Low-power contactless button system based on MEMS ScAlN pyroelectric detector

Liang, Xu; Ng, Doris K. T.; Chen, Weiguo; Li, Nanxi; Ho, Chong Pei; Goh, Duan Jian; Zhang, Yao; Zhang, Qingxin; Lee, Lennon Y. T.

doi:10.1117/12.2648806

Cited by 3 publications

(3 citation statements)

References 20 publications

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“…Applications of pyroelectric detectors are however not limited to just NDIR gas sensing. There have been demonstrations of pyroelectric detectors in applications such as contactless button, 9 energy harvesting, 10 thermal sensing. 11 In this work, we use CMOS compatible pyroelectric detectors for H2 sensing based on thermal conductivity principle.…”

Section: Introductionmentioning

confidence: 99%

Hydrogen sensor (400 ppm - 1%) based on 20% ScAlN pyroelectric detector for a sustainable society

Ng,

Chen,

Wang

et al. 2024

Terahertz, RF, Millimeter, and Submillimeter-Wave Technology and Applications XVII

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We develop H2 gas sensors based on CMOS compatible 20% ScAlN-based pyroelectric detectors fabricated in-house. Leveraging on the high thermal conductivity of H2, ScAlN-based pyroelectric detector is used in the H2 sensor for H2 to conduct away thermal energy received by the detector, resulting in a drop in signal received by the detector, thereby leading to different voltage signals measured for different H2 gas concentrations. The higher the H2 gas concentration, the lower the voltage measured as more thermal energy is conducted away from the detector. We successfully demonstrate H2 gas sensing with the signal received by the pyroelectric detector at concentration ranging from 400 ppm to 1% H2 concentration. The gases are cycled at 2-minute intervals between different concentrations of H2, using N2 as the reference gas. Our measurements show H2 sensing down to 400 ppm gas concentration with response time ranging from ~3-7 s. In addition, a linear relationship is also observed between the measured output signal from the H2 gas sensor and the H2 gas concentration flowing across the pyroelectric detector. The results show promise in using CMOS compatible 20% ScAlN-based pyroelectric detectors for development of thermal conductivity H2 gas sensor in H2 leakage sensing to increase confidence towards adoption of H2 as a clean energy as we move towards a sustainable society.

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Section: Introductionmentioning

confidence: 99%

Hydrogen sensor (400 ppm - 1%) based on 20% ScAlN pyroelectric detector for a sustainable society

Ng,

Chen,

Wang

et al. 2024

Terahertz, RF, Millimeter, and Submillimeter-Wave Technology and Applications XVII

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“…We develop an optical-based SF6 gas sensor based on complementary metal-oxide-semiconducter (CMOS) compatible pyroelectric detectors [11][12][13][14][15][16] to measure SF6 gas at different concentrations mixed with N2. The pyroelectric sensing layer used in this work for SF6 gas sensing is aluminum nitride (AlN) and 12% scandium aluminum nitride (ScAlN) respectively.…”

Section: Introductionmentioning

confidence: 99%

SF6 mixed in N2 gas sensing responses from CMOS-compatible AlN and ScAlN pyroelectric detectors

Ng,

Chen,

et al. 2024

MOEMS and Miniaturized Systems XXIII

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SF6 gas sensor is developed to measure SF6 gas at different concentrations mixed with N2 based on mid-IR absorption of SF6 at a wavelength of ~10.6 µm. An optical bandpass filter of ~10.6 µm is put in front of a thermal emitter source to allow light of this wavelength to pass through. A CMOS compatible pyroelectric detector is put on the other end of the gas channel to measure the voltage change due to presence of SF6 gas. Here, we use AlN-based and 12% ScAlN-based pyroelectric detectors respectively. The results show for 100% SF6 gas sensing, 12% ScAlN-based pyroelectric detector gives ~73% higher response compared to when using AlN-based pyroelectric detector. The voltage drop between reference N2 gas and different SF6 gas concentrations is also higher (up to 2x) when using 12% ScAlN-based pyroelectric detector. Based on the measured SF6 gas responses, we try to estimate the lower limit of detection of our gas sensors when using AlN-and ScAlN-based pyroelectric detectors respectively. Response times taken for both detectors to detect SF6 concentrations are measured to be ~6.26 s for AlN-based pyroelectric detector and ~1.99 s for 12% ScAlNbased pyroelectric detector. Finally, both pyroelectric detectors' electrical responses across different frequencies are measured and their 3-dB frequency cutoffs are extracted to be ~13.5 Hz and ~12.6 Hz for AlN-and 12% ScAlN-based pyroelectric detector respectively. The results provide more understanding on characteristics of pyroelectric detectors in SF6 greenhouse gas sensing based on mid-IR absorption.

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“…Furthermore, the nonlinear optical effect and piezoelectric effect of AlN can be further enhanced by doping Scandium (Sc) into it 14,15 . Sc-doped AlN is a common material implemented in micro-electromechanical systems (MEMS) [16][17][18][19] , contributed by its superior piezoelectric and pyroelectric property. In terms of optical property, the 2 nd order nonlinear coefficient of Sc-doped AlN material has been reported an order of magnitude larger than AlN material without doping 14 .…”

Section: Introductionmentioning

confidence: 99%

Scandium-doped aluminum nitride photonic integration platform

Li,

Chung,

Goh

et al. 2024

Integrated Optics: Devices, Materials, and Technologies XXVIII

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Aluminum nitride (AlN) is a promising photonics material contributed by its wide transparency window and remarkable nonlinear optical property. Moreover, its nonlinear effect can be further enhanced by doping Scandium (Sc). Such nonlinear optical property brings potential for high efficiency in nonlinear optical generation processes, such as 2 nd harmonic generation and frequency comb generation. Although the nonlinear optical property of Sc-doped AlN looks promising, its waveguide is facing challenge on loss reduction. In this work, we report Sc-doped AlN photonic integrated circuit with reduced waveguide loss of 6 dB/cm around 1550 nm. The waveguide has Sc doping concentration of 10%. Its etching process is tailored through a design of experiment (DoE) approach to achieve smooth surface. An annealing process is also applied to patterned waveguide for optical loss reduction. A loaded Q of 1.41×10 4 has also been reported from microring resonator on the same wafer. The reported result paves the way towards low-loss Sc-doped AlN for photonic integrated circuits.

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Low-power contactless button system based on MEMS ScAlN pyroelectric detector

Cited by 3 publications

References 20 publications

Hydrogen sensor (400 ppm - 1%) based on 20% ScAlN pyroelectric detector for a sustainable society

Hydrogen sensor (400 ppm - 1%) based on 20% ScAlN pyroelectric detector for a sustainable society

SF6 mixed in N2 gas sensing responses from CMOS-compatible AlN and ScAlN pyroelectric detectors

Scandium-doped aluminum nitride photonic integration platform

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