SF6 Gas Research Articles

Early Choriocapillaris Loss in a Porcine Model of RPE Cell Debridement Precedes Pathology That Simulates Advanced Macular Degeneration.

No large-mammal surgical models exist for geographic atrophy (GA), choroidal neovascularization (CNV), and pachychoroidal vascular remodeling. Our goal was to develop a porcine RPE debridement model of advanced macular degeneration to study photoreceptor cell loss and choroidal remodeling. Seven 2-month-old female domestic pigs were used for this study. After 25G vitrectomy, the area centralis was detached via subretinal bleb. A nitinol wire (Finesse Flex Loop) was used to debride RPE cells across a 3- to 5-mm diameter region. Fluid-air exchange was performed, and 20% SF6 gas injected. Animals underwent fundus photography, fluorescein angiography, optical coherence tomography (OCT), and OCT-angiography (OCTA) at 2 weeks, 1month, 2months, 3months, and 6 months postoperatively. Retinal histology was obtained at euthanasia, 2months (n = 3), 3months (n = 2), or 6months (n = 2) after surgery. RPE debridement resulted in GA with rapid loss of choriocapillaris, progressive loss of photoreceptors, and pachychoroidal changes in Sattler's and Haller's layers in all seven eyes undergoing debridement within 2 months. OCT and histological findings included subretinal disciform scar with overlying outer retinal atrophy; outer retinal tubulations and subretinal hyper-reflective material. OCTA revealed type 2 CNV (n = 4) at the edges of the debridement zone by 2 months, but there was no significant exudation noted at any time point. Surgical debridement of the RPE results in GA, CNV, and pachychoroid and reproduced all forms of advanced macular degeneration. This surgical model may be useful in examining the role of RPE and other cell replacement in treating advanced macular disease.

Dynamic Measurement and Prediction of Sulfur Hexafluoride Gas Weight Based on Non-Ideal Gas State Equation and Improved Random Forest

Real-time knowledge of sulfur hexafluoride (SF6) gas weight can effectively manage and maintain the power equipment using SF6. Firstly, the gas pressure and temperature sensors are utilized to measure SF6 gas pressure and temperature dynamically. Secondly, the measured gas pressure and temperature values are converted to the SF6 gas weight using equations for calculating non-ideal gas states. Finally, the dynamic prediction model of the SF6 gas weight is developed by combining the improved chimp optimization algorithm and random forest algorithm. The dynamic prediction model is trained using measured pressure and temperature data as inputs and the calculated SF6 gas weight as outputs. The trained prediction model enables the dynamic prediction of SF6 gas weight. The experimental results show that the mean absolute error, root mean square error, and mean absolute percentage error of the proposed prediction model reaches 51.54 kg, 103.59 kg, and 11.62%.

Performance of a novel charge sensor on the ion detection for the development of a high-pressure avalancheless ion TPC

Within the project of building a time projection chamber using 100 kg of high-pressure 86SeF6 gas to search for the neutrinoless double-beta decay in the NvDEx collaboration, we are developing a CMOS charge sensor, named Topmetal-S, which is tailored for the experiment to detect the ions without gas amplification. In this work, the performance of the sensor is presented. The equivalent noise charge of the sensor is measured to be about 120 to 140 e- depending on the operating point, with the charge injection capacitance calibrated against external capacitors. The signal waveforms are investigated with various chip parameters and experimental settings. In addition to electrons, both negatively and positively charged ions could be detected, and their waveforms are studied using air and SF6 gases. Using the sensor, the mobility of negative ions in ambient air in the atmospheric pressure is measured to be 1.555 ± 0.038 cm2 · V-1 · s-1. Our study demonstrates that the Topmetal-S chip could be used as the ion detection charge sensor for the experiment. Further work is ongoing to reduce the noise of the sensor and to develop a small readout plane with tens of the sensors.

Visualization of surface discharge area in SF6 based on infrared trap

A method for visualization of surface discharge area in SF6 based on infrared trap is proposed in this study. The infrared images of a heated insulator with a surface defect under different applied voltages were studied, and the infrared trap phenomenon was observed in the infrared image. When partial discharge occurs on the heated insulator surface, a spindle shaped infrared trap will be formed at the end of the defect. In the infrared trap area, the apparent temperature measured using the infrared camera decreases compared to that without discharge. The infrared trap area corresponds to surface discharge area. With the increase in the applied voltage, the discharge becomes more severe, the infrared trap area gradually expands, and the trap depth also increases. This infrared trap phenomenon found in this study can serve as a method to visualize the surface discharge area in SF6 gas.

