posted on 2024-01-29, 17:04authored byAsad Nauman, Hafiz Saad Khaliq, Jun-Chan Choi, Jae-Won Lee, Hak-Rin Kim
The prompt visual response is considered to be a highly
intuitive
tenet among sensors. Therefore, plasmomechanical strain sensors, which
exhibit dynamic structural color changes, have recently been developed
by using mechanical stimulus-based elastomeric substrates for wearable
sensors. However, the reported plasmomechanical strain sensors either
lack directional sensitivity or require complex signal processing
and device design strategies to ensure anisotropic optical responses.
To the best of our knowledge, there have been no reports on utilizing
anisotropic mechanical substrates to obtain directional optical responses.
Herein, we propose an anisotropic plasmomechanical sensor to distinguish
between the applied force direction and the force magnitude. We employ
a simple strain-engineered topological elastomer to mechanically transform
closely packed metallic nanoparticles (NPs) into anisotropic directional
rearrangements depending on the applied force direction. The proposed
structure consists of a heterogeneous-modulus elastomer that exhibits
a highly direction-dependent Poisson effect owing to the periodically
line-patterned local strain redistribution occurring due to the same
magnitude of applied external force. Consequently, the reorientation
of the self-assembled gold (Au)-NP array manifests dual anisotropy,
i.e., force- and polarization-direction-dependent plasmonic coupling.
The cost-effectiveness and simple design of our proposed heterogeneous-modulus
platform pave the way for numerous optical applications based on dynamic
transformation and topological inhomogeneities.