A collapse risk early warning device for fire accident investigation

Abstract

This invention provides a collapse risk early warning device for fire accident investigation, relating to the field of fire accident investigation safety protection technology. Specifically, it includes: a sensing material, an electrochemical sensor and signal processing unit, a Bluetooth signal transmission module, and a miniature audible and visual alarm. This solution prepares a novel sensing material. By attaching the sensing material to the structural component under test, the deformation signal is sensed, processed, and analyzed. The status data is then transmitted to an external receiving terminal via the Bluetooth signal transmission module. If a dangerous sign is detected, both on-site audible and visual alarms and remote wireless early warning are activated simultaneously, forming a double safety measure.

Description

Technical Field

[0001] This invention relates to the field of safety protection technology for fire accident investigation, and in particular to a collapse risk early warning device for fire accident investigation. Background Technology

[0002] After a fire, the high temperatures (up to 500℃-1000℃) can easily cause material degradation in building structures: concrete may crack, peel, or become internally void; steel softens significantly above 600℃, leading to deformation or breakage; and wood loses its load-bearing capacity due to carbonization and may crack, bend, or suffer other damage. Furthermore, the failure of local load-bearing systems (such as damage to beams, columns, or floor slabs) can trigger load transfer, leading to a chain reaction or even overall structural instability, such as roof collapse, wall collapse, or overturning of cantilevered structures, directly threatening the lives of investigators entering the site.

[0003] In addition to structural instability in the building, numerous small, unstable components were also present at the fire investigation site, such as broken and hanging pipes, tilted and deformed cabinets, and sharp, twisted sandwich panels. These risks could not only cause investigators to be injured, crushed, or even killed, but could also cut off access routes, interrupt evidence collection, and bury crucial evidence (such as traces of the ignition point and electrical wiring remnants), seriously affecting the reconstruction of the truth of the accident and the determination of responsibility.

[0004] Since a large number of these small unstable components were present at the fire investigation site, the probability of resulting casualties was actually greater than that of the building structure.

[0005] Under current technological conditions, fire investigators inevitably need to enter the post-disaster site to conduct investigations and sampling in order to accurately and quickly determine the direct cause of the fire. Meanwhile, to maintain the authenticity and originality of the fire scene, small unstable components are usually not cleaned up or are removed as little as possible during actual investigations. Therefore, monitoring the risk of collapse or falling of small unstable components at the fire scene to ensure the safety of fire investigators is a crucial measure.

[0006] Currently, the collapse risk early warning devices commonly used at domestic accident investigation sites are mainly divided into four categories, with differences in application scenarios and popularity:

[0007] Portable displacement monitoring equipment, represented by laser displacement sensors and wire displacement gauges, accounts for over 60% of applications in building collapse and tunnel accident investigations, and is equipped by approximately 55% of grassroots emergency investigation units.

[0008] Tilt and vibration monitoring equipment: including MEMS tilt sensors and piezoelectric vibration sensors, mostly used for monitoring vertical components such as walls, beams and columns after disasters, with an equipment rate of about 45% in grassroots units in China;

[0009] Video image recognition system: Deep learning-based structural monitoring camera, suitable for large-scale accident site monitoring, with an application rate of approximately 30% in provincial-level and above emergency investigation units;

[0010] Fiber Bragg grating stress monitoring system: requires temporary rental, has high cost per unit (150,000-200,000 RMB), accounts for less than 5% of applications, and is only used for major accident investigations.

[0011] The aforementioned equipment is mainly used in safety accident investigations, and its use in fire investigations is less frequent and has some shortcomings, mainly in the following aspects:

[0012] The focus is primarily on monitoring the risk of collapse of the building structure itself (such as walls, columns, beams, etc.), with very little attention paid to the numerous small unstable components found in fire investigations;

[0013] Low portability and deployment efficiency: Even portable displacement monitoring devices still weigh 3-5kg per unit, require tripod for fixation, and take 15-20 minutes per unit for deployment; video systems require brackets to be set up and cables to be connected, and the entire deployment takes more than 30 minutes.

[0014] High cost and poor accessibility: Video systems cost 80,000-120,000 yuan, fiber optic systems cost 150,000-200,000 yuan, and are only used by provincial-level units; the cost of tilt sensor equipment commonly used at the grassroots level is also 10,000-20,000 yuan, and the actual purchase price is even more expensive. It is difficult to universally deploy monitoring for the numerous unstable small components found in fire investigations.

[0015] Insufficient precision monitoring capability: The environment at fire scenes is complex, with numerous collapsed, tilted, and suspended components, which can easily cause obstruction and misjudgment for monitoring equipment based on laser, video, and fiber optic principles, thus reducing accuracy.

