High-performance electro-responsive ionic soft actuators based on polypyrrole coated functional carboxylated bacterial cellulose nanofibers for bioinspired applications

Low voltage high-performance soft actuators have attracted great attention in flexible haptic displays, soft robots, biomedical devices, and braille displays. Herein, we report a low voltage ionic soft actuator based on carboxylated bacterial cellulose (CBC) nanofibers, ionic liquid (IL), and polypyrrole (PPy) electrodes. The highly conductive PPy nanoparticles were homogeneously coated on the CBC-IL membrane surfaces by using a chemical polymerization method, because the carboxylated groups on CBC could enhance the adsorption of PPy nanoparticles. The proposed CBC-IL-PPy actuator displayed a peak-to-peak displacement of 11.66 mm and long working durability (97 % retention after 2 h) under a sinusoidal voltage of 2.0 V at 0.1 Hz, and wide actuation frequency. The enhanced actuation performances of the actuator were due to its increased specific capacitance, ionic conductivity, and ionic exchange capacity. Furthermore, the bioinspired applications of the actuators were successfully demonstrated such as soft robot touch finger, bionic active stent, grapple robot, and bionic wing. Thus, the proposed low voltage high-performance soft actuator will advance artificial muscles, soft robots, robotic interactions, biomedical active devices, and flexible haptic devices.