Quartz-enhanced photoacoustic spectroscopy sensing using trapezoidal- and round-head quartz tuning forks

Optical synchronous signal demodulation-based quartz-enhanced photoacoustic spectroscopy for remote, multi-point methane detection in complex environments

We present a novel optical synchronized signal demodulation (OSSD) method applied in quartz-enhanced photoacoustic spectroscopy (QEPAS) for remote gas sensing. Using 1 % of the laser source as an optical synchronization signal, kilometer-scale remote gas detection was achieved, overcoming the challenges of long-distance real-time detection in complex environments with conventional QEPAS. A time-sharing OSSD-QEPAS system for sewer methane detection was subsequently developed. The system's modulation depth was optimized, and the catalytic effect of water vapor on photoacoustic signals was validated, resulting in a CH₄ sensor achieving a detection limit of 445 ppb with a 300-ms averaging time, and an excellent linear dynamic range with a R2 = 0.999. To demonstrate the stability, robustness, and accuracy of the OSSD-QEPAS system, continuous methane measurements covering a 14-hour period at two different sewer locations on campus were performed.

Multivariate-coupled-enhanced photoacoustic spectroscopy with Chebyshev rational fractional-order filtering algorithm for trace CH4 detection

An innovative and miniature photoacoustic spectroscopy (PAS) gas sensor based on a multivariate-coupled amplification photoacoustic cell (MVCA-PAC) with a total length of 100 mm was developed to achieve ultra-sensitive trace CH4 detection. Acoustic pressure distribution simulations reveal that at the first-order resonance frequency, the MVCA-PAC achieves a maximum acoustic pressure approximately 3.9 times higher than that of a conventional photoacoustic cell. The absorption optical path of the MVCA-PAC reached 2068 mm through 22 reflections, resulting in a 2-fold increase in the amplitude of photoacoustic signals compared to the traditional photoacoustic cell with an equivalent absorption optical path. Furthermore, compared to a single-pass photoacoustic cell, the 2-f signal intensity of the MVCA-PAC increased by a factor of 4.5. Allan variance analysis indicated a detection limit of 0.572 ppm for CH4 detection with an averaging time of approximately 300 s. To further improve the measurement precision of the designed sensor, the Chebyshev rational fractional-order filtering (CRFOF) algorithm was introduced for PAS signal processing for the first time. Post-processing results demonstrated a 15.4-fold improvement in measurement precision, achieving a precision of 0.578 ppm. Finally, continuous monitoring of atmospheric CH4 over a 48-hour period validated the reliability and feasibility of the sensor.

Improved T-shaped quartz tuning fork with isosceles-trapezoidal grooves optimized for quartz-enhanced photoacoustic spectroscopy

The quartz tuning fork (QTF) being the acoustic-electrical conversion element for quartz-enhanced photoacoustic spectroscopy (QEPAS) system directly affects the detection sensitivity. However, the low electromechanical conversion efficiency characteristic of standard QTF limits the further enhancement of the system. Therefore, the optimized design for QTF is becoming an important approach to improve the performance of QEPAS. In this work, 9 kHz T-shaped QTFs with isosceles-trapezoidal grooves are firstly applied to gas sensing experiments. Four types of 9 kHz QTFs are fabricated and applied to gas detection experiments. Simulation results reveal QTFs with isosceles-trapezoidal grooves are conducive to optimizing the stress distribution and enhancing electromechanical conversion efficiency. The results of the gas sensing experiment (acetylene C2H2) indicate that the signal peak and signal-to-noise ratio values of T-shaped QTF with positive isosceles-trapezoidal grooves can reach 1.44 and 1.85 times greater than the normal QTF with rectangular cross-section prongs.

