Reduced Graphene Oxide/Mesoporous ZnO NSs Hybrid Fibers for Flexible, Stretchable, Twisted, and Wearable NO₂ E-Textile Gas Sensor

Abstract

E-textiles are gaining growing popularity recently due to low cost, light weight, and conformable compatibility with clothes in wearable and portable smart electronics. Here, an easy-handing, low cost, and scalable fabricating strategy is reported to fabricate conductive, highly flexible, and mechanically stretchable/twisted fiber gas sensor with great wearability and knittability. The proposed gas sensor is built using commercially available cotton/elastic threads as flexible/stretchable templates and reduced graphene oxide/mesoporous zinc oxide nanosheets as sensing layers to form conducting fibers. The as-prepared fiber demonstrates sensitive sensing response, excellent long-term stability (84 days), low theoretical detection limit (43.5 ppb NO2), great mechanical deformation tolerance (3000 bending cycles, 1000 twisting cycles and 65% strain strength), and washing durability in room-temperature gas detection. More significantly, scalable wearable characteristics including repairability, reliability, stability, and practicability have been efficiently improved, which are achieved by knotting the fractured fibers, incorporating multiple sensors in series/parallel and weaving multisensor array networks integrated into clothes. The good sensing properties, superior flexibility, and scalable applications of wearable fibers may provide a broad window for widespread monitoring of numerous human activities in personal mobile electronics and human–machine interactions.

Progress in wearable electronics/photonics—Moving toward the era of artificial intelligence and internet of things

“…Wearable electronics/photonics are rapidly emerging in diversified research areas for their promising future in broad applications, for example, robotics, 62‐64 medical devices, 65,66 environmental monitoring, 67 human‐machine interfaces (HMIs), 51,68 healthcare, 69 and so on. This section summarizes the various aspects of general wearable electronics and photonics in terms of materials, transducing mechanisms, and applications.…”

Multisensor Systems and Arrays for Medical Applications Employing Naturally-Occurring Compounds and Materials

“…Wearable e-textiles allow one to monitor not only ECG, EEG, but also pressure, stretch and chemical (bio)sensors enable the detection of body motion, physical activity and/or metabolic changes, which are (in)directly monitored by the sweat and/or body odor analysis [ 213 , 215 , 216 ]. Cotton and silk are widely used in the e-textile design due to their renewability, degradability, and mechanical durability; they can also adhere to conductive compounds and are suitable for many knitting technologies [ 217 , 218 , 219 ].…”

“…Cotton and PANI composites were applied in the sensing of NH 3 vapors [ 30 ], and in the design of wearable sensors for the monitoring of human body motion [ 220 ]. It was shown recently that cotton fabric modification with nanostructured ZnO resulted in the enhancement of ultraviolet protection factor, and in the applicability as gas sensors towards such VOCs as acetaldehyde, ammonia, ethanol [ 221 ] and NO 2 [ 219 ]. The modification of the cotton fabrics with PEDOT:PSS resulted in the development of a gas sensor toward acetone [ 222 ].…”

Graphene Oxide@3D Hierarchical SnO2 Nanofiber/Nanosheets Nanocomposites for Highly Sensitive and Low-Temperature Formaldehyde Detection

“…Based on the analysis, the loading of GO in SnO 2 NF/NSs can significantly enhance the selectivity of gas sensor to HCHO gas, and the 1% GO@SnO 2 NF/NSs based gas sensor exhibited the best selectivity to HCHO gas in contrast with other GO@SnO 2 NF/NSs nanocomposites and pure SnO 2 NF/NSs. Many reasons can be argued to explain the enhancement of selectivity for GO@SnO 2 NF/NSs nanocomposite-based sensors [42]. (i) The excellent selectivity of GO@SnO 2 NF/NSs nanocomposites for HCHO gas detection could be ascribed to higher HCHO adsorption interaction between sensing materials.…”