ABSTRACT
As it was discussed in previous chapters of Part I, soft continuum trunk and tentacle manipulators have high inherent dexterity and reconfigurability and have become an attractive candidate for safe manipulation and explorations in surgical and space robotic applications, recently. However, achieving accuracy in precise tasks is a challenge with these highly flexible structures, for which stiffness variable designs based on jamming, smart material, antagonistic actuation, and morphing structures have been introduced in the recent years. In this chapter, variable stiffness properties of an electroactive poly (sodium acrylate) (pNaAc) hydrogel are tested. An anisotropic stiffness ion pattern is printed on the hydrogel straps giving them shape memory properties. The hydrogel swells up to two times its original size and soften (4.2-0 KN/m) in an ethanol aquatic solution depending on the ethanol saturation while preserving its programmed shape. Changing the solution ethanol saturation can be used to control the hydrogel stiffness based of which a conceptual design for a stiffness controllable STIFF-FLOP module is presented and will be fabricated in the future.