Research on Joint Sensing Technology for Vibration and Dielectric Spectrum of Power Equipment in the Context of New Power Systems

Abstract This paper has carried out the test results of SF6 gas decomposition products and the dielectric spectrum detection, proposed method for the identifying equipment defects based on decomposition products, and the partial discharge detection and diagnosis method for the equipment discharge defects. Combining the above two methods, the GIS discharge defects are comprehensively evaluated by decomposition products and partial discharge detection, achieving the type prediction of latent faults in operating switch-gear. In the aspect of vibration signal analysis, this paper conducts the wavelet analysis of the vibration signals and obtains frequency spectrum results under multi-layer wavelet decomposition. In the aspect of dielectric spectrum analysis, a model of three HN function superposition was used to fit the experimental data to verify the validity of the model, and the characteristic parameters such as the DC conductivity were extracted. It was found their dependence on temperature basically conformed to the Arrhenius formula. On this basis, the thermal aging test platform for the epoxy resin samples was established, and an accelerated thermal aging experiment was conducted at the temperature of 115 °C. The dielectric response test system was used to measure dielectric spectra of the samples with different aging times, compare the dielectric spectra at different aging times, and analyze the reasons for the differences.

Adsorption of SF6 decomposition gases (H2S, SO2 and SOF2) on TM (Pd and Pt) modified monolayer ZrS2: A DFT study

Fast and effective detection of SF6 gas decomposition products is essential. In this study, the adsorption behaviors of H2S, SO2 and SOF2 on Pd-ZrS2 and Pt-ZrS2 monolayers were analyzed using density-functional theory (DFT), and the electronic properties of the different adsorption systems and their sensing properties were discussed in depth. The results show that the Pd and Pt modifications significantly improve the surface activity of the intrinsic ZrS2 monolayers, giving them better adsorption and sensing properties. The reasonable adsorption energies and significant sensitivity differences suggest that the Pd(Pt)-ZrS2 monolayers may be potential candidates for H2S, SO2 and SOF2 sensors. This study provides theoretical guidance for the prospective application of Pd(Pt)-ZrS2 in the operational condition assessment of GIS equipment.

Sub-ppm NDIR [formula omitted] gas sensor using ICEEMDAN-SG joint denoising algorithm

Due to the excellent insulation and arc extinguishing properties of SF6 gas, it is widely used in power equipment such as gas insulated switchgear or gas circuit breaker. Therefore, detection of SF6 gas leakage with high sensitivity is necessary. Non dispersive infrared (NDIR) technology have advantages such as miniaturization, low power consumption, simple structure, low cost, and non-destructive testing, making it suitable for building large-scale sensor networks. However, NDIR sensors are susceptible to noise coming from the emitter, the detector and the circuits, which receives little research attention. In this study, we propose a new denoising method by combining improved complete ensemble empirical mode decomposition with adaptive noise (ICEEMDAN) with Savitzky-Golay (S-G) to the noise suppression, which achieves a 7 dB signal-to-noise ratio improvement over the traditional wavelet threshold denoising, making the detection limit of the sensing system reach the level below 1 ppm.

Fiber-Optic Photoacoustic CO Sensor for Gas Insulation Equipment Monitoring Based on Cantilever Differential Lock-In Amplification and Optical Excitation Enhancement.

A fiber-optic photoacoustic CO sensor for gas insulation equipment is proposed, which relies on F-P interferometric cantilever-based differential lock-in amplification and optical multipass excitation enhancement. The sensor has excellent characteristics of high sensitivity, antielectromagnetic interference, fast response, and long-distance detection. The photoacoustic pressure waves in the two resonators of the differential photoacoustic cell (DPAC) are simultaneously detected by two fiber-optic interferometric cantilevers and processed differentially; thereby, the gas flow noise is effectively suppressed. Based on the comprehensive analysis of the superposition of photoacoustic excitation and multipass absorption, the diameter of the resonator is determined to be 6 mm. The optical power emitted by the 1566.6 nm distributed feedback laser is increased to 500 mW by an erbium-doped fiber amplifier. The near-infrared light is reflected 30 times in the multipass cell, which improves the order of magnitude of optical effective excitation. Due to the low sound velocity of SF6 gas, the resonant frequency of the DPAC with a resonator length of 80 mm is 760 Hz. The response time to CO/SF6 gas is 93 s with a flow rate of 500 sccm. The detection limit of the CO sensor is 53 ppb, which realizes the accurate and timely perception of the SF6 decomposition derivative CO and provides technical support for trouble-free operation of gas insulation equipment.

