Laser-Induced Graphene from Paper by Ultraviolet Irradiation: Humidity and Temperature Sensors


Laser-induced graphene (LIG) produced by irradiation of paper (paper-LIG)holds substantial promise for flexible devices. This article presents paper-LIG humidity and temperature sensors fabricated by single-step irradiation of common filter paper with a pulsed UV laser (355 nm). The influence of the process parameters on the conversion of cellulose fibers into LIG is discussed based on the resulting morphology, structure, conductivity, and chemical composition, revealing a distinct barrier to transformation and a propagation behavior not seen under CO2 laser irradiation. The obtained material is constituted by a porous, electrically conductive network of fibers. The paper-LIG relative humidity (RH) and temperature sensors with sensitivities of up to 1.3 x 10(-3)%RH-1 and - 2.8 x 10(-3) degrees C-1, respectively, are examined in terms of their linearity, reproducibility, and response time. A detailed discussion on the response mechanism is presented in the context of literature, pointing towards the absorption of water molecules in the interlayer spacing of graphene as the main reason for the increase in resistance with RH. Additionally, a contribution from variable range hopping along the ab plane of graphene at high RH is suggested. These results demonstrate the potential of paper-LIG for low-cost, sustainable, and environmentally friendly sensing.



subject category

Materials Science


Kulyk, B; Silva, BFR; Carvalho, AF; Barbosa, P; Girao, AV; Deuermeier, J; Fernandes, AJS; Figueiredo, FML; Fortunato, E; Costa, FM

our authors


This work was developed within the scope of project i3N, UIDB/50025/2020 and UIDP/50025/2020, and project CICECO-Aveiro Institute of Materials, UIDB/50011/2020 and UIDP/50011/2020, financed by national funds through the Portuguese Foundation for Science and Technology/MCTES (FCT I.P.). B.K. and A.F.C. acknowledge the PhD grants SFRH/BD/141525/2018 and DAEPHYS-FCT PD/BD/114063/2015, respectively, both financed by FCT I.P. E.F. acknowledges the European Research Council AdG grant 787410 from the project DIGISMART. The research contracts of P.B. and A.V.G. are funded by national funds (OE), through FCT I.P., in the scope of the framework contract foreseen in the numbers 4, 5, and 6 of article 23, of the Decree-Law 57/2016, of August 29, changed by Law 57/2017, of July 19.

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