[0016] In summary, there is an urgent need for a collapse and fall risk warning device specifically designed for fire investigation scenarios. This device should have advantages such as being lightweight and low-cost, and could be widely used at fire investigation sites. By monitoring the safety of components, especially small unstable components, and providing real-time safety warnings, it can comprehensively ensure the safety of fire investigators. Summary of the Invention

[0017] To address the shortcomings of existing technologies, this invention provides a collapse risk warning device for fire accident investigation. Specifically, it proposes the development of a reusable, inherently flame-retardant, self-adhesive, self-healing, and lightweight collapse risk warning device for fire accident investigation, to adapt to the monitoring needs of various post-disaster components, especially the numerous small unstable components present at fire investigation sites, thus achieving universal applicability.

[0018] The specific technical solution of the present invention is as follows:

[0019] On the one hand, the present invention provides a collapse risk warning device for fire accident investigation, including: sensing material, electrochemical sensor and signal processing unit, Bluetooth signal transmission module and miniature sound and light alarm;

[0020] The sensing material is used to detect the physical deformation signal of the material under test and directly convert the physical deformation signal into an electrical signal.

[0021] The electrochemical sensor and signal processing unit includes an internal circuit board and a housing. The internal circuit board is encapsulated within the housing, which is a USB flash drive-shaped shell for plug-and-play operation. The internal circuit board integrates an electrochemical analysis chip, a microprocessor (MCU), and a storage unit. The electrochemical sensor and signal processing unit are connected to the sensing material via microwires. The electrochemical analysis chip applies a constant microcurrent or voltage to the sensing material and acquires real-time, high-frequency data on the resistance and impedance changes of the sensing material. The MCU performs filtering, baseline calibration, and trend analysis on the acquired data. The storage unit records historical monitoring data.

[0022] The trend analysis specifically involves: obtaining deformation data of the tested material based on the resistance and impedance change data of the sensing material, thereby obtaining the current deformation rate of the tested material; setting different alarm thresholds according to the specific type of the tested material; and outputting an alarm signal to the miniature audible and visual alarm if the current deformation rate of the tested material is greater than the corresponding alarm threshold.

[0023] The Bluetooth signal transmission module specifically adopts the Bluetooth Low Energy (BLE) protocol to wirelessly transmit the status information processed by the microprocessor, including deformation rate and warning level, to an external receiving terminal.

[0024] The miniature audible and visual alarm includes an LED light and a miniature piezoelectric ceramic buzzer; it receives alarm signals from a microprocessor and emits flashing lights and a buzzing sound to provide a danger warning.

[0025] The preparation process of the sensing material specifically includes the following steps:

[0026] Step S1: Dissolve α-p-bromobenzoic acid and 1-vinylimidazole in an ethanol solution with a molar ratio of 1:0.8~1.5, and the ethanol solution concentration is 30%~60%. After mixing, stir and reflux for 12h~24h. After cooling to room temperature, pour the crude product into 100mL~300mL of diethyl ether, collect the obtained white precipitate, wash it with diethyl ether 3~5 times, and filter to obtain a white powder product. Then, use acetone as solvent, stir at room temperature, and replace with KPF6 for 6h~24h. Filter and collect the filtrate, precipitate the filtrate, and recrystallize the supernatant to obtain HA-vim.

[0027] Step S2: Take (4-vinylphenyl)dimethylsilane, 1,3-butadiene, and HA-vim in a molar ratio of (5~30):(10~50):(40~80), dissolve them in n-hexane to prepare a solution, wherein the total mass of the three materials accounts for 60%~90% of the total mass of the solution; add photoinitiator Irgacure-2959 so that the total molar amount of (4-vinylphenyl)dimethylsilane, 1,3-butadiene, and HA-vim is in a molar ratio of (95~99):(1~5), stir thoroughly, pour into a polytetrafluoroethylene mold, and initiate polymerization under a 650W ultraviolet lamp for 5 min~10 min. Dry the solvent in a 50℃ oven to constant weight to obtain the sensing material for a collapse risk warning device for fire accident investigation.

[0028] On the other hand, a method for using a collapse risk warning device for fire accident investigation, implemented using the aforementioned collapse risk warning device for fire accident investigation, includes the following steps:

[0029] Step 1: Fire investigators attach sensing materials to the structural components being tested, and a collapse risk warning device for fire accident investigation is placed on the ground and connected to the sensing materials via micro-wires.

[0030] Step 2: The collapse risk warning device for fire accident investigation starts working. After the deformation signal is sensed, processed and analyzed, the status data is sent to the external receiving terminal through the Bluetooth signal transmission module.

