Electro-Active Paper Materials Research Articles

Paper Actuators Made with Cellulose and Hybrid Materials

Recently, cellulose has been re-discovered as a smart material that can be used as sensor and actuator materials, which is termed electro-active paper (EAPap). This paper reports recent advances in paper actuators made with cellulose and hybrid materials such as multi-walled carbon nanotubes, conducting polymers and ionic liquids. Two distinct actuator principles in EAPap actuators are demonstrated: piezoelectric effect and ion migration effect in cellulose. Piezoelectricity of cellulose EAPap is quite comparable with other piezoelectric polymers. But, it is biodegradable, biocompatible, mechanically strong and thermally stable. To enhance ion migration effect in the cellulose, polypyrrole conducting polymer and ionic liquids were nanocoated on the cellulose film. This hybrid cellulose EAPap nanocomposite exhibits durable bending actuation in an ambient humidity and temperature condition. Fabrication, characteristics and performance of the cellulose EAPap and its hybrid EAPap materials are illustrated. Also, its possibility for remotely microwave-driven paper actuator is demonstrated.

Effect of Electrode Pattern on the Actuator Performance of Cellulose Electro-Active Paper

The effect of electrode patterns on the actuator performance of electro-active paper (EAPap) is studied. A rectangular electrode pattern has been typically used for EAPap actuator. Since the electrical field can be concentrated at the edge of electrodes, the electrode patterns of EAPap can influence the actuator performance. Thus, a fishbone pattern electrode was designed and fabricated on EAPap materials and its actuation characteristics were compared with the rectangular electrode ones. Two EAPap materials, DCell, which is made by dissolving cellulose pulp with N,N-Dimethylacetamide and LiCl followed by curing process, and cellophane were used. Bending displacements and the resonance frequencies of EAPap actuators were investigated. Although the bending displacements of the fishbone patterned EAPap actuators were slightly lower than the rectangular patterned actuators, the resonance frequencies of the fishbone patterned actuators were higher than the rectangular patterned actuators. Electrical field concentration around the edge of fishbone pattern electrode might result in increased bending stiffness of the actuator and electrical power consumption. Electrical power consumption and electrode damage of the fishbone pattern electrode were addressed.

Mechanical properties of cellulose-based electro-active paper

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.

Mechanical properties of cellulose electro-active paper under different environmentalconditions

The mechanical properties of cellulose-based electro-active paper (EAPap) areinvestigated under various environmental conditions. Cellulose EAPap has beendiscovered as a smart material that can be used as both sensor and actuator. Itsadvantages include low voltage operation, light weight, low power consumption,biodegradability and low cost. EAPap is made with cellulose paper coated withthin electrodes. EAPap shows a reversible and reproducible bending movementas well as longitudinal displacement under an electric field. However, EAPapis a complex anisotropic material which has not been fully characterized. Thisstudy investigates the mechanical properties of cellulose-based EAPap, includingYoung’s modulus, yield strength, ultimate strength and creep, along with orientationdirections, humidity and temperature levels. To test the materials in different humidityand temperature levels, a special material testing system was made that cancontrol the testing environmental conditions. The initial Young’s modulus ofEAPap is in the range of 4–9 GPa, which was higher than that of other polymermaterials. Also, the Young’s modulus is orientation dependent, which may beassociated with the piezoelectricity of EAPap materials. The elastic strength andstiffness gradually decreased when the humidity and temperature were increased.Creep and relaxation were observed under constant stress and strain, respectively.Through scanning electron microscopy, EAPap is shown to exhibit both layered andoriented cellulose macromolecular structures that impact both the elastic and plasticbehavior.

Cellulose Smart Material: Possibility and Challenges

This study presents an investigation of cellulose as a smart material that can be used for biomimetic sensor/actuator devices and microelectromechanical systems. This cellulose material is termed as electro-active paper (EAPap). First, the fabrication and recent improvement of EAPap materials are addressed. The actuation mechanism is explained by gathering all information on physical, chemical, electrical, and mechanical observations. In addition, the functional capability of sensor/actuator as a new smart material is discussed with experimental testimony. This smart material can be used for many applications, such as micro insect robots, micro flying objects, MEMS, biosensors, and flexible electrical displays. In summary, possibility of cellulose as smart material is addressed with challenges in this research.

Piezoelectric Effect of Electro-Active Paper Materials

The application of electroactive polymer devices requires the availability of their properties at various operating conditions. This in turn necessitates a structure-property relationship based on an in-depth understanding of the underlying mechanism responsible for their strain-field response. Cellulose-based Electro-Active Paper (EAPap) has been studied as an attractive Electro Active Polymer (EAP) material for artificial muscles. The feasibility of EAPap material as an actuator/sensor application is greatly dependant on piezoelectric effect. In this paper, converse and di rect piezoelectric ef fect s of Electro-Active Paper materials are studied to characterize piezoelectric effects of EAPap. All experiments were conducted in an environmental chamber that can control temperature and humidity.

Characterization of Electro-Active Paper Composite

This paper presents the characterization of Electro-active paper (EAPap). EAPap is a paper that produces large displacement with small force under electrical excitation. EAPap is made with a cellulose paper by constructing thin electrodes on both sides of the paper. When electrical voltage is applied to the electrodes the EAPap produces bending displacement. To be able to apply EAPap in many applications, characterization of EAPap is essential to understand and improve EAPap actuators. The characterization is done in terms of mechanical, electrical and physical tests. Mechanical strain and strength are investigated in sheet level and thermo-mechanical analysis is performed. Electrical resistance and admittance are analyzed to investigate the actuation mechanism. The actuation principle associated with piezoelectric effect is explained. EAPap has merits in terms of lightweight, dry condition, large displacement output, low actuation voltage and low power consumption. The most attractive characteristics of EAPap materials is their application potential for the development of biomimetic systems that are ultra-lightweight, low power, flexible, damage tolerant, noiseless, and agile.