Intracranial / in-vivo chamber signal monitoring sensor, preparation method therefor, and system thereof

Abstract

Provided in the present invention are an intracranial / in-vivo chamber signal monitoring sensor, a preparation method therefor, and a system thereof. The sensor comprises: a sensor base body, being of a cubic structure and prepared from a flexible deformable material, the sensor base body being detachably arranged in a closed space; a plurality of closed chambers, each closed chamber being formed in the sensor base body in a height direction of the sensor base body, and the plurality of closed chambers being periodically arranged in n×n; and a plurality of filling materials adapted to the number of the closed chambers, each filling material correspondingly filling one closed chamber, a material sound velocity of the filling material being greater than or equal to twice that of the flexible deformable material, or the material sound velocity of the flexible deformable material being greater than or equal to twice that of the filling material. The sensor adopted by the present invention has no toxic or side effects, and can be used for long-term, continuous, in-situ, accurate monitoring of environmental signals such as pressure, pH, and temperature in the intracranial / in-vivo chamber to carry out multi-modal sensing.

Description

Intracranial / body cavity signal monitoring sensor and preparation method and system thereof

Technical field

[0001] The present invention belongs to the technical field of medical devices, and in particular relates to an intracranial / body cavity signal monitoring sensor and a preparation method and system thereof. [Background Technology]

[0002] Real-time monitoring of pressure, pH, and temperature signals within the human body, particularly intracranial signals, is crucial before, during, and after surgical procedures. Changes in these signals within the human body's intracranial and internal cavities can reflect the normal functioning of organs, the body's health, and postoperative recovery. Therefore, timely and accurate monitoring of pressure, pH, and temperature signals within a patient's intracranial and internal cavities is crucial for clinical diagnosis and treatment guidance.

[0003] Currently, clinical monitoring of intracranial signals primarily relies on wired sensors. While these sensors offer relatively accurate measurements, the real-time monitoring process involves the use of percutaneous wires that pass through the skull, posing a risk of infection. Therefore, continuous monitoring using this method is typically limited to five days. Wireless detection methods, such as ultrasound Doppler, CT, and MRI, all indirectly detect intracranial signals by detecting other markers, but their accuracy is limited. Furthermore, crosstalk between multiple signals is unavoidable with wearable and implantable sensors.

[0004] Therefore, how to provide a multimodal sensor for monitoring intracranial / body cavity signals that is low-cost, bio-friendly, and has no toxic side effects, and can be used for long-term continuous in situ accurate monitoring of pressure, temperature, pH and other signals in the intracranial / body cavity, is a problem that technical personnel in this field urgently need to solve.

[0005] [Summary of the invention]

[0006] The technical problem to be solved by the present invention is that the existing technology of monitoring intracranial signals through wired sensors has technical problems such as the risk of patient infection, short continuous monitoring time, and signal crosstalk.

[0007] In order to solve the above problems, the first aspect of the present invention provides an intracranial / body cavity signal monitoring sensor, wherein the interior of the intracranial / body cavity has a confined space, and the sensor comprises: a sensor base, wherein the sensor base has a cubic structure, and the sensor base is made of a flexible deformable material. The environmental signal in the confined space is variable, and the sensor base is detachably arranged in the interior of the confined space. When the environmental signal changes, the sensor base undergoes adaptive deformation according to the changed environmental signal. The environmental signal includes a pressure signal and a temperature signal in the confined space. and pH signals; a plurality of closed chambers, each of the closed chambers is opened inside the sensor base along the height direction of the sensor base, and the plurality of closed chambers are periodically arranged, and the periodic arrangement is n×n, where n is a natural number greater than or equal to 3; a plurality of filling materials adapted to the number of the closed chambers, each of the filling materials correspondingly filling the interior of one of the closed chambers, the material sound velocity of the filling material being greater than or equal to twice the material sound velocity of the flexible deformable material, or the material sound velocity of the flexible deformable material being greater than or equal to twice the material sound velocity of the filling material.

[0008] In the first aspect, the size of the sensor substrate is (0.7mm-4mm)×(0.7mm-4mm)×(0.7mm-4mm); the filling material includes one of degradable polylactic acid, degradable polyhydroxyalkanoate, degradable polybutylene succinate, degradable polycaprolactone, degradable liquid metal, and gas; the cross-section of the closed chamber is circular, polygonal or elliptical; the center distance between two adjacent closed chambers is 0.07mm-0.7mm, and the cross-sectional size of each closed chamber is 0.07mm-0.7mm.

[0009] In the first aspect, the flexible deformable material includes one of a degradable gel material and a degradable flexible polymer material.

[0010] In the first aspect, the flexible deformable material is a polyvinyl alcohol / poly (N-isopropylacrylamide) double network hydrogel.

[0011] In the first aspect, the flexible deformable material is a polyvinyl alcohol / chitosan double network hydrogel.

[0012] A second aspect of the present invention provides an ultrasound monitoring system that can be used for intracranial / body cavity signal monitoring, wherein the interior of the intracranial / body cavity has a confined space, and the ultrasound monitoring system comprises: a sensor according to any one of claims 1 to 3, wherein the sensor is detachably installed inside the confined space; a wearable external ultrasound device, wherein the wearable external ultrasound device comprises an ultrasound probe and a processor, wherein the ultrasound probe is attached to the skin surface corresponding to the intracranial / body cavity, the ultrasound probe transmits ultrasound waves to the sensor and receives echo signals reflected by the sensor, the processor performs spectral analysis on the echo signals received by the ultrasound probe and obtains changes in monitoring data of the intracranial / body cavity, wherein the monitoring signal is one of the pressure signal, the temperature signal, and the pH signal in the confined space.

[0013] The third aspect of the present invention provides an ultrasonic multimodal monitoring system for monitoring intracranial / body cavity signals, wherein the interior of the intracranial / body cavity has a confined space, and the ultrasonic monitoring system comprises: the above-mentioned sensor, wherein several of the sensors are adjacently distributed inside the confined space, the flexible deformable materials in the several sensors are different from each other, and the distance between two adjacent sensors is 1 mm to 3 mm; a wearable external ultrasonic device, wherein the wearable external ultrasonic device comprises an ultrasonic probe and a processor, wherein the ultrasonic probe is attached to the skin surface corresponding to the intracranial / body cavity, the ultrasonic probe transmits ultrasonic waves to the several sensors and receives echo signals reflected by the several sensors, and the processor performs signal decoupling and spectrum analysis on the echo signals received by the ultrasonic probe and obtains changes in the environmental signals of the intracranial / body cavity.