[0031] Step 3: If a dangerous sign is detected, activate the on-site audible and visual alarm and the remote wireless early warning system simultaneously to form a double safety measure.

[0032] The beneficial effects of adopting the above technical solution are as follows:

[0033] This invention provides a collapse risk warning device for fire accident investigation, which has the following beneficial effects:

[0034] (1) For sensing materials, the present invention has the following beneficial effects:

[0035] This invention uses (4-vinylphenyl)dimethylsilane, 1,3-butadiene, and HA-vim to prepare sensing materials via photoinitiation. This reaction offers advantages such as mild conditions, no need for inert gas protection, and rapid reaction speed. Simultaneously, the silanol functional groups of (4-vinylphenyl)dimethylsilane can form hydrogen bonds with the imidazole and carboxylic acid groups of HA-vim after polymerization, giving the material a three-dimensional network structure, achieving viscoelasticity and self-healing properties. The imidazole cations and hexafluorophosphate anions in the polyionic liquid impart conductivity to the material, enabling it to detect component displacement and convert it into electrical signals for early warning. The fluorine and phosphorus elements in the ionic liquid provide inherent flame retardancy, reducing the risk of secondary combustion of fire evidence. The abundant fluorine in the material endows the sensing material with hydrophobic properties, allowing it to remain usable even in high-humidity environments after fire extinguishing. Furthermore, the carboxylic acid groups of HA-vim provide excellent adhesion to surfaces of different materials, which remains effective even under high humidity conditions, making it suitable for practical applications in fire investigations. Finally, the imidazole groups of HA-vim possess inherent antibacterial capabilities, allowing for repeated use in environments involving biological contamination, further reducing operating costs.

[0036] In summary, this sensing material possesses functions such as high sensing sensitivity, self-healing, hydrophobicity, inherent flame retardancy, and inherent antibacterial properties. It can sense strain changes in components at fire investigation sites, thereby altering resistance, generating current changes, providing early warning signals, and indicating collapse risks. The material exhibits excellent flame retardancy, being difficult to ignite, self-extinguishing upon removal of the flame, and drip-free, effectively preventing secondary accidents caused by residual heat. Simultaneously, it has good adhesion, effectively adhering to the surface of components of interest, thus achieving early and accurate sensing of component displacement changes. Its excellent hydrophobic and inherent antibacterial properties give it broad adaptability to high-humidity and biologically contaminated environments at fire investigation sites. After damage, the sensing material can automatically repair broken surfaces, possessing room-temperature self-healing capabilities, significantly increasing the material's reusability and reducing usage costs, facilitating widespread application, and demonstrating good economic benefits.

[0037] (2) Compared with existing monitoring equipment, the collapse risk early warning device for fire accident investigation of the present invention has the following beneficial effects:

[0038] High sensitivity and foresight: The sensing material is extremely sensitive to micro-strain, and can capture early instability signals of the structure before macroscopic collapse occurs, thus achieving forward-looking early warning.

[0039] Portability and rapid deployment: The USB-style design and self-adhesive sensing materials make the entire system lightweight and compact, and can be deployed within minutes of arriving on site.

[0040] Intelligent and remote: Built-in algorithms can intelligently identify risk trends, and Bluetooth transmission enables remote and mobile monitoring of personnel, keeping them away from direct danger areas.

[0041] Dual alarm protection: Combining on-site sound and light alarms with wireless alarms received by the terminal, it ensures that early warning information can be reliably received in complex and noisy on-site environments.

[0042] Low cost and easy for large-scale use: Except for the self-synthesized sensing material, the rest of the device (including the algorithm) is composed of mature commercial products, significantly reducing the overall cost. It is an order of magnitude cheaper than the tilt sensor equipment commonly used at the grassroots level. Since there are often numerous small unstable components to monitor at fire investigation sites, this device can be deployed on a large scale. The sensing material has self-healing properties; damaged material can repair itself, further reducing the application cost throughout its lifecycle. Attached Figure Description

[0043] Figure 1 Overall structural diagram of the collapse risk early warning device for fire accident investigation according to an embodiment of the present invention;

[0044] Figure 2 The preparation route of HA-vim in this invention embodiment;

[0045] Figure 3 Schematic diagram of the preparation of sensing materials according to an embodiment of the present invention;

[0046] Figure 4 Simulation diagrams of current density and electric field changes of sensing materials under different stretching lengths in embodiments of the present invention;

[0047] Among them, (a) the change in current density of the sensing material under different strain conditions, and (b) the change in electric field of the sensing material under different strain conditions;

[0048] Figure 5 Schematic diagram of adhesion strength test in an embodiment of the present invention;