Ppb-Level Ammonia Sensor for Exhaled Breath Diagnosis Based on UV-DOAS Combined with Spectral Reconstruction Fitting Neural Network

Ammonia (NH3) in exhaled breath (EB) has been a biomarker for kidney function, and accurate measurement of NH3 is essential for early screening of kidney disease. In this work, we report an optical sensor that combines ultraviolet differential optical absorption spectroscopy (UV-DOAS) and spectral reconstruction fitting neural network (SRFNN) for detecting NH3 in EB. UV-DOAS is introduced to eliminate interference from slow change absorption in the EB spectrum while spectral reconstruction fitting is proposed for the first time to map the original spectra onto the sine function spectra by the principle of least absolute deviations. The sine function spectra are then fitted by the least-squares method to eliminate noise signals and the interference of exhaled nitric oxide. Finally, the neural network is built to enable the detection of NH3 in EB at parts per billion (ppb) level. The laboratory results show that the detection range is 9.50-12425.82 ppb, the mean absolute percentage error (MAPE) is 0.83%, and the detection accuracy is 0.42%. Experimental results prove that the sensor can detect breath NH3 and identify EB in simulated patients and healthy people. Our sensor will serve as a new and effective system for detecting breath NH3 with high accuracy and stability in the medical field.

High-sensitivity trace gas detection based on differential Helmholtz photoacoustic cell with dense spot pattern

A high-sensitivity photoacoustic spectroscopy (PAS) sensor based on differential Helmholtz photoacoustic cell (DHPAC) with dense spot pattern is reported in this paper for the first time. A multi-pass cell based on two concave mirrors was designed to achieve a dense spot pattern, which realized 212 times excitation of incident laser. A finite element analysis was utilized to simulate the sound field distribution and frequency response of the designed DHPAC. An erbium-doped fiber amplifier (EDFA) was employed to amplify the output optical power of the laser to achieve strong excitation. In order to assess the designed sensor's performance, an acetylene (C2H2) detection system was established using a near infrared diode laser with a central wavelength 1530.3 nm. According to experimental results, the differential characteristics of DHPAC was verified. Compared to the sensor without dense spot pattern, the photoacoustic signal with dense spot pattern had a 44.73 times improvement. The minimum detection limit (MDL) of the designed C2H2-PAS sensor can be improved to 5 ppb when the average time of the sensor system is 200 s.

Wavelength-modulated photoacoustic spectroscopic instrumentation system for multiple greenhouse gas detection and in-field application in the Qinling mountainous region of China

We present a sensitive and compact quantum cascade laser-based photoacoustic greenhouse gas sensor for the detection of CO2, CH4 and CO and discuss its applicability toward on-line real-time trace greenhouse gas analysis. Differential photoacoustic resonators with different dimensions were used and optimized to balance sensitivity with signal saturation. The effects of ambient parameters, gas flow rate, pressure and humidity on the photoacoustic signal and the spectral cross-interference were investigated. Thanks to the combined operation of in-house designed laser control and lock-in amplifier, the gas detection sensitivities achieved were 5.6 ppb for CH4, 0.8 ppb for CO and 17.2 ppb for CO2, signal averaging time 1 s and an excellent dynamic range beyond 6 orders of magnitude. A continuous outdoor five-day test was performed in an observation station in China's Qinling National Botanical Garden (E longitude 108°29', N latitude 33°43') which demonstrated the stability and reliability of the greenhouse gas sensor.

Differential photoacoustic spectroscopy for flow gas detection based on single microphone

Differential photoacoustic spectroscopy (PAS) for flow gas detection based on single microphone is innovatively proposed and experimentally demonstrated. Unlike the traditional systems, only one microphone is used to suppress flowing gas noise. Wavelength modulation spectroscopy and second harmonic detection technique are applied in this PAS system with Q-point demodulation for acetylene (C2H2) gas detection. The experiment is conducted at 1 atm and 300 K. Different concentrations and flow rates of C2H2 from 0 sccm to 225 sccm are detected by using nitrogen (N2) as the carrier gas, which indicates that the system can respond well to flowing gases while maintaining the noise at the same level. The system response time decreases to 3.58 s while the gas velocity is 225 sccm. The detection limit of 43.97 ppb with 1 s integration time and normalized noise equivalent absorption (NNEA) coefficient of 4.0 × 10-9 cm-1 W Hz-1/2 is achieved at the flow rate of 225 sccm. The firstly proposed differential PAS based on single microphone greatly simplifies the system structure for flow gas detection, which provides a novel route for development of PAS with significant practical implementation prospects.

