Highly stretchable oil gel biomedical robots

Although functional polymeric soft-bodied robots have received widespread attention in fields such as precision industry and biomedical engineering, the limited reconfigurability has restricted their further development. To meet the requirements of biomedical applications for device safety and reconfigurability, an organosilica gel (Si-gel)/high-purity chromium dioxide (pCrO₂)@silica (SiO₂) micro-robot is constructed using a solvothermal reaction method, which exhibits excellent biocompatibility and reconfigurable actuation. Wettability tests show that the oil-based gel maintains a high contact angle of 114.75° even after 600 s of water droplet exposure, demonstrating strong hydrophobicity and stability. Mechanical testing indicates that the obtained Si-gel displays higher fracture elongation (an increase of 174.64%) and elastic recovery (over 90% after 20 cycles of 100% tensile strain and 15 cycles of 80% compressive strain) compared to the original polydimethylsiloxane (PDMS). Magnetic actuation results demonstrate that pre-magnetization under a 60 mT field can achieve customized motion speeds from 29.5 to 70.0 mm/s without changing the external magnetic field. The device exhibits excellent stability under repeated high-temperature exposure, repeated magnetization, and hundreds of continuous driving cycles. Furthermore, the micro-robot shows promising biocompatibility and enhanced organic–inorganic compatibility, suggesting its potential as an effective alternative to catheter-implanted biomedical aids.