[0014] The fourth aspect of the present invention provides a method for preparing a sensor, which includes: preparing a flexible deformable material; preparing a flexible metamaterial mold having a periodic column structure, wherein the periodic column structure is composed of a plurality of periodically arranged air holes; pouring the flexible deformable material into the flexible metamaterial mold, cyclically freezing and thawing at -20°C, demolding, and then sealing the plurality of air holes with the flexible deformable material to obtain the sensor.

[0015] In the fourth aspect, the preparation of the flexible deformable material includes: dissolving 10 ml of a 4 wt % carboxymethyl chitosan aqueous solution and 10 ml of a 20 wt % polyvinyl alcohol in deionized water at 90° C., adding 1.5 ml of a 4 wt % aluminum chloride hexahydrate solution after complete dissolution, and then mixing uniformly by magnetic stirring and degassing to obtain the flexible deformable material.

[0016] The fifth aspect of the present invention provides a method for preparing a sensor, which includes: preparing a flexible deformable material; pouring the flexible deformable material into a structureless rectangular mold for solidification, and then using a laser subtractive process to etch a plurality of periodically arranged air holes in the flexible deformable material, and then sealing the plurality of air holes with the flexible deformable material to obtain the sensor.

[0017] Beneficial effect: The present invention proposes a sensor for monitoring intracranial / body cavity signals, comprising a sensor matrix, a plurality of closed cavities and a plurality of filling materials. The sensor matrix is ​​made of a flexible deformable material, and each closed cavity is opened inside the sensor matrix along the height direction of the sensor matrix. The plurality of closed cavities are periodically arranged in n layers × n columns. A closed cavity is filled with a filling material. The material sound velocity of the filling material is different from the material sound velocity of the flexible deformable material, and the material sound velocity of the filling material is greater than or equal to twice the material sound velocity of the flexible deformable material, or the material sound velocity of the flexible deformable material is greater than or equal to twice the material sound velocity of the filling material, that is, the material sound velocity of the filling material and the flexible deformable material with a larger material sound velocity is at least 2 times the material sound velocity of the material with a smaller material sound velocity. The sensor matrix is ​​detachably arranged inside the enclosed space inside the intracranial / body cavity, so that the entire sensor is located inside the enclosed space and can perform sensing under ultrasonic conditions. A flexible sensor based on metamaterials is obtained by utilizing two materials with different material sound velocities and based on a periodic structure, and is combined with a wearable Wearing an external ultrasound device can monitor environmental signals within the body cavity. During operation, the wearable external ultrasound device transmits ultrasound waves within a specific frequency spectrum to the sensor. The ultrasound waves pass through each layer or column of filling material within the closed cavity in the transmission direction, generating Bragg scattering and reflecting an ultrasonic echo signal of a specific frequency. The echo signal is then received by the wearable external ultrasound device. When the environmental signal within the closed cavity changes, the sensor also deforms, causing the frequency range of the reflected echo signal to change. By detecting changes in the frequency components of the ultrasonic echo, the environmental signals within the intracranial / internal body cavity can be monitored. Moreover, the sensor performs sensing by reflecting ultrasound waves and does not require external power supply. Therefore, it can perform long-term continuous in-situ monitoring of the patient's intracranial / internal body cavity environmental signals. This is safer and more stable, and can be used for long-term monitoring and assessment of the overall environmental health status of the cranial and internal body cavities. The sensor of the present invention can be used in conjunction with a small external ultrasound probe, without relying on large-scale detection equipment in the hospital. It is suitable for daily rehabilitation and health monitoring, reducing medical costs.

Brief Description of the Drawings

[0018] In order to more clearly illustrate the embodiments of this specification or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0019] FIG1 is a top view of the structural design of a sensor according to an embodiment of the present invention;

[0020] FIG2 is a perspective schematic diagram of the air column structure of the sensor according to an embodiment of the present invention;

[0021] FIG3 is a first schematic diagram showing the principle of reflection enhancement and reflection frequency shift of a flexible metamaterial to a high-frequency sound field caused by pressure deformation in an embodiment of the present invention;

[0022] FIG4 is a second schematic diagram showing the principle of reflection enhancement and reflection frequency shift of a flexible metamaterial to a high-frequency sound field caused by pressure deformation in an embodiment of the present invention;

[0023] FIG5 shows the scattered acoustic field of a flexible metamaterial with an original reflection frequency of 9.2 MHz designed in an embodiment of the present invention at different pressure values, the peak frequency shift of the pressure-flexible metamaterial when the ambient pressure changes, and the characteristic reflection spectrum of the material in the frequency domain at different pressures. FIG5 shows the scattered acoustic field of a flexible metamaterial with an original reflection frequency of 9.2 MHz designed in an embodiment of the present invention at different pressure values, the peak frequency shift of the pressure-flexible metamaterial when the ambient pressure changes, and FIG1 shows the characteristic reflection spectrum of the material in the frequency domain at different pressures.

[0024] FIG6 shows the scattered acoustic field of a flexible metamaterial with an original reflection frequency of 9.2 MHz designed in an embodiment of the present invention at different pressure values, the peak frequency shift of the pressure-flexible metamaterial when the ambient pressure changes, and FIG2 of the characteristic reflection spectra of the material in the frequency domain at different pressures (the legend “0%” in the figure corresponds to the original state without applied pressure);

[0025] Figure 7 shows the scattered acoustic field of the designed flexible metamaterial with an original reflection frequency of 9.2 MHz at different pressure values, the peak frequency shift of the pressure-flexible metamaterial when the ambient pressure changes, and Figure 3 of the characteristic reflection spectrum of the material in the frequency domain at different pressures;

[0026] FIG8 is a graph showing the test results of the deformation range of a flexible metamaterial with an original reflection frequency of 9.2 MHz designed in accordance with an embodiment of the present invention (deformation corresponds to pressure change);

[0027] FIG9 is a graph showing the deformation resolution test results (deformation corresponds to pressure change) of a flexible metamaterial with an original reflection frequency of 9.2 MHz designed in accordance with an embodiment of the present invention;

[0028] FIG10 is a schematic diagram of an overall detection system constructed based on an implantable flexible metamaterial according to an embodiment of the present invention;

[0029] FIG11 is a schematic diagram showing a flexible metamaterial as a wireless intracranial physiological sensor through ultrasound reflection in an embodiment of the present invention;

[0030] FIG12 is a size-temperature curve diagram of a flexible metamaterial for monitoring temperature according to an embodiment of the present invention;

[0031] FIG13 is a size-pH curve of a flexible metamaterial for monitoring pH in an embodiment of the present invention;