High-sensitivity narrow‑band T-shaped cantilever Fabry-perot acoustic sensor for photoacoustic spectroscopy

Photoacoustic spectroscopy (PAS) has been rapidly developed and applied to different detection scenarios. The acoustic pressure detection is an important part in the PAS system. In this paper, an ultrahigh sensitivity Fabry-Perot acoustic sensor with a T-shaped cantilever was proposed. To achieve the best acoustic pressure effect, the dimension of the cantilever structure was designed and optimized by finite element analysis using COMSOL Multiphysics. Simulation results showed that the sensitivity of such T-shaped cantilever was 1.5 times higher than that based on a rectangular cantilever, and the resonance frequency of T-shaped cantilever were able to modulate from 800 Hz to 1500 Hz by adjusting the multi-parameter characteristics. Experimental sensing results showed that the resonance frequency of T-shaped Fabry-Perot acoustic sensor was 1080 Hz, yielding a high sensitivity of 1.428 μm/Pa, with a signal-to-noise ratio (SNR) of 84.8 dB and a detectable pressure limit of 1.9 μPa/Hz1/2@1 kHz. We successfully used such acoustic sensor to measure acetylene (C2H2) concentration in the PAS. The sensitivity of PAS for C2H2 gas was 3.22 pm/ppm with a concentration range of 50 ppm ∼100 ppm, and the minimum detection limit was 24.91ppb.

Signal enhancement of the gas detection based on quartz-enhanced photothermal spectroscopy technology

This paper presents an improved gas sensor based on the dual-excitation of quartz-enhanced photothermal spectroscopy (QEPTS) using a single quartz tuning fork (QTF) for signal detection. The silver coating on one side of the QTF was chemically etched to increase the laser power interacted with QTF for QEPTS signal excitation. By etching the silver coating on one side of QTF, the reflection structure between the silver coating of the other side of QTF and the external flat mirror was established. The device uses an absorption gas cell with an optical range length of 3 m, making the laser beam interact with the gas more completely and posing more gas concentration information. Acetylene was selected as the target gas to verify the performance of the sensor. The experimental results show that the signal amplitude with a flat mirror was 1.41 times that without a flat mirror, and 2.47 times that of traditional QEPTS sensor. The system has a minimum detection limit (MDL) of 1.10 ppmv, corresponding to a normalized noise equivalent absorption coefficient (NNEA) of 7.14 × 10-9 cm-1·W·Hz-1/2. Allan variance analysis results show that when the integration time is 700 s, the MDL of the system is 0.21 ppmv. The proposed gas sensor can play an important role on detecting trace gas in many fields.

Methane measurement method based on F-P angle-dependent correlation spectroscopy

This study explores a gas measurement method based on Fabry-Perot (F-P) angle-dependent correlated spectroscopy, which achieves highly sensitive and selective gas measurements by adjusting the angle to match the F-P interference peak with the gas absorption peak. Methane (CH4) is the chosen target gas, and an F-P etalon is designed with parameters matching the CH4 absorption peak. An angle-scanning measurement system is established to enable correlated spectroscopic detection of CH4 gas. Angle-scanning measurements reveal distinct absorption signals at the angle where the F-P interference peak aligns with the CH4 absorption peak. Gas measurements of standard samples demonstrate a linear relationship between the apparent absorbance at the on/off positions and CH4 concentration, allowing for accurate CH4 concentration measurements. The study further investigates the detection limit of the experimental system, achieving a 3σ detection limit of 720 ppm under the on/off measurement mode. A conical incidence model is developed to analyze the impact of beam divergence angles on the transmittance of the F-P cavity. Simulations are conducted to assess absorption signals in the presence of extreme cross-interference, demonstrating the method's robust resistance to cross-interference. The F-P correlated spectroscopy method described in this paper, as a non-dispersive spectroscopic measurement technique, holds promise for designing high-sensitivity gas sensors and imaging applications.

