ZnO nanorods grown cellulose film is a fascinating inorganic-organic hybrid nanocomposite in terms of synergistic
properties with semiconductive functionality of ZnO and renewability and flexibility of cellulose film. This paper reports
the fabrication and evaluation of cellulose ZnO hybrid nanocomposite (CEZOHN). ZnO nanorod is well grown on a
cellulose film by simple chemical reaction with direct seeding and hydrothermal growing. CEZOHN has unique electric,
electro-mechanical and photo-electrical behaviors. The performance of CEZOHN is estimated by measuring induced
photocurrent under UV exposure. Mechanism of UV sensing and its possible applications for flexible and wearable UV
sensor are addressed.
Cellulose is one of abundant renewable biomaterials in the world. Over 1.5 trillion tons of cellulose is produced per year in nature by biosynthesis, forming microfibrils which in turn aggregate to form cellulose fibers. Using new effective methods these microfibrils can be disintegrated from the fibers to nanosized materials, so called cellulose nanocrystal (CNC) and cellulose nanofiber (CNF). The CNC and CNF have extremely good strength properties, dimensional stability, thermal stability and good optical properties on top of their renewable behavior, which can be a building block of new materials. This paper represents recent advancement of cellulose nanocrystals and cellulose nanofibers, followed by their possibility for smart materials. Natural behaviors, extraction, modification of cellulose nanocrystals and fibers are explained and their synthesis with nanomaterials is introduced, which is necessary to meet the technological requirements for smart materials. Also, its challenges are addressed.
Development of tactile sensing technology has promoted intelligent human-machine interaction and recently has evolved out as one of the most promising area of electronics. Tactile sensing is a milestone in this field as it can extend the detection mode of tactile sensor through air. In this paper, we fabricated a tactile sensor using cellulose nanocrystal modified with graphene by isocyanate grafting. The new material is transparent, ecofriendly and integrated the capability of tactile sensing with fast response, high stability and high reversibility. Various materials from conducting metals to a human hand were checked for tactile sensing capability. It is found that the fabricated sensor could detect a human hand at a distance up to 6 mm away from the sensor. Combining the results, the discrete, flexible dual-mode tactile sensor fulfilled the technical and operational objectives of this work .
Iron oxide/cellulose nanocomposite film is fabricated by impregnation of iron oxide nanoparticles into a regenerated cellulose film. The crystal structure, chemical functional group, morphological analysis, thermal stability and mechanical properties of the nanocomposite films are investigated by the wide-angle X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis, and mechanical pull test. The investigated results show that the iron oxide is interacted with hydroxyl groups of the regenerated cellulose film. The tensile strength and elastic modulus of iron oxide/cellulose films are significantly enhanced up to 39% and 57% of pristine regenerated cellulose film, respectively.
Miniaturization of optical systems has promoted a revolution in lens technology and this emerging field has much interest for medical practitioners as well as electronic engineers. Tunable liquid lens capable of adjusting its focal length have special curiosity in this regard where in micro-scale actuators are often integrated. Here we demonstrate a lens consisting of a transparent elastomer liquid composite containing organo modified cellulose nanocrystals. The actuator with the working voltage of only up to 0.8kV was capable to produce an area expansion and thereby altering the curvature of the lens (focal length) reversibly in 5 seconds. The effect of filler concentration on optical property and dielectric behavior of the composites were also analyzed.
Inorganic-organic hybrid composite has attracted as its combined synergistic properties. Cellulose based inorganicorganic hybrid composite was fabricated with semiconductive nanomaterials which has functionality of nanomaterial and biocompatibility piezoelectricity, high transparency and flexibility of cellulose electro active paper namely EAPap. ZnO is providing semiconductive functionality to EAPap for hybrid nanocomposite by simple chemical reaction. Cellulose- ZnO hybrid nanocomposite (CEZOHN) demonstrates novel electrical, photoelectrical and electromechanical behaviors. This paper deals with methods to improve electromechanical property of CEZOHN. The fabrication process is introduced briefly, charging mechanism and evaluation is studied with measured piezoelectric constant. And its candidate application will be discussed such as artificial muscle, energy harvester, strain sensor, flexible electrical device.
Reconfigurable lens is biomimetic as it mimics human eye and is a transparent actuating material that can change its curvature in the presence of external stimuli. Focus tunable, adaptive lenses provide several advantages over traditional lens assemblies in terms of compactness, cost, efficiency and flexibility. To further improve the simplicity and compact nature of adaptive lenses, we present lens system which makes use of an inline, transparent electro active polymer actuator. This paper reports the preliminary development we have achieved in reconfigurable lens systems made with cellulose nanocrystals (CNC) using the principle of Kerr effect. Preparation of the hydrophobic CNC solution as well as the optical properties of the lens has been discussed. This soft gel actuator was analyzed by measuring the electric birefringence in the pulse field of constant and sinusoidal voltage based on the use of modulation of elliptic light polarization.
