Kiri-Grip: Integrated Kirigami-EMG Robotic Hand with Geometric Optimization of Cut Topologies for Assistive Grasping

Overview

Assistive grasping of slippery, delicate, or thin objects remains challenging for individuals with hand impairments. Current prosthetic hands and assistive grippers often rely on rigid linkages or bulky external hardware that limit compliance, portability, and accessibility. Kiri-Grip is the first integrated system combining an EMG-actuated robotic hand with a kirigami soft gripper whose cut geometry determines its encapsulating shape and grasping mechanics. Nine kirigami designs were parametrically modeled in OpenSCAD and laser-cut from 0.127-mm polyester film, then evaluated using standardized force-displacement measurements and pull-out tests. Grippers consistently displayed four-stage mechanical responses of bending, unfolding, locking, and stretching to failure that were characterized by displacement-dependent strain-stiffening controlled solely by geometry. Long-ribbon topologies outperformed corresponding standard-ribbon designs; Wing_Long achieved the highest pull-out force (26 N), geometric efficiency (η = 0.86), and repeatability (CV < 15%). Increased ribbon length also improved enclosure completeness. When integrated with the EMG-actuated robotic hand, the system enabled reliable myoelectric open/close actuation across users without need for recalibration through adaptive baseline detection. In human-participant trials, individuals with musculoskeletal disorder, neuromotor deficit, and upper-limb difference successfully grasped objects that current assistive devices struggle with, including slippery, thin, and fragile objects. These results show that kirigami cut geometry can facilitate assistive grasping through soft, conformal contact and strong gripping hold within a myoelectrically controlled robotic hand system. By integrating rigid EMG-actuated grasping for heavy-duty tasks with kirigami compliance for delicate objects, Kiri-Grip covers the full spectrum of everyday grasping beyond what current assistive devices can handle.

Competition history

• CSEF 2026 Applied Mechanics (Senior Division) · Entry S-02-25

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