[0032] FIG14 is a diagram showing the scattered sound field of a flexible metamaterial having an original reflection frequency of 9.2 MHz at different temperatures designed in accordance with an embodiment of the present invention;

[0033] FIG15 is a graph showing the peak frequency shift of a flexible metamaterial with an original reflection frequency of 9.2 MHz when the ambient temperature changes according to an embodiment of the present invention;

[0034] FIG16 is a diagram showing the scattered acoustic field of a flexible metamaterial having an original reflection frequency of 9.2 MHz at different pH values ​​designed in accordance with an embodiment of the present invention;

[0035] FIG17 is a graph showing the peak frequency shift of a flexible metamaterial with an original reflection frequency of 9.2 MHz when pH changes according to an embodiment of the present invention;

[0036] FIG18 is a graph showing the deformation resolution test results (deformation corresponds to strain) of a flexible metamaterial for monitoring temperature with an original reflection frequency of 9.2 MHz designed in accordance with an embodiment of the present invention;

[0037] Figure 19 is a diagram showing the effects of individual factors on the pressure, temperature and pH metabolic gels in an embodiment of the present invention (Figure a is a schematic diagram of the experimental setup for multi-gel measurement. For pressure measurement, the multi-gel samples are placed in a sealed chamber; Figures bc are photographs and ultrasound images of the multi-gel samples, which can monitor three meta-gels simultaneously; Figures df are the frequency responses of the three meta-gels to changes in environmental pressure, temperature and pH).

[0038] Reference numerals:

[0039] 1. Sensor substrate;

[0040] 2. Close the chamber;

[0041] 3. Wearable external ultrasound device;

[0042] 4. Skin surface;

[0043] 5. Ultrasonic probe;

[0044] 6. Cavity wall. [Specific implementation method]

[0045] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0046] Example 1

[0047] As shown in Figure 1-2, this embodiment 1 provides an intracranial / body cavity signal monitoring sensor, which is used in conjunction with a wearable external ultrasound device 3. The wearable external ultrasound device 3 transmits ultrasound to the sensor and receives and processes the echo signal reflected by the sensor. The sensor includes: a sensor base 1, which has a cubic structure and is made of a flexible deformable material. The interior of the intracranial / body cavity has a confined space, and the environmental signal in the confined space is variable. The sensor base 1 is detachably arranged inside the confined space. When the environmental signal changes, the sensor base reacts according to the changed environmental signal. Adaptive deformation, the environmental signal includes a pressure signal, a temperature signal and a pH signal in the enclosed space; a plurality of closed chambers 2, each of the closed chambers 2 is opened inside the sensor base 1 along the height direction of the sensor base 1, and the plurality of closed chambers 2 are periodically arranged, and the periodic arrangement is n×n, n is a natural number greater than or equal to 3; a plurality of filling materials, each of the filling materials is filled in the interior of one of the closed chambers 2, the material sound velocity of the filling material is different from the material sound velocity of the flexible deformable material, and the material sound velocity of the filling material with a larger material sound velocity is at least twice the material sound velocity of the material with a smaller material sound velocity.

[0048] Specifically, the present invention proposes a sensor for monitoring intracranial / body cavity signals, comprising a sensor matrix 1, a plurality of closed cavities 2 and a plurality of filling materials. The sensor matrix 1 is made of a flexible deformable material, and each closed cavity 2 is opened inside the sensor matrix 1 along the height direction of the sensor matrix 1. The plurality of closed cavities 2 are periodically arranged in n layers × n columns. A closed cavity 2 is filled with a filling material. The material sound velocity of the filling material is different from the material sound velocity of the flexible deformable material, and the material sound velocity of the filling material is greater than or equal to twice the material sound velocity of the flexible deformable material, or the material sound velocity of the flexible deformable material is greater than or equal to twice the material sound velocity of the filling material, that is, the material sound velocity of the filling material and the flexible deformable material is at least twice the material sound velocity of the material sound velocity of the filling material. The sensor matrix 1 is detachably arranged inside the closed space inside the intracranial / body cavity, so that the entire sensor is located inside the closed space and can perform sensing under ultrasonic conditions, using two materials. A flexible sensor based on metamaterials, fabricated from materials with different sound velocities and based on a periodic structure, can be used in conjunction with a wearable external ultrasound device 3 to monitor signals within a body cavity. In actual operation, the wearable external ultrasound device 3 transmits ultrasound waves within a specific frequency spectrum to the sensor. The ultrasound waves sequentially pass through each layer or row of filling materials within the closed cavity 2 along the transmission direction, generating Bragg scattering and reflecting an ultrasound echo signal of a specific frequency. The echo signal is then received by the wearable external ultrasound device 3. When environmental signals such as pH, pressure, or temperature within the closed cavity change, the sensor also deforms, causing the frequency range of the reflected echo signal to change. By detecting changes in the frequency components of the ultrasound echo, changes in environmental signals within the intracranial / internal body cavity can be monitored. Furthermore, the sensor performs sensing by reflecting ultrasound waves and does not require external power supply. Therefore, it can provide long-term, continuous, in-situ monitoring of the patient's intracranial / internal body cavity environment, making it safer and more stable. It can be used for long-term monitoring and assessment of the overall environmental health status of the intracranial and internal body cavities.

[0049] The monitoring principle of this invention is based on the spectral characteristic reflection of flexible metamaterials. Taking air columns as the filling material, for example, a sealed, periodically arranged structure of air columns is designed within the flexible, deformable material. The periodic arrangement of air columns consists of at least three layers. An incident ultrasound wave first strikes the first layer of air columns, then the second, and finally the third. This periodic arrangement of air columns forms a phononic crystal structure with an acoustic bandgap, capable of reflecting sound waves of specific frequencies. When environmental signals within the cranial or internal cavities change, the flexible, deformable material attached to the tissues or organs in the body deforms accordingly. This deformation causes the metamaterial to expand or contract, shifting the corresponding lattice constant and, consequently, shifting its acoustic characteristic reflection frequency. By monitoring this shift, environmental signals within the body cavity can be indirectly obtained, allowing the health of the tissues or organs to be assessed.

[0050] The present invention obtains an acoustic metamaterial that responds to deformation in response to signal stimulation with characteristic frequency reflection by periodically arranging filling materials in a flexible deformable material. The acoustic metamaterial can be used as a sensor for monitoring environmental signals in the intracranial / body cavities, and can be used as an implantable health monitoring device for medically monitoring the pressure of human body cavities, such as the environmental signals of body cavities (such as the cranial cavity, thoracic cavity, abdominal cavity, etc.); since the sensor of the present invention uses a flexible deformable material as a base material and is combined with a periodically distributed filling material, it is passive and thus has flexible characteristics and good conformal ability when attached.

