Four-electrode subcutaneous blood glucose sensor with integrated sterilization barrier

Abstract

The application discloses a four-electrode subcutaneous blood glucose sensor with an integrated sterilization barrier and belongs to the field of medical devices. The four-electrode subcutaneous blood glucose sensor comprises a sensor electrode, a needle helper and a transmitter. The sensor electrode adopts an L-shaped flexible polymer substrate, and a first working electrode and a second working electrode, a reference electrode and a counter electrode are arranged on two sides of the substrate to form a four-electrode system, so that the interference of tissue liquid impurities is inhibited, and baseline drift is reduced. The needle helper is internally provided with coaxial double springs to realize automatic puncture and automatic needle withdrawal, so that the implantation operation is simplified, and trauma is reduced. The puncture needle, the needle barrel, the electrode fixing seat and the lower cover of the transmitter are combined to form an integrated sterilization barrier, so that invasive components are completely closed and sterile, and the pollution problem caused by the failure of split sterilization and sealing is solved. The application effectively improves the subcutaneous continuous glucose monitoring precision, wearing convenience and sterile protection reliability, and is suitable for long-term blood glucose continuous management of diabetes.

Description

Technical Field

[0001] This invention relates to the field of medical device technology, specifically to a four-electrode subcutaneous blood glucose sensor with an integrated sterilization barrier. Background Technology

[0002] Diabetes, as a prevalent chronic metabolic disease, relies on high-frequency, continuous blood glucose data for both clinical diagnosis and daily health management. Compared to the instantaneous testing mode of traditional finger-prick blood sampling, subcutaneous implantable continuous glucose monitoring (CGM) systems can collect blood glucose signals from tissue fluid around the clock, dynamically presenting blood glucose trends, and have now become the mainstream technology in the field of blood glucose management. The entire monitoring system typically consists of three core components: sensing electrodes, implantable auxiliary components, and signal processing transmitters. Although related products have been commercialized, existing products still have many technical shortcomings in terms of detection performance, user experience, operational reliability, and long-term adaptability due to limitations in electrode structure design, material processing, mechanical structure, aseptic protection, and overall system integration.

[0003] Firstly, regarding the electrode system, most mainstream subcutaneous blood glucose monitoring sensors on the market employ a two- or three-electrode structure. These electrodes have limited functional zones and rely solely on a single working electrode for signal acquisition. Subcutaneous tissue fluid has a complex composition, containing proteins, electrolytes, metabolic impurities, and other interfering substances, which can easily trigger fluctuations in electrode interface potential and non-specific electrochemical reactions, resulting in high noise levels and significant baseline drift. This signal distortion problem is further exacerbated under conditions of drastic blood glucose fluctuations, making it difficult to guarantee detection accuracy.

[0004] Secondly, in terms of implantation operation, the existing products have complex needle device structures and cumbersome operation steps, and insufficient puncture accuracy and stability, which can easily cause patients to experience strong pain or implantation position deviation, affecting the detection accuracy of the sensor.

[0005] Furthermore, in the field of aseptic protection and sterilization adaptation, the sensing probe and puncture needle of implantable blood glucose sensors are invasive medical components that must be kept sterile throughout the entire process. Because the bio-enzymes on the sensor surface are sensitive to gaseous sterilization media such as ethylene oxide, and the precision circuit chips inside the transmitter are not resistant to high-energy radiation sterilization, the industry generally adopts a production model of component disassembly, independent sterilization, and separate packaging. Currently, there is no integrated sterilization space on the market, and the sealing structure lacks stability, making it prone to seal failure. Summary of the Invention

