmission circuit; the infrared photonic circuit is used for analyzing the scattered first optical signal based on the silicon photon frequency comb generator to obtain a first analysis result; the visible light circuit is used for detecting the reflected second light signal to obtain a second analysis result; and the ASIC chip is used for determining the concentration information of the blood sugar in the blood of the user to be tested according to the first analysis result and the second analysis result. The invention can measure the blood glucose concentration in a noninvasive mode by adopting the Raman spectrum, improves the effectiveness and the accuracy of the blood glucose concentration, can be integrated on a bracelet, and improves the convenience of blood glucose measurement.

Description

A Silicon Photonic Chip for Blood Glucose Monitoring

Technical Field

The present invention relates to the technical field of medical sensors, and in particular to a blood sugar monitoring silicon photonic chip.

Background Art

Diabetes is a chronic disease that impairs the body's regulation and use of glucose as fuel. Insulin is a pancreatic hormone that helps glucose move from the blood into cells to be used as energy. When the body doesn't produce enough insulin or can't use it well, glucose can build up in the blood and lead to serious health problems such as blindness, kidney failure and stroke.

People with diabetes must accurately monitor and carefully control their blood sugar levels to keep them within a normal range and prevent complications. Portable finger-prick blood glucose meters, which require patients to prick their fingertips and place a drop of blood on a test strip for chemical analysis, remain the most common way to measure blood sugar. Having to perform such tests multiple times a day is inconvenient, painful, and impossible to do while sleeping or driving. There is also a continuous glucose monitor (CGM) that has emerged as a minimally invasive, user-friendly alternative to traditional blood glucose meters. Instead of measuring blood sugar levels directly, CGM measures glucose concentration in interstitial fluid through thin electrodes coated with glucose-sensitive enzymes placed under the skin, but it can cause skin irritation and sometimes inflammation. In addition, the accuracy of minimally invasive sensors is not as high as fingertip devices.

About 1 in 10 adults in the world suffer from diabetes, a total of more than 500 million people. In 2022, there will be about 140 million diabetics in my country, accounting for almost 10% of the country's population. Such a vast market has also attracted many manufacturers with technological advantages, such as Texas Instruments, ams and OSRAM, to enter the field of medical sensors represented by blood glucose monitoring.

At present, the mainstream blood sugar monitoring method is to accurately monitor the glucose content in human blood through blood sampling. Some companies have also launched "patch-type" blood sugar monitoring patches that can be implanted in the skin, which contain sensor chips. However, as a consumable part, the sensor needs to be replaced every 7-14 days, which is very expensive.

Current non-invasive blood glucose monitoring products use a variety of sensor technologies, including near-infrared spectroscopy, Raman spectroscopy, and reverse ion osmosis, but various technologies still need to further address the problem of poor correlation between test indicators and blood glucose.

The main difficulty of this project is how to accurately analyze blood sugar content using non-invasive methods. If the sensor is integrated into a smartwatch, the illuminated area will be limited to the human wrist, which further increases the difficulty of principle verification and prototype development of such sensors. The algorithm development technology is technically difficult, and light reflection is also difficult to achieve. This monitoring sensor technology has been tested on humans and compared with the results of capillary blood samples from venous blood draws and skin acupuncture to confirm the technical feasibility. However, Apple also needs to improve the sensor size to adapt to the requirements of smartwatches, and ensure the accuracy of sensor monitoring. This stage requires a lot of time for verification.

Summary of the invention

In order to overcome the deficiencies of the prior art, an object of the present invention is to provide a blood sugar monitoring silicon photonic chip.

To achieve the above object, the present invention provides the following solutions:

A blood sugar monitoring silicon photonic chip, comprising: an infrared photonic circuit, a visible light circuit, a signal transmission circuit and an ASIC chip;

The infrared photon circuit and the visible light circuit are connected to the ASIC chip via the signal transmission circuit;

The infrared photonic circuit is used to analyze the first scattered light signal based on the silicon photonic frequency comb generator to obtain a first analysis result; the visible light circuit is used to detect the second reflected light signal to obtain a second analysis result; the ASIC chip is used to determine the blood sugar concentration information in the blood of the user to be tested based on the first analysis result and the second analysis result.