[0051] In some possible implementations, the size of the sensor substrate 1 is (0.7 mm-4 mm)×(0.7 mm-4 mm)×(0.7 mm-4 mm).

[0052] This is because the small size of the sensor base 1 (0.7mm-4mm) × (0.7mm-4mm) × (0.7mm-4mm) makes it easy to place it inside the enclosed space of the intracranial cavity to monitor the environmental signals of the intracranial cavity; and because of its small size, the sensor can be implanted into both ends of the tissue / organ in the tested cranial cavity / body cavity by injection, and the environmental signals of the intracranial cavity can be monitored in a minimally invasive / non-invasive manner, reducing surgical wounds.

[0053] In some possible implementations, the filling material includes degradable polylactic acid, degradable polyhydroxyalkanoate, degradable polybutylene succinate, degradable polycaprolactone, degradable liquid metal or gas.

[0054] This is because, by using degradable filling materials (such as degradable polylactic acid, polyhydroxyalkanoate, polybutylene succinate, polycaprolactone, liquid metal, gas and other degradable materials with significant sound velocity differences from flexible deformable materials), the sensor is made biodegradable and degrades on its own after a period of time without the need for further surgery to remove it, causing no secondary harm to the patient. It also has good biocompatibility in the body and can flexibly achieve short-term or long-term pressure monitoring.

[0055] In some possible embodiments, the cross-section of the closed chamber 2 is circular, polygonal or elliptical; the center distance a between two adjacent closed chambers 2 is 0.07 mm-0.7 mm, and the cross-sectional size d of each closed chamber 2 is 0.07 mm-0.7 mm.

[0056] This is because, by adjusting the periodic parameters of the sensor (such as the center distance a between two adjacent closed chambers 2, and the cross-sectional size d of each of the closed chambers 2), the initial reflection frequency of the sensor is adjusted to meet different application requirements. Taking carboxymethyl chitosan and polyvinyl alcohol double cross-linked hydrogel as a flexible deformable material and a cylindrical air column as a filling material as an example, by adjusting the center distance between the air columns and the diameter of the air columns between 0.07mm-0.7mm, the initial reflection frequency of the flexible metamaterial can be adjusted between 2.58MHz and 25.75MHz, which can be used for targeted design of in vivo cavities of different depths and sizes. For example, for deep cavity pressure monitoring in human tissue, a lower frequency ultrasound is used for monitoring to achieve a better penetration effect. At this time, a flexible metamaterial with a lower reflection frequency can be selected for design, preparation and implantation.

[0057] In some possible implementations, preferably, the center distance a between two adjacent closed chambers is 0.1 mm-0.3 mm, and the cross-sectional dimension d of each closed chamber is 0.1 mm-0.3 mm.

[0058] In some possible embodiments, the sensor further includes two adhesive layers, which are symmetrically arranged at both ends of the sensor base 1, and the sensor base 1 is adhered to the inside of the confined space through the adhesive layers; or the sensor base 1 is arranged inside the confined space by sewing.

[0059] Those skilled in the art will understand that an adhesive layer is added to each end of the sensor base 1, and the sensor base 1 is adhered to the interior of the confined space by adhering the adhesive layer to the cavity wall 6 of the cranial cavity / body cavity or the surface of the cavity tissue, or the sensor base 1 is arranged inside the confined space by directly suturing the two ends of the sensor base 1 to the cavity wall 6 of the cranial cavity / body cavity or the surface of the cavity tissue with surgical thread, so that the sensor is fixed to the cavity wall 6 of the monitored body cavity or the surface of the cavity tissue, and can be deformed as the cavity environment signal changes, thereby affecting the ultrasonic echo of the sensor.

[0060] In some possible embodiments, the adhesion layer is a chitosan adhesion layer.

[0061] Those skilled in the art will understand that the chitosan adhesion layer can be used to form a strong adhesion with the cavity wall 6 of the cranial cavity / body cavity or the biological tissue in the cavity, and can be pasted on both ends of the tissue / organ in the cranial cavity / body cavity being tested. When the pressure in the cranial cavity / body cavity changes, the sensor will undergo corresponding deformation.

[0062] In some possible implementations, the flexible deformable material includes a degradable gel material or a degradable flexible polymer material (such as Ecoflex, polydimethylsiloxane, and other silicone-based elastomer materials).

[0063] This is because the degradable gel material or degradable flexible polymer material can produce corresponding deformation when the pressure in the cranial cavity / body cavity changes, thereby causing the frequency range of the echo signal reflected by the sensor to change accordingly. By detecting the changes in the frequency components of the ultrasonic echo, the pressure changes inside the cranial cavity / body cavity can be monitored.

[0064] In some possible implementations, the flexible deformable material is polyvinyl alcohol / poly(N-isopropylacrylamide) double network hydrogel (PVA / PNIPAM).

[0065] This is because PVA / PNIPAM, as a flexible deformable material, can produce corresponding deformation when the temperature in the cranial cavity / body cavity changes, thereby causing the frequency range of the echo signal reflected by the sensor to change accordingly. By detecting the changes in the frequency component of the ultrasonic echo, the temperature changes inside the cranial cavity / body cavity can be monitored.

[0066] In some possible embodiments, the flexible deformable material is polyvinyl alcohol / chitosan double network hydrogel (PVA / CS).

[0067] This is because PVA / CS, as a flexible deformable material, can produce corresponding deformation when the pH in the cranial cavity / body cavity changes, thereby causing the frequency range of the echo signal reflected by the sensor to change accordingly. By detecting the changes in the frequency components of the ultrasonic echo, the pH changes inside the cranial cavity / body cavity can be monitored.

[0068] In addition, during the implantation process, the flexible metamaterial can be implanted into both ends of the tissue / organ in the cranial cavity / body cavity being tested by injection or open method. When the environmental signal of the cranial cavity / body cavity changes, the sensor will undergo corresponding deformation.

[0069] Example 2

[0070] As shown in Figures 10-11, this embodiment 2 provides an ultrasound monitoring system for monitoring signals in an intracranial / internal body cavity. The intracranial / internal body cavity has a confined space within it. The ultrasound monitoring system includes: the sensor of the above-mentioned embodiment 1, which is detachably mounted within the confined space; and a wearable external ultrasound device 3, which includes an ultrasound probe 5 and a processor. The ultrasound probe 5 is attached to the skin surface 4 corresponding to the intracranial / internal body cavity. The ultrasound probe 5 transmits ultrasound waves to the sensor and receives echo signals reflected by the sensor. The processor performs spectral analysis on the echo signals received by the ultrasound probe 5 and obtains changes in monitoring data for the intracranial / internal body cavity. The monitoring data is one of the pressure signal, the temperature signal, and the pH signal within the confined space. Specifically, the processor performs spectral analysis on the echo signals received by the ultrasound probe 5 to obtain the movement of the characteristic reflection frequency of the sensor, and calculates the deformation of the sensor based on the movement, thereby obtaining changes in monitoring data for the intracranial / internal body cavity.