[0006] The purpose of this invention is to provide a four-electrode subcutaneous blood glucose sensor with an integrated sterilization barrier, so as to solve the problems of poor detection stability, insufficient anti-interference ability, inconvenient implantation operation and low reliability of sterile protection in the existing subcutaneous implantable blood glucose monitoring sensors.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A four-electrode subcutaneous blood glucose sensor with an integrated sterilization barrier, comprising: The sensor electrode adopts an L-shaped flexible polymer substrate and includes an implantation arm and a connecting arm. The implantation arm is used for subcutaneous implantation, and the connecting arm is used to arrange conductive contacts and connect to the transmitter. The sensor electrode adopts a four-electrode system, including a first working electrode, a second working electrode, a reference electrode, and a counter electrode. The first working electrode and the second working electrode are arranged on one side of the L-shaped flexible polymer substrate, and the reference electrode and the counter electrode are arranged on the other side of the L-shaped flexible polymer substrate. The needle assist device includes a housing, a needle assist spring, a needle retraction spring, a sensor bracket, a puncture needle, a needle retraction bracket, and a transmitter bracket. The needle assist spring and the needle retraction spring are arranged coaxially. The needle assist spring provides puncture power, and the needle retraction spring provides needle retraction return force. The sensor bracket is used to hold the connecting arm of the sensor electrode, ensuring that the implantation arm of the sensor electrode is coaxially aligned with the puncture needle. A hollow needle with a wall thickness of 0.05mm to 0.15mm is used to drive the implantation arm of the sensor electrode to enter the subcutaneous tissue synchronously. The needle retraction bracket is connected to the tail end of the puncture needle, enabling the puncture needle to retract rapidly under the action of the needle retraction spring. The transmitter bracket is used to fix the transmitter. The transmitter includes a transmitter upper cover, a transmitter lower cover, a circuit board, and an electrode holder; the transmitter upper cover and transmitter lower cover are sealed together to form a closed cavity, the circuit board is disposed in the closed cavity, and the electrode holder is disposed inside the transmitter lower cover to engage the connecting arm of the sensor electrode, so that the conductive contact of the sensor electrode is aligned and connected with the spring contact of the circuit board. The sterilization barrier is a closed sterile cavity formed by the puncture needle, the puncture needle barrel, the electrode holder, and the transmitter cover. The implantation arm of the sensor electrode is pre-installed in the inner cavity of the puncture needle and is entirely contained within the sterile cavity.

[0008] As a further aspect of the present invention: the housing includes an upper cover and a lower cover of the needle aid device. A transverse guide hole is provided on the side of the upper cover of the needle aid device. The button of the needle aid device is slidably installed in the transverse guide hole. At least one set of elastic locking claws extends from the end of the button of the needle aid device. The elastic locking claws are tightly locked on the inner wall of the upper cover of the needle aid device. The upper surface of the button of the needle aid device is tightly connected with several limiting heads of the transmitter bracket to limit and lock the needle aid spring in the pre-compressed state.

[0009] As a further aspect of the present invention: the housing includes an upper cover and a lower cover of the needle aid. An axial guide hole is provided at the center of the top surface of the upper cover of the needle aid. The needle aid button is slidably installed in the axial guide hole along the axial direction. At least one set of elastic locking claws extends from the lower end of the needle aid button. The elastic locking claws are tightly engaged with the limiting step provided on the inner wall of the upper cover of the needle aid, thereby limiting and locking the needle aid spring in the pre-compressed state.

[0010] As a further aspect of the present invention: the implantation arm of the sensor electrode has a length of 5-20 mm and a width of 0.5-2 mm, and the end of the implantation arm has a rounded corner structure; the width of the connecting arm of the sensor electrode is greater than that of the implantation arm.

[0011] As a further aspect of the present invention: both the first working electrode and the second working electrode are pure carbon working electrodes, the reference electrode is an Ag / AgCl reference electrode, the counter electrode is a pure carbon counter electrode, and glucose oxidase is sprayed onto the surfaces of the first working electrode and the second working electrode.

[0012] As a further aspect of the present invention: the upper cover and the lower cover of the needle aid are engaged by a snap-fit ​​mechanism to form a housing, and a rotating cover is provided at the end of the housing.

[0013] As a further aspect of the present invention: the puncture needle barrel is assembled inside the rotating cover. When the rotating cover is rotated to unlock, the puncture needle barrel rotates synchronously with the rotating cover, and the seal between the puncture needle barrel and the lower cover of the transmitter is released.

[0014] As a further aspect of the present invention: the puncture needle includes a puncture needle silicone ring, the puncture needle barrel includes a barrel silicone ring and a barrel silicone plug, the barrel silicone ring is disposed on the upper end of the puncture needle barrel by secondary injection molding or assembly, and the barrel silicone plug is disposed on the bottom of the puncture needle barrel for sealing.

[0015] As a further aspect of the present invention: the circuit board integrates signal amplification, filtering, analog-to-digital conversion, microprocessing, and wireless communication units; the circuit board connects to the reference electrode contact, the first working electrode contact, the second working electrode contact, and the counter electrode contact respectively through spring contacts, for collecting the four-electrode output current signal and calculating the glucose concentration, and wirelessly transmitting it to an external terminal.

[0016] This invention also provides a method of using a four-electrode subcutaneous blood glucose sensor with an integrated sterilization barrier, applied to the aforementioned four-electrode subcutaneous blood glucose sensor with an integrated sterilization barrier, comprising the following steps: Rotate the cap to unlock the puncture needle syringe, separating the sterilization barrier sealing structure; Remove the lower cover of the needle aid and the silicone plug of the syringe, press the button on the needle aid, and the needle aid spring will release and push the puncture needle and the implantation arm with the sensor electrode to be implanted under the skin. After the puncture is completed, the needle retraction spring rebounds, causing the puncture needle to retract. Remove the needle adapter, attach the transmitter to the connecting arm of the sensor electrode to complete the wearing process, and continuously collect blood glucose signals and wirelessly upload them to the mobile terminal.

