Interventional LC passive wireless continuous tissue internal pressure monitoring sensor

Abstract

The invention relates to the field of electronic medical instruments, in particular to a sensor capable of continuously monitoring internal pressure of tissue based on an LC oscillating circuit. The invention aims to overcome the defects in the background technology, and provides an intrusive LC passive wireless continuous tissue internal pressure monitoring sensor which has the characteristics of convenience in use and accuracy in measurement. According to the technical scheme, the intrusive LC passive wireless continuous pressure sensor is characterized by comprising a base, a probe and a pressure detection circuit; the probe is vertically fixed at the center of the base; the pressure detection circuit comprises a capacitor arranged on the probe and an inductor arranged on the base; the sensor is formed by folding and bonding a flexible circuit board.

Description

Technical Field

[0001] The present invention relates to the field of electronic medical devices, and in particular to a sensor based on an LC oscillation circuit capable of continuously monitoring the pressure inside tissues. Background Art

[0002] Pressure monitoring within tissues can enable the diagnosis and treatment of tissue diseases, a typical example being intraocular pressure. Intraocular pressure monitoring is a very important diagnostic technology in the field of ophthalmology. Early diagnosis and treatment are crucial for eye diseases such as glaucoma. Glaucoma is the second leading cause of blindness worldwide, and its irreversible optic nerve damage is closely related to the continued increase in intraocular pressure. Therefore, accurate measurement of intraocular pressure is of great significance for the management of glaucoma. Currently, most clinical tonometer measurements are "snapshots", that is, they can only measure intraocular pressure at a certain moment. Continuous monitoring of intraocular pressure can provide a comprehensive view of intraocular pressure changes. In comparison, the data obtained from continuous intraocular pressure testing can help doctors make more accurate diagnoses for patients and even determine the exact dosage of medication for patients.

[0003] Despite the many advances in intraocular pressure monitoring technology in recent years, existing technologies still have limitations. Although traditional intraocular pressure measurement methods are considered the gold standard for intraocular pressure measurement, these methods are difficult to achieve 24-hour continuous monitoring and have a significant impact on patients' daily activities. Non-contact tonometers and rebound tonometers usually require trained clinicians to operate. In addition, the inability to monitor continuously makes it difficult to collect key intraocular pressure fluctuations in patients, and the value of the measured data is very limited. In addition, although some wearable corneal contact lens sensors can achieve continuous monitoring, they mainly rely on changes in corneal curvature to indirectly measure intraocular pressure. The accuracy of this method is limited because it requires calibration of the relationship between intraocular pressure and corneal curvature for each patient.

[0004] Unlike traditional measurement methods, the LC resonant sensor monitors changes in pressure-measuring capacitance and converts them into electrical signals, improving measurement accuracy. This electrical signal is wirelessly transmitted from the sensor's serpentine inductor to an external inductor with which it interacts. The signal received by the external inductor is then processed using precision instruments such as an impedance analyzer. The key to this technology lies in accurately converting the internal pressure of the tissue being measured into a signal that is easily readable and analyzable. Summary of the Invention

[0005] The purpose of the present invention is to overcome the deficiencies in the above-mentioned background technology and to provide an invasive LC passive wireless continuous tissue internal pressure monitoring sensor, which should be easy to use and have accurate measurement characteristics.

[0006] The technical solution of the present invention is:

[0007] An intrusive LC passive wireless continuous pressure sensor, characterized by comprising a base, a probe and a pressure detection circuit;

[0008] The probe is fixed vertically to the center of the base; the pressure detection circuit includes a capacitor arranged on the probe and an inductor arranged on the base; and the sensor is formed by folding and bonding a flexible circuit board.

[0009] The flexible circuit board includes a main body as a base and branches extending from both sides of the main body as probes; the branches include a first folding arm and a second folding arm.

[0010] The folding includes: the first folding arm is folded to be close to the bottom surface of the body, and the second folding arm is folded to form the probe.

[0011] The inductor is a coil located on the top surface of the main body; the capacitor is an electrode sheet located on the bottom surfaces of the two second folding arms; and both ends of the inductor are connected to the electrode sheets respectively through wires.

[0012] The bottom surface of the second folding arm is further provided with a spacing unit; the spacing units are respectively located above and below the probe capacitor.