[0071] Specifically, when using ultrasound for detection, an ultrasound probe 5 can be attached to the skin surface 4, transmitting ultrasound waves toward the sensor composed of the flexible metamaterial. By receiving the echo signal reflected by the acoustic metamaterial and performing spectrum analysis on the echo signal, the shift in the acoustic characteristic reflection frequency of the flexible metamaterial can be monitored on the spectrum, thereby achieving real-time monitoring of the cranial cavity / body cavity monitoring data. The sensor of the present invention can be used in conjunction with a small external ultrasound probe 5, without relying on large-scale detection equipment in the hospital. It is suitable for daily rehabilitation and health monitoring, reducing medical costs.

[0072] It should be noted that the sensor provided in this embodiment 2 for use in the ultrasound monitoring system for intracranial / body cavity signal monitoring is the sensor described in this embodiment 1, and its implementation principle and technical concept are exactly the same as those in embodiment 1. Therefore, for the parts not described in detail in this embodiment 2, please refer to embodiment 1 and will not be repeated here.

[0073] Example 3

[0074] This embodiment 3 provides an ultrasonic multimodal monitoring system for monitoring signals in an intracranial / body cavity, wherein the interior of the intracranial / body cavity has a confined space. The ultrasonic monitoring system includes: the sensor in the above-mentioned embodiment 1, wherein several of the sensors are adjacently distributed inside the confined space, the flexible deformable materials in the several sensors are different from each other, and the distance between two adjacent sensors is 1 mm to 3 mm; a wearable external ultrasonic device, wherein the wearable external ultrasonic device includes an ultrasonic probe and a processor, wherein the ultrasonic probe is attached to the skin surface corresponding to the intracranial / body cavity, the ultrasonic probe transmits ultrasonic waves to the several sensors and receives echo signals reflected by the several sensors, and the processor performs signal decoupling and spectrum analysis on the echo signals received by the ultrasonic probe to obtain changes in the environmental signals of the intracranial / body cavity.

[0075] The wearable external ultrasound device of Example 3 can monitor multiple sensors simultaneously. The ultrasound probe's pulse repetition frequency can reach 10 kHz, allowing for cyclical, repetitive sequential scanning of different components. Within a 0.1 ms time interval, changes in the body's internal environment can be ignored. Ultrasound can also distinguish sensors with a spacing of 1 mm to 3 mm. Therefore, by setting different ultrasound scan lines on different sensors, multiple sensors can be monitored simultaneously. By selecting the reflected echo signal of a specific scan line, signal decoupling and monitoring of a specific sensor are achieved, thereby enabling monitoring of a specific signal.

[0076] It should be noted that, since there is only one sensor in Example 2, Example 2 can only monitor one of the environmental signals such as pressure, temperature and pH in the intracranial / body cavity, while Example 3 is provided with multiple sensors, and the flexible deformable materials of the multiple sensors are different. In this way, compared with Example 2, Example 3 can simultaneously monitor multiple environmental signals such as pressure, temperature and pH, so as to achieve the technical effect of real-time and long-term monitoring of multiple signal conditions in the intracranial / body cavity.

[0077] For example, the number of sensors in this embodiment 3 can be two, where the flexible deformable material in one sensor is PVA / PNIPAM, and the flexible deformable material in the other sensor is PVA / CS; ultrasonic waves are transmitted to the two sensors through an ultrasonic probe and echo signals reflected by the two sensors are received, and the processor performs signal decoupling and spectrum analysis on the echo signals received by the ultrasonic probe to obtain changes in temperature and pH of the intracranial / body cavity.

[0078] It should be noted that the sensor provided in this embodiment 3 for the ultrasound monitoring system for intracranial / body cavity signal monitoring is the sensor described in this embodiment 1, and its implementation principle and technical concept are exactly the same as those in embodiment 1. Therefore, for the parts not described in detail in this embodiment 3, please refer to embodiment 1 and will not be repeated here.

[0079] As shown in Figure 3-19, in order to further illustrate the technical solution of the present application in detail to support the technical problem to be solved by the present application, the preparation method of the sensor for intracranial / body cavity pressure monitoring is specifically illustrated below, such as Example 4-10, in which air is used as the filling material to form a periodic column structure (periodically arranged air columns) with several closed chambers 2. The air columns can be demolded by a mold method or obtained by using laser subtractive processing on a flexible deformable material.

[0080] It should be noted that the sensor in the sensor preparation method provided in Examples 4-10 is the sensor described in Example 1, and its implementation principle and technical concept are exactly the same as those in Example 1. Therefore, for the parts not described in detail in Examples 4-10, please refer to Example 1 and will not be repeated here.

[0081] Example 4

[0082] This embodiment 4 provides a method for preparing a sensor, which includes the following steps:

[0083] A flexible deformable material is prepared, the flexible deformable material comprising: dissolving 10 ml of a 4 wt% carboxymethyl chitosan aqueous solution and 10 ml of a 20 wt% polyvinyl alcohol in deionized water at 90° C., adding 1.5 ml of a 4 wt% aluminum chloride hexahydrate solution after complete dissolution, and then mixing the mixture by magnetic stirring and degassing to obtain the flexible deformable material;

[0084] A flexible metamaterial mold having a periodic column structure is prepared, wherein the periodic column structure is composed of a plurality of periodically arranged air holes, and the lattice constant of the periodic column structure is 1 mm and the diameter is 0.7 mm;

[0085] The flexible deformable material is poured into the flexible metamaterial mold, subjected to cyclic freezing and thawing at -20°C, and demolded, and then a plurality of the air holes are sealed with the flexible deformable material to obtain the sensor.

[0086] The sensor obtained in Example 4 is a flexible metamaterial made from a double-crosslinked hydrogel of carboxymethyl chitosan and polyvinyl alcohol, with an initial reflection frequency of 9.2 MHz. The flexible metamaterial has a periodic column structure with a lattice constant a of 1 mm and an air column diameter d of 0.7 mm. This periodic air column structure has three layers in the y-direction. The flexible metamaterial obtained in Example 4, with an initial center frequency of 2.1 MHz, exhibited a clear correspondence between its deformation and the characteristic acoustic reflection frequency during strain testing using an acoustic probe. The corresponding strain value can be obtained through frequency shifting.

