A PPG sensor module and a wearable device

Abstract

The utility model provides a kind of PPG sensor module and wearable equipment, transmitting end and receiving end are synchronously encapsulated in the surface of substrate by transparent adhesive layer, the light-shielding adhesive layer between the two is directly filled in the isolation groove of transparent adhesive layer to form, compared with traditional module structure, same optical distance (i.e. the center distance of transmission and reception) under, structure is more compact, module volume is reduced by nearly 50%;Meanwhile, the preparation process is also more simple.

Description

Technical Field

[0001] This utility model relates to the field of sensor technology, and in particular to a PPG sensor module and wearable device. Background Technology

[0002] With the development of modern technology, wearable products offer users increasingly rich and convenient functions, such as health monitoring, activity tracking, and information reminders. For wearable products providing health monitoring functions, this is generally achieved through a PPG (Photoplethysmography) module. The PPG module contains a transmitter that provides light signals of different wavelengths and a photoelectric sensor that receives the signals. When monitoring a user, the transmitter emits light, which is transmitted and reflected in human tissue and then received by the photoelectric sensor and converted into an electrical signal. The photoplethysmography method is used to analyze and process the changes in light within the human tissue to obtain physiological parameters reflecting the user's health status, such as heart rate and blood pressure, thus achieving non-invasive real-time detection.

[0003] In the existing technology, due to the small space of the smart bracelet itself, the PPG sensor module used in the smart bracelet is arranged in a long strip. That is, the transmitter, receiver and light-blocking component in the PPG module are arranged in a long strip and mounted and packaged at a certain optical distance. However, this packaging method not only occupies a large structural space, but also has high cost and long processing cycle. Utility Model Content

[0004] To overcome the above shortcomings, this utility model provides a PPG sensor module and a wearable device.

[0005] The technical solution provided by this utility model is as follows: On the one hand, this utility model provides a PPG sensor module, including: A rectangular packaging substrate includes an emitter die-bonding region and a receiver die-bonding region, wherein an emitter chip is disposed in the emitter die-bonding region and a receiver chip is disposed in the receiver die-bonding region; A reflective adhesive layer is formed in the non-emitting chip area of ​​the emitter die-bonding region, and the upper surface of the reflective adhesive layer is lower than the upper surface of the emitter chip; A transparent adhesive layer, covering the transmitter chip and receiver chip, is formed on the entire rectangular package substrate surface, and an isolation groove is formed between the transmitter die-bonding area and the receiver die-bonding area. A light-shielding adhesive layer is filled into the isolation groove.

[0006] On the other hand, this utility model also provides a wearable device, including the above-mentioned PPG sensor module.

[0007] This utility model provides a PPG sensor module and wearable device. The transmitter and receiver can be simultaneously encapsulated on the substrate surface through a transparent adhesive layer. The light-shielding adhesive layer between them is directly filled in the isolation groove of the transparent adhesive layer. Compared with the traditional module structure, the structure is more compact and the module volume is reduced by nearly 50% for the same optical distance (i.e., the center distance between the transmitter and receiver). At the same time, the manufacturing process is also simpler. Attached Figure Description

[0008] Figure 1 This is a top view of a PPG sensor module in one embodiment of the present invention; Figure 2 for Figure 1 The diagram shows a cross-sectional view of the PPG sensor module.

[0009] Figure label: A1 - First emitter die-bonding area, A2 - Second emitter die-bonding area, B - Receiver die-bonding area, 11 / 12 / 13 - Emitter chip, 14 - Receiver chip, 1 - Rectangular packaging substrate, 2 - Reflective adhesive layer, 3 - Transparent adhesive layer, 4 - Light-shielding adhesive layer, S1 / S2 / S3 / S4 - Optical distance between emitter chip and receiver chip Detailed Implementation

[0010] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the specific embodiments of this utility model will be described below with reference to the accompanying drawings. Obviously, the accompanying drawings described below are merely some embodiments of this utility model. For those skilled in the art, other drawings and other embodiments can be obtained based on these drawings without creative effort. Furthermore, in this application, directional terms such as "front," "rear," "upper," "lower," "left," and "right" are defined relative to the indicated placement of the components in the drawings. It should be understood that these directional terms are relative concepts, used for relative description and clarification, and can change accordingly depending on the placement of the components in the drawings.