[0049] Figure 6 Comparative experimental diagram of the antibacterial properties of the sensing materials against Escherichia coli in Example 3 of this invention;

[0050] Figure 7 The response and recovery time curves of the sensing material in Embodiment 3 of the present invention;

[0051] Figure 8 Experimental diagrams showing the adhesion of sensing materials to different substrates in embodiments of the present invention;

[0052] In the diagram, (a) - wood, (b) - glass, (c) - iron, (d) - aluminum, (e) - copper, (f) - rubber;

[0053] Figure 9 The energy spectrum diagram showing the uniform distribution of C, N, O, F, and P elements on the surface of the sensing material in Embodiment 4 of the present invention;

[0054] In the diagram, (a) - carbon (C), (b) - nitrogen (N), (c) - oxygen (O), (d) - iron (F), (e) - phosphorus (P);

[0055] Figure 10 The curves of elongation at break and fracture strength of the sensing material in Embodiment 5 of the present invention;

[0056] Figure 11 The curves of elongation at break and fracture strength of the sensing material in Embodiment 6 of the present invention;

[0057] Figure 12 A schematic diagram of the water contact angle of the sensing material in Embodiment 6 of the present invention;

[0058] Figure 13 The curves of elongation at break and fracture strength of the sensing material in Embodiment 7 of the present invention;

[0059] Figure 14 A comparative experimental diagram of the antibacterial properties of the sensing material against Escherichia coli in Example 7 of this invention. Detailed Implementation

[0060] The specific implementation methods of this application will be further described in detail below with reference to the accompanying drawings and embodiments.

[0061] Example 1

[0062] This invention provides a collapse risk early warning device for fire accident investigation, such as... Figure 1 As shown, it includes: sensing materials, an electrochemical sensor and signal processing unit, a Bluetooth signal transmission module, and a miniature audible and visual alarm.

[0063] The sensing material detection directly converts physical deformation signals into electrical signals;

[0064] The electrochemical sensor and signal processing unit includes an internal circuit board and a housing. In this embodiment, a commercially available USB flash drive-type electrochemical sensor and signal processing unit (BIOSYS P15E Max) is used. The internal circuit board is encapsulated in the housing, which is a USB flash drive-shaped shell, achieving excellent portability and plug-and-play functionality. The internal circuit board integrates a high-precision electrochemical analysis chip, a microprocessor (MCU), and a storage unit, and is connected to the sensing material via microwires. The electrochemical analysis chip is used to apply a constant microcurrent or voltage to the material and collect the resistance and impedance change data of the tested material in real time and at high frequency. The MCU performs filtering, baseline calibration, and trend analysis on the collected data to determine the current deformation rate and alarm threshold of the tested material. The storage unit is used to record historical monitoring data for post-event analysis.

[0065] The Bluetooth signal transmission module, specifically a commercially available low-power Bluetooth module in this embodiment, is co-located on the same circuit board as the electrochemical sensor and signal processing unit. It employs the Bluetooth Low Energy (BLE) protocol to wirelessly transmit the microprocessor-processed status information (including real-time deformation data, warning levels, etc.) to an external receiving terminal, such as a smartphone, tablet computer carried by investigators, or a dedicated central monitoring station. This module ensures the real-time performance and reliability of data transmission, with an effective communication distance covering the typical fire investigation site area.

[0066] The miniature audible and visual alarm can be integrated with or deployed separately from the sensing unit. It includes high-brightness multi-color LED beads and a miniature piezoelectric ceramic buzzer. When the deformation data exceeds the preset alarm threshold, the microprocessor will immediately trigger the miniature audible and visual alarm to sound an alarm. The miniature audible and visual alarm emits flashing lights (visual alarm) and high-decibel intermittent buzzing sounds (auditory alarm), providing intuitive and immediate danger warnings to investigators at the scene and in the surrounding area.

[0067] On the other hand, a method for using a collapse risk warning device for fire accident investigation, implemented using the aforementioned device, includes the following steps: Fire investigators attach sensing material to the structural component being tested; the collapse risk warning device is placed on the ground and connected to the sensing material via micro-wires to minimize the impact on the tested component; after activating the USB-type sensor, the system begins automatic operation. After sensing, processing, and analyzing the deformation signal, normal state data is sent to the monitoring terminal via Bluetooth. Once a dangerous sign is detected, the system simultaneously activates on-site audible and visual alarms and remote wireless warnings, forming a double safety measure.

[0068] Example 2:

[0069] The limiting oxygen index test of this invention refers to the standard GB / T 2406.2-2009, and the UL-94 vertical burning test refers to the standard GB / T 2408-2021.

