Mechanical properties of cellulose-based electro-active paper (EAPap) are characterized in this work. Cellulose-based EAPap has been studied as a potential actuator concept, as a result of its low actuation voltage, lightweight, low power consumption, biodegradability and low cost. EAPap is made from cellulose paper, coated with thin electrically conducting electrodes. This EAPap shows a reversible and reproducible bending movement as well as a longitudinal displacement under electric field excitation. However, the EAPap is a complex anisotropic material, which has not been extensively characterized. It is important to have extended property data for EAPap so that the actuator performance can be optimized, and this requires additional material testing. Our material test results show that EAPap has two distinct elastic constants. The initial Young's modulus of EAPap is in the range of 4–9 GPa, which is higher than other polymer materials. This modulus is also orientation dependent, which may be associated with the piezoelectricity of the EAPap materials. Another important property is that the dynamically induced mechanical strains of these materials exhibit linear creep behaviour as confirmed by constant stress and low frequency cyclic loading tests. From scanning electron microscope investigations, cellulose EAPap exhibits a layered, anisotropic cellulose macromolecular structure that exhibits both elastic and plastic deformations, as well as substantial temperature and humidity dependence.

On September 26, 2002, NASA announced that a consortium of six universities including: The University of Maryland, Virginia Tech, The University of Virginia, North Carolina A&T State University, North Carolina State University, and Georgina Tech had submitted the winning proposal for a National Institute of Aerospace. The Institute began formal operations in January of 2003 in Hampton, VA, and its mission included research, education, outreach, and technology transfer. One important focus of the NIA was to stimulate research among its member universities of potential benefit to NASA and to develop additional partnerships to further NIA focus areas. The work described in this paper is such an activity in bio-inspired actuator materials. This work was originally advocated and developed at Inha University, and it is being extended by teams from Inha University, North Carolina A&T State University, and NASA Langley so that the potential for these actuators as devices for special applications is better understood. This paper focuses on important performance characteristics of electro-active paper (EAPap) actuators and the potential of thes actuators to propel autonomous devices. EAPap is a paper that produces large displacement with small force under an electrical excitation. EAPap is made with chemically treated papers with electrodes on both outer surfaces. When electrical voltage is applied to the electrodes, a tip displacement is produced. One drawback in such actuators is that the actual power produced is variable, and the displacement is relatively unstable. Further, the performance tends to degrade in time and as a function of how the papers are processed. Environmental factors also impact the performance of the product including temperature and humidity. The use of such materials in ambulatory devices requires attention to these concerns and further research is needed to find what initial applications are most congruent with EAPap performance and service lift. In this paper, we have extended the knowledge base of EAPap to include additional ranges of temperature and humidity. We have also looked beyond the current tests on cantilevered beam actuators to segmented plate sections and have tested the ability of these actuators to perform as oscillatory devices both in and out of phase, and to chart their performance vs. time humidity and temperature thus emulating a rudimentary wing or walking assembly.

This paper focuses on the mechanical and electrical characteristics of electro-active paper (EAPap) as a bioinspired actuator and the potential use of these actuators in some specific applications. EAPap can undergo a large bending displacement at a relatively low voltage under low power consumption in dry conditions. EAPap samples as tested are made from chemically treated cellulose paper. When an electrical field is applied to the electrodes, a "bending displacement" is produced as the material tends to deform into a constant curvature coil. However, the EAPap is a complex anisotropic material, which has not been extensively characterized and additional basic and design testing is required before developing application devices from EAPap.Mechanical properties of selected EAPap materials along three material axes are addressed. EAPap material exhibits two distinct elastic constants connected by a bifurcation point along the stress strain diagram. The initial Young's modulus of EAPap is in the range of 5-8GPa, -quite high compared to other polymer materials. The thermomechanical analysis of EAPap is investigated to determine such factors as the degree of dimensional change due to dehydration and the maximum use temperature. Fatigue test identifies critical properties of this under-analyzed class of materials to provide a measure of its fatigue capabilities. The Electrical impedance analysis and dielectric property measurement with frequency are also important information that allows us to characterize the electrical behavior of EAPap. The performance of Eapap is measured in terms of tip displacement, blocking force and electrical power consumption. Through this series of tests, better understanding of the EAPap materials is obtained to researchers and designers interested in smart materials and EAP areas.

Cellulose-based Electro-Active Papers (EAPap) have been studied as potential actuators as a result of their low voltage operation, light weight, and low power consumption. In addition, they are bio-degradable and potentially inexpensive.1 The construction of many EAPap electromechanical actuators has been based on cellulose paper film coated with thin electrode layers. This EAPap actuator has shown a reversible and reproducible bending movement as well as longitudinal displacement under low voltage alternating current. However, the EAPap is a complex anisotropic material, which has not been extensively characterized and additional basic and design testing is required before developing EAPap application and devices. It is important to know the extended fatigue and elastic properties of EAPap materials, and this requires testing and evaluation. It has been known that the cellulose based EAPap has two distinct elastic constants connected by a bifurcation point along the stress strain diagram.2 The initial Young’s modulus of EAPap is in the range of 5-8GPa, - quite high compared to other polymer materials.3 Since these materials are anisotropic, elastic properties also differ as a function of orientation. These materials are sensitive to humidity and temperature. Fatigue tests conducted and described in this paper identify critical properties of this under-analyzed class of materials to provide a measure of its fatigue capabilities. Mechanical strain of EAPap materials has been evaluated, and it appears to follow closely a linear creep model as confirmed by low frequency cyclic (fatigue) loading. The creep parameter has also been determined to be a function of temperature and load level for all the EAPap materials tested.

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