Ultra-Sensitive and Fast Humidity Sensors Based on Direct Laser-Scribed Graphene Oxide/Carbon Nanotubes Composites

• Published in: Nanomaterials (Basel, Switzerland) Switzerland), 2023-04, Vol.13 (9), p.1473
• Main Authors: Al-Hamry, Ammar, Lu, Tianqi, Chen, Haoran, Adiraju, Anurag, Nasraoui, Salem, Brahem, Amina, Bajuk-Bogdanović, Danica, Weheabby, Saddam, Pašti, Igor A, Kanoun, Olfa
• Format: Article
• Language: English
• Subjects: Adsorption; Analysis; Carbon; carbon nanotubes; Circuits; Composite materials; Dehumidification; Direct laser writing; Energy dispersive X ray analysis; Fourier transforms; Graphene; Graphite; Homogeneity; Humidification; Humidity; humidity sensor; Identification and classification; impedance spectroscopy; Infrared spectroscopy; Investigations; laser direct writing; Lasers; Methods; Multi wall carbon nanotubes; nanocomposite; Nanotechnology; Nanotubes; Oxides; Photoelectric emission; Properties; reduced graphene oxide; Relative humidity; Reproducibility; Response time; Scanning microscopy; Sensors; Shelf life; Spectroscopy; X ray analysis
• ISSN: 2079-4991; 2079-4991
• DOI: 10.3390/nano13091473

In this paper, the relative humidity sensor properties of graphene oxide (GO) and graphene oxide/multiwalled nanotubes (GO/MWNTs) composites have been investigated. Composite sensors were fabricated by direct laser scribing and characterized using UV-vis-NIR, Raman, Fourier transform infrared, and X-ray photoemission spectroscopies, electron scanning microscopy coupled with energy-dispersive X-ray analysis, and impedance spectroscopy (IS). These methods confirm the composite homogeneity and laser reduction of GO/MWNT with dominant GO characteristics, while ISresults analysis reveals the circuit model for rGO-GO-rGO structure and the effect of MWNT on the sensor properties. Although direct laser scribing of GO-based humidity sensor shows an outstanding response (|Δ |/| | up to 638,800%), a lack of stability and repeatability has been observed. GO/MWNT-based humidity sensors are more conductive than GO sensors and relatively less sensitive (|Δ |/| | = 163,000%). However, they are more stable in harsh humid conditions, repeatable, and reproducible even after several years of shelf-life. In addition, they have fast response/recovery times of 10.7 s and 9.3 s and an ultra-fast response time of 61 ms when abrupt humidification/dehumidification is applied by respiration. All carbon-based sensors' overall properties confirm the advantage of introducing the GO/MWNT hybrid and laser direct writing to produce stable structures and sensors.