[0070] The adhesion strength test method is as follows: Place a sensing material (10cm × 2cm × 1mm) between the two substrates. Before measurement, apply 100g pressure for 5 minutes to establish good contact. Then, separate the specimen using a tensile testing machine at a fixed speed of 500 mm / min. Calculate the strength by dividing the maximum load by the initial adhesion area. Measurements for each component should be repeated at least three times. Figure 5 As shown.

[0071] In this embodiment, the HA-vim preparation route and the preparation of the sensing material are as follows: Figure 2 , Figure 3 As shown in the example, the 30-day weight gain rate test method is as follows: The prepared sensing material is placed in an indoor environment and weighed daily. The percentage of the weight gain after 30 days relative to the original weight is the 30-day weight gain rate. A stable 30-day weight gain rate indicates that the material does not absorb moisture or dry out, characterizing the product's stability.

[0072] The elongation at break and tensile strength tests were performed using an electronic universal testing machine at room temperature. The specimens were cut into rectangular pieces (10cm × 2cm × mm), and the elongation at break was 50 mm / min. -1 Tensile tests are performed. Elongation at break is defined as the length of deformation (measured with an elongator) at fracture divided by the original length of the sample. Fracture strength is the tensile strength of the material at fracture. For example... Figure 4 As shown, (a) represents the change in current density of the sensing material under different strain conditions, and (b) represents the change in electric field of the sensing material under different strain conditions.

[0073] To evaluate the antibacterial effect of the sensing material, *Escherichia coli* (ATCC25922) was selected as the model microorganism. 0.5 g of pre-sterilized sensing material sample was mixed with 2 mL of *E. coli* suspension adjusted to 10⁶ CFU / mL in sterile phosphate-buffered saline (PBS). The mixture was incubated at 37°C with shaking for 24 hours. After incubation, the bacterial suspension was serially diluted (10-fold), and 100 μL from each dilution was evenly spread onto LB agar plates. After incubation at 37°C for 18 hours, colony counts were determined.

[0074] The 12-hour self-healing efficiency test method in the embodiment is as follows: Two identical samples are taken from the prepared sensing material. One sample is used as the original sample to directly test its fracture stress. The other sample is cut with a 1cm long and 1cm deep incision on its surface using a scalpel. The samples are then realigned and left to stand at room temperature for 12 hours without any external force. The fracture strength is then measured under the same conditions. The percentage of the fracture strength of the original sample is the 12-hour self-healing efficiency.

[0075] In strain sensing, the material is cut into a rectangle (10cm × 2cm × 1mm), and electrode clamps are fixed to both ends. The signal after strain is applied to the material is monitored using a USB-based electrochemical workstation. The change in resistance of the material is recorded using this USB-based electrochemical workstation. The relative resistance change is calculated using the following formula:

[0076] ;

[0077] Where R0 and R are the initial resistance and the resistance when strain is applied, respectively.

[0078] In the embodiment, the normalization factor GF is calculated by the following formula:

[0079] ;

[0080] in It represents the percentage of strain in the material, and ΔR is the change in the perceived material resistance before and after strain.

[0081] In the embodiment, the test method for response time and recovery time is as follows: electrode clamps are fixed at both ends of a rectangular material (size, 10cm×2cm×1mm), a 10% strain is applied to it (simulating the displacement change of the component monitored at the fire investigation site by 10%), and then the clamps are immediately removed. The response time and recovery time of the audible and visual alarm after the strain change are monitored by a USB flash drive electrochemical workstation.

[0082] Example 3:

[0083] Step A1. Dissolve α-p-bromobenzoic acid and 1-vinylimidazole (molar ratio 1:0.8) in ethanol (30% concentration). After mixing, stir and reflux for 12 h. After cooling to room temperature, pour the crude product into diethyl ether (100 mL), collect the resulting white precipitate, wash three times with diethyl ether, and filter to obtain a white powder product. Then, using acetone as solvent, stir at room temperature and replace with KPF6 for 6 h, filter and collect the filtrate. Precipitate from the filtrate, and recrystallize the supernatant to obtain HA-vim, yield 63%.

[0084] Step A2. Dissolve (4-vinylphenyl)dimethylsilane, 1,3-butadiene, and HA-vim in n-hexane at a molar ratio of 5:15:80 to prepare a solution. The total mass of the above three materials accounts for 80% of the total mass of the solution. Add photoinitiator Irgacure-2959. The total molar ratio of (4-vinylphenyl)dimethylsilane, 1,3-butadiene, and HA-vim to the molar ratio of photoinitiator is 95:5. After thoroughly stirring the above materials, pour them into a polytetrafluoroethylene mold and initiate polymerization under a 650W ultraviolet lamp for 5 min. Dry the solvent in a 50°C oven until constant weight.

