ELECTROMECHANICAL SYSTEMS BASED ON POLYMER HYDROGELS FOR MICRO-SCALE ACTUATORS

The paper proposes a novel approach to the construction of actuators for automation and robotics based on the use of new electroactive polymer materials – swelling hydrogels. The hydrogel pH-sensitive materials containing two polymer components, crosslinked polyacrylic acid and polyvinyl alcohol, are obtained. A procedure for the synthesis of hybrid hydrogel is described, and the achieved values of their characteristics, degrees of swelling in water and water solution of salt, are given. A method of hydrogel elements preparation with a specified geometric configuration was developed, and cylindrical and also ring-shaped samples were prepared. Mechanical properties of the prepared hydrogels at compression were measured. It is shown that the hybrid hydrogels exhibit higher strength and elasticity than the one-component polyacrylic acid hydrogels obtained by the same method. An actuator design is proposed with a hydrogel as a controlled element. An experimental layout of such actuator was constructed. The stability of material characteristics was determined, and methods for the electrodes fixation and electric current supply were developed. It was found that ring-shaped samples of hydrogels demonstrate electromechanical response – compression when electric current passes through their cross section. This fact was the evidence that these hydrogels can be used as a linearly operating generator of mechanical force. It is shown that this effect is more pronounced for samples swollen in water solution of sodium sulfate rather than in distilled water.