[0017] Compared with the prior art, the present invention has at least the following beneficial effects: (1) The present invention adopts a four-electrode system, which includes a first working electrode and a second working electrode, a reference electrode and a counter electrode. The dual working electrodes can provide richer detection signals, the reference electrode provides a stable reference potential, and the counter electrode forms a current loop, effectively suppressing potential fluctuations and non-specific electrochemical reactions caused by interfering substances in the tissue fluid, and significantly improving the stability and anti-interference ability of the detection signal.

[0018] (2) The present invention uses an L-shaped flexible polymer substrate, including an implant arm and a connecting arm. The implant arm is slender and has rounded ends, which facilitates minimally invasive subcutaneous implantation. The connecting arm is wider and used to arrange conductive contacts. The structure transition is smooth, avoiding stress concentration and improving the mechanical reliability and wearing comfort of the sensor assembly.

[0019] (3) The present invention uses the puncture needle, sensor electrode, electrode fixing seat, transmitter lower cover and puncture needle barrel to form an integrated sterile cavity, which realizes the sterile isolation from the implantation end to the transmitter assembly area, avoids the risk of sealing failure caused by component disassembly, independent sterilization and separate packaging, and effectively ensures the sterile safety of the implantation process.

[0020] (4) The needle assist device of the present invention adopts a coaxially arranged needle assist spring and needle retraction spring to realize the automatic release of puncture power and automatic retraction of puncture needle, and the entire process is automated, which reduces the difficulty of implantation operation and the pain of patients; the rotating cap design effectively prevents accidental triggering and improves the safety of use.

[0021] (5) The transmitter of the present invention adopts a miniaturized packaging structure. The electrode fixing seat can quickly and firmly engage the connecting arm of the sensor electrode, ensuring that the conductive contact of the sensor electrode and the spring contact of the circuit board are accurately aligned and have stable contact.

[0022] (6) The downward force of the top button is completely coaxial and collinear with the direction of the puncture needle. The stimulation force applied by the user can avoid generating any lateral interference force, but instead will be converted into the normal pressure force of the needle aid on the human skin. This positive pressure can firmly lock the lower cover of the needle aid to the skin surface, effectively blocking the shaking and deflection of the shell at the moment of stimulation, and ensuring that the puncture needle cuts into the subcutaneous tissue in a vertical posture. Attached Figure Description

[0023] The invention will now be further described with reference to the accompanying drawings.

[0024] Figure 1 This is a schematic diagram of the sensor electrode structure in an embodiment of the present invention; Figure 2 This is a front view schematic diagram of the overall structure of Embodiment 1 of the present invention; Figure 3 yes Figure 2 A sectional view of the structure; Figure 4 This is an exploded view of the overall structure of Embodiment 1 of the present invention; Figure 5 This is an exploded schematic diagram of the sterilization barrier structure according to an embodiment of the present invention; Figure 6 This is a cross-sectional view of the overall structure of Embodiment 2 of the present invention; Figure 7 This is a partial exploded view of the structure of Embodiment 2 of the present invention.

[0025] In the picture: 100. Sensor electrode; 101. Reference electrode contact; 102. First working electrode contact; 103. First working electrode; 104. Reference electrode; 105. Second working electrode contact; 106. Counter electrode contact; 107. Counter electrode; 108. Second working electrode; 200. Needle aid; 210. Needle aid top cover; 2101. Limiting step; 211. Needle aid button; 2111. Elastic locking claw; 212. Needle aid spring; 213. Needle retraction spring; 214. Sensor bracket; 215. Puncture needle; 216. Transmitter bracket; 2161. Limiting head; 217. Needle retraction bracket; 218. Puncture needle silicone ring; 220. Needle aid bottom cover; 221. Rotating cover; 231. Transmitter top cover; 232. Circuit board; 233. Transmitter bottom cover; 234. Puncture needle syringe; 235. Electrode holder; 236. Syringe silicone ring; 237. Syringe silicone plug; 238. Lateral guide hole; 239. Axial guide hole. Detailed Implementation

[0026] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] In the description of this invention, it should be understood that the terms "upper", "lower", "left", "right", "front", "rear", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or a specific orientational structure and operation. Therefore, they should not be construed as limitations on this invention.

[0028] Furthermore, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking," etc., should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0029] Example 1 Please see Figure 1-5 As shown, this embodiment provides a four-electrode subcutaneous blood glucose sensor with an integrated sterilization barrier, comprising three parts: sensor electrode 100, needle aid 200, and transmitter.

