Hydrogel-reinforced polypyrrole electroactuator.

Robust electroactuators that are lightweight, power-efficient and capable of generating high forces at a low actuation voltage are of great demand in the design of micro-electromechanical systems (MEMS) for biomedical applications. In this work, electroactive composite films of alginate hydrogel and polypyrrole/polyethylene glycol (PPy/PEG) are synthesized and characterized as actuators for driving an implantable insulin micropump. A porous and flexible alginate hydrogel back layer is used to mechanically reinforce the PPy/PEG film by enhancing the actuator's resistance to its generated tension but without increase of its overall rigidness. Scanning electron microscopy (SEM) reveals that the PPy/PEG grows through the alginate hydrogel layer, thus forming a well-integrated composite and eliminating the possibility of delamination in long term applications. Mechanical test proves this alginate-PPy/PEG composite film to be more stretchable than the PPy/PEG film, and electroactuation test in phosphate buffered saline (PBS) demonstrated a large deformation at +2 V in 60 s. Taken together, our work here indicates great promise for this new type of composite actuator to be used in biomedical MEMS.