Comparison of simulations of the gas conduction in HVDC GIL by application of nonlinear conductivity model and ion-drift-diffusion model

PurposeGas insulated systems, such as gas insulated lines (GIL), use insulating gas, mostly sulfur hexalfluoride (SF6), to enable a higher dielectric strength compared to e.g. air. However, under high voltage direct current conditions, charge accumulation and electric field stress may occur, which may lead to partial discharge or system failure. Therefore, numerical simulations are used to design the system and determine the electric field and charge distribution. Although the gas conduction shows a more complex current–voltage characteristic compared to solid insulation, the electric conductivity of the SF6 gas is set as constant in most works. The purpose of this study is to investigate different approaches to address the conduction in the gas properly for numerical simulations.Design/methodology/approachIn this work, two approaches are investigated to address the conduction in the insulating gas and are compared to each other. One method is an ion-drift-diffusion model, where the conduction in the gas is described by the ion motion in the SF6 gas. However, this method is computationally expensive. Alternatively, a less complex approach is an electro-thermal model with the application of an electric conductivity model for the SF6 gas. Measurements show that the electric conductivity in the SF6 gas has a nonlinear dependency on temperature, electric field and gas pressure. From these measurements, an electric conductivity model was developed. Both methods are compared by simulation results, where different parameters and conditions are considered, to investigate the potential of the electric conductivity model as a computationally less expensive alternative.FindingsThe simulation results of both simulation approaches show similar results, proving the electric conductivity for the SF6 gas as a valid alternative. Using the electro-thermal model approach with the application of the electric conductivity model enables a solution time up to six times faster compared to the ion-drift-diffusion model. The application of the model allows to examine the influence of different parameters such as temperature and gas pressure on the electric field distribution in the GIL, whereas the ion-drift-diffusion model enables to investigate the distribution of homo- and heteropolar charges in the insulation gas.Originality/valueThis work presents numerical simulation models for high voltage direct current GIL, where the conduction in the SF6 gas is described more precisely compared to a definition of a constant electric conductivity value for the insulation gas. The electric conductivity model for the SF6 gas allows for consideration of the current–voltage characteristics of the gas, is computationally less expensive compared to an ion-drift diffusion model and needs considerably less solution time.

CoO-SnSe monolayer: A high potential candidate for SF6 characteristic decomposition gas adsorption and detection

Insulation performance testing of gas-insulated switchgear (GIS) and treatment of SF6 decomposition products under partial discharge are two crucial studies. In this paper, the adsorption behavior and sensor properties of five characteristic decomposition gases of SF6 (HF, H2S, SO2, SOF2, SO2F2) on intrinsic and CoO-doped SnSe monolayers are investigated in detail based on density-functional theory. The results showed that the adsorption behaviors of HF, H2S, SOF2 and SO2F2 on SnSe monolayers were all physisorption among which the best adsorption was SO2 with an adsorption energy of −0.618 eV, which is a weak chemisorption. After doping with CoO, the adsorption capacity of SnSe monolayer for five gases was significantly enhanced, in which the adsorption energies for SO2 and SOF2 reached −1.356 eV and −1.175 eV, respectively. In addition, the conductivity of the system is greatly improved, with the bandgap changing from 1.129 eV to 0 eV. The microscopic mechanism of the interaction of gas molecules with CoO-SnSe monolayers has been revealed by energy band structure (Eg), density of states (DOS), Milligan charge analysis (∆Q) and electrostatic potential. Finally, the sensitivity (S) and desorption time (τ) of the five adsorption systems were calculated to illustrate the macroscopic gas-sensitive properties of the system. This work will help to explore the application of CoO-SnSe monolayers in SF6 decomposition gas sensing detection and adsorption treatment.

