April 2025
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2 Reads
Sensors and Actuators B Chemical
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Publications (18)
March 2025
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3 Reads
March 2025
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6 Reads
ACS Sensors
Highly sensitive, selective, and compact hydrogen (H2) sensors for safety and process monitoring are needed due to the growing adoption of H2 as a clean energy carrier. Current resonant frequency-based H2 sensors face a critical challenge in simultaneously achieving high sensitivity, low operating frequency, and miniaturization while maintaining a high figure of merit (FOM). This study addresses these challenges by introducing a novel piezoelectric micro diagram (PMD) H2 sensor that achieves an unprecedented FOM exceeding 10⁴. The sensor uniquely integrates a PMD resonator with a palladium (Pd) sensing layer, operating on a stress-based mechanism distinct from traditional mass-loading principles. Despite a low operating frequency of 150 kHz, the sensor demonstrates a remarkable sensitivity of 18.5 kHz/% H2. Comprehensive characterization also reveals a minimal cross-sensitivity to humidity and common gases and a compact form factor (600 μm lateral length) suitable for IC integration. The sensor’s performance was systematically evaluated across various Pd thicknesses (40–125 nm) and piezoelectric stack covering ratios (50% and 70%), revealing a trade-off between sensitivity and response time. This PMD H2 sensor represents a significant advancement in resonant frequency-based H2 sensing, offering superior sensitivity, compact size, and robust performance for diverse applications in H2 detection and monitoring.
March 2024
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7 Reads
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2 Citations
March 2024
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4 Reads
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1 Citation
January 2024
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11 Reads
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1 Citation
October 2023
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15 Reads
June 2023
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47 Reads
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5 Citations
Abstract Gas sensors are useful for monitoring of greenhouse gases. As the move toward complementary metal‐oxide‐semiconductor (CMOS) compatible pyroelectric room temperature detectors is gaining traction due to its scalability to 8‐in./12‐in. wafer area and integrable with CMOS electronics, CMOS compatible aluminum nitride (AlN)‐ and scandium aluminum nitride (ScAlN)‐based pyroelectric detectors are developed for sensing of CO2and CH4gases, which are two of the greenhouse gases that contribute significantly to global warming. Leveraging gas absorption at respective mid‐infrared (IR) wavelengths, CO2 and CH4 gases are detected at various concentrations with fast response time ≈1 s. A compound parabolic collector (CPC) is designed and integrated into the gas sensor to enhance the optical flux received by the detector, which demonstrates ≈10× signal improvement in its presence. Further factors such as the effect of sensing area reduction and response to random gas concentrations are also tested on AlN‐ and ScAlN‐based pyroelectric detectors respectively to observe the gas sensing behaviors of both detectors. The results obtained provide further understanding of the behavior of CMOS AlN‐ and ScAlN‐based pyroelectric detectors as IR gas sensors, which can potentially inspire new design and design selection for various gas sensing applications.
March 2023
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18 Reads
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5 Citations
March 2023
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23 Reads
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2 Citations
Citations (7)
... The system was powered by an external power, and the ultrasonic echo signal was displayed as an envelope on the oscilloscope. In this work, we added the same horn separately to a single PMUT of three different structures to concentrate the output pressure [24,40]. In addition, different ambient temperatures and humidity levels will lead to different ultrasonic transmission losses in the air [39]. ...
- Citing Conference Paper
January 2024
... Complementary Metal Oxide Semiconductor (CMOS) and Micro-Electro-Mechanical System (MEMS) devices play significant roles in emerging research fields such as artificial intelligence (AI) [1], 5G communication [2,3], the Internet of Things (IoT) [4], and satellite communication [5,6]. With the continuous development of material science and microfabrication processes, high-performance CMOS and MEMS devices have been the subject of extensive investigations and have advanced significantly [7,8]. ...
- Citing Conference Paper
January 2023
... These microstructures exploit the conservation of etendue and restrict the angular spread of light by expanding its areal spread. Unlike conventional bulky Winston cones used for beam condensing [27][28][29], our microphotonic structures are highly miniaturized and compact. Our results further demonstrate seamless integration of the angular-selective microstructures with commercial mid-IR photodetectors, which not only improves the photodetector's SNR, but also enables directional photoresponse centering at the normal direction. ...
- Citing Article
- Full-text available
August 2022
ACS Sensors
... Due to its large size, an optical path length of 37.3 cm was achieved, resulting in a detection limit of 0.5 ppm. Despite such a sensor has high sensitivity, the large size limits its applications, especially in the field of internet of things and mobile terminals, 15 where miniaturization and the capability of being able to integrate with different sensors are demanded. Furthermore, the long optical path can cause the device to reach saturation easily when measuring high-concentration gases, thereby narrowing the sensor's detection range. ...
- Citing Article
November 2021
Photonics Research
... where FA is the fractional absorbance, V0 is the voltage of the detector in N2 gas, and V is the voltage of the detector in target gas. Due to the influence of factors such as the IR emitter and light path, practical considerations require modifications to the Beer-Lambert Law Equation (3) [21]: ...
- Citing Conference Paper
June 2021
... In industrial production, CO 2 detection can not only enhance production efficiency but also can mitigate environmental pollutions. 8,9 In view of this, research on CO 2 detection technologies have an inestimable value and farreaching impact on various areas, thereby creating an urgent demand for CO 2 sensors. ...
- Citing Article
July 2021
Sensors and Actuators B Chemical
... Piezoelectric and electrostatic are the two most feasible approaches to probe the mechanical domain. [160][161][162] Nevertheless, as the most significant and mature photonic platform [163][164][165] and many demonstrations in sensing applications, [166][167][168][169] silicon does not exhibit a piezoelectric effect and is not effectively guide acoustic modes. Many existing realizations of light-sound coupling are built on unconventional material platforms. ...
- Citing Conference Paper
March 2021