[0087] Furthermore, by varying the ratio of raw materials in the hydrogel, the modulus parameters of the hydrogel can be adjusted within a certain range, enabling better mechanical adaptation for different attachment locations. The periodic air column structure can be designed with three or more layers in the y-direction, with the greater the number of layers, the higher the reflectivity.

[0088] Example 5:

[0089] This Example 5 is the same as Example 4, and also uses a double-crosslinked hydrogel of carboxymethyl chitosan and polyvinyl alcohol. The difference is that the lattice constant of the periodic column structure in this Example 5 is 0.1 mm, the diameter is 0.07 mm, and the original reflection frequency of the corresponding flexible metamaterial is 25.75 MHz.

[0090] The preparation process is similar to that of Example 4, except that the size of the mold used for casting needs to be proportionally enlarged to twice its original size, that is, the lattice constant of the periodic column is adjusted to 0.1 mm and the diameter is adjusted to 0.07 mm.

[0091] In addition to Example 5, the inventors also experimented with other methods of proportionally scaling the lattice constant and diameter in Example 4 to produce the corresponding original reflection frequency of the flexible metamaterial. The results are shown in Table 1 below. In this way, the lattice constant and diameter can be flexibly adjusted according to the actual requirements of the original reflection frequency (of course, the lattice constant a and diameter d do not necessarily need to be adjusted in proportion):

[0092] Table 1: Correspondence between structural parameter design of flexible metamaterials and original reflection frequency

[0093] Example 6:

[0094] This embodiment 6 provides a method for preparing a sensor, which includes the following steps:

[0095] A flexible deformable material is prepared, the flexible deformable material comprising: dissolving 10 ml of a 4 wt% carboxymethyl chitosan aqueous solution and 10 ml of a 20 wt% polyvinyl alcohol in deionized water at 90° C., adding 1.5 ml of a 4 wt% aluminum chloride hexahydrate solution after complete dissolution, and then mixing the mixture by magnetic stirring and degassing to obtain the flexible deformable material;

[0096] After the flexible deformable material is poured into a structureless rectangular mold and solidified, a laser subtractive process is used to etch a number of periodically arranged air holes in the flexible deformable material, and then the air holes are sealed with the flexible deformable material to obtain the sensor.

[0097] This Example 6 is the same as Example 4 and Example 5, and also uses a double-crosslinked hydrogel of carboxymethyl chitosan and polyvinyl alcohol. The difference is that this Example 6 pours the hydrogel material into a structureless rectangular mold for solidification, and then uses a laser subtractive process to etch periodic air holes in the hydrogel. The air holes are then sealed with hydrogel, and the flexible metamaterial of the present invention can also be obtained.

[0098] Example 7:

[0099] The carboxymethyl chitosan and polyvinyl alcohol double cross-linked hydrogels in Examples 4, 5, and 6 can be replaced with other hydrogel materials with similar modulus and density (such as polyacrylamide sodium alginate double network hydrogel, polyacrylic acid chitosan double network hydrogel, polyacrylic acid gelatin double network hydrogel, chitosan polyvinyl alcohol double network hydrogel, etc.). The same process can be used to prepare them, and the corresponding original reflection frequency remains basically unchanged.

[0100] Example 8:

[0101] The hydrogel materials in Examples 4, 5, and 6 can be replaced with other silicone-based elastomer materials with similar modulus and density, such as polydimethylsiloxane, Ecoflex flexible material, etc., and can be prepared using the same process, and the corresponding original reflection frequency remains basically unchanged.

[0102] Example 9:

[0103] The air holes in Examples 4, 5, 6, 7, and 8 are replaced with polylactic acid (PLA), polyhydroxyalkanoate (PHA), polybutylene succinate (PBS), polycaprolactone (PCL), liquid metal, other gases, and other degradable materials with a significant sound velocity difference from the first material. Taking the solid material of polylactic acid PLA as an example, unlike the air column, which needs to be completely wrapped and sealed by the matrix material, the PLA column can be embedded in the matrix material, and the upper and lower surfaces may not be covered by the matrix material. Of course, non-solid materials such as liquid metal and gas still need to be completely wrapped and sealed by the matrix material.

[0104] Example 10:

[0105] Replacing the air holes in Examples 4, 5, 6, 7, and 8 with other non-degradable materials having a significant difference in sound velocity from the first material, such as iron, aluminum, steel and other metal materials, and using the non-degradable flexible first material as the matrix can meet the needs of long-term monitoring.

[0106] Example 11

[0107] This embodiment 11 provides a method for preparing a sensor, the method comprising the following steps:

[0108] preparing a flexible deformable material, the preparation comprising: dissolving 10 ml of a 1 wt% aqueous solution of poly(N-isopropylacrylamide) and 10 wt% polyvinyl alcohol in deionized water at 90° C., adding a 10 wt% ammonium persulfate solution, a 0.07 wt% N,N'-methylenebisacrylamide solution, and a 0.0001 wt% tetramethylethylenediamine solution after complete dissolution, and then mixing uniformly by magnetic stirring and degassing to obtain the flexible deformable material;

[0109] A flexible metamaterial mold was prepared with a periodic column structure consisting of a plurality of periodically arranged air holes. The periodic column structure had a lattice constant of 1 mm and a diameter of 0.7 mm. The periodic structure had three layers in the y-direction.

[0110] The flexible deformable material is poured into the flexible metamaterial mold, subjected to cyclic freezing and thawing at -20°C, and demolded, and then a plurality of the air holes are sealed with the flexible deformable material to obtain the sensor.

[0111] The flexible metamaterial with an initial center frequency of 9.2 MHz obtained in Example 11 was used in conjunction with an acoustic probe. In the temperature test, it was shown that its temperature change had a clear correspondence with the acoustic characteristic reflection frequency. The corresponding temperature value could be obtained through frequency shift, with a sensitivity of approximately 80 kHz / °C and a temperature resolution of 0.1°C.

[0112] Example 12

[0113] This embodiment 12 provides a method for preparing a sensor, the method comprising the following steps:

[0114] A flexible deformable material is prepared, the preparation comprising: dissolving a 1.2 wt% chitosan aqueous solution and 10 ml of a 1 wt% polyvinyl alcohol in deionized water at 90° C., adding a 1 wt% acetic acid solution after complete dissolution, and then mixing the mixture by magnetic stirring and degassing to obtain the flexible deformable material;

[0115] A flexible metamaterial mold was prepared with a periodic column structure consisting of a plurality of periodically arranged air holes. The periodic column structure had a lattice constant of 1 mm and a diameter of 0.7 mm. The periodic structure had three layers in the y-direction.

