Direct writing of two- and three-dimensional Cu-based microstructures by femtosecond laser reductive sintering of the Cu₂O nanospheres

Abstract

In this study, we investigate the direct-writing properties of Cu-based microstructures on both glass and Cu-thin-film-coated glass substrates used in femtosecond laser reductive sintering of Cu2O nanospheres. The conductivity of the micropatterns fabricated on the bare glass substrates are evaluated. The patterns exhibit high electrical conductivity. Such highly conductive patterning in the ambient environment is useful for the wiring of electrical devices and drawing electric circuits. In contrast, two types of microstructures are fabricated from multi- and single- layered Cu2O nanospheres at high and low pulse energies, respectively, only on the Cu-thin-film-coated glass substrates. The microstructures fabricated from the multi- and the single-layered Cu2O nanospheres consist mainly of Cu and Cu2O, respectively. A two-step structure is fabricated by internal writing in a Cu2O nanosphere solution film without feeding materials or piling up the layers. This direct-writing technique of Cu-based microstructures is promising for fabricating microsensors and actuators in printable electronics.