posted on 2024-01-05, 06:29authored byChaerin Yu, Hyunmin Cho, Won-Sup Lee, Junhee Jo, Hyesu Kim, Won Seok Chang
Femtosecond-laser-induced selective
fishbone-inspired and trapezoidal
structures provide low surface energies for liquid metal (LM) and
LM-phobic surfaces. This laser-based technique is suitable for processing
heat-vulnerable flexible substrates and minimizing changes in their
physical properties, which can be analyzed by Fourier-transform infrared
spectroscopy. In this study, we developed a femtosecond-laser-assisted
fishbone-inspired patterning process for a selective LM wettable surface
on a flexible substrate. Because the ribs of the fishbone-inspired
structure were developed between laser-ablated lines, the entire LM-phobic
pattern was covered without processing the entire surface area. In
the fishbone-inspired pattern, the region directly exposed to the
femtosecond laser served as the “spines”, while the
burrs, which were a byproduct of laser processing, acted as the “ribs”.
A minimum line width of ∼40 μm was realized using this
structural mechanism. The patterned LM-phobic surface exhibited low
surface energy with a 156° contact angle for the LM material.
The patterned LM on a flexible poly(dimethylsiloxane) substrate maintained
a stable electrical connection with minimal deviations, even under
bending, twisting, and stretching conditions. These processes and
structures can be used to fabricate flexible, stretchable, and wearable
electronic devices.