Perovskite photodetector-based laser absorption spectroscopy for gas detection

A gas detection method based on CH3NH3PbI3 (MAPbI3) and poly (3,4-ethylenedioxythiophene): poly (4-styrene sulfonate) (PEDOT:PSS) composite photodetectors (PDs) is proposed. The operation of the PD primarily relies on the photoelectric effect within the visible light band. Our study involves constructing a gas detection system based on tunable diode laser spectroscopy (TDLAS) and MAPbI3/PEDOT:PSS PD, and O2 was selected as the target analyte. The system has achieved a minimum detection limit (MDL) of 0.12% and a normalized noise equivalent absorption coefficient (NNEA) of 8.83 × 10-11 cm-1⋅W⋅Hz-1/2. Furthermore, the Allan deviation analysis results indicate that the system can obtain sensitivity levels as low as 0.058% over an averaging time of 328 seconds. This marks the first use of MAPbI3/PEDOT:PSS PD in gas detection based on TDLAS. Despite the detector's performance leaves much to be desired, this innovation offers a new approach to developing spectral based gas detection system.

High-Sensitivity Differential Helmholtz Photoacoustic System Combined with the Herriott Multipass Cell and Its Application in Seed Respiration

A highly sensitive photoacoustic detection system using a differential Helmholtz resonator (DHR) combined with a Herriott multipass cell is presented, and its implementation to sub-ppm level carbon dioxide (CO2) detection is demonstrated. Through the utilization of erbium-doped optical fiber amplifier (EDFA), the laser power was amplified to 150 mW. Within the multipass cell, a total of 22 reflections occurred, contributing to an impressive 33.6 times improvement in the system sensitivity. The normalized noise equivalent absorption coefficient (NNEA) was 8.64 × 10-11 cm-1·W·Hz-1/2 [signal-to-noise ratio, (SNR) = 1] and according to the Allan variance analysis, a minimum detection limit of 500 ppb could be achieved for CO2 at 1204 s, which demonstrates the long-term stability of the system. The system was applied to detect the respiration of rice and upland rice seeds. It is demonstrated that the system can monitor and distinguish the respiration intensity and respiration rate of different seeds in real time.

ELM combined with differential Raman spectroscopy for the detection of microplastics in organisms

Aiming at the problems of low extraction efficiency, high false detection rate, weak Raman signal and serious interference by fluorescence signal in the detection of microplastics in marine organisms, this paper establishes a set of rapid detection methods for microplastics in organisms, including confocal Raman spectroscopy, fluorescence imaging, differential Raman spectroscopy, and rapid identification of microplastics based on the ELM modeling assistance. Firstly, to address the problem of low extraction efficiency of microplastics, we explored and optimized the digestion method of tissues, which effectively improved the digestion effect of fish tissues and excluded the influence of tissues on microplastics detection. Aiming at the problems of high misdetection rate and low pre-screening efficiency of microplastics, fluorescence imaging technology is adopted to realize the visualization and detection of microplastics, which effectively improves the detection efficiency and precision of microplastics. Based on the confocal microscopy Raman spectroscopy detection system built independently in the laboratory, using 784/785 nm as the excitation light, the differential Raman spectroscopy technique effectively excludes the interference of fluorescence signals in the Raman spectra, and improves the signal-to-noise ratio of the Raman spectra, and the recovery rate of the Raman characteristic peaks in the differential Raman spectroscopy reaches 100 % compared to the traditional baseline correction method, which is 33.3 % higher than that of the baseline correction method. Finally, a microplastic identification model is constructed based on ELM to assist in realizing the rapid and accurate identification of microplastics. The more complete detection method of microplastics in marine organisms proposed in this paper can realize the rapid and nondestructive, efficient and accurate detection of microplastics in fish, which can help to further promote the development of marine microplastics monitoring technology.

Ultra-highly sensitive dual gases detection based on photoacoustic spectroscopy by exploiting a long-wave, high-power, wide-tunable, single-longitudinal-mode solid-state laser

Photoacoustic spectroscopy (PAS) as a highly sensitive and selective trace gas detection technique has extremely broad application in many fields. However, the laser sources currently used in PAS limit the sensing performance. Compared to diode laser and quantum cascade laser, the solid-state laser has the merits of high optical power, excellent beam quality, and wide tuning range. Here we present a long-wave, high-power, wide-tunable, single-longitudinal-mode solid-state laser used as light source in a PAS sensor for trace gas detection. The self-built solid-state laser had an emission wavelength of ~2 μm with Tm:YAP crystal as the gain material, with an excellent wavelength and optical power stability as well as a high beam quality. The wide wavelength tuning range of 9.44 nm covers the absorption spectra of water and ammonia, with a maximum optical power of ~130 mW, allowing dual gas detection with a single laser source. The solid-state laser was used as light source in three different photoacoustic detection techniques: standard PAS with microphone, and external- and intra-cavity quartz-enhanced photoacoustic spectroscopy (QEPAS), proving that solid-state laser is an attractive excitation source in photoacoustic spectroscopy.

