Soft grippers offer advantages in human-machine interactions, yet many grapple with the challenge of low response times. While bistable structures could enhance this characteristic, the performance of current grippers utilizing such structures is constrained by predefined structural parameters and grasping modes. 

A recent initiative led by Dr. LI Yingtian of the Shenzhen Institute of Advanced Technology (SIAT) at the Chinese Academy of Sciences (CAS). The team has introduced a pioneering soft gripper, leveraging a reprogrammable bistable actuator. In contrast to conventional bistable actuators, this novel design allows precise control over diverse sensitivities, offering multiple gripping modes and adjustable response speeds through straightforward reprogramming. 

Published on October 09 in IEEE/ASME Transactions on Mechatronics, the study outlines a soft gripper comprising a bistable frame and a soft pneumatic bi-directional actuator connected by an unstretchable cable. During programming, the pneumatic actuator shortens longitudinally, pulling the frame through the cable. This process gradually accumulates strain energies in the lateral plates, reducing the energy required for the fast snap-through of the structure. Consequently, the structure showcases its reprogrammable nature by adapting to various intermediary states with different sensitivities. 

The research delves into the force-displacement relationship of the frame and predicts trigger forces. Results indicate that, by reprogramming the structure's sensitivity, the force needed to initiate a fast snap-through could be less than 0.005 times its maximum value. 

To highlight the uniqueness of the proposed actuator, the researchers prototyped multiple grippers, conducting tests that demonstrated multimodal, swift, and highly sensitive grasping capabilities. Impressively, the gripper even exhibited the ability to respond to the contact of a swimming fish and capture it within a mere 0.18 seconds. 

Dr. LI shared insights, stating, “Our research team has devoted years to exploring the ultra-tunable bistable structure, with numerous achievements published in international journals. Ongoing studies are investigating additional applications in the fields of robotics and bioengineering to further prove their practicability.”