Microspring Fabrication by Anisotropic Gelation

Abstract

Springs are fundamental mechanical parts that can store mechanical energies by their deformation. Although metals are generally used as materials for springs, hydrogel-based microscale springs have recently been reported with inspiration from micro-/nanoscale biological structures and functions in living organisms. In this chapter, firstly, resent hydrogel microspring formation methods, including self-folding, liquid rope-coiling, stereolithography and templating, are introduced. After overviewing those technologies, a formation method of hydrogel microsprings by using anisotropic gelation with bevel tip capillaries is mainly discussed. Sodium alginate solution is ejected into calcium chloride solution via a bevel-tip capillary. The ejected sodium alginate rapidly gelates with reaction to