[0013] An expansion unit is further provided on the bottom surface of the second folding arm; the expansion unit is located above the capacitor of the probe.

[0014] The probe comprises, from top to bottom, a rectangular parallelepiped needle rod, a quadrangular pyramid-shaped needle head and a quadrangular pyramid-shaped needle tip.

[0015] In one of the branches: the front end of the second folding arm is provided with a first extension piece and a second extension piece, the side of the second folding arm is provided with a first side edge, the side of the first extension piece is provided with a second side edge, and the side of the second extension piece is provided with a third side edge; in the other branch: the front end of the second folding arm is provided with a first folding piece and a second folding piece, the side of the second folding arm is provided with a fourth side edge, and the front end of the fourth side edge is provided with a third folding piece and a fourth folding piece.

[0016] The needle rod is formed by the second folding arm, the first side and the fourth side; the needle head is formed by the first extension piece, the second side, the first folding piece and the third folding piece; the needle tip is formed by the second extension piece, the third side, the second folding piece and the fourth folding piece.

[0017] A first flange is provided on the side surface of the first side edge; and a second flange is provided on the side surface of the fourth side edge.

[0018] The beneficial effects of the present invention are:

[0019] 1. The present invention is designed based on an LC oscillation circuit and can sensitively monitor signals. Moreover, since the signal is transmitted wirelessly, the reduction in measurement accuracy caused by excessive wiring is avoided.

[0020] 2. The present invention does not require energy supply, avoids the risk of battery leakage, reduces the possibility of circuit failure, and improves the safety of patients wearing sensors.

[0021] 3. The present invention is formed by folding a flexible printed circuit (FPC), and the circuit design is simple and easy to manufacture.

[0022] 4. The present invention is small in size and stable in structure, and can be worn for a long time. Moreover, the fluctuation of intraocular pressure can be continuously recorded anytime and anywhere by wearing a portable reading device integrated into glasses, eye masks, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of the three-dimensional structure of the present invention.

[0024] Figure 2 It is a schematic diagram of the three-dimensional structure of the present invention (semi-expanded state).

[0025] Figure 3 It is a schematic diagram of the three-dimensional structure of the present invention (expanded state).

[0026] Figure 4 It is a schematic diagram of the top structure of the present invention (expanded state).

[0027] Figure 5 It is a bottom view structural schematic diagram of the present invention (expanded state).

[0028] Figure 6 It is a schematic diagram of the present invention intervening in the eyeball.

[0029] Figure 7 It is a schematic diagram of the usage of the present invention and an external reading device.

[0030] Figure 8 It is a spatial structure diagram of the pressure detection circuit of the present invention.

[0031] Figure 9 It is a topological diagram of the present invention and an external reading device;

[0032] Reference numerals:

[0033] Base 1, probe 2, needle rod 2-1, needle head 2-2, needle tip 2-3, main body 3, branch 4, first folding arm 4-1, second folding arm 4-2, first extension piece 4-31, second extension piece 4-32, first side 4-41, second side 4-42, third side 4-43, fourth side 4-44, first folding piece 4-51, second folding piece 4-52, third folding piece 4-53, fourth folding piece 4-54, first flange 4-61, second flange 4-62, coil 5-1, electrode sheet 5-2, wire 5-3, through hole 5-4, stretching part 5-5, spacer unit 6, expansion unit 7, eyeball 10, reading device 11. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0035] The present invention provides an invasive LC passive wireless continuous pressure sensor, which inserts a pressure detection circuit into the tissue, so that the internal pressure of the tissue is converted into electric current and magnetic field in sequence, and the magnetic field signal is read by an external reading device, thereby realizing real-time monitoring of the internal pressure of the tissue. This overcomes the defect of the existing technology that it is difficult to measure the internal pressure of the tissue, and has extremely high medical value.

[0036] like Figure 1 As shown, an intrusive LC passive wireless continuous pressure sensor includes a base 1, a probe 2 and a pressure detection circuit.

[0037] The probe is fixed vertically to the center of the base. The probe monitors the pressure change of the internal vitreous body by intervening in the eyeball. The base is located outside the eyeball and does not intervene in the eyeball.

