Ilievski and colleagues made soft elastomer actuators with embedded air channels (PneuNets), including grippers gentle enough to lift a raw egg.
As reported in: Ilievski, Mazzeo, Shepherd et al. (2011). Soft Robotics for Chemists. Angewandte Chemie International Edition. doi:10.1002/anie.201006464
Brown and colleagues built a universal gripper from a bag of granular material that hardens under vacuum; volume changes under 0.5% gripped objects reliably.
As reported in: Brown, Rodenberg, Amend et al. (2010). Universal robotic gripper based on the jamming of granular material. Proceedings of the National Academy of Sciences. doi:10.1073/pnas.1003250107