Cellulose Electro-active Paper Research Articles

Parameter identification of partially covered piezoelectric cantilever power scavenger based on the coupled distributed parameter solution

ABSTRACTAmong the various techniques of power scavenging, piezoelectric energy harvesting usually has more power density. Although piezoceramics are usually more efficient than other piezoelectric materials, since they are very brittle and fragile, researchers are looking for alternative materials. Recently Cellulose Electro-active paper (EAPap) has been recognized as a smart material with piezoelectric behavior that can be used in energy scavenging systems. The majority of researches in energy harvesting area, use unimorph piezoelectric cantilever beams. This paper presents an analytical solution based on distributed parameter model for partially covered pieoelectric cantilever energy harvester. The purpose of the paper is to describe the changes in generated power with damping and the load resistance using analytical calculations. The analytical data are verified using experiment on a vibrating cantilever substrate that is partially covered by EAPap films. The results are very close to each other. Also asymptotic trends of the voltage, current and power outputs are investigated and expressions are obtained for the extreme conditions of the load resistance. These new findings provide guidelines for identification and manipulation of effective parameters in order to achieve the efficient performance in different ambient source conditions.

Analytical and experimental investigation of partially covered piezoelectric cantilever energy harvester

Electrical energy is normally generated through different sources such as hydroelectric, wind, heat, nuclear transformation, chemical reactions or vibrations. Nowadays, harvesting power from mechanical vibration is one of the novel technologies that usually can be done by systems based on electromagnetic, electrostatic, piezoelectric and combination of them. Piezoelectric systems can convert motion from the vibrating structures into electrical power. Cellulose Electro-active paper (EAPap) has been recognized as a novel smart piezoelectric material that can be used for energy harvesting purposes. One of the most prevalent method for vibration energy harvesting is using unimorph piezoelectric cantilever beams. In this paper, an analytical solution based on distributed parameter model is presented to calculate the generated energy from vibration of cantilever substrate that is partially covered by EAPap material. In the studied structure, piezoelectric layer thickness in comparison to the length of the beam and thickness of substrate material can be considered very thin. Thus its effect on the vibration behavior of structure is negligible. The results are validated by experimental values. The analytical data was found to be very close to experimental results and finite element simulation values. Findings from this study provide guidelines on system parameters that can be manipulated for more efficient performance in different ambient source conditions.

Recent Progress on Cellulose-Based Electro-Active Paper, Its Hybrid Nanocomposites and Applications.

We report on the recent progress and development of research into cellulose-based electro-active paper for bending actuators, bioelectronics devices, and electromechanical transducers. The cellulose electro-active paper is characterized in terms of its biodegradability, chirality, ample chemically modifying capacity, light weight, actuation capability, and ability to form hybrid nanocomposites. The mechanical, electrical, and chemical characterizations of the cellulose-based electro-active paper and its hybrid composites such as blends or coatings with synthetic polymers, biopolymers, carbon nanotubes, chitosan, and metal oxides, are explained. In addition, the integration of cellulose electro-active paper is highlighted to form various functional devices including but not limited to bending actuators, flexible speaker, strain sensors, energy harvesting transducers, biosensors, chemical sensors and transistors for electronic applications. The frontiers in cellulose paper devices are reviewed together with the strategies and perspectives of cellulose electro-active paper and cellulose nanocomposite research and applications.

Cellulose electro-active paper fabricated by facile solvent exchange pretreatment and its physical and electromechanical properties

The cellulose electro-active paper (EAPap) has been discovered as a smart material that can be used for sensors, actuators and flexible electronics. EAPap is made from regenerated cellulose that requires dissolving cellulose pulp using solvents with a heating process. However the heating process in dissolving cellulose is very critical to the performance of EAPap. In this paper, we introduce a new fabrication process of cellulose EAPap with a pretreatment process of cellulose, which simplifies the fabrication process and does not require the heating process. The pretreatment process includes the first immersion of cellulose into deionized water and the second immersion it into N,N-dimethylacetamide (DMAc) solvent, followed by twice repeat of the immersions. The pretreated cellulose was dissolved using lithium chloride (LiCl)/DMAc solvent without heating, which gives a cellulose solution. The pretreated cellulose solution was compared with another cellulose solution made with the LiCl/DMAc solvent and a heating process in terms of viscosity and solubility. Cellulose EAPap samples were made by using two cellulose solutions and their physical and electromechanical properties were compared in terms of transparency, ion concentration, surface morphology, Young’s modulus, dielectric constant and piezoelectric charge constant. The pretreatment of cellulose results in similar or better physical properties of EAPap, which simplifies the cellulose EAPap fabrication.