[0085] The prepared warning material was tested and found to have a limiting oxygen index of 35.1%, a UL-94 vertical burning test rating of V-0, an adhesion strength (iron) of 116 kPa, a 30-day weight gain of 1.22%, an elongation at break of 580%, a tensile strength of 2375 kPa, and an antibacterial efficiency of 99.9%. Figure 6 As shown, the left side represents the control group, and the right side represents the sensing material. The water contact angle is 80.8°, the self-healing efficiency at room temperature for 12 hours is 72%, and the standardization factor is 76. The sensing material, along with a USB flash drive electrochemical sensor, a Bluetooth signal sensor, and a miniature audible and visual alarm, was used to construct a collapse and fall risk warning device for fire accident investigation. Testing showed a response time of 100 ms and a recovery time of 200 ms. The response and recovery time curves of the sensing material are shown below. Figure 7 As shown.

[0086] Example 4:

[0087] Step B1. Dissolve α-p-bromobenzoic acid and 1-vinylimidazole (molar ratio 1:1.5) in ethanol (60% concentration). After mixing, stir and reflux for 24 h. After cooling to room temperature, pour the crude product into diethyl ether (300 mL), collect the resulting white precipitate, wash 5 times with diethyl ether, and filter to obtain a white powder product. Then, using acetone as solvent, stir at room temperature and replace with KPF6 for 24 h, filter and collect the filtrate. Precipitate from the filtrate, and recrystallize the supernatant to obtain HA-vim, yield 77%.

[0088] Step B2. Take (4-vinylphenyl)dimethylsilane, 1,3-butadiene and HA-vim in a molar ratio of 30:10:60, dissolve them in n-hexane to prepare a solution, the total mass of the above three materials accounts for 90% of the total mass of the solution; add photoinitiator Irgacure-2959, the total molar ratio of (4-vinylphenyl)dimethylsilane, 1,3-butadiene and HA-vim to the molar ratio of photoinitiator is 99:1, after the above materials are thoroughly stirred, pour into a polytetrafluoroethylene mold, irradiate under a 650W ultraviolet lamp to initiate polymerization for 10 min, and dry the solvent in a 50℃ oven to constant weight.

[0089] The prepared early warning material was tested and found to have a limiting oxygen index of 31.2%, a UL-94 vertical burning test rating of V-0, an adhesion strength (iron) of 63 kPa, a 30-day weight gain of 0.85%, an elongation at break of 516%, a tensile strength of 1739 kPa, an antibacterial efficiency of 98.1%, a water contact angle of 90.5°, a self-healing efficiency of 92% at room temperature over 12 hours, and a specification factor of 55. The sensing material was combined with a USB flash drive electrochemical sensor, a Bluetooth signal sensor, and a miniature audible and visual alarm to form a collapse and fall risk early warning device for fire accident investigation. Testing showed a response time of 200 ms and a recovery time of 200 ms. Figure 8 Figures (a)-(f) show experimental diagrams illustrating the adhesion of sensing materials to different substrates. Figure 9 As shown in (a)-(e), these are energy spectrum diagrams of uniform distribution of C, N, O, F, and P elements on the surface of the sensing material.

[0090] Example 5:

[0091] Step C1. Dissolve α-p-bromobenzoic acid and 1-vinylimidazole (molar ratio 1:1) in ethanol (50% concentration). After mixing, stir and reflux for 16 h. After cooling to room temperature, pour the crude product into diethyl ether (200 mL), collect the resulting white precipitate, wash four times with diethyl ether, and filter to obtain a white powder product. Then, using acetone as solvent, stir at room temperature and replace with KPF6 for 12 h, filter and collect the filtrate. Precipitate from the filtrate, and recrystallize the supernatant to obtain HA-vim, yield 81%.

[0092] Step C2. Take (4-vinylphenyl)dimethylsilane, 1,3-butadiene and HA-vim in a molar ratio of 10:50:40, dissolve them in n-hexane to prepare a solution, the total mass of the above three materials accounts for 60% of the total mass of the solution; add photoinitiator Irgacure-2959, the total molar ratio of (4-vinylphenyl)dimethylsilane, 1,3-butadiene and HA-vim to the molar ratio of photoinitiator is 98:2, after the above materials are thoroughly stirred, pour into a polytetrafluoroethylene mold, irradiate under a 650W ultraviolet lamp to initiate polymerization for 6 min, and dry the solvent in a 50℃ oven to constant weight.