Adsorption and sensing SF6 decomposed gases (SO2, SO2F2, SOF2, H2S, and HF) on Ti and Co decorated B4CN3 monolayer- A DFT study

With frequent switching of high power and high voltage circuits, SF6 gas decomposes into low fluorine gases, which causes deterioration of SF6 gas. Therefore, such decomposed gases must be sensed and captured timely for the smooth operation of the SF6 power circuit breaker (PCB). The current study aimed to employ density functional theory (DFT) calculations to explore the adsorption and gas sensing properties of SF6 decomposed products (SO2, SO2F2, SOF2, H2S and HF) on titanium (Ti) and cobalt (Co) decorated B4CN3 monolayer. The findings revealed that pure B4CN3 could not capture gas molecules with sufficient adsorption energy and faced instantaneous release. Similarly, Ti and Co decoration can significantly activate the B4CN3 for adsorption and gas sensing. Adsorption analysis showed that SO2, SO2F2, SOF2, H2S, and HF chemically adsorbed on Ti decorated B4CN3 monolayer having adsorption energy of −1.31, −1.61, −1.35, −1.20, and −1.01 eV. Whereas, gas adsorption on Co decorated B4CN3 has −1.29, −1.58, −1.31, −1.18, and −0.95 eV, respectively. The gas sensing mechanism was evaluated by calculating band structure, work functions, and transport transmission. Despite having comparatively lower adsorption energies, Co decorated B4CN3 was found to be more sensitive to all gas molecules than Ti decorated B4CN3. The release time of gas molecules at room temperature can be shortened to nanoseconds either by rising temperature to 498 K or by just UV exposure at 298 K. Our study provides some significant theoretical insights into the gas sensing abilities of Ti and Co decorated B4CN3 monolayer for sensing SF6 decomposed products.

Gas gains over 104 and optimisation using 55Fe X-rays in low pressure SF6 with a novel Multi-Mesh ThGEM for directional dark matter searches

The Negative Ion Drift (NID) gas SF6 has favourable properties for track reconstruction in directional Dark Matter (DM) searches utilising low pressure gaseous Time Projection Chambers (TPCs). However, the electronegative nature of the gas means that it is more difficult to achieve significant gas gains with regular Thick Gaseous Electron Multipliers (ThGEMs). Typically, the maximum attainable gas gain in SF6 and other Negative Ion (NI) gas mixtures, previously achieved with an 55Fe X-ray source or electron beam, is on the order of 103 [1,2,3,4]; whereas electron drift gases like CF4 and similar mixtures are readily capable of reaching gas gains on the order of 104 or greater [5,9,7,8,6]. In this paper, a novel two stage Multi-Mesh ThGEM (MMThGEM) structure is presented. The MMThGEM was used to amplify charge liberated by an 55Fe X-ray source in 40 Torr of SF6. By expanding on previously demonstrated results [10], the device was pushed to its sparking limit and stable gas gains up to ˜50000 were observed. The device was further optimised by varying the field strengths of both the collection and transfer regions in isolation. Following this optimisation procedure, the device was able to produce a maximum stable gas gain of ˜90000. These results demonstrate an order of magnitude improvement in gain with the NID gas over previously reported values and ultimately benefits the sensitivity of a NITPC to low energy recoils in the context of a directional DM search.

Effect on thermal, mechanical, and biodegradable properties of plasma‐treated fish scale powder/linear low‐density polyethylene polymer composite films

AbstractIn the present work, we report the effect of low‐temperature plasma treatment on thermal, mechanical, and biodegradable properties of polymer composite blown films prepared from carp fish scale powder (CFSP) and linear low‐density polyethylene (LLDPE). The CFSP was melt compounded with LLDPE using a filament extruder to prepare 1, 2, and 3 wt.% of CFSP in LLDPE polymer composite filaments. These filaments were further pelletized and extruded into blown films. The blown films extruded with 1, 2, and 3 wt.% of CFSP in LLDPE were tested for thermal and mechanical properties. It was observed that the tensile strength decreased with the increased loading content of CFSP, and 1% CFSP/LLDPE exhibited the highest tensile strength. To study the effect of low‐temperature plasma treatment, 1% CFSP/LLDP polymer composite with high tensile strength was plasma treated with O2 and SF6 gas before blow film extrusion. The 1% CFSP/LLDPE/SF6‐extruded blown films showed increased thermal decomposition, crystallinity, tensile strength, and modulus. This may be due to the effect of crosslinking by the plasma treatment. The maximum thermal decomposition rate, crystallinity %, tensile strength, and modulus obtained for 1% CFSP/LLDPE/SF6 film were 500.02°C, 35.79, 6.32 MPa, and 0.023 GPa, respectively. Furthermore, the biodegradability study on CFSP/LLDPE films buried in natural soil for 90 days was analyzed using x‐ray fluorescence. The study showed an increase in phosphorus and calcium mass percent in the soil. This is due to the decomposition of the hydroxyapatite present in the CFSP/LLDPE biocomposite.