Preferably, the size of the infrared photonic circuit is 8*3 mm ² .

Preferably, the infrared photonic circuit comprises a SiN optical chip integrated with a III-V optical amplifier; the SiN optical chip is manufactured using a 3 um thick silicon process.

Preferably, the SiN optical chip comprises a one-dimensional grating coupler, a variable optical attenuator, an intensity modulator and a polarization modulator.

Preferably, the base material of the SiN optical chip is glass.

Preferably, ultra-fine optical fibers are laid on the circuit board of the SiN optical chip.

Preferably, the infrared photonic circuit further comprises an on-chip spectrometer; the on-chip spectrometer is prepared by one low-pass arrayed waveguide grating and a plurality of high-pass arrayed waveguide gratings.

According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects:

The present invention provides a blood sugar monitoring silicon photonic chip, comprising: an infrared photonic circuit, a visible light circuit, a signal transmission circuit and an ASIC chip; the infrared photonic circuit and the visible light circuit are connected to the ASIC chip through the signal transmission circuit; the infrared photonic circuit is used to analyze the first light signal scattered back based on the silicon photonic frequency comb generator to obtain a first analysis result; the visible light circuit is used to detect the second light signal reflected back to obtain a second analysis result; the ASIC chip is used to determine the blood sugar concentration information in the blood of the user to be tested according to the first analysis result and the second analysis result. The present invention can measure blood sugar concentration in a non-invasive way using Raman spectroscopy to improve its effectiveness and accuracy, and can be integrated on a bracelet to improve the convenience of blood sugar measurement.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

FIG1 is a schematic diagram of a chip structure in an embodiment of the present invention;

FIG2 is a schematic diagram of the principle of Raman scattering in an embodiment provided by the present invention;

FIG3 is a schematic diagram of Raman spectrum distribution of different substances in the embodiments provided by the present invention;

FIG. 4 is a schematic diagram showing a comparison of Raman spectra of a 532 nm light source and a 785 nm wavelength in an embodiment provided by the present invention.

DETAILED DESCRIPTION

The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

The terms "first", "second", "third" and "fourth" in the specification and claims of the present application and the drawings are used to distinguish different objects rather than to describe a specific order. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a series of steps, processes, methods, etc. are not limited to the listed steps, but may optionally include steps that are not listed, or may optionally include other step elements inherent to these processes, methods, products or devices.

In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

Figure 1 is a schematic diagram of the chip structure in an embodiment provided by the present invention. As shown in Figure 1, the present invention provides a blood glucose monitoring silicon photonic chip, including: an infrared photonic circuit, a visible light circuit, a signal transmission circuit and an ASIC chip; the infrared photonic circuit and the visible light circuit are connected to the ASIC chip through the signal transmission circuit; the infrared photonic circuit is used to analyze the first scattered light signal based on the silicon photonic frequency comb generator to obtain a first analysis result; the visible light circuit is used to detect the second reflected light signal to obtain a second analysis result; the ASIC chip is used to determine the blood glucose concentration information in the blood of the user to be tested based on the first analysis result and the second analysis result.

Alternatively, most sports bracelets on the market currently use green LED as a light source, which is incident on the surface of the skin. By detecting the reflected signal, the user's heart rate, blood pressure, blood oxygen and other information can be obtained. In addition to the visible light LED light source, it is also equipped with a near-infrared light source that can penetrate into deeper layers of the skin. Combined with the on-chip spectrometer of the silicon photonic chip, the concentration information of blood sugar, alcohol and other substances in the user's blood can be obtained.

