Wearable Carbon Monoxide Sensors Based on Hybrid Graphene/ZnO Nanocomposites

Abstract

In this work, wearable resistive gas sensors based on hybrid graphene/zinc oxide (ZnO) nanocomposites were fabricated on a flexible cotton fabric and employed to monitor odorless and colorless carbon monoxide (CO). Dip-coating and chemical bath deposition (CBD) was used to deposit the graphene layer and grow the ZnO nanorods, respectively. The films were characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and X-Ray diffraction (XRD) to investigate their morphological structures, elemental composition, and crystal phase, respectively. Those characterizations were also confirming the growth of ZnO nanorods on the already-deposited graphene layer on fabrics. From the gas sensor measurements at room temperature, it was revealed that these graphene/ZnO nanocomposites were highly sensitive and selective towards CO gas at low concentration down to 10 ppm. The shortest response and recovery times of the sensors were measured to be 280 s and 45 s, respectively. Moreover, in comparison to bare graphene sensors, the surface modification by ZnO nanorods could obviously enhance the sensing response by up to 40% (i.e., doubled sensitivity). These flexible hybrid sensors are therefore expected to be a promising alternative for the existing rigid CO sensors in the market by offering unique nanostructures, low-cost fabrication, high flexibility, and good sensing performances. INDEX TERMS Wearable gas sensor, carbon monoxide, graphene, zinc oxide, fabric-based sensor.

Superhydrophobic ZnO Nanowires: Wettability Mechanisms and Functional Applications

“…37 Another option for CO gas sensing is growing ZnO nanowires on graphene on cotton fabric. 93 Other gases, such as acetaldehyde, ammonia, and ethanol can also be detected by a sensor based on ZnO-functionalized cotton fabric. 94 ZnO nanowires can be used in UV photodetectors.…”

“…In a humid environment, the response is up to 22% lower . Another option for CO gas sensing is growing ZnO nanowires on graphene on cotton fabric . Other gases, such as acetaldehyde, ammonia, and ethanol can also be detected by a sensor based on ZnO-functionalized cotton fabric …”

Room-temperature ppb-level trimethylamine gas sensors functionalized with citric acid-doped polyvinyl acetate nanofibrous mats

“…[29][30][31][32][33] Inorganic semiconductors often produced low selectivity despite their high responsivity and low power consumption. [34][35][36] They also required to be operated at high temperatures (few hundred degrees Celsius) limiting their applications. 37 Another approach based on integrated gallium nitride (GaN) light-emitting diodes (LEDs) was also introduced to activate the active layer for gas sensors at room temperature.…”

Hybrid learning method based on feature clustering and scoring for enhanced COVID-19 breath analysis by an electronic nose

“…It is a device combining broad-spectrum chemical sensor array with a gas sampling chamber and machine learning to mimic human olfactory perception and provide a digital breathprint of the VOCs. Among other various gas sensor types (e.g., gravimetric microelectromechanical system (MEMS) and optical, capacitive, and photoacoustic gas sensors [27] , [28] , [29] , [30] , [31] , [32] , [33] , [34] , [35] , [36] , [37] , [38] , [39] , [40] ), chemoresistive gas sensors based on the metal-oxide semiconductor (MOS) have been widely used as the main components of the e-nose considering their advantageous properties (i.e., high sensitivity, mature material synthesis technology, high robustness, low fabrication cost, short response time, and simple sensing method) [41] .…”