Promoting sensitivity and selectivity of SF6 gas sensor based on metal (Rh, Pd, Ag)-doped monolayer GaTe: A DFT study

In this study, a novel gas-sensitive material based on transition metal (Rh, Pd and Ag) doped GaTe monolayer is proposed. The adsorption properties of Rh-GaTe, Pd-GaTe and Ag-GaTe single molecule membranes on four SF6 decomposition gases (H2S, SO2, SOF2, SO2F2) were investigated by using density functional theory (DFT). The adsorption energy, QT, DOS, work function and energy band structure were analyzed. For further analysis, differential charge density, molecular orbital theory and recovery time were also investigated. The results show that Rh-GaTe, Pd-GaTe and Ag-GaTe are promising materials for gas detection.

Clinical Outcome in Lens Drop evacuation after a High-Risk Characteristics Proliferative Diabetic Retinopathy Post Pars Plana Vitrectomy Case

Introduction : Vitrectomy surgery affects zonular strength, which increases the risk of lens drop and can be sight- threatening if not managed correctly. Pars plana vitrectomy (PPV) and evacuation of dislocated lens fragments have to be done very carefully.
 Case Illustration : A 42-year-old female with blurred vision in the right eye for two months and a history of right-eye surgery three months ago due to proliferative diabetic retinopathy (PDR) was tamponed with SF6 gas. On examination was found visual acuity (VA) was 6/120, with cloudy lens and attached retina. The patient was diagnosed with a right-eye complicated cataract with advanced PDR post-PPV and planned to undergo phacoemulsification. While waiting for the surgery, the lens dropped into the posterior chamber, then planned to do the evacuation immediately. Dropped lens evacuation, PPV, retro-pupil IOL implantation, and silicone oil (SO) tamponing were done. Two months after the SO evacuation, the best corrected VA improved to 6/15.
 Discussion : Cataract progression after vitrectomy is common. In a vitrectomized eye, there is a lack of vitreous tamponade and a less stable lens. Peripheral zonules are attached to the pars plana, which can be disrupted during the vitrectomy surgery. Improvements in visual acuity and lower rates of complications were found if the lens fragment was evacuated soon.
 Conclusion : Cataract surgery is better done soon after PPV to prevent dropped lenses into the posterior chamber, whether the zonulisis sign is seen or not. The interval between the dropped lens incident and evacuation was associated with better final visual outcomes.

Explainable artificial intelligence-based evidential inferencing on process faults in plasma etching

The fault detection and classification (FDC) modeling proposed in this study is a research approach that is intended to improve the performance of plasma process models by leveraging optical emission spectroscopy (OES) data containing plasma information (PI) and enhancing model interpretability using explainable artificial intelligence (XAI) algorithms. Status variable identification data that included normal and abnormal states of bias power, pressure, SF6 gas flow, and O2 gas flow were collected during a silicon etching process with SF6, O2 gas plasma. Additional variables were derived from the OES data and included additional PI, such as O and F radicals, which were computed using actinometry, and electron temperature and electron density computed using the line ratio method. By building a high-performance FDC model and interpreting its results using XAI algorithms, we propose solutions to the limitations of the FDC model in semiconductor plasma processes.

Monitoring SF6 Gas Leakage Based on a Customized Binocular System

Sulfur hexafluoride (SF6) gas is extensively utilized as an insulating and arc-quenching medium in the circuit breakers and isolating switches of electrical equipment. It effectively isolates the circuits from the atmosphere and promptly extinguishes arcs. Therefore, the issue of SF6 gas leakage poses a significant threat to the related application fields, and the detection of SF6 gas leakage becomes extremely important. Infrared imaging detection offers advantages including non-contact, high precision, and visualization. However, most existing infrared detection systems are equipped with only one filter to detect SF6 gas. The images captured contain background noise and system noise, making these systems vulnerable to interference from such noises. To address these issues, we propose a method for monitoring SF6 gas leakage based on a customized binocular imaging (CBI) system. The CBI system has two filters, greatly reducing the interference of system noise and background noise. The first filter features the absorption resonant peak of SF6 gas. The second filter is used to record background noise and system noise. One aspect to note is that, in order to avoid the interference of other gases, the central wavelength of this second filter should keep away from the absorption resonant peaks of those gases. Accordingly, the central wavelengths of our customized filters were determined as 10,630 nm and 8370 nm, respectively. Then, two cameras of the same type were separately assembled with a customized filter, and the CBI prototype was accomplished. Finally, we utilized the difference method using two infrared images captured by the CBI system, to monitor the SF6 gas leakage. The results demonstrate that our developed system achieves a high accuracy of over 99.8% in detecting SF6 gas. Furthermore, the CBI system supports a plug-and-play customization to detect various gases for different scenarios.

