Fabrication of interdigitated electrodes of graphene oxide/silica by femtosecond laser-induced forward transfer for sensing applications

Graphene-based materials, such as graphene oxide (GO), have been receiving much attention due to their graphene-like properties and compatibility with other materials. At the same time, novel printing methods have been developed for fabricating high-resolution patterns, such as Laser-Induced Forward Transfer (LIFT), which allows microscale transferring of a variety of materials to distinct substrates, enabling the design of micro- and nanodevices for biomedical and opto-electronic application. In this work, we propose the use of LIFT with fs-laser pulses for creating high-resolution interdigitated electrodes of tetraethyl orthosilicate functionalized with GO. The fs-LIFT approach successfully allowed micro-patterning of lines with widths on the order of 2 μm, with threshold energy of 70 nJ, and the reduction of graphene oxide to fabricate silica/GO films in an efficient, controlled, and localized way, without material degradation. As a proof of principle, interdigitated electrodes fabricated by fs-LIFT were successfully used as the sensing units of an impedimetric electronic tongue for taste recognition and heavy metals ions detection (Al3+, Hg2+, Co2+, and Cu2+) at different concentrations of 100 nmol l−1, 10 μmol l−1, and 1 mmol l−1.