[0116] The flexible deformable material is poured into the flexible metamaterial mold, subjected to cyclic freezing and thawing at -20°C, and demolded, and then a plurality of the air holes are sealed with the flexible deformable material to obtain the sensor.

[0117] The flexible metamaterial with an initial center frequency of 9.2 MHz obtained in Example 12, in conjunction with an acoustic probe, shows in a pH test that its pH change has a clear correspondence with the acoustic characteristic reflection frequency, and the corresponding temperature value can be obtained by frequency shift, with a sensitivity of approximately 256.4 kHz / pH and a temperature resolution of 0.1 pH. Based on Examples 11 and 12, the sensor obtained in Example 11 and the sensor obtained in Example 12 (i.e., the flexible metamaterial) are connected to a common base to ensure that the height of each flexible metamaterial is uniform, and the spacing between adjacent sensors is 1 mm. In conjunction with the acoustic probe and the ultrasonic monitoring system processing algorithm and process, simultaneous monitoring of temperature and pH can be achieved.

[0118] Example 13:

[0119] Example 13 is the same as Example 11, and also uses a double cross-linked hydrogel of poly(N-isopropylacrylamide) and polyvinyl alcohol. The difference is that the lattice constant of the periodic column structure in Example 13 is 1 mm, the diameter is 0.7 mm, and the original reflection frequency of the corresponding flexible metamaterial is 2.58 MHz.

[0120] Example 14:

[0121] This embodiment 14 provides a method for preparing a sensor, the method comprising the following steps:

[0122] preparing a flexible deformable material, the preparation comprising: dissolving 10 ml of a 1 wt% aqueous solution of poly(N-isopropylacrylamide) and 10 wt% polyvinyl alcohol in deionized water at 90° C., adding a 10 wt% ammonium persulfate solution, a 0.07 wt% N,N'-methylenebisacrylamide solution, and a 0.0001 wt% tetramethylethylenediamine solution after complete dissolution, and then mixing the mixture uniformly by magnetic stirring and degassing to obtain the flexible deformable material;

[0123] After the flexible deformable material is poured into a structureless rectangular mold and solidified, a laser subtractive process is used to etch a number of periodically arranged air holes in the flexible deformable material, and then the air holes are sealed with the flexible deformable material to obtain the sensor.

[0124] Example 15:

[0125] The poly(N-isopropylacrylamide) and polyvinyl alcohol double cross-linked hydrogels in Examples 11, 12, 13, and 14 can be replaced with other hydrogel materials with similar modulus and density (such as polyacrylamide sodium alginate double network hydrogel, polyacrylic acid chitosan double network hydrogel, polyacrylic acid gelatin double network hydrogel, chitosan polyvinyl alcohol double network hydrogel, etc.). The same process can be used for preparation, and the corresponding original reflection frequency remains basically unchanged.

[0126] Although cylindrical air hole structures are more suitable for the air hole design of the present invention due to their isotropic geometric properties, flexible metamaterials with similar narrowband reflection capabilities and strain-induced reflection band frequency shift functions can be obtained by replacing the cylindrical air holes in Examples 4-15 with air columns of other shapes such as rectangular parallelepiped columns, polygonal prisms, and elliptical columns of similar size (of course, since the circular shape is an isotropic structure and other shapes are anisotropic structures, the incident properties in different directions may vary). The present invention does not limit the shape of the air holes, and air column structures of other shapes can be changed without affecting the characteristic reflection peak frequency shift of the flexible metamaterial when deformed.

[0127] Performance testing:

[0128] The ultrasonic incident direction is controlled so that the ultrasonic wave is first incident on the first layer of filling material, then on the second layer of filling material, and then on the third layer of filling material (of course, if there is a fourth layer of filling material, a fifth layer of filling material..., the incident can continue).

[0129] Taking the flexible metamaterial obtained in Example 4 as an example, as shown in Figures 3-4, the original reflection frequency of the flexible metamaterial is 9.2MHz, and there is no obvious reflection of the 9.2MHz acoustic signal before pressure is applied; after pressure is applied, the lattice constant decreases and the characteristic reflection frequency increases, resulting in a significant reflection enhancement of the 9.2MHz acoustic signal; the movement of the reflection spectrum of the acoustic metamaterial obtained by simulation before and after pressure is applied (as shown in Figures 5-7) can also reflect the trend of change in the echo frequency caused by this deformation. The metamaterial is calibrated with a precise motion guide in the range of 0 to 20cmH20 to obtain the corresponding relationship between the pressure and the characteristic reflection frequency of the flexible metamaterial as shown in Figure 7. The greater the applied pressure, the higher the corresponding reflection frequency. In terms of resolution, as shown in Figures 8-9, the contraction deformation of 0.1mmHg reciprocating pressure can be distinguished, with a sensitivity of 5.7kHz / mmHg. Different test ranges or accuracies can be achieved by adjusting the structural design of the flexible metamaterial to meet the needs of different application scenarios. For example, under the premise that the air filling ratio d / a in Figure 1 remains unchanged (i.e., when d and a change in equal proportions), the smaller the lattice constant a is designed, the higher the corresponding original reflection frequency, the larger the frequency shift caused by the same deformation, and the easier it is to detect, thus increasing the accuracy; while the larger the lattice size is designed, the lower the corresponding reflection frequency, the smaller the frequency shift caused by the same deformation (the smaller the frequency shift, the more difficult it is to detect), the lower the accuracy, and the corresponding larger the measurement range. The size-dependent narrowband reflection characteristics of the metamaterial of the present invention are based on the fact that the multi-layer periodically arranged air columns in the hydrogel constitute the phononic crystal structure in the metamaterial, which can be explained by the characteristic reflection theory of phononic crystals.

[0130] By utilizing the above characteristics, the deformation of the flexible metamaterial can be calculated by detecting the movement of the characteristic reflection frequency of the flexible acoustic metamaterial connected to the tissue / organ in the body, thereby reflecting the pressure changes in the intracranial / body cavity to which it is connected. For example:

[0131] Application scenario 1: Continuous monitoring of one or more intracranial signals. This flexible metamaterial can be used to continuously monitor changes in intracranial pressure, temperature, pH, and other signals, and detect elevated intracranial signals before abnormal intracranial signals present related symptoms and signs. Especially in the early stages of mild to moderate increases in intracranial pressure, temperature, pH, and other signals, when there are no obvious changes in vital signs, consciousness, or pupils, the monitoring of intracranial pressure, temperature, pH, and other signals has clearly identified the degree of increase in intracranial pressure, temperature, pH, and other signals. This can help to conduct timely CT scans to detect delayed hematomas and postoperative recurrent hematomas, thereby guiding early intervention.

