Herein, we design and synthesize a nickel-based metal–organic framework (Ni-MOF) with an exhaustive set of features to obtain a magnetically and electrically responsive active material at the few-nanometer scale for use in dual-responsive soft actuators. A careful structural investigation was performed to determine the structure–property relationship. The enhanced electrochemical properties achieved through the fabrication of robust structural features involving dominant mesoporosity and an enlarged specific surface area significantly improved the electro-ionic actuation performance under ultralow input voltages. This resulted in a record peak-to-peak bending deflection of 30 mm at an ultralow input voltage of ±1.0 V along with an ultrafast rising time of 1.52 s representing an actuation enhancement of up to almost six times over standard devices. Along with these improvements, the nickel present in the metallic configuration of the nanoscale Ni-MOF-derived active material (Ni-MOFs-700C) conferred a soft ferromagnetism with a saturated magnetization of 40.2 A m2 kg–1 and very low remanence of 6.4 A m2 kg–1, which was sufficient to effectively deliver substantial magnetoactive actuation under low magnetic fields and high excitation frequencies. A magneto–electro-ionic soft actuator fabricated using the newly developed Ni-MOF-derived active material was successfully utilized to achieve hovering motion in a hummingbird robot under magnetic and electrical stimuli.
A Dual-Responsive Magnetoactive and Electro–Ionic Soft Actuator Derived from a Nickel-Based Metal–Organic Framework
Design and synthesis of magnetically and electrically driven dual-responsive soft actuators (MESAs) from a nickel-based metal–organic framework. The MESA is successfully utilized to demonstrate the hovering motion of a hummingbird robot under magnetic and electric fields.