Thermo-flow and temperature sensing behaviour of graphene based on surface heat convection

• Published in: Micro & nano letters 2013-10, Vol.8 (10), p.681-685
• Main Authors: Al-Mumen, Haider, Rao, Fubo, Dong, Lixin, Li, Wen
• Format: Article
• Language: English
• Subjects: bilayer graphene film; bilayer graphene hot wire; bilayer graphene sheet; capillarity; capillary tubes; Convection; Detection; Devices; downstream connection; electric resistance; few‐layer graphene film; few‐layer graphene hot wire; few‐layer graphene sheet; flow rates; flow sensors; Graphene; graphene thermistor; Heat transfer; length‐to‐width ratios; microfluidic chamber; microfluidics; microsensors; minimised environmental interference; nanoscale flow sensor; nanoscale temperature sensor; nanosensors; Nanostructure; nanowires; Negative temperature coefficient; negative temperature coefficients; normalised resistance; packaging; sensing response; sheet materials; Special Section: Expanded Papers from NEMS 2013; surface heat convection; temperature 293 K to 353.15 K; temperature 70 degC; temperature sensing behaviour; temperature sensors; thermal inertia; thermistors; thermo‐flow sensing behaviour; thin film sensors; thin graphene sheets; upstream connection; Wire
• ISSN: 1750-0443; 1750-0443
• DOI: 10.1049/mnl.2013.0326

This letter studies the surface heat convection of thin graphene sheets and the application of graphene wires as nanoscale flow and temperature sensors. Graphene wires with relatively large length-to-width ratios were designed and fabricated using bi- and few-layer graphene sheets. Prior to testing, the devices were packaged in a microfluidic chamber with capillary tubes as upstream and downstream connections to minimise environmental interference. The thermal inertia of the graphene wire was studied at 70°C and the flow sensing behaviour of the device was characterised by monitoring normalised resistance changes at different flow rates. The authors experimental results demonstrated the negative temperature coefficients of the bi- and few-layer graphene films. Moreover, the flow sensing resolutions of ∼ 0.07 l/min and 0.1 l/min were achieved from the bi- and few-layer graphene hot wires, respectively. The temperature sensing behaviour of the graphene thermistor was studied in a small temperature range from room temperature to 80°C. The larger negative temperature coefficient of the bi-layer graphene resulted in a higher sensing response than the few-layer one.