Spectrometer is a photoelectric instrument designed by using the principle of optical dispersion and modern advanced electronic technology to conduct spectral research and material structure analysis. Its basic function is to measure the spectral characteristics of the studied light (reflection, absorption, scattering or stimulated fluorescence of the studied material, etc.), including spectral line characteristics such as wavelength and intensity. Generally, spectral instruments can be divided into four parts: light source and lighting system, spectroscopic system, detection and receiving system, and transmission, storage and display system.

Furthermore, Raman spectroscopy detection is used in this embodiment. Raman spectroscopy detection only requires a single wavelength. The principle of Raman scattering is shown in Figure 2. When light of a specific wavelength is incident on a certain substance, the light interacts with the molecules, and most of the scattered photons have unchanged energy. This process is called Rayleigh scattering. A very small part of the light (about 1e ^-9 ) collides inelastically with the molecules, and the energy of the photons changes. This process is called Raman scattering. The Raman spectrum distribution of different substances is different, which can be used as the identity card of the substance, as shown in Figure 3.

By quantitatively analyzing the Raman scattering spectrum of a substance, the concentration information of a certain substance can be obtained. The intensity of the Raman spectrum is inversely proportional to the fourth power of the wavelength. The smaller the wavelength, the greater the intensity of the Raman spectrum. However, due to the strong fluorescence background in the visible light spectrum, the near-infrared wavelength is selected as the light source of the Raman spectrum, and the typical wavelength is 785nm. Figure 4 is a comparison of the Raman spectra of 532nm light source and 785nm wavelength. It can be seen that when 532nm is used as the light source, the fluorescence signal is very strong, and some Raman peaks have been submerged in the background signal. The appropriate wavelength of incident light is selected according to the sample being detected.

Furthermore, in this embodiment, a frequency comb light source based on a micro-ring is used, which has the following functions:

1) Higher spectral resolution

Current sports bracelets use LEDs as the spectrum, which has a wide line width at a specific wavelength and low resolution. However, the line width of microrings is very small, which can achieve higher spectral resolution.

2) Higher optical power

Since the frequency comb spectrum is discrete, the optical power is concentrated on each single frequency, the corresponding optical power is improved, and the power consumption of the entire system is reduced.

3) Higher integration

The microring is small in size and the spectrum it produces covers a larger wavelength range, eliminating the need for multiple single-wavelength lasers. The size of the chip is a very important parameter for a bracelet.

Specifically, this embodiment integrates III-V optical amplifiers on SiN optical chips. After a single wavelength of light enters the microring, due to the Kerr nonlinear effect of SiN, a four-wave mixing process occurs, generating two new wavelengths. The new wavelengths further oscillate in the microring, resulting in a four-wave mixing effect, thereby generating a broadband comb spectrum composed of multiple groups of wavelengths. The heterogeneous integration of SiN chips and III-V chips involved here is a feature of this embodiment (silicon photonics technology). As for the scheme of the on-chip spectrometer, the arrayed waveguide grating, as a wavelength division multiplexing device, usually adopts a traditional axisymmetric "horseshoe" device structure. This device structure has different bending parts and bending radii of different arrayed waveguides, which will cause phase errors between different output waveguides of the AWG. Especially for a micro Raman spectrometer with a wide working wavelength range, the resulting phase error will be very significant. As a result, the insertion loss of the edge channel will be very large, which is an unacceptable disadvantage for a micro Raman spectrometer that strives for high resolution and high accuracy. To this end, this embodiment proposes a design scheme for reducing the phase error of the AWG used in a micro-Raman spectrometer. The AWG design using an array waveguide structure with the same bending radius can greatly reduce the phase error between the middle channel and the edge channel of the AWC, and provides a wide bandwidth design of an AWG device using cascade technology.