[0093] The prepared early warning material was tested and found to have a limiting oxygen index of 28.7%, a UL-94 vertical burning test rating of V-1, an adhesion strength (iron) of 88 kPa, a 30-day weight gain of 0.51%, an elongation at break of 950%, a tensile strength of 1076 kPa, an antibacterial efficiency of 92.3%, a water contact angle of 116.2°, a self-healing efficiency of 83% at room temperature over 12 hours, and a specification factor of 37. When combined with a USB flash drive electrochemical sensor, a Bluetooth signal sensor, and a miniature audible and visual alarm, a collapse and fall risk early warning device for fire accident investigation was constructed. Testing showed a response time of 300 ms and a recovery time of 300 ms. Figure 10 The figure shown is a graph of the elongation at break and the tensile strength of the sensing material in this embodiment.

[0094] Example 6:

[0095] Step D1. Dissolve α-p-bromobenzoic acid and 1-vinylimidazole (molar ratio 1:1.2) in ethanol (35% concentration). After mixing, stir and reflux for 20 h. After cooling to room temperature, pour the crude product into diethyl ether (150 mL), collect the resulting white precipitate, wash three times with diethyl ether, and filter to obtain a white powder product. Then, using acetone as solvent, stir at room temperature and replace with KPF6 for 20 h, filter and collect the filtrate. Precipitate from the filtrate, and recrystallize the supernatant to obtain HA-vim, yield 87%.

[0096] Step D2. Dissolve (4-vinylphenyl)dimethylsilane, 1,3-butadiene, and HA-vim in n-hexane at a molar ratio of 20:30:50 to prepare a solution. The total mass of the above three materials accounts for 65% of the total mass of the solution. Add photoinitiator Irgacure-2959. The total molar ratio of (4-vinylphenyl)dimethylsilane, 1,3-butadiene, and HA-vim to the molar ratio of photoinitiator is 97:3. After thoroughly stirring the above materials, pour them into a polytetrafluoroethylene mold and initiate polymerization under a 650W ultraviolet lamp for 8 minutes. Dry the solvent in a 50°C oven until constant weight.

[0097] The prepared early warning material was tested and found to have a limiting oxygen index of 30.3%, a UL-94 vertical burning test rating of V-0, an adhesion strength (iron) of 96 kPa, a 30-day weight gain of 0.73%, an elongation at break of 902%, a tensile strength of 2031 kPa, an antibacterial efficiency of 96.7%, a water contact angle of 95.2°, a self-healing efficiency of 91% at room temperature over 12 hours, and a specification factor of 61. When combined with a USB flash drive electrochemical sensor, a Bluetooth signal sensor, and a miniature audible and visual alarm, a collapse and fall risk early warning device for fire accident investigation was constructed. Testing showed a response time of 150 ms and a recovery time of 200 ms. Figure 11 The figure shown is a graph of the elongation at break and the tensile strength of the sensing material in this embodiment.

[0098] Example 7:

[0099] Step E1. Dissolve α-p-bromobenzoic acid and 1-vinylimidazole (molar ratio 1:0.9) in ethanol (55% concentration). After mixing, stir and reflux for 22 h. After cooling to room temperature, pour the crude product into diethyl ether (300 mL), collect the resulting white precipitate, wash 5 times with diethyl ether, and filter to obtain a white powder product. Then, using acetone as solvent, stir at room temperature and replace with KPF6 for 24 h, filter and collect the filtrate. Precipitate from the filtrate, and recrystallize the supernatant to obtain HA-vim, yield 83%.

[0100] Step E2. Dissolve (4-vinylphenyl)dimethylsilane, 1,3-butadiene, and HA-vim in n-hexane at a molar ratio of 15:20:65 to prepare a solution. The total mass of the three materials should account for 70% of the total mass of the solution. Add photoinitiator Irgacure-2959. The ratio of the total molar amount of (4-vinylphenyl)dimethylsilane, 1,3-butadiene, and HA-vim to the molar amount of photoinitiator should be 98.5:1.5. After thoroughly stirring the above materials, pour them into a polytetrafluoroethylene mold and initiate polymerization under a 650W UV lamp for 7 minutes. Dry the solvent in a 50°C oven until constant weight.

[0101] The prepared early warning material was tested and found to have a limiting oxygen index of 32.5%, a UL-94 vertical burning test rating of V-0, an adhesion strength (iron) of 151 kPa, a 30-day weight gain of 0.83%, an elongation at break of 756%, a tensile strength of 2211 kPa, an antibacterial efficiency of 98.9%, a water contact angle of 90.7°, a self-healing efficiency of 90% at room temperature for 12 hours, and a specification factor of 63. When combined with a USB flash drive electrochemical sensor, a Bluetooth signal sensor, and a miniature audible and visual alarm, a collapse and fall risk early warning device for fire accident investigation was constructed. Testing showed a response time of 120 ms and a recovery time of 100 ms. Figure 12 The diagram shown is a schematic of the water contact angle of the sensing material in this embodiment; Figure 13 The figure shown is a graph of the elongation at break and the tensile strength of the sensing material in this embodiment; as shown Figure 14 The image shows a comparative experimental diagram of the antibacterial properties of the sensing materials against Escherichia coli, with the control group on the left and the sensing materials on the right.