[0030] like Figure 1 As shown, the sensor electrode 100 of this invention uses an L-shaped flexible polymer substrate, specifically an L-shaped flexible polyimide substrate, and includes an implantation arm and a connecting arm. The implantation arm is slender, with a length of 5–20 mm and a width of 0.5–2 mm, and a rounded end structure, which facilitates minimally invasive subcutaneous implantation and reduces tissue damage. The connecting arm is wider and is used to arrange conductive contacts and connect to the transmitter. The structure transitions smoothly to avoid stress concentration.

[0031] The sensor employs a four-electrode system. Two sets of pure carbon working electrodes, designated as the first working electrode 103 and the second working electrode 108, are screen-printed on the front side of an L-shaped flexible polyimide substrate using carbon paste. The surfaces of these two pure carbon working electrodes are modified with glucose oxidase using a layered spraying cross-linking fixation process: first, a base layer containing Nafion is sprayed; then, a glucose oxidase buffer solution is sprayed; finally, a glutaraldehyde cross-linking sealing layer is sprayed. This three-layer composite coating covalently fixes the glucose oxidase to the working electrode surface, preventing enzyme detachment. An Ag / AgCl reference electrode 104 and a pure carbon counter electrode 107 are printed on the reverse side of the L-shaped flexible polyimide substrate. Four sets of conductive contacts are formed at the end of the connecting arm: a reference electrode contact 101 and a first working electrode contact 102 on the front side; a second working electrode contact 105 and a counter electrode contact 106 on the back side. These four sets of conductive contacts correspond one-to-one with the elastic springs of the transmitter's circuit board 232.

[0032] After the sensor is implanted subcutaneously, glucose oxidase on the surface of the working electrode undergoes a specific enzymatic reaction with glucose in the tissue fluid, generating a current signal related to glucose concentration. The reference electrode 104 provides a stable reference potential, and the counter electrode 107 forms a current loop. The current signal is transmitted to an external device via wires and converted into glucose concentration using a standard curve, enabling long-term, stable, and continuous glucose monitoring. The dual-working-electrode arrangement can provide redundant detection signals or achieve differential detection, further suppressing common-mode interference and improving detection accuracy.

[0033] like Figures 2 to 4 As shown, the needle assist device 200 consists of components such as a needle assist device upper cover 210, a needle assist device lower cover 220, a rotating cover 221, a needle assist spring 212, a needle withdrawal spring 213, a sensor bracket 214, a puncture needle 215, a needle withdrawal bracket 217, and a transmitter bracket 216. It has a simple structure and is easy to operate, enabling rapid assembly of the sensor and the puncture needle 215, precise puncture, and automatic needle withdrawal.

[0034] The upper cover 210 and lower cover 220 of the needle aid device are fitted together by a snap-fit ​​mechanism to form a housing. A transverse guide hole 238 is provided on the side of the upper cover 210. The needle aid device button 211 is inserted into the transverse guide hole 238 in a horizontally slidable manner. At least one set of elastic locking claws 2111 extends from the end of the button 211. In the initial unactivated state, the elastic locking claws 2111 are tightly engaged with the inner wall of the upper cover 210. The upper surface of the button 211 is tightly abutted with several limiting heads 2161 of the transmitter bracket 216, which limit and lock the needle aid spring 212, which is already in a pre-compressed state, to prevent it from being released accidentally. After pressing the needle assist button 211, the elastic locking claw 2111 is compressed, the needle assist button 211 moves inward, and the upper end face of the needle assist button 211 separates from the limiting head 2161 of the transmitter bracket 216. The needle assist spring 212 is then released to provide puncture power. The rotating cover 221 is located at the end of the housing and is used to rotate and unlock the puncture needle barrel 234 component, while preventing accidental pressing of the needle assist button 211 during transportation and storage to trigger puncture. The needle assist spring 212 and the needle retraction spring 213 are coaxially arranged in the housing, providing puncture power and needle retraction reset force respectively: when the needle assist spring 212 is released, it pushes the puncture needle 215 forward quickly to complete the subcutaneous puncture; the needle retraction spring 213 is released and rebounds after the puncture is in place, driving the puncture needle 215 to detach from the tissue and retract into the housing. The whole process is automated and minimally invasive.

[0035] The sensor bracket 214 is fixed in the middle of the housing and is used to clamp the connecting arm of the sensor electrode 100, ensuring that the implantation arm of the sensor electrode 100 is coaxially aligned with the puncture needle 215, thus ensuring the stability of the sensor electrode 100 and the precise implantation position during puncture. The puncture needle 215 is a hollow needle with a wall thickness of 0.05mm to 0.15mm, a sharp tip, and a small outer diameter, which drives the implantation arm of the sensor electrode 100 to enter the subcutaneous tissue simultaneously during puncture.