Cellulose Electro-Active Paper: From Discovery to Technology Applications

Cellulose electro-active paper (EAPap) is an attractive material of electro-active polymers (EAPs) family due to its smart characteristics. EAPap is thin cellulose film coated with metal electrodes on both sides. Its large displacement output, low actuation voltage and low power consumption can be used for biomimetic sensors/actuators and electromechanical system. Because cellulose EAPap is ultra-lightweight, easy to manufacture, inexpensive, biocompatible, and biodegradable, it has been employed for many applications such as bending actuator, vibration sensor, artificial muscle, flexible speaker, and can be advantageous in areas such as micro-insect robots, micro-flying objects, microelectromechanical systems, biosensors, and flexible displays.

셀룰로오스 EAPap 용 은잉크 제조 및 잉크젯 프린팅

This paper reports a customized silver ink and its inkjet printing process on a cellulose electroactive paper (EAPap). To synthesize a silver ink, silver nanoparticle is synthesized from silver nitrate, polyvinylpyrrolidone and ethylene glycol, followed by adding a viscosifier, hydroxyethylcellulose solution, and a surfactant, diethylene glycol. The silver ink is used in an inkjet printer (Fujifilm Dimatix DMP-2800 series) to print silver electrodes on cellulose EAPap. After printing, the electrodes are heat treated at 200oC. The sintered electrodes show that the thickness of the electrodes linearly increases as the number of printing layers increases. The electrical resistivity of the printed electrodes is 23.5 µΩ-cm. This customized ink can be used in inkjet printer to print complex electrode patterns on cellulose EAPap to fabricate flexible smart actuators, flexible electronics and sensors.

Electrode effects of a cellulose-based electro-active paper energy harvester

The possibility of cellulose-based electro-active paper (EAPap) as a vibrational energy transducer was investigated in this paper. Thin cellulose EAPap film specimens were prepared by the regenerating process. Three different metal electrodes of gold, silver and aluminum were deposited on a 50 × 50 mm2 cellulose film using a thermal evaporator. An aluminum cantilever beam was used as a vibrational bender and EAPap was attached close to the root of the cantilever beam. The voltage output of the EAPap was measured under harmonic base excitation of the cantilever beam. The EAPap with aluminum electrode provided the largest open circuit voltage output compared to those with gold or silver electrodes. The output voltages of the EAPap increased linearly with increase of the area of the electrodes. The output voltages also increased with increasing input acceleration but became saturated at a certain magnitude. From the experimental results, we conclude that EAPap with metal electrodes can be used as a flexible energy harvesting transducer by external mechanical stress, and the output voltage is related to the electrode material due to its work function.

폴리아닐린이 코팅된 Electro-Active Paper 작동기 성능평가

Bending actuators composed of cellulose with an electrically conducting polymer (CP) are fabricated and their performance is characterized in the air. Two different counter ions, perchlorate and tetrafluoroborate are used as dopant ions in the polyaniline CP processing. CPcellulose- CP trilayer and CP-cellulose bilayer samples are fabricated with different dopant ions, and their actuation performance is evaluated in terms of tip displacement, blocked force and electrical power consumption along with the humidity level and actuation frequency. The trilayer samples substantially enhanced the tip displacement compared to the bilayer ones. The actuation performance of the trilayer actuator is three times better than that of original cellulose electroactive paper (EAPap) actuator. The displacement and blocked force of CP-EAPap actuators are dependent on the humidity and frequency.

두께를 증가시킨 셀룰로오스 Electro-Active Paper 의 제조와 특성평가

This paper reports fabrication and characterization of cellulose Electro-Active Paper (EAPap) with increased thickness. Usual thickness of cellulose EAPap was 15 μm. This thickness needs to be increased to enhance the mechanical force output of EAPap. To fabricate thick cellulose EAPap, the fabrication process parameters including casting and drying processes should be investigated. In this paper, the casting thickness is increased from 800 μm to 1500 μm, and heating times on a hot plate before and after curing process are introduced at 40 and 60℃ for 30 and 60 minutes, respectively. Thickness measurement, Thermal Gravitational Analysis (TGA), UV-transmittance, Young’s modulus, and piezoelectric charge constant are measured. Heated EAPaps with increased thickness have similar TGA result, higher transmittance, higher Young’s modulus and lower piezoelectric charge constant.