Cellulose is one of attractive natural polysaccharides in nature due to its good chemical stability, mechanical strength, biocompatibility, hydrophilic, and biodegradation properties [1-2]. The main disadvantages of biopolymer films like cellulose are their poor mechanical properties. Modification of polymers with inorganic materials is a new way to improve polymer properties such as mechanical strength [3-4]. Presently, the use of graphene/graphene oxide (GO) in materials research has attracted tremendous attention in the past 40 years in various fields including biomedicine, information technology and nanotechnology[5-7]. Graphene, a single sheet of graphite, has an ideal 2D structure with a monolayer of carbon atoms packed into a honeycomb crystal plane. Using both experimental and theoretical scientific research, researchers including Geim, Rao and Stankovich [8-10] have described the attractiveness of graphene in the materials research field. Due to its sp<sup>2</sup> hybrid carbon network as well as extraordinary mechanical, electronic, and thermal properties, graphene has opened new pathways for developing a wide range of novel functional materials. Perfect graphene does not exist naturally, but bulk and solution processable functionalized graphene materials including graphene oxide (GO) can now be prepared [11-13].The large surface area of GO has a number of functional groups, such as -OH, -COOH, -O- , and C=O, which make GO hydrophilic and readily dispersible in water as well as some organic solvents , thereby providing a convenient access to fabrication of graphene-based materials by solution casting. According to several reports [15-17], GO can be dispersed throughout a selected polymer matrix to make GO-based nanocomposites with excellent mechanical and thermal properties. Since GO is prepared from low-cost graphite, it has an outstanding price advantage over CNTs, which has encouraged studies of GO/synthetic polymer composites [18-20]. In some reported papers, graphene oxide has also been used to reinforce polysaccharide matrices such as carboxymethyl cellulose-starch. Here, we report a simple and environmentally benign preparation of GO/cellulose nanocomposite films by a simple solution mixing-curing method.
Paper based composite with semiconductor nanomaterial is a fascinating orgnic-inorganic hybrid composite that has improved properties of flexibility, biocompatibility and functionality. Cellulose Electro-Active Paper (EAPap) is a kind of paper electric device. To improve functionality of EAPap, ZnO is used as hybrid inorganic composition. Cellulose- ZnO hybrid nanocomposite (CEZOHN) is fabricated by seeding and growing ZnO on cellulose film with a simple chemical reaction. CEZOHN reveals not only electrical, eletromechanical behavior but also photoelectrical behavior. This paper reports specially photo-response and sensitivity of CEZOHN under several light source: UV light, sun and fluorescent light. The fabrication process is briefly introduced, and induced voltage, induced current under light source are investigated. Also, the ZnO effect of CEZOHN and its mechanism is studied and its possibility of application as photosensor, photodiode, photovoltaic device will be discussed.
A previously synthesized silver nanoparticle based conductive silver ink was used in this work to print conductive electrodes on cellulose electro-active paper (EAPap) by using an inkjet printer. Then, Inkjet printed cellulose EAPap experienced a post-deposition heat treatment-sintering process to enhance electrical conductivity of printed electrodes by converting those printed patterns into continuous metallic state. The dependences of electrical bulk resistivity of printed electrodes on both sintering temperature and sintering time were checked. It was found that, higher sintering temperatures and longer sintering process result lower resistivity. In addition, the uniformity of the thicknesses of printed electrodes through transverse direction and the relationship between thickness and the number of printing also had been analyzed. Those printed electrodes also showed very good adhesion on cellulose EAPap.
Cellulose films coated with ZnO nanoparticles constitute an important material for practical applications ranging from the film paint industry to the technologically appealing area of optoelectronic paper. ZnO-cellulose hybrid nanocomposite was fabricated by growing ZnO on regenerated cellulose directly. This organic-inorganic nanocomposite exhibits excellent piezoelectric behavior. This paper reports electrical and electromechanical behaviors of the ZnOcellulose hybrid nanocomposite. The fabrication process is briefly introduced, and induced voltage, remnant polarization as well as piezoelectricity between cellulose substrate and ZnO-layers are investigated. Also its charging and discharging behaviors are studied, and its application possibility for super capacitor, paper battery, field effect transistor will be discussed.
This paper investigates a direct inkjet printing method for electrode patterning on cellulose Electro-Active Paper
(EAPap). Flexibility and transparency of the EAPap are advantageous for a versatile substrate in flexible printable
electronics. The effects of curing conditions are evaluated by electrical resistivity and morphological analysis. To
fabricate EAPap device, inter-digital transducer (IDT) electrodes are printed on the EAPap with drop-on-demand inkjet
printing method. Silver patterns are obtained from organometallic silver ink by jetting and heat treatment at 160°C in air.
IDT patterns are made on cellulose for variety and extensive application of inkjet printing electronics.
TiO<sub>2</sub> and GaN thin film were successfully fabricated on Si substrate by a sol-gel method. However, thin films did not
show crystallinity structure without any treatment. To increase the crystallinity of thin films, TiO<sub>2</sub> thin films were
annealed while GaN was annealed under NH3 gas flow. The annealing temperature range was 700~900°C, and the
effects of thermal effect on the structural and electrical properties of TiO<sub>2</sub> and GaN films were studied. The resulting
films show high crystallinity as indicated via the XRD analysis. As annealing temperature increases up to 900°C, the
grain size and the surface roughness increases. Sol-gel thin film driven Schottky diodes are fabricated with Si and Al
electrodes, and characterized by measuring their current-voltage behavior with -2~2 V range. TiO<sub>2</sub> and GaN Schottky
diode with high crytallinity structure show a high forward current.