Miniaturized Bistable Prestressed Shells With Mechanical Switching for Compact Grippers

ABSTRACT Miniaturized grippers are essential for manipulating objects in confined spaces, such as minimally invasive surgery or inspection tasks in narrow spaces. Conventional miniaturized designs struggle to balance structural simplicity with complex motion, as well as low energy consumption with sufficient energy release. Bistable structures—especially bistable shells—offer a promising solution by enabling rapid, energy‐efficient self‐shape transitions. However, bistable shell–driven grippers face two major challenges: (1) their shape transition typically depends on external actuation systems that increase system complexity and hinder miniaturization, and (2) the fabrication of bistable shells at millimeter‐scale remains technically challenging, limiting their integration into compact devices. This work proposes a miniaturized bistable gripper confined within a 15‐mm‐diameter cylindrical envelope. It is based on a plastically formed prestressed shell whose two stable states can be mechanically switched. Compared with existing bistable grippers, often larger than 50 mm, the proposed design significantly reduces size while maintaining reliable bistable performance. Moreover, the miniaturized fabrication process of bistable shells was investigated to identify geometric and forming conditions that ensure robust bistability under millimeter‐scale constraints. The resulting gripper offers a structurally simple, energy‐efficient solution with reliable performance in constrained spaces, showing strong potential for micromanipulation, surgical robotics, and confined‐environment tasks.