Soft Actuators Based on Spin?Crossover Particles Embedded in Thermoplastic Polyurethane

Molecular spin-crossover (SCO) complexes are phase-change materials that develop large spontaneous strains across the thermally induced phase transition, which can be advantageously used in designing soft actuators. Herein, a bilayer bending cantilever, made of thermoplastic polyurethane (TPU) with embedded [Fe(NH2trz)3](SO4) SCO particles (25 wt%), is presented. The proposed actuator fabricated by blade casting an SCO@TPU layer on conducting Ag@TPU film to convert electrothermal input into mechanical response. Experiments conducted characterize curvature beams, then further analyzed using Euler–Bernoulli beam theory. change, free transformation strain, and effective work density associated 0.11 mm?1, 1.6%, 1.25 mJ cm?3, respectively. Further, open- closed-loop response investigated custom-built setup. open-loop identification suggests gain increases monotonously when control current increases. This natural adaptive character explain drastically diminished time proportional–integral–derivative experiments (2–3 s). Finally, tracking carried out evaluate robustness without payloads. results for 30 240 endurance cycles reveal mean positioning error 0.8%.