Wireless neural probes based on one-port SAW delay line and neural firing-dependent varicap diode

Adv Materials Technologies

Singh

Jeong

et al. 2023

Self Cite

Despite extensive research on ultraviolet (UV) sensors based on core–shell heterostructures, most of them exhibit low sensitivities, slow response/recovery times, and unsatisfactory long‐term stabilities, thereby limiting their use in real‐time applications. To solve these problems, a highly sensitive and stable surface acoustic wave (SAW) UV sensor based on novel tantalum pentoxide (Ta2O5) coated 1D zinc oxide (ZnO)/tin dioxide (SnO2) core–shell nanostructures is introduced. The fabricated SAW‐based UV sensor system, including sensor interface electronics, exhibits a high UV response, fast response/recovery time, and long‐term stability. Prior to device fabrication, coupling of mode (COM) modeling is performed to calculate the optimal parameters for the SAW device. Photoluminescence and X‐ray photoelectron spectroscopy measurements reveal that the Ta2O5 layer coating effectively suppresses the recombination of photogenerated carriers, leading to an increase in the carrier density and improvement in the UV sensing properties. The evaluated sensitivity and linearity of the proposed sensor are 120.36 ppm (mW cm−2)−1 and 0.988, respectively, in the range of 1–60 µW cm−2. The sensing mechanism of the proposed UV sensor is discussed in detail. Using COMSOL simulations and photo‐corrosion experiments, it is found that the Ta2O5 coated ZnO/SnO2 core–shell heterostructure minimizes the effects of humidity and improves stability.

Section: Optimal Parameters Considerations and Analytical Comsol Simu...mentioning

confidence: 99%

Development of Highly Stable and Sensitive SAW UV Sensor Based on Ta₂O₅ Coated 1D ZnO/SnO₂ Core–Shell Nanostructures

Adv Materials Technologies

Singh

Jeong

et al. 2023

Self Cite

“…We hereby omit a detailed derivation process of the COM modeling and instead, deal only with the modeling results because the detailed process has been already explained in our previous reports. [28][29][30] Through the COM modeling, the optimal design parameters of the two-port SAW delay line were extracted. Various structural parameters such as IDT pair, aperture length, cavity, and metal thickness were varied in the modeling to determine the optimal ones.…”

Section: Coupling Of Mode (Com) Modeling Of Saw Sensorsmentioning

confidence: 99%

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

Adv Materials Technologies

Singh

Lee

2022

Self Cite

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...

“…COM modeling was performed to extract the optimal structural parameters (IDT pairs, aperture, and distance between reflector bars) for the SAW sensor. We omit a detailed deriving process of the COM modeling and instead mention the modeling results only because the detailed process has been already explained several times in our previous reports [11][12][13]. sensors were designed to have different center frequencies in which each sensor was ~ 20 MHz bandwidth range.…”

Section: Coupling Of Mode (Com) Modelingmentioning

confidence: 99%

Deployment of Underground Wireless Sensor Network Based on Magnetic Core Antennas and Multiple Surface Acoustic Wave Sensor Modules

J. Electr. Eng. Technol.

Park

Lee

2020

Self Cite

For the first time, a 3less (batteryless, chipless, wireless) underground sensor system was developed for real time monitoring of variations in temperature, humidity, and hydrogen gas concentrations around underground utility burials. The completed sensor system consists of several magnetic core antennas, surface acoustic wave (SAW) sensors, and a measurement system. Each SAW sensor was activated by pure magnetic energy, and showed high sensor performances in sensitivity and linearity. A long readout distance was observed between the upper and underground antennas, and wireless magnetic communication was analyzed in terms of the interdistances, the angles between antennas, and the underground constituent mediums. A circulator was employed to discern magnetic signals emitting and receiving in between the upper and underground systems. A COMSOL simulation and coupling of mode (COM) modeling were also conducted to determine optimal design parameters for the sensor modules, and to predict the experimental results in advance.