[0036] The needle retraction bracket 217 is connected to the tail end of the puncture needle 215. Under the action of the needle retraction spring 213, the puncture needle 215 is quickly retracted, avoiding discomfort or infection risk caused by needle retention. The transmitter bracket 216 is located at the front end of the housing and is used to fix the transmitter. After puncture, the transmitter can be directly aligned and fastened with the connecting arm of the sensor electrode 100, simplifying the wearing process.

[0037] like Figure 3 and Figure 4 As shown, the transmitter has a miniaturized package structure, mainly composed of transmitter top cover 231, transmitter bottom cover 233, circuit board 232 and electrode fixing base 235. The overall shape is small and thin, suitable for wearing on the human body surface, and has both structural strength and waterproof and dustproof capabilities.

[0038] The transmitter top cover 231 is injection molded from medical-grade engineering plastic, with a smooth surface that conforms to the skin, providing both protection and fixation. The transmitter bottom cover 233 is sealed to the transmitter top cover 231 via snap-fit ​​or ultrasonic welding, forming a closed cavity that houses the circuit board 232 and electrode mounting base 235, providing excellent moisture resistance, sweat resistance, and biocompatibility.

[0039] Circuit board 232 is the core functional module, integrating signal amplification, filtering, analog-to-digital conversion, microprocessing, and wireless communication units. Circuit board 232 achieves reliable connection with the four sets of conductive contacts (reference electrode contact 101, first working electrode contact 102, second working electrode contact 105, and counter electrode contact 106) of sensor electrode 100 through spring contacts. The first working electrode 103 and the second working electrode 108 output detection current signals related to glucose concentration, the reference electrode 104 outputs a stable potential reference signal, and the counter electrode 107 circuit provides compensation current. Circuit board 232 collects the detection current of the two sets of working electrodes, and combines the potential calibration of the reference electrode 104 and the current of the counter electrode 107 circuit to complete the signal closed-loop conversion of glucose concentration.

[0040] The electrode holder 235 is located inside the transmitter's lower cover 233. The electrode holder 235 has internal adhesive padding for cushioning, allowing for quick and secure engagement of the sensor electrode 100's connecting arm. This ensures precise alignment and stable contact between the four sets of conductive contacts of the sensor electrode 100 and the spring contacts of the circuit board 232, preventing poor contact due to shaking or pulling during wear. The electrode holder 235 is sealed internally with adhesive to reduce the impact of mechanical stress on the sensor electrode 100, while also ensuring stable signal transmission.

[0041] The transmitter features a low-power design with a built-in micro battery, allowing for continuous operation for several days to two weeks. Its IPX7 sealing rating meets daily waterproof and sweatproof requirements, making it suitable for extended wear.

[0042] like Figure 5 As shown, the sterilization barrier is composed of a puncture needle 215, a sensor electrode 100, an electrode holder 235, a transmitter lower cover 233, and a puncture needle barrel 234, forming an integrated sterile protective cavity from the implantation end to the transmitter assembly area, ensuring that key components are in a sterile isolation state throughout the implantation process and avoiding microbial contamination.

[0043] The puncture needle 215 is sealed and enclosed by the puncture needle barrel 234, forming a sterile isolation cavity at the front end to prevent the puncture needle 215 from contacting the external non-sterile environment. The implantation arm of the sensor electrode 100 is pre-installed in the inner cavity of the puncture needle 215. The connecting arm of the sensor electrode 100 is limited and fixed by the electrode fixing seat 235, and the whole is placed in the sterile cavity. The electrode contact end of the connecting arm is connected to the sterile area inside the transmitter lower cover 233. The transmitter lower cover 233, as the rear sealing element of the sterilization barrier, fits tightly with the puncture needle barrel 234 and the electrode fixing seat 235 to form a closed sterile space and block the invasion path of external microorganisms.

[0044] The puncture needle 215 includes a puncture needle silicone ring 218, the puncture needle syringe 234 includes a syringe silicone ring 236 set by secondary injection molding or assembly, and the bottom includes a syringe silicone plug 237 for sealing. The multiple sealing structure ensures the reliability of the sterile barrier.

[0045] During the factory assembly stage, the implantation arm of the sensor electrode 100 is inserted into the inner cavity of the puncture needle 215, and the connecting arm of the sensor electrode 100 is snapped into the electrode fixing seat 235. The puncture needle 215 is housed inside the puncture needle barrel 234, and the barrel silicone ring 236 and the puncture needle silicone ring 218 form a multi-layer radial seal, while the barrel silicone plug 237 seals the bottom. The transmitter lower cover 233 fits tightly against the upper end of the puncture needle barrel 234, and together with the electrode fixing seat 235, they enclose and seal the sterile cavity, forming a complete sterilization barrier. The entire device is sterilized using integrated ethylene oxide sterilization, eliminating the need to separate the electrodes, puncture needles, and transmitter for separate sterilization, thus avoiding problems such as enzyme inactivation and circuit board irradiation damage.