[0011] One embodiment of this utility model discloses a PPG sensor module, comprising: A rectangular packaging substrate includes an emitter die-bonding area and a receiver die-bonding area. An emitter chip is disposed in the emitter die-bonding area, and a receiver chip is disposed in the receiver die-bonding area. A reflective adhesive layer is formed in the non-emitter chip area of ​​the emitter die-bonding area, and the upper surface of the reflective adhesive layer is lower than the upper surface of the emitter chip. A transparent adhesive layer is formed on the entire surface of the rectangular packaging substrate, covering the emitter chip and the receiver chip, and an isolation groove is formed between the emitter die-bonding area and the receiver die-bonding area. A light-shielding adhesive layer is filled in the isolation groove.

[0012] The rectangular packaging substrate is flat, providing physical support for other structures in the PPG sensor module while providing circuit support for the transmitter and receiver chips via conductive lines. Materials can include PCB, BT, FR4, and copper. Its specific dimensions can be designed based on the available space in the wearable device; ensuring it can be installed within the device. The thickness of the rectangular packaging substrate is also rigorously calculated and optimized to minimize thickness while maintaining mechanical strength, meeting the requirements for thinness and lightness in wearable devices. The number and distribution of the transmitter and receiver die-bonding areas can be designed according to actual needs, such as symmetrical or asymmetrical configurations, combinations of multiple transmitter die-bonding areas with one receiver die-bonding area, or combinations of one transmitter die-bonding area with multiple receiver die-bonding areas. For example, in one instance... Figure 1 As shown, the PPG sensor module employs two emitter die-bonding regions, including a first emitter die-bonding region A1 and a second emitter die-bonding region A2 respectively disposed on both sides of the receiver die-bonding region B; on the surface of the rectangular packaging substrate, along the long side of the rectangle, there are three segments, namely the first emitter die-bonding region, the receiver die-bonding region, and the second emitter die-bonding region; and the first emitter die-bonding region and the second emitter die-bonding region are symmetrically arranged about the axis of symmetry of the long side of the rectangular packaging substrate.

[0013] The reflective adhesive layer is applied around each emitter chip in the emitter bonding area by dispensing adhesive droplets onto specific locations (possibly multiple locations), which then flow freely to cover the first and second emitter bonding areas. It should be noted that the reflective adhesive layer does not cover the receiver bonding area. The reflective adhesive layer material is a mixture of resin / silicone and light-reflecting particles. The resin can be epoxy resin, thermosetting polyimide resin, phenolic resin, urea resin, melamine resin, unsaturated polyester resin, diallyl phthalate resin, thermosetting polyurethane resin, etc., preferably thermosetting silicone resin or epoxy resin. The light-reflecting particles are generally white inorganic pigments, such as oxides like titanium dioxide, zinc oxide, and zirconium oxide, lead white (lead carbonate), calcium carbonate, and clay minerals like kaolinite, preferably titanium dioxide. It should be understood that the emitting chips configured on the same emitter bonding area have the same height. To avoid affecting light emission, the upper surface of the reflective adhesive layer does not exceed the upper light-emitting surface of each emitting chip. Light is emitted from the side of the chip facing away from the rectangular package substrate (the light-emitting surface). The upper surface of the reflective adhesive layer can be slightly lower than the upper surface of each emitting chip, or it can be flush with the upper surface of each emitting chip. To reflect the light emitted downwards and scattered light from the emitter bonding area to the transparent adhesive layer, thus improving light emission efficiency, the reflective adhesive layer must have a high reflectivity, such as greater than 85%. The transparent adhesive layer itself is a transparent insulating material and can be made of colorless and transparent resin or silicone. When the emitting chip or receiver chip is connected to the rectangular package substrate using wire bonding, the transparent adhesive layer covers and encapsulates the emitting chip, receiver chip, and their wire bonding. The light-shielding adhesive layer material is a mixture of resin or silicone and light-reflecting particles, possessing high reflectivity. Therefore, it prevents the lateral light emitted by the emitting chip in the emitter bonding area from directly propagating to the receiver bonding area, avoiding interference with the detection data of the PPG sensor. The reflectivity and material of the light-shielding adhesive layer can be the same as or different from those of the reflective adhesive layer. In one example, both the reflective adhesive layer and the light-shielding adhesive layer are high-reflectivity white adhesives internally doped with TiO2.

[0014] The working principle of a PPG sensor module is as follows: the emitting chip emits light into the skin tissue, penetrating the epidermis to reach the subcutaneous capillary network. The light undergoes absorption, scattering, and transmission / reflection within the tissue. While the absorption of light by muscles, bones, veins, and other connecting tissues remains relatively constant, the absorption by blood flowing in arteries varies. Blood, due to its heme content, absorbs light significantly more strongly than other tissues, becoming the primary variable. The receiving chip converts the received light intensity changes into electrical signals, forming the raw PPG signal. By measuring the change in absorbance caused by minute changes in blood volume, physiological indicators such as the wearer's heart rate and blood oxygen saturation are indirectly calculated. The emitting chip used can be an LED chip or a VCSEL chip, as long as it emits light of a specific wavelength and intensity. The receiving chip often uses a photodiode, such as a silicon photodiode.

