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.
In an earlier work we reported the discovery of cellulose as a smart material that can be used in sensors and actuators. While the cellulose-based Electro-Active Paper (EAPap) actuator has many merits -lightweight, dry condition, biodegradability, sustainability, large displacement output and low actuation voltageits performance is sensitive to humidity. We report here on an EAPap made with a cellulose and sodium alginate that produces its maximum displacement at a lower humidity level than the earlier one. To fabricate this EAPap, we dissolved cellulose fibers into a aqueous solution of NaOH/urea. Sodium alginate (0, 5 or 10% by weight) was then added to this cellulose solution. The solution was cast into a sheet and hydrolyzed to form a wet cellulose-sodium alginate blend film. After drying, a bending EAPap actuator was made by depositing thin gold electrodes on both sides of it. The performance of the EAPap actuator was then evaluated in terms of free displacement and blocked force with respect to the actuation frequency, activation voltage and content of sodium alginate. The actuation principle is also discussed.
A preliminary study on a new hybrid soft composite with magnetically tunable equivalent tensile modulus, with a primary focus on an experimental investigation as a proof-of-concept, is presented here. Thin soft composite devices were designed and fabricated using state-of-the-art molding technology and two magnetic-responsive materials: a magneto-rheological fluid (MRF) and a magneto-rheological elastomer (MRE). Mechanical properties such as composite equivalent tensile modulus (CETM) were measured using tensile test equipment. A change of up to 300% can be achieved in the CETM by applying a 0.3 T magnetic field using permanent magnets. The results presented in this work can shed some light on the investigation of the proposed new soft composite for use in diverse applications, including those that are foldable and wearable, in which the stress-strain property needs to be locally tuned or controlled by the magnetic field intensity.
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