[0102] The various embodiments in this application are described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

[0103] The scope of protection of this application is not limited to the embodiments described above. Obviously, those skilled in the art can make various modifications and variations to this disclosure without departing from the scope and spirit of this disclosure. If such modifications and variations fall within the scope of the methods disclosed herein and their equivalents, then the intent of this disclosure also includes such modifications and variations.

Claims

1. A collapse risk warning device for fire accident investigation, characterized in that, include: Sensing materials, electrochemical sensors and signal processing units, Bluetooth signal transmission modules, and miniature audible and visual alarms; The sensing material is used to detect the physical deformation signal of the material under test and directly convert the physical deformation signal into an electrical signal. The electrochemical sensor and signal processing unit includes an internal circuit board and a housing. The internal circuit board is encapsulated within the housing, which is a USB flash drive-shaped shell for plug-and-play operation. The internal circuit board integrates an electrochemical analysis chip, a microprocessor (MCU), and a storage unit. The electrochemical sensor and signal processing unit are connected to the sensing material via microwires. The electrochemical analysis chip applies a constant microcurrent or voltage to the sensing material and acquires real-time, high-frequency data on the resistance and impedance changes of the sensing material. The MCU performs filtering, baseline calibration, and trend analysis on the acquired data. The storage unit records historical monitoring data. The trend analysis specifically involves: obtaining deformation data of the tested material based on the resistance and impedance change data of the sensing material, thereby obtaining the current deformation rate of the tested material; setting different alarm thresholds according to the specific type of the tested material; and outputting an alarm signal to the miniature audible and visual alarm if the current deformation rate of the tested material is greater than the corresponding alarm threshold. The Bluetooth signal transmission module specifically adopts the Bluetooth Low Energy (BLE) protocol to wirelessly transmit the status information processed by the microprocessor, including deformation rate and warning level, to an external receiving terminal. The miniature audible and visual alarm includes an LED light and a miniature piezoelectric ceramic buzzer; it receives alarm signals from a microprocessor and emits flashing lights and a buzzing sound to provide a danger warning. The preparation process of the sensing material specifically includes the following steps: Step S1: Dissolve α-p-bromobenzoic acid and 1-vinylimidazole in an ethanol solution with a molar ratio of 1:0.8~1.5, and the ethanol solution concentration is 30%~60%. After mixing, stir and reflux for 12h~24h. After cooling to room temperature, pour the crude product into 100mL~300mL of diethyl ether, collect the obtained white precipitate, wash it with diethyl ether 3~5 times, and filter to obtain a white powder product. Then, use acetone as solvent, stir at room temperature, and replace with KPF6 for 6h~24h. Filter and collect the filtrate, precipitate the filtrate, and recrystallize the supernatant to obtain HA-vim. Step S2: Take (4-vinylphenyl)dimethylsilane, 1,3-butadiene, and HA-vim in a molar ratio of (5~30):(10~50):(40~80), dissolve them in n-hexane to prepare a solution, wherein the total mass of the three materials accounts for 60%~90% of the total mass of the solution; add photoinitiator Irgacure-2959 so that the total molar amount of (4-vinylphenyl)dimethylsilane, 1,3-butadiene, and HA-vim is in a molar ratio of (95~99):(1~5), stir thoroughly, pour into a polytetrafluoroethylene mold, and initiate polymerization under a 650W ultraviolet lamp for 5 min~10 min. Dry the solvent in a 50℃ oven to constant weight to obtain the sensing material for a collapse risk warning device for fire accident investigation. The aforementioned collapse risk warning device for fire accident investigation is used to implement a method of using the collapse risk warning device for fire accident investigation, including the following steps: Step 1: Fire investigators attach sensing materials to the structural components being tested, and a collapse risk warning device for fire accident investigation is placed on the ground and connected to the sensing materials via micro-wires. Step 2: The collapse risk warning device for fire accident investigation starts working. After the deformation signal is sensed, processed and analyzed, the status data is sent to the external receiving terminal through the Bluetooth signal transmission module. Step 3: If a dangerous sign is detected, activate the on-site audible and visual alarm and the remote wireless early warning system simultaneously to form a double safety measure.

Images