Architected Load Paths Enable Stiffening and Motion Programming in Soft Pneumatic Actuators

Soft pneumatic robots exploit compliant chamber inflation to generate large and adaptive deformations, but increased pressure often produces ballooning rather than useful force or stiffness. This actuation-load-bearing decoupling limits their use in tasks that require both controlled motion and mechanical support. Here we report MARS (Monolithic Architected Reinforcement Strategy), a single-material soft pneumatic actuator that embeds beam-column-inspired load paths within an unchanged external envelope. Internal lateral beams guide bending and restrain lateral expansion, whereas radial columns tether the chamber wall and suppress ballooning. Together, these load paths redirect pneumatic deformation toward ordered structural engagement during actuation. Compared with an unconstrained baseline, MARS maintained its intended morphology up to 200 kPa and showed a 5.8-fold pressure-induced increase in lateral stiffness. At matched bending angles, it generated 8.4-fold higher tip force than the baseline. Selective removal of lateral beams further programmed the same monolithic template into continuous-bending, localized hinge-like-bending, and torsional variants. These variants enabled crawling-robot locomotion, load-bearing dexterous grasping, and EEG-guided wearable hand assistance. By coupling pneumatic actuation with internal load-path engagement, MARS establishes an architecture-guided strategy for mechanically supportive and motion-programmable soft pneumatic structures.