[0015] The specific number and arrangement of the emitting chips should be designed according to the detection items of the wearable device; this embodiment does not impose any restrictions. For example, if the wearable device only detects blood oxygen saturation, then at least one red light emitting chip and one infrared light emitting chip should be configured, or two red light emitting chips and two infrared light emitting chips can also be configured, etc. Figure 1 and Figure 2 The PPG sensor module shown is used to simultaneously detect heart rate and blood oxygen saturation. Each emitter bonding area contains three emitter chips with different emission wavelengths. Emitter chips 11 and 12 are arranged side-by-side near the edge of the emitter bonding area, while emitter chip 13 is roughly located in the center of the emitter bonding area. The three emitter chips are arranged in a triangular pattern. Emitter chips 11 and 12 are two emitter chips with emission wavelengths of 660nm and 940nm, or 660nm and 870nm, used for detecting blood oxygen saturation; and emitter chip 13 is one emitter chip with an emission wavelength of 530nm, used for detecting heart rate. The three emitter chips and receiver chip 14 used here are all vertically structured. After being bonded to the corresponding pads with conductive adhesive, they are then connected to the other polarity pad in the corresponding area via wire bonding. The optical distances S1 / S2 / S3 / S4 between the transmitting chip and the receiving chip are optimal values ​​obtained through extensive optical simulations and experiments to ensure the accuracy of the light signals received by the receiving chip. These values ​​are determined by considering the emission angle and intensity of the transmitting chip, the receiving range of the receiving chip, and the attenuation law during light propagation.

[0016] The reflective adhesive layer 2 covers only the non-emitting chip areas in the first and second emitter die-bonding areas on the surface of the rectangular package substrate 1, and does not cover the receiving die-bonding area; it surrounds each emitter chip, fills the gaps between the emitter chips, covers only the chip sidewalls, and its height does not exceed the light-emitting upper surface of the emitter chip, so that the light scattered towards the bottom of the rectangular package substrate is reflected back and emitted from the transparent adhesive layer.

[0017] A transparent adhesive layer 3 covers the entire surface of the rectangular packaging substrate, including a first emitter die-bonding area, a receiver die-bonding area, and a second emitter die-bonding area; it protects the emitter chip and receiver chip from the influence of the external environment and is transparent, with its upper surface height exceeding the upper surfaces of the emitter chip and receiver chip. A light-shielding adhesive layer 4 is prepared by creating a groove between the first emitter die-bonding area, the receiver die-bonding area, and the second emitter die-bonding area and then filling it with light-shielding adhesive, forming a dam wall structure that isolates the three areas, with its height extending from the surface of the rectangular packaging substrate to the upper surface of the transparent adhesive layer.

[0018] In the manufacturing process, the transparent adhesive layer is formed by molding, and the light-shielding adhesive layer is formed by slotting the transparent adhesive layer and then coating it with light-shielding adhesive in the isolation groove and curing it. The isolation groove consists of two strip-shaped grooves that run through the width of the rectangular package substrate, completely isolating the three areas; it also has a certain width to facilitate the filling of the light-shielding adhesive. Specifically, the process includes: first, die bonding the transmitter chip and receiver chip to designated positions on the rectangular package substrate, which may include wire bonding after die bonding; second, injecting high-reflectivity white adhesive doped with TiO2 into the first and second transmitter die bonding areas on the surface of the rectangular package substrate and curing it into a reflective adhesive layer. To avoid affecting light emission, the height of the reflective adhesive layer must not exceed the upper surface of the transmitter chip. Next, a transparent adhesive layer is prepared by pressing a pre-designed mold onto the surface of the rectangular packaging substrate. A liquid or semi-solid transparent material is injected into the mold and cured under appropriate pressure and temperature conditions according to the material properties. After curing, the mold can be removed. Then, isolation grooves are made along the edge between the first emitter die-bonding area, the receiver die-bonding area, and the second emitter die-bonding area. The depth of the isolation grooves extends to the surface of the rectangular packaging substrate. For the rectangular packaging substrate, the isolation grooves on its surface separate different areas. The injected white glue only fills the opened isolation grooves and does not flow to other positions, ensuring that the height of the light-shielding adhesive layer is flush with the transparent adhesive layer. Finally, the entire rectangular packaging substrate is cut apart along the edge of the adjacent light-emitting device to obtain a single PPG sensor module that simultaneously encapsulates the emitter and receiver.

