Chemo-mechanical Model for Actuation Based on Biological Membranes*

Abstract

Plants have the ability to develop large mechanical force from chemical energy available with bio-fuels. The energy released by adenosine tri-phosphate (ATP) hydrolysis assists the transport of ions and fluids to achieve volumetric expansion and homeostasis. Materials that develop pressure and hence strain similar to bio-materials are classified as nastic materials. Recent calculations for controlled actuation of an active material inspired by biological transport mechanism demonstrated the feasibility of developing such a material with actuation energy densities on the order of 100 kJ/m³. The initial investigation was based on capsules that generate pressure, thus causing strain in the surrounding matrix material. This paper focuses on our efforts to fabricate a representative actuation structure and describes the chemo-mechanical constitutive equation for such a material. The actuator considered in this work is a laminated plate dispersed with biological transporters. The initial design and a mathematical model to predict the fluid flux and strain developed in such an actuator are presented here.