Moisture-resistant, stretchable NOx gas sensors based on laser-induced graphene for environmental monitoring and breath analysis

Li Yang; Guanghao Zheng; Yaoqian Cao; Chuizhou Meng; Yuhang Li; Huadong Ji; Xue Chen; Guangyu Niu; Jiayi Yan; Ye Xue; Huanyu Cheng

doi:10.1038/s41378-022-00414-x

Moisture-resistant, stretchable NO_x gas sensors based on laser-induced graphene for environmental monitoring and breath analysis

Microsyst Nanoeng. 2022 Jul 8:8:78. doi: 10.1038/s41378-022-00414-x. eCollection 2022.

Authors

Li Yang¹, Guanghao Zheng², Yaoqian Cao³, Chuizhou Meng², Yuhang Li⁴, Huadong Ji², Xue Chen⁵, Guangyu Niu⁶, Jiayi Yan², Ye Xue¹, Huanyu Cheng⁷

Affiliations

¹ State Key Laboratory of Reliability and Intelligence of Electrical Equipment, School of Health Sciences and Biomedical Engineering, Hebei University of Technology, Tianjin, 300130 China.
² School of Mechanical Engineering, Hebei University of Technology, Tianjin, 300130 China.
³ Department of Respiratory and Critical Care Medicine, Tianjin Medical University General Hospital, Tianjin, 300052 China.
⁴ Institute of Solid Mechanics, Beihang University (BUAA), Beijing, 100191 China.
⁵ School of Electrical Engineering, Hebei University of Technology, Tianjin, 300130 China.
⁶ School of Architecture and Art Design, Hebei University of Technology, Tianjin, 300130 China.
⁷ Department of Engineering Science and Mechanics, The Pennsylvania State University, University Park, PA 16802 USA.

Abstract

The accurate, continuous analysis of healthcare-relevant gases such as nitrogen oxides (NO_x) in a humid environment remains elusive for low-cost, stretchable gas sensing devices. This study presents the design and demonstration of a moisture-resistant, stretchable NO_x gas sensor based on laser-induced graphene (LIG). Sandwiched between a soft elastomeric substrate and a moisture-resistant semipermeable encapsulant, the LIG sensing and electrode layer is first optimized by tuning laser processing parameters such as power, image density, and defocus distance. The gas sensor, using a needlelike LIG prepared with optimal laser processing parameters, exhibits a large response of 4.18‰ ppm^-1 to NO and 6.66‰ ppm^-1 to NO₂, an ultralow detection limit of 8.3 ppb to NO and 4.0 ppb to NO₂, fast response/recovery, and excellent selectivity. The design of a stretchable serpentine structure in the LIG electrode and strain isolation from the stiff island allows the gas sensor to be stretched by 30%. Combined with a moisture-resistant property against a relative humidity of 90%, the reported gas sensor has further been demonstrated to monitor the personal local environment during different times of the day and analyze human breath samples to classify patients with respiratory diseases from healthy volunteers. Moisture-resistant, stretchable NO_x gas sensors can expand the capability of wearable devices to detect biomarkers from humans and exposed environments for early disease diagnostics.

Keywords: Electronic properties and materials; Environmental, health and safety issues.