  Two-dimensional shape-morphing networks are common in biological systems and
have garnered attention due to their nontrivial physical properties that
emanate from their cellular nature. Here, we present the fabrication and
characterization of inhomogeneous shape-morphing networks composed of
thermoresponsive microfibers. By strategically positioning fibers with varying
responses, we construct networks that exhibit directional actuation. The
individual segments within the network display either a linear extension or
buckling upon swelling, depending on their radius and length, and the
transition between these morphing behaviors resembles Landau's second-order
phase transition. The microscale variations in morphing behaviors are
translated into observable macroscopic effects, wherein regions undergoing
linear expansion retain their shape upon swelling, whereas buckled regions
demonstrate negative compressibility and shrink. Manipulating the macroscale
morphing by adjusting the properties of the fibrous microsegments offers a
means to modulate and program morphing with mesoscale precision and unlocks
novel opportunities for developing programmable microscale soft robotics and
actuators.