[0019] In traditional manufacturing processes, the transmitter and receiver chips are first mounted on separate substrates and packaged to obtain the transmitter and receiver devices. Then, the packaged transmitter and receiver devices are surface-mounted and assembled onto a third substrate. For better comparison, this embodiment uses a traditional process to fabricate a PPG module, first mounting the transmitter and receiver chips on separate substrates, and then assembling them onto a third substrate. Figure 1 The optical distance patches of the module shown are arranged on the surface of another substrate, i.e., the optical distances S1 / S2 / S3 / S4 between the transmitting chip and the receiving chip are... Figure 1 and Figure 2 The same; the final packaged module dimensions are 13mm × 5mm × 1.0mm. Figure 1 and Figure 2 The PPG sensor module shown measures 12.8mm × 3.6mm × 0.7mm, which is nearly 50% smaller than the traditional module structure. Compared to traditional manufacturing processes, the PPG sensor module in this embodiment can reduce one SMT placement step and occupies a smaller volume.

[0020] In other embodiments, the shape of the isolation trench can be a straight line spanning the rectangular packaging substrate along the width direction, or it can be designed as a sawtooth shape, a broken line shape, a curve shape, etc., according to special actual needs. This embodiment does not limit this, as long as it can completely isolate the three regions of the first emitter die-bonding region, the receiver die-bonding region, and the second emitter die-bonding region.

[0021] Another embodiment of this utility model provides a wearable device including the aforementioned PPG sensor module. After the PPG sensor module is installed in a suitable position, it can be used to detect the user's physiological parameters. The physiological parameters referred to here are any data that can reflect the user's health, including but not limited to blood pressure, blood sugar, heart rate, and blood oxygen saturation. This embodiment does not impose any limitations on these parameters.

[0022] It should be noted that the above embodiments can be freely combined as needed. The above are merely preferred embodiments of this utility model. It should be pointed out that for those skilled in the art, several improvements and modifications can be made without departing from the principle of this utility model, and these improvements and modifications should also be considered within the protection scope of this utility model.

Claims

1. A PPG sensor module, characterized in that, include: A rectangular packaging substrate includes an emitter die-bonding region and a receiver die-bonding region, wherein an emitter chip is disposed in the emitter die-bonding region and a receiver chip is disposed in the receiver die-bonding region; A reflective adhesive layer is formed in the non-emitting chip area of ​​the emitter die-bonding region, and the upper surface of the reflective adhesive layer is lower than the upper surface of the emitter chip; A transparent adhesive layer, covering the transmitter chip and receiver chip, is formed on the entire rectangular package substrate surface, and an isolation groove is formed between the transmitter die-bonding area and the receiver die-bonding area. A light-shielding adhesive layer is filled into the isolation groove.

2. The PPG sensor module as described in claim 1, characterized in that: Along the length of the rectangular packaging substrate, the emitter die-bonding region includes a first emitter die-bonding region and a second emitter die-bonding region respectively disposed on both sides of the receiver die-bonding region; The isolation groove is formed between the first emitter bonding region and the receiver bonding region, and between the receiver bonding region and the second emitter bonding region.

3. The PPG sensor module as described in claim 2, characterized in that, The first emitter die-bonding region and the second emitter die-bonding region are symmetrically arranged about the axis of symmetry of the long side of the rectangular packaging substrate.

4. The PPG sensor module as described in claim 1, characterized in that, The emission die-bonding area contains three emission chips with different emission wavelengths, which are arranged in a triangular pattern.

5. The PPG sensor module as described in claim 2, characterized in that, The first and second emission die-bonding regions each contain three emission chips with different emission wavelengths, arranged in a triangular pattern.

6. The PPG sensor module as described in claim 4 or 5, characterized in that, The emission wavelengths of the three emitting chips are 660nm, 940nm and 530nm, respectively, or the emission wavelengths of the three emitting chips are 660nm, 870nm and 530nm, respectively.

7. The PPG sensor module as described in any one of claims 1-5, characterized in that, The isolation groove is a strip-shaped groove that runs through the width of the packaged rectangular substrate.

8. The PPG sensor module as described in any one of claims 1-5, characterized in that, The minimum size of the PPG sensor module is 12.8mm × 3.6mm × 0.7mm.

9. A wearable device, characterized in that, Includes the PPG sensor module as described in any one of claims 1-8.

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