Effects of Solvent Systems on Its Structure, Properties and Electromechanical Behavior of Cellulose Electro-Active Paper

This paper reports a comparative study on the influence of solvent systems on its structure, properties and electromechanical behavior of cellulose electro-active paper. Three types of solvent systems, namely N,N’-dimethylacetamide (DMAc)/LiCl, Trifluoroacetic acid (TFA) and 1-butyl-3-methylimidazolium chloride (BMICL) were studied to dissolve cellulose. Regenerated cellulose from DMAc/LiCl showed the best thermal and tensile properties whereas cellulose regenerated from BMICL exhibited high bending deformation with poor thermal and tensile properties, which might be due to the entrapped residual ionic liquid upon regeneration process. The cellulose regenerated with TFA showed the lowest thermal stability and tensile strength. Details of fabrication and characterization of regenerated cellulose films from three solvent systems are explained. Keywords: Cellulose, DMAc/LiCl, TFA, BMICL, Thermal stability, Mechanical properties, Electromechanical behavior, Cellulose Regeneration, Thermal and Tensile Properties, Electromechanical Behavior

Flexible Patch Rectennas for Wireless Actuation of Cellulose Electro-active Paper Actuator

This paper reports a flexible patch rectenna for wireless actuation of cellulose electro-active paper actuator (EAPap). The patch rectenna consists of rectifying circuit layer and ground layer, which converts microwave to dc power so as to wirelessly supply the power to the actuator. Patch rectennas are designed with different slot length at the ground layer. The fabricated devices are characterized depending on different substrates and polarization angles. The EAPap integrated with the patch rectenna is actuated by the microwave power. Detailed fabrication, characterization and demonstration of the integrated rectenna-EAPap actuator are explained.

원격구동 셀룰로오스 종이 작동기의 응용연구

셀룰로오스 EAPap 작동기는 생체 모방형 작동기의 하나로 생체적합하고 가볍고 비교적 낮은 전압에서도 큰 변위를 발생시킨다는 장점을 가지고 있다. 셀룰로오스를 재생하면서 셀룰로오스 파이버를 배열함으로써 압전 종이를 만들었다. 한편 셀룰로오스에 탄소나노튜브, 산화금속 나노분말, 전도성 고분자, 이온성 유체등을 물리적, 화학적으로 결합시켜 다양한 하이브리드 나노복합재를 만들었다. 본 논문에서는 셀룰로오스 EAPap 의 제조공정 및 이를 응용한 바이오센서, 화학센서, 유연트랜지스터, 그리고 작동기의 응용 디바이스에 대해 소개한다. 또한 셀룰로오스 EAPap을 무선으로 구동하는 기술에 대해 소개한다. 이는 생체모방로봇, 정찰 등에 활용될 수 있다.

Piezoelectric electro-active paper (EAPap) speaker

Film type piezoelectric speaker using cellulose electroactive paper (EAPap) in audible range was studied by acoustic characterization. The speaker was fabricated by depositing thin metal electrodes on both sides of EAPap. The local piezoelectric behavior of thin EAPap surface was visualized at 6 kHz and 221 Hz. The performance of EAPap film speaker as a function of size was evaluated in the audible frequency range, resulting in enhancement of speaker performance in low frequency range. From the measurement of geometric effect of EAPap speaker on audible performance, the circular type speaker shows better performance than rectangular one. Therefore we suggest that the piezoelectric EAPap has a potential for acoustic applications.

Application of Paper Material to Electronic Actuators and Sensors

This paper investigates the possibility of cellulose paper for actuators sensors and field effect transistors. Fabrication of cellulose Electro‑Active Paper（EAPap）in terms of stretching regenerating and washing processes and its application possibility in robust biomimetic actuator strain sensor temperature and humidity sensors chemical sensor biosensor and transistor are illustrated. The cellulose EAPap is biodegradable biocompatible flexible and low cost.