[0038] like Figure 1 As shown, the base is disc-shaped, and the probe extends vertically downward from the center of the bottom surface of the base. The probe includes a needle shaft 2-1, a needle head 2-2, and a needle tip 2-3 from top to bottom. The needle shaft is a rectangular parallelepiped, the needle head is a quadrangular pyramid, and the needle tip is a quadrangular pyramid. The cross-sections of the needle head and needle tip gradually decrease from top to bottom.

[0039] The pressure detection circuit is provided on the base and the probe, and is used to sequentially convert changes in eyeball pressure into electrical signals and magnetic fields. The pressure detection circuit is an LC oscillator circuit, including a capacitor and an inductor. The capacitor is a pair of parallel electrode sheets 5-2 provided on the probe. The inductor is a coil 5-1 provided on the base, and the coil is a spiral wire extending from the inside out and curved in a wavy shape. The two ends of the inductor are respectively connected to the two electrode sheets via a wire 5-3.

[0040] The sensor is formed by folding and bonding a flexible circuit board. The base layer of the flexible circuit board serves as the base and probe of the sensor, and the conductive layer of the flexible circuit board serves as the pressure detection circuit of the sensor.

[0041] like Figure 2 、 Figure 3 、 Figure 4 、 Figure 5 As shown, the flexible circuit board includes a body 3 and two branches 4 extending from either side of the body. The body serves as the sensor base, and the branches, after being folded and bonded, serve as the sensor probes. The branches include a first folding arm 4-1 and a second folding arm 4-2, with the second folding arm connected to the body via the first folding arm.

[0042] In one of the branches: the front end of the second folding arm (the end close to the needle tip) is provided with a first extension piece 4-31 and a second extension piece 4-32, the side of the second folding arm is provided with a first side edge 4-41, the side of the first extension piece is provided with a second side edge 4-42, and the side of the second extension piece is provided with a third side edge 4-43; the side of the first side is provided with a first flange 4-61; the first side edge is connected to the second side edge, and the second side edge is not connected to the third side edge.

[0043] In the other branch: the front end of the second folding arm (the end close to the needle tip) is provided with a first folding piece 4-51 and a second folding piece 4-52, the side of the second folding arm is provided with a fourth side edge 4-44, and the front end of the fourth side edge is provided with a third folding piece 4-53 and a fourth folding piece 4-54; the side of the fourth side edge is provided with a second flange 4-62; the first folding piece is not connected to the third folding piece; the third folding piece is not connected to the fourth folding piece.

[0044] The electrode sheet is located on the bottom surface of the second folding arm ( Figure 5 The electrode sheets on both sides are located inside the probe rod and arranged in parallel after folding. The wire is located at the bottom surface of the first folding arm, the second folding arm and the body ( Figure 5 The main body is provided with two through holes 5-4 that pass through the top and bottom surfaces, and the wires pass through the through holes and connect the two ends of the inductor.

[0045] The folded parts include:

[0046] 1. Folding is performed between the main body and the first folding arm; folding is performed between the first folding arm and the second folding arm;

[0047] 2. The second folding arm, the first extension piece, and the second extension piece are connected as one body and are not folded; the first side edge and the second side edge are connected as one body and are not folded; the second folding arm and the first side edge are folded; the first extension piece and the second side edge are folded; the second extension piece and the third side edge are folded; and the first side edge and the first flap are folded;

[0048] 3. Fold between the second folding arm and the first folding piece; fold between the first folding piece and the second folding piece; fold between the second folding arm and the fourth side; fold between the fourth side and the third folding piece; fold between the third folding piece and the fourth folding piece; fold between the fourth side and the second flange.

[0049] The folding methods include:

[0050] 1. A 180-degree mountain fold is used between the main body and the first folding arm so that the first folding arm is close to the bottom surface of the main body;

[0051] 2. A 90-degree valley fold is used between the first folding arm and the second folding arm so that the two second folding arms are folded in parallel to form a probe;

[0052] 3. The second folding arm, the first side, the fourth side, the first flange, and the second flange are folded to form a needle bar;

[0053] 4. The first extension piece, the second side, the first folding piece and the third folding piece are folded together to form a needle head;

[0054] 5. The second extension piece, the third side, the second folding piece and the fourth folding piece are folded to form a needle tip.