[0046] The working method of the four-electrode sterile implantable blood glucose monitoring sensor assembly provided by the present invention is as follows: S1: When in use, rotate the rotating cover 221 to the unlocked state, and the puncture needle syringe 234 rotates together with the rotating cover 221 to unlock the sealing structure.

[0047] S2: Remove the lower cover 220 of the needle aid and the silicone stopper 237 of the syringe barrel 234 of the puncture needle.

[0048] S3: Press the needle assist button 211, the needle assist spring 212 is released, and the puncture needle 215 is pushed forward quickly along the axis to complete the subcutaneous puncture. The implantation arm of the sensor electrode 100 enters the subcutaneous tissue simultaneously.

[0049] S4: After the puncture is completed, the needle withdrawal spring 213 is released and rebounds, causing the needle withdrawal bracket 217 and the puncture needle 215 to detach from the tissue and retract into the housing.

[0050] S5: Remove the needle aid 200, align and fasten the transmitter on the transmitter bracket 216 with the connecting arm of the sensor electrode 100, and electrically connect the four sets of conductive contacts of the sensor electrode 100 with the corresponding spring contacts of the circuit board 232.

[0051] S6: The glucose oxidase on the surface of the first working electrode 103 and the second working electrode 108 undergoes an enzymatic reaction with glucose in the human tissue fluid to generate a current signal. The reference electrode 104 provides a reference potential, and the counter electrode 107 forms a current loop.

[0052] S7: The circuit board 232 receives the current signal output from the four electrodes. After amplification, filtering, and analog-to-digital conversion, the microprocessor performs differential detection and concentration calculation, and uploads the glucose concentration data to the external terminal in real time through the wireless communication unit.

[0053] Example 2 Please see Figure 6 and Figure 7 As shown, this embodiment provides a four-electrode subcutaneous blood glucose sensor with an integrated sterilization barrier, comprising three parts: a sensor electrode 100, a needle assist device 200, and a transmitter. The sensor electrode 100 and the transmitter have the same structure as in Embodiment 1. The needle assist device 200 also consists of components such as a needle assist device upper cover 210, a needle assist device lower cover 220, a rotating cover 221, a needle assist spring 212, a needle withdrawal spring 213, a sensor support 214, a puncture needle 215, a needle withdrawal support 217, and a transmitter support 216.

[0054] The difference between this embodiment and implementation 1 is that: an axial guide hole 239 is provided in the center area of ​​the top surface of the needle aid cover 210, and the needle aid button 211 is embedded in the axial guide hole 239 in a manner that can slide up and down along the axial direction.

[0055] The mechanical central axis of the needle assist button 211, the elastic release axis of the needle assist spring 212 and the needle withdrawal spring 213, and the subcutaneous movement trajectory line of the puncture needle 215 guiding the sensor electrode 100 implantation arm are all located on the same vertical axis in space (i.e., coaxial and collinear configuration).

[0056] The lower end of the needle assist button 211 is provided with at least one set of elastic locking claws 2111. In the initial unactivated state, the elastic locking claws 2111 are tightly engaged with the limiting step 2101 provided on the inner wall of the needle assist cover 210, limiting and locking the needle assist spring 212, which is already in a pre-compressed high-energy state, to prevent it from being released accidentally. The sensor bracket 214, the needle retraction bracket 217, and the transmitter bracket 216 are all arranged sequentially along this axis in the inner cavity of the housing.

[0057] When the user applies a downward, vertical pressure to the top surface of the needle aid button 211, the button 211 overcomes the initial static friction and moves downward along the axial guide hole 239. During the displacement, the elastic locking claw 2111 is squeezed by the guide ramp of the inner wall of the needle aid, undergoing radially inward elastic contraction deformation, and thus completely disengaging from the limiting step 2101.

[0058] At this moment, the axial elastic potential energy of the needle-assisted spring 212 is released instantaneously, generating a downward high transient driving force. This force propels the needle-retracting bracket 217 and the puncture needle 215, along with the implantation arm of the sensor electrode 100, downward at high speed along the coaxial axis, completing the invasive implantation of the sensor electrode 100 into the subcutaneous tissue fluid. When the needle-retracting bracket 217 and the puncture needle 215 are pushed to the preset maximum puncture depth, the locking protrusion on the outer periphery of the needle-retracting bracket 217 abuts against the preset limiting block on the inner wall of the lower cover 220 of the needle-assisted device. This forces the locking protrusion to undergo inward elastic deformation, thereby releasing the axial locking of the needle-retracting spring 213. At this time, the elastic potential energy of the needle-retracting spring 213, which is in a compressed state, is released, generating a rebound force that drives the puncture needle 215 to quickly retract upward and back into the housing, achieving needle-body separation.