Rapid Recovery Technology of SF6/N2 Mixed Insulation Gas in Electrical Equipment

SF6 mixed gas is widely used as an insulation and arc extinguishing medium in electrical equipment in cold regions of northern China. Due to its low liquefaction temperature, existing gas recovery technologies are unable to achieve efficient and rapid recovery of SF6/N2 mixed insulation gases. In response to this challenge, a two-stage membrane separation and recovery technology has been proposed, which can efficiently and quickly separate SF6 and N2 from the mixed gas. The volume fraction (V/V) of obtained product SF6 gas reaches 90%, and the use of compression and refrigeration units can achieve rapid filling of 50 m3/h mixed gas. At the same time, the enrichment and recovery of trace SF6 gas in the exhaust gas are achieved. After enrichment, the volume fraction (V/V) of SF6 gas reaches 92%, and the volume fraction (V/V) of SF6 gas in the emptied mixed gas is 600 μL/L, far below the national standard value, solving the problems in actual production.

TSFF-Net: A novel lightweight network for video real-time detection of SF6 gas leaks

Detecting Sulphur hexafluoride (SF6) gas leaks using infrared video images is the latest technology. However, the current algorithm for autonomous real-time detection is imprecise and incapable of performing the real-time monitoring task effectively. In response to the aforementioned issues, we present a temporal–spatial feature fusion network (TSFF-Net) specifically designed for video real-time detection of SF6 gas leaks. Compared with the existing SF6 gas leak detection model based on deep learning, the biggest feature of TSFF-Net is the introduction of foreground pixel images with SF6 gas movement characteristics, which greatly enhances the model’s ability to detect SF6 gas leaks. Simultaneously, by designing a new attention feature fusion module, introducing the Neck module of motion features, and the Backbone module to enhance small target feature extraction, we achieve high-precision SF6 gas leak detection in various complex scenarios, such as sparse leaks, complex backgrounds, camera shake, etc. The mean average precision (mAP) of TSFF-Net in the validation set was 56.3%, which is 13.2% higher than that of Yolov8s. In addition, the model proposed in this paper has parameters that are only 2.6 M, making it suitable for deployment on mobile or embedded devices. The code and test results are at https://github.com/1jianyao/TSFF-Net/tree/main.

Cantilever enhanced fiber-optic photoacoustic microprobe for diffusion detection of sulfur dioxide

A cantilever enhanced fiber-optic photoacoustic microprobe with the cavity volume of only 119 μL is designed to detect SO2, which has the obvious advantages of passive sensing, anti-electromagnetic interference and low cost. A UV multi-mode fiber and a single-mode fiber are applied to transmit excitation light emitted by UV-LED and probe light, respectively. The lens assembly based on a collimating lens and a focusing lens is added to improve the light energy of UV-LED coupling into UV-fiber. Based on theoretical analysis and finite element method, a photoacoustic cavity with a radius of 1.5 mm and a length of 15 mm is designed, which is conducive to the realization of photoacoustic enhancement and rapid response at high frequencies. SO2 gas diffuses into the PA cavity through a hole with the diameter of 0.5 mm and a gap of the cantilever with the width of 0.5 µm. A fiber-optic cantilever based on F-P interference is adopted to detect sound pressure. The frequency characteristic and response time of the sensor in different backgrounds of SF6 and N2 are analyzed experimentally. Compared with N2, the photoacoustic microprobe operates in SF6 background with lower resonance frequency and longer response time, which is due to the high density and low thermal diffusivity of SF6 gas. With the flow rate of 250 SCCM in the external cavity, the response time of the photoacoustic microprobe to SO2/SF6 and SO2/N2 are 96 s and 40 s, respectively. The detection limits of SO2 in SF6 and N2 background are 35 ppb and 5 ppb, respectively.