[0055] 6. The overlapping parts after folding need to be bonded with adhesive to ensure the stability of the structure;

[0056] 7. Adhesive coating is applied between the first flange of one branch and the second folded arm of the other branch, and between the second folded arm of one branch and the second flange of the other branch; the flanges are used for bonding to ensure that the capacitor is enclosed in the sealed structure;

[0057] 8. The adhesive is also coated between the second side 4-42 and the first folding sheet 4-51, between the first folding sheet 4-51 and the third folding sheet 4-53, between the third folding sheet 4-53 and the first extension sheet 4-31, between the third side 4-43 and the second folding sheet 4-52, between the second folding sheet 4-52 and the fourth folding sheet 4-54, and between the fourth folding sheet 4-54 and the second extension sheet 4-32; since there is no sealing requirement for the needle head and the needle tip, no corresponding flange is set for bonding; in order to ensure that the electrode sheets on both sides are arranged in parallel and do not touch, a spacing unit 6 is set on the bottom surface of the second folding arm. After folding, the second folding arms on both sides are blocked by the spacing unit so as to always maintain a fixed distance. Figure 5 As shown, the spacing unit is arranged on the bottom surface of one of the branches and is located at both ends of the electrode sheet. Figure 2 As shown, the spacing units are arranged above and below the capacitor.

[0058] The spacer unit is made of a biocompatible material suitable for contact with human tissue, such as polytetrafluoroethylene (PTFE), polyethylene terephthalate (PET), medical-grade silicone, or double-sided adhesive PI with a suitable thickness bonded to a flexible circuit board. Other materials may also be used.

[0059] The spacer unit, the second folding arm, the first side, and the fourth side form a sealed structure, and the capacitor is wrapped inside the sealed structure to prevent the aqueous humor in the vitreous body from invading between the electrode sheets, thereby ensuring the accuracy of pressure monitoring.

[0060] The sharp shape of the needle tip can facilitate the sensor probe to enter the eye through a small incision on the eyeball. In order to prevent the outflow of aqueous humor in the vitreous body after the intervention, an expansion unit 7 is also provided on the probe. The expansion unit is located at the top of the probe. After the expansion unit absorbs the aqueous humor, the volume increases and the incision is blocked to prevent the outflow of aqueous humor. Figure 5 As shown, the expansion unit is arranged on the bottom surface of the second folding arm of one of the branches and is located at the inner end of the second folding arm (close to the side of the body). Figure 2 As shown, the expansion unit is located above the spacing unit and outside the sealing structure. The expansion unit is made of a material that is easy to absorb water and expand and has biocompatibility, such as silicone hydrogel.

[0061] The spacing unit and the expansion unit are both fixed by bonding.

[0062] The flexible circuit board is thin and made of soft material. When the probe is inserted into the eyeball, the body bends in an arc shape due to close contact with the surface of the eyeball. The wavy coil can better adapt to the tension generated by the deformation of the body.

[0063] A laser cutting stage is needed to cut along the folding line (do not cut through the flexible circuit board and avoid the conductive layer) to make the flexible circuit board easier to fold.

[0064] Since a valley fold is adopted between the first folding arm and the second folding arm, the conductor is provided with a wavy curved stretching portion 5-5 at the folding position, so that the conductor can adapt to the tension generated during folding, ensuring that good electrical conductivity is maintained after folding.

[0065] The working principle of the present invention is:

[0066] An incision is made on the surface of the eyeball 10 (the size of the incision is determined by the size of the probe, the length of the incision is slightly larger than the size of the needle tip, and the difference between the length of the incision and the side length of the probe cross section is less than 1 mm). The probe is inserted into the eyeball through the incision, with the base close to the surface of the eyeball; the pressure detection circuit can sensitively monitor the pressure changes of the vitreous body inside the eyeball; when the vitreous body pressure changes, the spacing between the electrode plates of the capacitor of the pressure detection circuit changes, thereby generating a current. When the current passes through the inductor, a magnetic field is generated. Finally, the external reading device 11 obtains the intraocular pressure change signal through the magnetic field, realizing wireless transmission of the signal. The present invention safely and effectively transmits the intraocular pressure change signal to the reading device through this wireless transmission method.