Specifically, in spectroscopy, signal processing is a key step in the spectral analysis process. The data of spectral analysis is usually the collected photoelectric signal, and the role of signal processing is to turn the collected data into a meaningful spectrum. A spectrum is usually an image that shows the light intensity at different wavelengths, thereby revealing information about the sample. One of the most commonly used signal processing methods in spectral analysis is peak fitting. Peak fitting is to find the peak position and height in the data by processing the spectral data. This method can be used to quantitatively analyze the concentration of chemicals in the sample because the height of the peak is proportional to the concentration. Peak fitting can also be used for qualitative analysis because each compound has its own unique spectral fingerprint. Another commonly used signal processing method is spectrometer calibration. Spectrometer calibration is to calibrate the wavelength of the spectrometer by measuring standard light sources of different wavelengths. This method can ensure the accuracy of the spectrometer and ensure the consistency of each measurement result. In signal processing, the use of filters is also very common. Filters can filter out interfering elements of spectral data, thereby improving the quality of spectral data. Commonly used filters include low-pass, high-pass, band-pass and band-shadow filters. These filters can filter data according to demand, thereby obtaining more accurate and reliable spectral data.

Furthermore, the micro-Raman spectrometer needs to identify the presence of a certain substance by displaying the characteristic spectrum of the substance within a certain spectral range (wavelength range). In order to improve its scope of application and detect several more substances, it is necessary to have a wider range of working wavelengths. This requires a wide-bandwidth AWG. However, it is quite difficult to obtain wide bandwidth (wide working wavelength range) and high resolution (small wavelength interval between adjacent channels) at the same time, which means that the number of channels (working wavelength range/wavelength interval between adjacent channels) is very large. If both the resolution of the AWG and a wider working wavelength range are required, the result can only be that the number of channels of a single AWG device is too large, which causes great difficulties in the design, simulation and process manufacturing of the AWG device. Considering the best combination of a wider wavelength range (i.e., the micro-Raman spectrometer can detect as many substances as possible) and resolution, it is necessary to ensure sufficient AWG bandwidth and lower resolution. The solution of this embodiment is to adopt the cascade technology of AWG, that is, to cascade one low-pass AWG and several high-pass AWGs. The research goal of this application is to work in a wavelength range of 810nm-914nm, that is, a wavelength range of 104nm. In this way, with a resolution of 1nm, it can be achieved by only two-stage cascade, with the first stage being a 4-channel AWC and the second stage being four 26-channel AWGs. Although this solution will increase the insertion loss of the AWG accordingly, considering that the first-stage AWG in the solution of this embodiment has only 4 output channels, it is easier to achieve its low insertion loss in design and production. Therefore, the insertion loss of the overall device is less affected.

This embodiment provides a design scheme for obtaining an AWG with a wide working band and low phase error. This scheme makes the layout of the AWG device more compact, not only can reduce the phase error, but also makes the size of the overall device very easy to meet the requirements of miniaturization. It is more suitable for the miniaturization requirements of the micro Raman spectrometer for its spectroscopic chip. In addition, all waveguides are on the same plane and have no intersection, which ensures the feasibility of process manufacturing.

On the other hand, the unique silicon photonics process of this embodiment enables it to play an advantage in the processing of the two chips, frequency comb and AWG. The silicon photonics technology of this embodiment adopts a 3um thick silicon process, which is convenient for integration with III-V, and the processing tolerance of the waveguide is large, which is convenient for preparing phase-sensitive optical devices. The main components of the silicon transmitter chip are a one-dimensional grating coupler, a variable optical attenuator, an intensity modulator, and a polarization modulator. Connect the chip to OCI1500 to measure the reflectivity distribution. The silicon transmitter chip obtains test results at a spatial resolution of 10μm, and several reflection peaks appear inside the silicon transmitter chip. The grating number is the same as the corresponding channel number. To determine the position of the reflection peak, a signal is applied to the modulator to observe and analyze the changes in the reflection peak. OCI1500 realizes the identification, positioning and return loss measurement of each device in the chip. OFDR test results In the field of silicon photonics testing, OFDR can quickly and accurately measure the performance of the coupling point between the optical fiber and the chip, the loss of each device inside the chip, and whether the small distance between each device meets the design requirements. As silicon photonics develops increasingly mature, the OFDR market is also gradually expanding. Most manufacturers of silicon photonics chips, optical devices, and optical modules need to use OFDR to detect whether their product performance parameters meet the design and control product quality.

