In this work, the major methods for implementing flexible sensing technology—flexible surface acoustic wave (SAW) sensors—are summarized; the working principles and device characteristics of the flexible SAW sensors are introduced; and the latest achievements of the flexible SAW sensors in the selection of the substrate materials, the development of the piezoelectric thin films, and the structural design of the interdigital transducers are discussed. This paper focuses on analyzing the research status of physical flexible SAW sensors such as temperature, humidity, and ultraviolet radiation, including the sensing mechanism, bending strain performance, device performance parameters, advantages and disadvantages, etc. It also looks forward to the development of future chemical flexible SAW sensors for gases, the optimization of the direction of the overall device design, and systematic research on acoustic sensing theory under strain. This will enable the manufacturing of multifunctional and diverse sensors that better meet human needs.

Exposure to sulfur mustard can result in severe injury or even fatalities in humans. Therefore, the development of reliable and high-performance sensors for detecting sulfur mustard is critical. Herein, WO₃ thin films are prepared as sulfur mustard simulant (e.g., 2-chloroethyl ethylsulfide, 2-CEES) sensing materials using sputter deposition followed by high-temperature annealing. The 2-CEES gas sensors fabricated via WO₃ porous films realize high-performance detection of 2-CEES at 260 °C with an impressive detection limit (15 ppb), fast response (58 s), long-term stability, and good selectivity. Through systematic optimization of deposition and annealing parameters, WO₃ porous thin films with tailored oxygen vacancy concentrations were prepared, facilitating device fabrication. This approach provides an effective strategy for the batch production of miniaturized devices enabling real-time monitoring of vesicant agents.

There have been many studies on surface acoustic wave (SAW) sensors for detecting sulfur-containing toxic or harmful gases. This paper aims to give an overview of the current state of polymer films used in SAW sensors for detecting deleterious gases. By covering most of the important polymer materials, the structures and types of polymers are summarized, and a variety of devices with different frequencies, such as delay lines and array sensors for detecting mustard gas, hydrogen sulfide, and sulfur dioxide, are introduced. The preparation method of polymer films, the sensitivity of the SAW gas sensor, the limit of detection, the influence of temperature and humidity, and the anti-interference ability are discussed in detail. The advantages and disadvantages of the films are analyzed, and the potential application of polymer films in the future is also forecasted.

There have been many researches on the surface acoustic wave (SAW) sensors for detecting sulfur-containing toxic or harmful gases. This paper aims to give an overview of the current state of the polymer films used in SAW sensors for detecting deleterious gases. By covering most of the important polymer materials, the structures and types of polymers are summarized, and a variety of devices with different frequency, such as delay lines and array sensors for detecting mustard gas, hydrogen sulfide and sulfur dioxide are introduced. The preparation method of polymer films, the sensitivity of the SAW gas sensor, the limit of detection, the influence of temperature and humidity, and the anti-interference ability are discussed in detail. The advantages and disadvantages of the films are also analyzed, and the potential application of polymer films in the future is also forecasted.

The effective detection of isopropyl methylfluorophosphonate (GB, sarin), a type of organophosphine poisoning agent, is an urgent issue to address to maintain public safety. In this research, a gas-sensitive film material, poly (4-hydroxy-4,4-bis trifluoromethyl)-butyl-1-enyl)-siloxane (SXFA), with a structure of hexafluoroisopropyl (HFIP) functional group was synthesized by using methyl vinylpropyl dichlorosilane and hexafluoroacetone trihydrate as initial materials. The synthesis process products were characterized using FTIR. SXFA was prepared on a 200 MHz shear surface wave delay line using the spin-coating method for GB detection. A detection limit of <0.1 mg/m³ was achieved through conditional experiments. Meanwhile, we also obtained a maximum response of 2.168 mV at a 0.1 mg/m³ concentration, indicating the much lower detection limit of the SAW-SXFA sensor. Additionally, a maximum response standard deviation of 0.11 mV with a coefficient of variation of 0.01 and a maximum recovery standard deviation of 0.22 mV with a coefficient of variation of 0.02 were also obtained through five repeated experiments. The results show that the SAW-SXFA sensor has strong selectivity and reproducibility, good selectivity, positive detection ability, high sensitivity, and fast alarm performance for sarin detection.

Sample preparation technique, for the analysis of δ¹³C ratios in oil and gas samples, has gradually been recognized as one of the most crucial steps of the whole analytical process. In this study, a new convenient method, syringe solid phase extraction (SSPE), was proposed for measuring δ¹³C in natural gas samples. Based on conditional experiments of temperature and time, SSPE fitted with activated carbon adsorbent was applied with a gas chromatography/isotope ratio mass spectrometry (GC/IRMS) system for trace carbon isotope analysis. The results showed that isotopic fractionation was not clearly observed during the adsorption and desorption process, and the δ¹³C ratios measured by SSPE-GC/IRMS were in good agreement with the known δ¹³C ratios of CH₄~C₅H₁₂ measured by GC/IRMS with the accuracy all within ±0.48‰. A natural gas sample was applied to verify the efficiency of this new method, and the obtained results confirmed that SSPE-GC/IRMS is a reliable technique characterized with simplicity, efficiency, and reliability.