[0067] In the reading device: the mutual inductance coil and the inductor form a mutual inductance coupling, converting the magnetic field into current, realizing wireless signal transmission; the impedance analyzer (including the signal measurement resistance module and the impedance analysis module) is responsible for in-depth analysis and processing of the received current signal; the impedance analysis module measures the impedance of the mutual inductance coil to obtain its amplitude and phase changes with frequency, and obtains the frequency response curve. The resonant frequency of the sensor can also be determined by this frequency response curve. When the sensor is subjected to pressure, its resonant frequency will shift, and this shift can be observed by the movement of the frequency response curve. The shift of the frequency response curve and the resonant frequency of the sensor are related to a certain pressure. When the pressure inside the eyeball increases, the resonant frequency will decrease; when the pressure inside the eyeball decreases, the resonant frequency will increase. By recording the changes in the frequency response curve, the shift of the resonant frequency can be accurately measured, and the pressure applied to the sensor can be calculated.

[0068] The present invention can perform continuous and accurate wireless monitoring of intraocular pressure, is highly convenient, and provides an innovative technical solution for intraocular pressure monitoring.

[0069] The accompanying drawings show preferred embodiments of the present invention. However, the present invention can be implemented in many different forms and is not limited to the embodiments described in this specification. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

Claims

1. An intrusive LC passive wireless continuous pressure sensor, characterized by: It comprises a base (1), a probe (2) and a pressure detection circuit; The probe is fixed vertically to the center of the base; the pressure detection circuit includes a capacitor arranged on the probe and an inductor arranged on the base; and the sensor is formed by folding and bonding a flexible circuit board.

2. The intrusive LC passive wireless continuous pressure sensor according to claim 1, characterized in that: The flexible circuit board comprises a body (3) serving as a base and branches (4) extending from both sides of the body serving as probes; the branches comprise a first folding arm (4-1) and a second folding arm (4-2).

3. The intrusive LC passive wireless continuous pressure sensor according to claim 2, characterized in that: The folding includes: the first folding arm is folded to be close to the bottom surface of the body, and the second folding arm is folded to form the probe.

4. The intrusive LC passive wireless continuous pressure sensor according to claim 3, characterized in that: The inductor is a coil (5-1) located on the top surface of the main body; the capacitor is an electrode sheet (5-2) located on the bottom surfaces of the two second folding arms; and both ends of the inductor are connected to the electrode sheets respectively through wires (5-3).

5. The intrusive LC passive wireless continuous pressure sensor according to claim 4, characterized in that: The bottom surface of the second folding arm is further provided with a spacing unit (6); the spacing units are respectively located above and below the probe capacitor.

6. The intrusive LC passive wireless continuous pressure sensor according to claim 5, characterized in that: The bottom surface of the second folding arm is further provided with an expansion unit (7); the expansion unit is located above the capacitor of the probe.

7. The intrusive LC passive wireless continuous pressure sensor according to claim 1 or 6, characterized in that: The probe comprises, from top to bottom, a rectangular parallelepiped needle rod (2-1), a quadrangular pyramid-shaped needle head (2-2), and a quadrangular pyramid-shaped needle tip (2-3).

8. The intrusive LC passive wireless continuous pressure sensor according to claim 7, characterized in that: In one of the branches: the front end of the second folding arm is provided with a first extension piece (4-31) and a second extension piece (4-32), the side of the second folding arm is provided with a first side edge (4-41), the side of the first extension piece is provided with a second side edge (4-42), and the side of the second extension piece is provided with a third side edge (4-43); in the other branch: the front end of the second folding arm is provided with a first folding piece (4-51) and a second folding piece (4-52), the side of the second folding arm is provided with a fourth side edge (4-44), and the front end of the fourth side edge is provided with a third folding piece (4-53) and a fourth folding piece (4-54).

9. The intrusive LC passive wireless continuous pressure sensor according to claim 8, characterized in that: The needle rod is formed by the second folding arm, the first side and the fourth side; the needle head is formed by the first extension piece, the second side, the first folding piece and the third folding piece; the needle tip is formed by the second extension piece, the third side, the second folding piece and the fourth folding piece.

10. The intrusive LC passive wireless continuous pressure sensor according to claim 9, characterized in that: A first flange (4-61) is provided on the side surface of the first side edge; and a second flange (4-62) is provided on the side surface of the fourth side edge.

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