New silicone casting method enables scalable soft robot fabrication

Soft robots promise safe, adaptable interaction for medical applications like rehabilitation and surgery, but their real-world adoption has been hindered by labor-intensive, error-prone fabrication methods. To address this, Thakker, Dela Cruz, Massoud, and Libby (arXiv:2607.15422) introduce a standardized two-part silicone pour casting procedure for soft pneumatic actuators. The key innovations include a cavity-clearing technique that prevents internal clogging during casting and a sensor embedding protocol that reliably integrates thin-film flex sensors for bending measurement. The team also developed automated image processing to calibrate the sensors against actuator bending angles, eliminating manual calibration errors.

The researchers validated their approach through extensive experiments: Finite Element Modeling (FEM) predicted stress and deformation under pressure, which closely matched real-world pneumatic actuation tests with PID pressure control. Staircase and sinusoidal profile inputs showed repeatable performance with minimal hysteresis (consistent with viscoelastic behavior). Most importantly, two different operators independently fabricated 24 actuators using the same procedure, and all achieved consistent angle responses. This reproducibility—a major bottleneck in soft robotics—is a significant step toward scalable manufacturing. The work will be presented at the IEEE RAS/EMBS International Conference on Biomedical Robotics and Biomechatronics (BioRob 2026).