SnO<sub>2</sub>-Based Ultra-Flexible Humidity/Respiratory Sensor for Analysis of Human Breath
Moumita Deb,
Mei-Yu Chen,
Po-Yi Chang,
Pin-Hsuan Li,
Ming-Jen Chan,
Ya-Chung Tian,
Ping-Hung Yeh,
Olivier Soppera,
Hsiao-Wen Zan
Affiliations
Moumita Deb
Department of Photonics, College of Electrical and Computer Engineering, National Yang Ming Chiao Tung University, 1001 Ta Hsueh Rd., Hsinchu 30010, Taiwan
Mei-Yu Chen
Department of Physics, Tamkang University, 151, Yingzhuan Rd., Tamsui, New Taipei City 25137, Taiwan
Po-Yi Chang
Department of Photonics, College of Electrical and Computer Engineering, National Yang Ming Chiao Tung University, 1001 Ta Hsueh Rd., Hsinchu 30010, Taiwan
Pin-Hsuan Li
Department of Photonics, College of Electrical and Computer Engineering, National Yang Ming Chiao Tung University, 1001 Ta Hsueh Rd., Hsinchu 30010, Taiwan
Ming-Jen Chan
Department of Medicine, Chang Gung University, Taoyuan 333, Taiwan
Ya-Chung Tian
Department of Medicine, Chang Gung University, Taoyuan 333, Taiwan
Ping-Hung Yeh
Department of Physics, Tamkang University, 151, Yingzhuan Rd., Tamsui, New Taipei City 25137, Taiwan
Olivier Soppera
Université de Haute-Alsace, CNRS, IS2M UMR 7361, F-68100 Mulhouse, France
Hsiao-Wen Zan
Department of Photonics, College of Electrical and Computer Engineering, National Yang Ming Chiao Tung University, 1001 Ta Hsueh Rd., Hsinchu 30010, Taiwan
Developing ultraflexible sensors using metal oxides is challenging due to the high-temperature annealing step in the fabrication process. Here, we demonstrate the ultraflexible relative humidity (RH) sensor on food plastic wrap by using 808 nm near-infrared (NIR) laser annealing for 1 min at a low temperature (26.2–40.8 °C). The wettability of plastic wraps coated with sol-gel solution is modulated to obtain uniform films. The surface morphology, local temperature, and electrical properties of the SnO2 resistor under NIR laser irradiation with a power of 16, 33, and 84 W/cm2 are investigated. The optimal device can detect wide-range RH from 15% to 70% with small incremental changes (0.1–2.2%). X-ray photoelectron spectroscopy reveals the relation between the surface binding condition and sensing response. Finally, the proposed sensor is attached onto the face mask to analyze the real-time human breath pattern in slow, normal, and fast modes, showing potential in wearable electronics or respiration monitoring.