TT-type resonator-based differential photoacoustic spectroscopy for trace gas detection

A novel TT-type resonator was proposed for the first time, to our knowledge, to realize differential photoacoustic (PA) detection for trace gas measurement. The special design of the TT-type resonator allows us to install the microphone at the resonant center of the acoustic field to maximize the use of the absorption-induced PA signal. To meet the requirement of low gas consumption and easy integration, the TT-type resonator-based PA cell was fabricated as a fiber-coupled module with an inner volume of only 1.1 ml. For validation, the TT-type PA cell was integrated to a photoacoustic spectroscopy (PAS) system for acetylene detection. As a result, a linearity of 0.99999 was achieved in a concentration range from 0 to 5000 ppm with a noise equivalent sensitivity of 101 ppb. The proposed TT-type resonator contributes a new style of PA cell structure to the field of PAS gas detection, combining the advantages of easy integration, low gas consumption, differential detection, and photoacoustic enhancement together.

Geometry optimization of cantilever-based optical microphones

The introduction of cantilever-based fiber-optic microphones (FOMs) has proven to be effective in acoustic sensing. Further improvements in cantilevers face two key constraints: the challenge of achieving minimal sizes with sufficient reflective area and the trade-off between sensitivity and response bandwidth. Herein, we present a geometry optimization framework for a cantilever-based FOM that addresses this issue. Employing drumstick-shaped cantilevers housed within a Fabry-Perot (F-P) interferometric structure, we showcase a heightened sensitivity of 302.8 mV/Pa at 1 kHz and a minimum detectable acoustic pressure (MDP) of 2.35 µPa/H z. Notably, these metrics outperform those of the original rectangular cantilever with identical dimensions. Furthermore, our proposed cantilever effectively mitigates the reduction in resonance frequencies, thereby improving the response bandwidth. This geometry optimization framework offers considerable design flexibility and scalability, making it especially suitable for high-performance acoustic sensing applications.

Near-infrared dual-gas sensor for simultaneous detection of CO and CH4 using a double spot-ring plane-concave multipass cell and a digital laser frequency stabilization system

A novel double spot-ring plane-concave multipass cell (DSPC-MPC) gas sensor was proposed for simultaneous detection of trace gases, which has lower cost and higher mirror utilization than the traditional multipass cell with 129 m, 107 m, 85 m, 63 m and 40 m effective optical path lengths adjustable. The performance of the DSPC-MPC gas sensor was evaluated by measuring CO and CH4 using two narrow linewidth distributed feedback lasers with center wavelengths of 1567 nm and 1653 nm, respectively. An adjustable digital PID laser frequency stabilization system based on LabVIEW platform was developed to continuously stabilize the laser frequency within ∼±30.3 MHz. The Allan deviation results showed that the minimum detection limits for CO and CH4 were 0.07 ppmv and 0.008 ppmv at integration times of 711 s and 245 s, respectively. The proposed concept of DSPC-MPC provides more ideas for the realization of gas detection under different absorption path lengths and the development of multi-component gas sensing systems.

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.

Mid-infrared all-fiber light-induced thermoelastic spectroscopy sensor based on hollow-core anti-resonant fiber

In this article, a mid-infrared all-fiber light-induced thermoelastic spectroscopy (LITES) sensor based on a hollow-core anti-resonant fiber (HC-ARF) was reported for the first time. The HC-ARF was applied as a light transmission medium and gas chamber. The constructed all-fiber structure has merits of low loss, easy optical alignment, good system stability, reduced sensor size and cost. The mid-infrared transmission structure can be utilized to target the strongest gas absorption lines. The reversely-tapered SM1950 fiber and the HC-ARF were spatially butt-coupled with a V-shaped groove between the two fibers to facilitate gas entry. Carbon monoxide (CO) with an absorption line at 4291.50 cm-1 (2.33 µm) was chosen as the target gas to verify the sensing performance. The experimental results showed that the all-fiber LITES sensor based on HC-ARF had an excellent linear response to CO concentration. Allan deviation analysis indicated that the system had excellent long-term stability. A minimum detection limit (MDL) of 3.85 ppm can be obtained when the average time was 100 s.