Highly Durable, Biomimetic Electro-Active Paper Actuator Based on Cellulose Polypyrrole-Ionic Liquid (CPIL) Nanocomposite

Cellulose has received much attention as a emerging smart material, named as electro-active paper (EAPap), which can produce a large bending displacement with applied external electrical field. In spite of many advantages over other reported electro active polymers, there are some issues to be addressed: its actuator performance: (i) sensitive to environmental humidity, (ii) humidity dependent displacement output of the actuator and (iii) degradation of performance with time. In present paper, we have successfully developed the highly durable EAPap actuator working at ambient condition with large displacement output. To improve the performance and durability of EAPap, nanoscaled PPy layer into cellulose EAPap was formed by in-situ polymerization technique. Cellulose-PPy-IL nanocomposite based EAPap actuator showed nearly 100% improvement of the actuator performance compared that of pure cellulose based EAPap actuator systems.

Electrical and Mechanical Characterization of Nanoscale-Layered Cellulose-Based Electro-Active Paper

In order to understand the electro-mechanical behavior of piezoelectric electro active paper (EAPap), the converse and direct piezoelectric characterization of cellulose EAPap was studied and compared. A delay between the electrical field and the induced strain of EAPap was observed due to the inner nano-voids or the localized amorphous regions in layer-by-layered structure to capture or hold the electrical charges and remnant ions. The linear relation between electric field and induced strain is also observed. The electro-mechanical performance of EAPap is discussed in detail in this paper.

Evaluation of cellulose electro-active paper made by tape casting and zone stretching methods

Cellulose has been discovered as a smart material that can be used as sensor and actuator material. In this paper, cellulose smart material termed as electro-active paper (EAPap) is prepared by an automated process that includes tape casting and zone stretching. To evaluate characteristics of the EAPap, its Young’s modulus and piezoelectric charge constant are measured depending on the orientation angle, in comparison with the manually fabricated EAPap results. The zone stretching method can effectively align the cellulose fibers in the EAPap so as to improve its Young’s modulus as well as piezoelectric charge constant. The 0 degree oriented sample shows its maximum Young’s modulus and the 45 degree oriented sample exhibits the maximum piezoelectric charge constant. This 45 degree is associated with its shear piezoelectricity. The actuator performance of EAPap is evaluated by measuring its bending displacement depending on the orientation angle and the excitation voltage. The 45 degree oriented sample exhibits the maximum bending displacement. Details of the material preparation, the automation process, characterization and the actuator performance are addressed. This automated process that includes tape casting and zone stretching is suitable for mass production of the EAPap.

Fabrication and testing of cellulose EAPap actuators for haptic application

Piezoelectric behavior of the cellulose electro-active paper (EAPap) actuators is studied for a possible haptic actuator. Using a thin stretched EAPap film with a material fiber orientation of 45°, stacked and unimorph EAPap actuators are prepared and their performance is investigated as functions of frequency and applied electric field. A small actuation displacement is observed from the stacked EAPap actuator. The displacement of the stacked actuator is dependent on the actuation frequency. The actuation displacement and resonance frequency of the unimorph type EAPap actuators are investigated with different beam lengths. At 1 Hz, the piezoelectric constant d 33 of the 32-layer-stacked EAPap actuator is about 150 pm/V and decreases as the operating frequency increases. A unimorph EAPap actuator with 60 mm length and 10 mm width shows a 75 μm of bending displacement at 10 Hz. From the experimental study, we demonstrate the feasibility of the cellulose EAPap for haptic applications.

Nanocoating of ionic liquid and polypyrrole for durable electro-active paper actuators working under ambient conditions

This paper reports that nanocoating of polypyrrole (PPy) and ionic liquid (IL) on cellulose film improves the electromechanical performance and durability of a cellulose electro-active paper actuator. Cellulose–PPy–IL nanocomposites were fabricated by the polymerization-induced adsorption process of PPy followed by subsequent activation in IL solutions. X-ray photoelectron spectroscopy, transmission electron microscopy and secondary ion mass spectroscopy analyses validated the successful nanocoating of the PPy and IL layers on the cellulose. The results revealed that the cellulose–PPy–IL nanocomposites are suitable for durable bending actuators working under ambient conditions. Preparation, characterization and performance test of the nanocomposites are explained.

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.