[0059] Compared to the side-button lateral trigger mode in Embodiment 1, the design of relocating the button to the top of the needle assist device improves the problem of mechanical instability caused by lateral forces. Specifically, it exhibits the following significant and beneficial technical effects: 1. Effectively reduces lateral shear force and overturning moment, ensuring the vertical puncture accuracy of the four-electrode system.

[0060] When the user presses the side button, the direction of force is perpendicular to the direction of movement of the puncture needle. Uneven force application can easily cause a lateral component force to be generated in the entire needle aid device. This can cause a slight horizontal slippage or angular tilt of the contact surface between the lower cover of the needle aid device and the skin at the moment of activation, making it impossible for the puncture needle to penetrate at the preset vertical angle. This can easily cause the flexible sensor electrode to bend or fold under the skin, or fail to reach the preset tissue layer, resulting in signal distortion.

[0061] The downward pressure of the top button is completely coaxial with the direction of needle advancement. The user-applied activation force avoids any lateral interference, instead transforming into a normal pressure force between the lower cover of the needle and the skin. This positive pressure firmly locks the lower cover of the needle onto the skin surface, effectively preventing any shaking or deflection of the casing during activation, ensuring the needle enters the subcutaneous tissue vertically. This is crucial for the four-electrode technology involved in this invention, because only by ensuring that the working electrode, counter electrode, and reference electrode have highly consistent and stable preset spatial geometric poses in the complex subcutaneous tissue fluid can signal baseline drift be effectively suppressed, leveraging the high precision and anti-interference advantages of the four electrodes.

[0062] 2. A physical linkage mechanism of first normal compression and then threshold activation is constructed to significantly reduce the patient's puncture pain.

[0063] When the side button is pressed, it cannot apply a direct pre-tightening force to the skin underneath. At the moment the puncture needle pierces the skin, the skin's elasticity causes significant inward indentation and parasitic rebound (elastic cushioning behavior), which prolongs the time it takes for the needle tip to pierce the epidermis, increases puncture resistance, and thus leads to significant clinical pain and micro-trauma tearing.

[0064] When using the top axial button, the downward pressure applied by the finger is first transmitted completely through the outer shell of the needle guide to the contact surface between the lower cover of the needle guide and the skin before reaching the critical threshold of the elastic locking claw's deformation and release. This means that before the puncture needle is ejected, the local epidermis is pre-pressed downwards, flattened, and maintained in a state of high tension (passively tightened skin). When the button displacement reaches the critical point and the claw disengages instantaneously, the thin-walled hollow puncture needle can pierce the epidermis at extremely high speed while the skin is under high tension and with zero rebound. The above-mentioned linkage structure of button pressure and spring release shortens the time for the needle tip to pierce the epidermis, achieving minimally invasive implantation and helping to reduce patient discomfort during implantation.

[0065] 3. Optimize the stress field distribution of the internal structure to significantly improve the long-term stability of the sterile barrier and mechanical seal.

[0066] Laterally excited asymmetric forces can cause long-term unilateral bending stress on precision injection-molded components inside the needle amplifier (such as sensor holders and transmitter holders). Over the product's shelf life of several years, material creep can cause this asymmetric stress concentration to lead to minute plastic deformation of the snap-fit ​​mechanism, resulting in misalignment of the internal alignment components. More seriously, asymmetric forces can disrupt the balanced radial sealing force between the puncture needle's silicone ring and the syringe's silicone plug, leading to microleakage in the sterile cavity and failure to pass stringent medical device sterility testing.

[0067] The axial force at the top ensures that the internal stress field of the entire needle aid housing and internal sterilization barrier components (puncture needle barrel, electrode holder, etc.) is completely axisymmetrically distributed throughout its entire life cycle and at the moment of activation. This completely symmetrical mechanical structure eliminates any risk of warping or deformation of the injection molded parts due to stress concentration, effectively maintaining the mechanical seal stability of the integrated sterile cavity from the time the product leaves the factory until the rotating cap is removed, effectively blocking the risk of bacterial contamination and improving the safety and reliability of the entire device.

[0068] The preferred embodiments of the present invention have been described in detail above and should not be construed as limiting the scope of the invention. All equivalent variations and modifications made within the scope of the claims of this invention should still fall within the patent coverage of this invention.