High-sensitivity methane detection based on QEPAS and H-QEPAS technologies combined with a self-designed 8.7 kHz quartz tuning fork

Methane (CH4) is a greenhouse gas as well as being flammable and explosive. In this manuscript, quartz-enhanced photoacoustic spectroscopy (QEPAS) and heterodyne QEPAS (H-QEPAS) exploring a self-designed quartz tuning fork (QTF) with resonance frequency (f0) of ∼8.7 kHz was utilized to achieve sensitive CH4 detection. Compared with the standard commercial 32.768 kHz QTF, this self-designed QTF with a low f0 and large prong gap has the merits of long energy accumulation time and low optical noise. The strongest line located at 6057.08 cm-1 in the 2v3 overtone band of CH4 was chosen as the target absorption line. A diode laser with a high output power of > 30 mW was utilized as the excitation source. Acoustic micro-resonators (AmRs) were added to the sensor architecture to amplify the intensity of acoustic waves. Compared to the bare QTF, after the addition of AmRs, a signal enhancement of 149-fold and 165-fold were obtained for QEPAS and H-QEPAS systems, respectively. The corresponding minimum detection limits (MDLs) were 711 ppb and 1.06 ppm for QEPAS and H-QEPAS sensors. Furthermore, based on Allan variance analysis the MDLs can be improved to 19 ppb and 27 ppb correspondingly. Compared to the QEPAS sensor, the H-QEPAS sensor shows significantly shorter measurement timeframes, allowing for measuring the gas concentration quickly while simultaneously obtaining f0 of QTF.

Mineral oil emulsion species and concentration prediction using multi-output neural network based on fluorescence spectra in the solar-blind UV band

The accurate monitoring of oil spills is crucial for effective oil spill recovery, volume determination, and cleanup. Oil slicks become emulsified under the effects of wind and waves, which increases the consistency of the oil spills. This phenomenon makes oil spills more challenging to handle and exacerbates environmental pollution. In this study, the variation of the solar-blind ultraviolet (UV) fluorescence spectra obtained from simulated oil spills with different oil types and oil-water ratios was investigated. By designing and constructing a multi-angle excitation and detection system, an apparent fluorescence peak of the oil emulsions was observed at around 290 nm under 220 nm excitation. By utilizing competitive adaptive reweighted sampling (CARS) and multi-output neural network algorithms, both the types and concentrations of the emulsified oils were obtained simultaneously. The classification accuracy for identifying the oil type exceeds 98%, and the mean absolute percentage error (MAPE) for concentration regression is around 2%. The results indicate that active solar-blind UV fluorescence could become a supplementary method for on-site oil spill detection to achieve comprehensive monitoring of oil spills. This study provides potential applications for UV-induced fluorescence spectrometry in oil spill on-site monitoring during the daytime.

Acoustic Imaging Method for Gas Leak Detection and Localization Using Virtual Ultrasonic Sensor Array

An acoustic imaging method for detecting and locating gas leaks based on a virtual ultrasonic sensor array is proposed and experimentally demonstrated. A scanning sensor array of only two sensors is used to collect the acoustic signals generated by the leakage hole. The matrix of the leakage signal is processed by the cross-power spectrum method to achieve time consistency, afterward, the location of the leakage source can be calculated by the virtual beamforming method. The influence of the number of sensors and the distance between adjacent sensors on the effect of the proposed method are compared and discussed. To verify the effectiveness and operability of the detection and localization method, several experiments were carried out. Furthermore, a series of experiments were conducted to assess the accuracy and stability of this method. The experimental results demonstrate that the proposed method based on a virtual sensor array can achieve highly accurate localization of gas leaks and performs well regarding stability.