[0132] Application Scenario 2: Guiding clinical treatment and patient prognosis. Intracranial pressure monitoring is crucial for guiding the treatment of intracranial diseases. This system allows doctors to observe changes in intracranial pressure, temperature, pH, and other signals, and promptly adjust treatment plans. This is particularly valuable for guiding the use of intracranial pressure-reducing measures such as mannitol, mild hypothermia therapy, and the decision to perform decompressive craniectomy.

[0133] Finally, it should be noted that the above embodiments are only specific implementations of the present invention, which are used to illustrate the technical solutions of the present invention, rather than to limit them. The scope of protection of the present invention is not limited thereto. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that any person skilled in the art can modify or easily conceive of changes to the technical solutions described in the above embodiments within the technical scope disclosed by the present invention, or replace some of the technical features therein with equivalents. However, these modifications, changes, or replacements do not deviate from the essence of the corresponding technical solutions within the scope of the technical solutions of the embodiments of the present invention. They should all be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

[0134] Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the description and implementation methods. They can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to the specific details and illustrations shown and described herein.

Claims

1. An intracranial / intrabody cavity signal monitoring sensor, wherein the interior of the intracranial / intrabody cavity has a sealed space, characterized in that, The sensor includes: A sensor substrate, the sensor substrate having a cubic structure, the sensor substrate being made of a flexible deformable material. The environmental signal in the closed space is variable. The sensor substrate is detachably disposed inside the closed space. When the environmental signal changes, the sensor substrate undergoes an adaptive deformation according to the changed environmental signal. The environmental signal includes a pressure signal, a temperature signal, and a pH signal in the closed space; A plurality of closed chambers, each of the closed chambers being formed inside the sensor substrate along the height direction of the sensor substrate. The plurality of closed chambers are arranged periodically, and the periodic arrangement is n×n, where n is a natural number greater than or equal to 3; A plurality of portions of filling materials adapted to the number of the closed chambers, each portion of the filling material being correspondingly filled inside one of the closed chambers. The sound velocity of the filling material is greater than or equal to twice the sound velocity of the flexible deformable material, or the sound velocity of the flexible deformable material is greater than or equal to twice the sound velocity of the filling material.

2. The intracranial / intrabody cavity signal monitoring sensor according to claim 1, wherein: The size of the sensor substrate is (0.7 mm - 4 mm)×(0.7 mm - 4 mm)×(0.7 mm - 4 mm); The filling material includes one of degradable polylactic acid, degradable polyhydroxyalkanoate, degradable polybutylene succinate, degradable polycaprolactone, degradable liquid metal, and gas; The cross-section of the closed chamber has a circular, polygonal, or elliptical structure; the center distance between adjacent two closed chambers is 0.07 mm - 0.7 mm, and the cross-sectional size of each closed chamber is 0.07 mm - 0.7 mm.

3. The intracranial / intrabody cavity signal monitoring sensor according to claim 2, wherein: The flexible deformable material includes one of degradable gel materials and degradable flexible polymer materials.

4. The intracranial / intrabody cavity signal monitoring sensor according to claim 2, wherein: The flexible deformable material is a polyvinyl alcohol / poly(N-isopropylacrylamide) double-network hydrogel.

5. The intracranial / intrabody cavity signal monitoring sensor according to claim 2, wherein: The flexible deformable material is a polyvinyl alcohol / chitosan double-network hydrogel.

6. An ultrasonic monitoring system that can be used for signal monitoring in an intracranial / intrabody cavity, wherein the interior of the intracranial / intrabody cavity has a sealed space, characterized in that, The ultrasonic monitoring system includes: The sensor according to any one of claims 1 - 3, the sensor being detachably installed inside the closed space; A wearable external ultrasound device, the wearable external ultrasound device comprising an ultrasound probe and a processor, the ultrasound probe being attached to the skin surface corresponding to the intracranial / intrabody cavity, the ultrasound probe emitting ultrasonic waves to the sensor and receiving the echo signals reflected by the sensor, the processor performing spectral analysis on the echo signals received by the ultrasound probe and obtaining the change in the monitoring signal of the intracranial / intrabody cavity, the monitoring signal being one of the pressure signal, the temperature signal, and the pH signal in the enclosed space.

7. An ultrasonic multimodal monitoring system for intracranial / intravascular cavity signal monitoring, wherein the interior of the intracranial / intravascular cavity has a sealed space, characterized in that, The ultrasonic monitoring system includes: The sensor according to any one of claims 1-2, a plurality of the sensors being adjacent to each other and distributed inside the enclosed space, the flexible deformable materials in the plurality of sensors being different from each other, and the distance between two adjacent sensors being 1 mm to 3 mm; A wearable external ultrasound device, the wearable external ultrasound device comprising an ultrasound probe and a processor, the ultrasound probe being attached to the skin surface corresponding to the intracranial / intrabody cavity, the ultrasound probe emitting ultrasonic waves to a plurality of the sensors and receiving the echo signals reflected by the plurality of sensors, the processor performing signal decoupling and spectral analysis on the echo signals received by the ultrasound probe and obtaining the change in the environmental signal of the intracranial / intrabody cavity.

8. A method for preparing a sensor according to claim 1, characterized in that, The preparation method includes: Preparing a flexible deformable material; Preparing a flexible metamaterial mold with a periodic column structure, the periodic column structure being composed of a plurality of air holes arranged periodically; Pouring the flexible deformable material into the flexible metamaterial mold, freeze-thawing cyclically at -20 °C, demolding, and then sealing a plurality of the air holes with the flexible deformable material to obtain the sensor.

9. The preparation method according to claim 8, characterized in that, The preparation of the flexible deformable material includes: Dissolving 10 ml of a 4 wt% aqueous solution of carboxymethyl chitosan and 10 ml of 20 wt% polyvinyl alcohol in deionized water at 90 °C, adding 1.5 ml of a 4 wt% aluminum chloride hexahydrate solution after complete dissolution, and then mixing evenly by magnetic stirring, degassing to obtain the flexible deformable material.

10. A method for preparing a sensor as claimed in claim 1, characterized in that, The preparation method includes: Preparing a flexible deformable material; Pouring the flexible deformable material into an unstructured rectangular parallelepiped mold for curing, using a laser subtractive process to etch a plurality of air holes arranged periodically in the flexible deformable material, and then sealing a plurality of the air holes with the flexible deformable material to obtain the sensor.

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