Upon stretching, a ribbon kirigami with parallel major cuts exhibits multistable behaviors that can maintain at multiple stable configurations. This work investigates the phenomena of a ribbon kirigami with one of the major cuts replaced by a wide cut, of which the multistable behaviors of the wide-cut located cell, the stable configurations, and the energy barriers between the stable configurations are explored. It is observed that the introduction of the wide cut results in local symmetry breaking, enabling bidirectional transition of the stable configurations in such a kirigami. The results also reveal that the geometries of major cuts and the stretch level enable reprogramable dynamic behaviors, such as the number of transitions once triggered. A kirigami-Morse code system is hereby presented, utilizing dynamic reconfiguration and showing a refreshable mechanical readout utilizing reprogrammability. The kirigami has potential for developing metamaterials with unique dynamic features.

A soft bistable actuator can generate high-speed motion between two prescribed stable positions, which is very useful for boosting the actuation of soft robots. Generally, the stroke of such an actuator is completely determined once the design is finalized, which prohibits its applications in robots that perform multiple tasks. In the current work, a bistable actuator with adjustable characteristics is proposed by exploring its strain energy landscape, in which the energy barrier is manipulatable via electroactive twisted and coiled polymer fibers. As such, the actuator can operate in either bistable or postbistable mode, both of which exhibit adjustable stiffness. A kinetostatic model that combines the chained beam constraint model and the mechanics of electroactive materials is established to characterize the actuator design. Experimental results validate the kinetostatic model and the behaviors of the actuator. As a robotic demonstration, a gripper that is formed by two actuators is prototyped, and it exhibits an adjustable load capacity (up to 6.5 times its weight under a 3 V voltage).