Sensitivity is one of the most important parameters to put in the foreground in all sensing applications. Its increase is therefore an ongoing challenge, particularly for surface acoustic wave (SAW) sensors. Herein, finite element method (FEM) simulation using COMSOL Multiphysics software is first used to simulate the physical and electrical properties of SAW delay line. Results indicate that 2D configuration permits to accurately obtain all pertinent parameters, as in 3D simulation, with very substantial time saving. A good agreement between calculation and experiment, in terms of transfer functions (S21 spectra), was also shown to evaluate the dependence of the SAW sensors sensitivity on the operating frequency; 2D simulations have been conducted on 104 MHz and 208 MHz delay lines, coated with a polyisobutylene (PIB) as sensitive layer to dichloromethane (DCM). A fourfold increase in sensitivity was obtained by doubling frequency. Both sensors were then realized and tested as chem-sensors to detect zinc ions in liquid media. 9-{[4-({[4-(9anthrylmethoxy)phenyl]sulfanyl} methyl)]methyl] anthracene (TDP-AN) was selected as the sensing layer. Results show a comparable response curves for both designed sensors, in terms of limit of detection and dissociation constants K_d values. On the other hand, experimental sensitivity values were of the order of [7.0 ± 2.8] × 10⁸ [°/M] and [16.0 ± 7.6] × 10⁸ [°/M] for 104 MHz and 208 MHz sensors, respectively, confirming that the sensitivity increases with frequency.

Blast waves generated by energetic materials involve very fast time variations in the pressure. One important issue for blast wave metrology is the accurate measurement (typical precision in the range of ±5% or better) of the static overpressure peak. For most near field configurations, this measurement requires ultra-fast sensors with response times lower than a few microseconds. In this paper, we design, model, fabricate and characterize a new ultra-fast sensor using piezo-resistive gauges at the center of a miniaturized and rectangular silicon membrane. When a pressure step of 10 bar is applied to the membrane, the signal delivered to the sensor output presents dampened oscillations, with a resonant frequency of 20.6 MHz and quality factor of 24,700 ns after the arrival of the shock wave. After removing undesirable drifts that appear after 700 ns, we may expect the sensor to have a response time (at ±5%) of 1.2 µs. Consequently, the proposed pressure sensor could be advantageously used for the accurate measurement of static overpressure peaks in blast wave experiments.

Surface acoustic waves (SAW) devices are used in several domains varying from telecommunication and mechanics to chemical and biological sensing. Their ability to function in either liquid or gaseous environments make them devices of choice for the detection of several types of analytes (DNA, antibodies/antigens, gases, pesticides, heavy metals …) in real time and without labeling. Compared to other chemical and biological sensors, the SAW ones are highly sensitive and can achieve very low limits of detection. Among the large variety of acoustic devices, SAW sensors are the most promising ones, as their operating frequencies can be varied from several hundred MHz to a few GHz. However, they are still the subject of constant development; therefore, simulation becomes a powerful tool to design optimised structure for highly sensitive devices. This study concerns 3D Finite Element Method (FEM) simulation of SAW sensors using COMSOL Multiphysics software. A SAW delay line was designed on 36°lithium tantalate (LiTaO₃) piezoelectric substrate. Interdigital transducers (IDTs) were patterned in Cr/Au (20 nm/80 nm) layers with the same periodicity of λ = 40 μm. A metallized Cr/Au (20 nm/80 nm) sensing area of 80 µm length separates the input and output IDTs. The corresponding frequency is thus of order of 104 MHz. Simulations were made on well-known structure to define a model that can account for and predict the electrical behaviour of SAW transducers for the future optimisations. The results show good agreement between COMSOL numerical simulation and experimental S21 spectra. Accordingly, we can use the built model for simulations intended to optimize the structure of devices, mainly for increasing their sensitivity.

Surface acoustic wave sensors functionalized with a thin layers of polypyrrole ionic imprinted polymer were designed and realized for the selective detection of lead ions. Polypyrrole films were electrodeposited on gold surface and acrylic acid was used as a chelating agent. Detection of the analyte is ensured by the strong affinity between carboxylic groups and lead ions. The detection limit of, the developed IIP piezoelectric sensor was of order of 0.1 pM, largely inferior to the maximum allowable concentration required by the European Commission for lead and its compounds (of order of 0.48 μM). Selectivity tests investigated with cobalt, copper, mercury and nickel ions, indicate that the designed sensors are selective of lead ions.

This work presents the simulation and optimization of a novel surface acoustic wave (SAW) hydrogen sensor based on a graphene oxide (GO) layer decorated with palladium nanoparticles (Pd NPs) on a lithium niobate (LiNbO ₃ ) substrate. A finite element method (FEM) was used to model the sensor, and a response surface methodology (RSM) was applied to optimize key parameters, including substrate thickness, interdigital transducer spacing, and operating frequency. The design space was statistically explored using the least squares method (LSM). The optimized configuration yielded an insertion loss of −1.06 dB at 80 MHz with a 74.74 µm substrate thickness and 6.90 mm transducer spacing. The sensor demonstrated excellent performance, with time delay and amplitude sensitivities of 26 ns and 0.72 dB per atomic fraction (af) of hydrogen in Pd, respectively. These results highlight the potential of the proposed SAW device for reliable hydrogen leak detection in safety-critical environments.