Compared with traditional chips using transistors, the core of the silicon photonic chip design of this embodiment is to replace "electricity" with "light". Silicon photonic technology is used to integrate optoelectronic functions into silicon-based chips through semiconductor processes. When current flows to the conversion module, the electrical signal is converted into an optical signal through the photoelectric effect, and then emitted to the ultra-fine optical fiber laid on the circuit board. When the optical signal reaches another chip, it is converted into an electrical signal again, thereby increasing the connection speed between chips. Unlike ordinary silicon materials, which mainly rely on glass, the basic material used in silicon photonic technology is glass. Since light is transparent to glass and no interference occurs, in theory, signals can be transmitted by integrating optical waveguide paths in glass, which is very suitable for large-scale communication within computers and between multiple cores.

In fact, products that "replace electricity with light" are already very common in daily life. For example, optical fiber uses light signals to transmit electrical signals instead of early copper cables, which greatly improves the bandwidth of the network. However, if only optical signals are used for communication, it will be greatly limited by the size of optical equipment. It is difficult to shrink the complex photoelectric conversion module to nanometer size and use it at the chip level. Although there are continuous breakthroughs in the laboratory, the yield and cost have never been able to meet the requirements of mass production. At the same time, the development of bus technologies such as PCIe has continuously increased the bandwidth, which has also made this technical route fade out of everyone's sight.

However, as the manufacturing process of integrated circuits has approached the limit of Moore's Law, silicon photonics technology has once again entered the sight of manufacturers. The biggest advantage of silicon photonics technology is that it has a very high transmission rate, which can make the data transmission speed between processor cores 100 times faster or even higher. In addition, using light instead of electricity to transmit information consumes much less power than traditional methods, and the requirements for heat dissipation are greatly reduced.

The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

The principles and implementation methods of the present invention are described in this article using specific examples. The description of the above embodiments is only used to help understand the method and core idea of the present invention. At the same time, for those skilled in the art, according to the idea of the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims (4)

1. A blood glucose monitoring silicon optical chip, comprising: an infrared photonic circuit, a visible light circuit, a signal transmission circuit and an ASIC chip;

The infrared photonic circuit and the visible light circuit are connected with the ASIC chip through the signal transmission circuit;

The infrared photonic circuit is used for analyzing the scattered first optical signal based on the silicon photon frequency comb generator to obtain a first analysis result; the visible light circuit is used for detecting the reflected second light signal to obtain a second analysis result; the ASIC chip is used for determining the concentration information of blood sugar in blood of a user to be tested according to the first analysis result and the second analysis result;

The infrared photonic circuit comprises a SiN optical chip integrated with a III-V optical amplifier; the SiN optical chip is prepared by a 3um thick silicon process;

the SiN optical chip comprises a one-dimensional grating coupler, a variable optical attenuator, an intensity modulator and a polarization modulator; the infrared photonic circuit further comprises an on-chip spectrometer; the on-chip spectrometer adopts a cascade technology of an AWG; the cascade technology of the AWG adopts 1 low-pass AWG and a plurality of high-pass AWGs to be cascaded; the first stage AWG has 4 output channels; the second stage is 4 AWG of 26 channels; the working wavelength range of the ASIC chip is 810nm-914nm; the AWG employs an array waveguide structure of the same bend radius.

2. The blood glucose monitoring silicon optical chip of claim 1, wherein the infrared photonic circuit has a size of 8 x 3mm ².

3. The blood glucose monitoring silicon optical chip of claim 1, wherein the base material of the SiN optical chip is glass.

4. The blood glucose monitoring silicon optical chip of claim 1, wherein the SiN optical chip is laid in an ultra-fine fiber on a circuit board.