Claims

1. A four-electrode subcutaneous blood glucose sensor with an integrated sterilization barrier, characterized in that, include: The sensor electrode uses an L-shaped flexible polymer substrate and includes an implantation arm and a connecting arm. The implantation arm is used for subcutaneous implantation, and the connecting arm is used to arrange conductive contacts and connect to the transmitter. The sensor electrode adopts a four-electrode system, including a first working electrode, a second working electrode, a reference electrode, and a counter electrode. The first and second working electrodes are arranged on one side of the L-shaped flexible polymer substrate, and the reference electrode and the counter electrode are arranged on the other side of the L-shaped flexible polymer substrate. The needle assist device includes a housing, a needle assist spring, a needle retraction spring, a sensor bracket, a puncture needle, a needle retraction bracket, and a transmitter bracket. The needle assist spring and the needle retraction spring are arranged coaxially. The needle assist spring provides puncture power, and the needle retraction spring provides needle retraction return force. The sensor bracket is used to hold the connecting arm of the sensor electrode, ensuring that the implantation arm of the sensor electrode is coaxially aligned with the puncture needle. The puncture needle is a hollow needle with a wall thickness of 0.05mm to 0.15mm, used to drive the implantation arm of the sensor electrode into the subcutaneous tissue synchronously. The needle retraction bracket is connected to the tail end of the puncture needle, enabling rapid retraction of the puncture needle under the action of the needle retraction spring. The transmitter bracket is used to fix the transmitter. The transmitter includes a transmitter upper cover, a transmitter lower cover, a circuit board, and an electrode holder; the transmitter upper cover and transmitter lower cover are sealed together to form a closed cavity, the circuit board is disposed in the closed cavity, and the electrode holder is disposed inside the transmitter lower cover to engage the connecting arm of the sensor electrode, so that the conductive contact of the sensor electrode is aligned and connected with the spring contact of the circuit board. The sterilization barrier is a closed sterile cavity formed by the puncture needle, the puncture needle barrel, the electrode holder, and the transmitter cover. The implantation arm of the sensor electrode is pre-installed in the inner cavity of the puncture needle and is entirely contained within the sterile cavity.

2. The four-electrode subcutaneous blood glucose sensor with an integrated sterilization barrier according to claim 1, characterized in that, The housing includes an upper cover and a lower cover for the needle assist device. A transverse guide hole is provided on the side of the upper cover. The needle assist device button is slidably installed in the transverse guide hole. At least one set of elastic locking claws extends from the end of the button. The elastic locking claws are tightly locked on the inner wall of the upper cover. The upper surface of the button is tightly connected to several limiting heads of the transmitter bracket to limit and lock the needle assist spring in a pre-compressed state.

3. A four-electrode subcutaneous blood glucose sensor with an integrated sterilization barrier according to claim 1, characterized in that, The housing includes an upper cover and a lower cover of the needle aid. An axial guide hole is provided at the center of the top surface of the upper cover. The needle aid button is slidably installed in the axial guide hole. At least one set of elastic locking claws extends from the lower end of the needle aid button. The elastic locking claws are tightly engaged with the limiting step provided on the inner wall of the upper cover of the needle aid, thereby limiting and locking the needle aid spring in a pre-compressed state.

4. A four-electrode subcutaneous blood glucose sensor with an integrated sterilization barrier according to claim 2 or 3, characterized in that, The implantation arm of the sensor electrode is 5-20 mm long and 0.5-2 mm wide, with a rounded end; the connecting arm of the sensor electrode is wider than the implantation arm.

5. A four-electrode subcutaneous blood glucose sensor with an integrated sterilization barrier according to claim 2 or 3, characterized in that, Both the first and second working electrodes are pure carbon working electrodes, the reference electrode is an Ag / AgCl reference electrode, and the counter electrode is a pure carbon counter electrode. Glucose oxidase is sprayed onto the surfaces of the first and second working electrodes.

6. A four-electrode subcutaneous blood glucose sensor with an integrated sterilization barrier according to claim 2 or 3, characterized in that, The upper cover and lower cover of the needle aid are connected by a snap-fit ​​mechanism to form a housing, and a rotating cover is provided at the end of the housing.

7. A four-electrode subcutaneous blood glucose sensor with an integrated sterilization barrier according to claim 6, characterized in that, The puncture needle cartridge is installed inside the rotating cover. When the rotating cover is rotated to unlock, the puncture needle cartridge rotates synchronously with the rotating cover, and the seal between the puncture needle cartridge and the lower cover of the transmitter is released.

8. A four-electrode subcutaneous blood glucose sensor with an integrated sterilization barrier according to claim 2 or 3, characterized in that, The puncture needle includes a puncture needle silicone ring, and the puncture needle barrel includes a barrel silicone ring and a barrel silicone plug. The barrel silicone ring is set on the upper end of the puncture needle barrel by secondary injection molding or assembly, and the barrel silicone plug is set on the bottom of the puncture needle barrel for sealing.

9. A four-electrode subcutaneous blood glucose sensor with an integrated sterilization barrier according to claim 2 or 3, characterized in that, The circuit board connects to the reference electrode contact, the first working electrode contact, the second working electrode contact, and the counter electrode contact via spring contacts, respectively, for acquiring the four-electrode output current signal.

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