Frequency-dependent surface acoustic wave behavior of hydrogen-sensitive nanoscale PdNi thin films

Liu

Mei

et al. 2019

Sensors

A Pd-Ni alloy thin-film coated surface acoustic wave (SAW) device is proposed for sensing hydrogen. The Pd-Ni thin-film was sputtered onto the SAW propagation path of a SAW device with a delay line pattern to build the chip-sized hydrogen sensor. The prepared sensor chip was characterized by employing a differential oscillation loop. The effect of the Pd-Ni film thickness on sensing performance was also evaluated, and optimal parameters were determined, allowing for fast response and high sensitivity. Excellent working stability (detection error of 3.7% in half a year), high sensitivity (21.3 kHz/%), and fast response (less than 10 s) were achieved from the 40 nm Pd-Ni alloy thin-film coated sensing device.

Section: Introductionmentioning

confidence: 99%

Development of a High Stability Pd-Ni Alloy Thin-Film Coated SAW Device for Sensing Hydrogen

Liu

Mei

et al. 2019

Sensors

“…There are a lot of SAW sensor on different gases, such as H 2 [4,5], H 2 S [6] or VOC [7]. Most of the SAW gas sensor utilizes a sensitive film between the transmitting IDT and receiving IDT, and the sensor response changes accordingly when the sensitive film reacts with target gases.…”

Section: Introductionmentioning

confidence: 99%

Passive wireless surface acoustic wave CO2 sensor with carbon nanotube nanocomposite as an interface layer

Chyu

Sensors and Actuators A: Physical

2014

A passive wireless CO 2 sensing system based on surface acoustic wave (SAW) device and carbon nanotube nanocomposite thin film was studied. The electrical resistance change of the carbon nanotube nanocomposite thin film was examined first, and about 10% resistance increase was observed when the thin film is exposed to pure CO 2. The frequency change for SAW sensor coated with nanocomposites film was around 0.03% when the device is exposed to pure CO 2. However, the performance of the CO 2 SAW sensor is severely influenced by environmental humidity. With additional ultrathin parylene film packaging, the SAW sensor frequency change from relative humidity of 0% to 100% at room temperature decreased from over 0.1% to less than 0.01%. It was found that the lowest detection limit of the CO 2 SAW sensor is 1% CO 2 concentration, with 0.0036% frequency change. Wireless module was tested and showed promising transmission distance at preferred parallel orientation.

Adv Materials Technologies

“…Various types of hydrogen sensors have been reported in the literature with different operation mechanisms and sensing materials, including resistance type, [4][5] optical fiber, [6][7][8] electrochemical-based type, [9] and methods using surface acoustic wave (SAW) technology. [10][11][12][13] Most available resistive types of hydrogen sensors usually operate at high temperatures which precludes their commercialization. The high operating temperature of resistive based hydrogen sensors can also lead to the explosive hazards and energy consumption.…”

mentioning

confidence: 99%

Development of Highly Sensitive and Stable Surface Acoustic Wave‐Based Hydrogen Sensor and Its Interface Electronics

Kim

Singh

Lee

2022

cause significant damage to humans. ≈4%-75% of the hydrogen content in air is combustible, therefore real-time monitoring of hydrogen leakages is essential to prevent potentially catastrophic events in practical applications. As previously reported in the literature, the hydrogen is generated in transformer insulating oil due to local heating, corona, and arcing. [1][2][3] Gas chromatography and photoacoustic spectroscopy are the typically used methods to measure the concentration of hydrogen leaking out through a ultrafine porous filter from the insulating oil near the drain of a transformer, but the sensor systems involved are bulky, too complex, expensive, and a significant amount of time is required to obtain the final results. Various types of hydrogen sensors have been reported in the literature with different operation mechanisms and sensing materials, including resistance type, [4][5] optical fiber, [6][7][8] electrochemical-based type, [9] and methods using surface acoustic wave (SAW) technology. [10][11][12][13] Most available resistive types of hydrogen sensors usually operate at high temperatures which precludes their commercialization. The high operating temperature of resistive based hydrogen sensors can also lead to the explosive hazards and energy consumption. Among various types of gas sensors, in particular, SAW-based hydrogen gas sensors have drawn attention owing to their high sensitivity, room temperature operation, stability, and low minimum detection level. The sensing mechanism of the SAW sensor is based on the adsorption of target gas molecules on the surface of sensing materials which induces changes in the mass (mass loading), conductivity (electric loading), and elasticity (elastic loading) of sensing film deposited in the propagation path. Any changes, such as mass, resistance, and elastic properties of sensing material lead to modification of SAW propagation properties, resulting in a frequency shift of SAW sensors. Previous studies have shown that mass, electric, and elastic loading are the three factors likely to contribute to the frequency shift of SAW-based sensors. [14] Moreover, several factors may concurrently contribute to the frequency shift of SAW-based sensors. Therefore, it is important to study the contribution of each factor to better understand the detection mechanism for the production of high performance SAW A surface acoustic wave (SAW)-based hydrogen sensor and its corresponding interface electronics have been developed to measure the hydrogen concentration in air at room temperature. Two SAW delay lines with center frequencies of 284 and 284.3 MHz are employed for the sensor system to eliminate any environmental disturbances emerging from temperature and humidity variations on a sensor output. A beehive-configured and Cu-doped SnO 2 nanostructure is used as a hydrogen-sensitive material to have a high surface to volume ratio, high sensitivity, and selectivity for the target hydrogen. The smallest frequency difference detectable in our sensor system including oscil...