This PDF file contains the front matter associated with SPIE Proceedings Volume 10969, including the Title Page, Copyright information, Table of Contents, Author and Conference Committee lists.

Recent advances in materials engineering, chip miniaturization, wireless communication, power management, and manufacturing technologies have shaped our perspectives on wearable electronics in ways that wearing a Fitbit is as casual as driving to work. However, establishing a robust sensor-to-skin interface remains as a significant challenge due to the drastic contrast in soft, dynamic human skin and rigid electronics, limiting the adoption of technology to leisurebased applications. Here, we present an engineering solution by combining the respective merits of thin-film nanostructures, soft materials, and miniature electronic components and developing a soft, hybrid, wireless, wearable platform. We exploit conventional CMOS processes to fabricate metal/polymer nanostructures, implemented as dry contact electrodes (thickness ~3 μm) as well as a flexible interconnection system (thickness ~10 μm). The electrodes are further optimized by incorporating an open-mesh network geometric features allowing for prolonged, intimate contact throughout repeated and dynamic deformation of human skin. The skin-electrode impedance and the signal-to-noise ratio are ~18 kΩ and 29.52 dB, respectively, from electromyogram (EMG) recordings, matching the qualities of Ag/AgCl hydrogel electrodes. The stretchable circuit layer contains pad metal structures compatible for integration of surface mount chip components using a conventional reflow soldering process, allowing for easy integration of commercially available integrated circuit solutions. Silicone-based elastomer is used as both the carrier substrate for the thin-film structures and the backing layer providing the necessary adhesiveness to the skin. We verify that the completed system can be stretched up to 10% based on computational and experimental analysis. Finally, we demonstrate the robustness of the system functionality by showcasing human-machine interfaces (HMI) based on a single-channel forearm EMG with a real-time classification distinguishing four different hand gestures (accuracy: 95.9%) as well as the control of a robotic hand using three devices simultaneously.

Surface-functionalizations are of essential importance for diverse areas from biomedicine to biosensing, nanocomposites, water treatment, and energy harvesting devices. One facile and rapid way to functionalize any materials surface is by mussel inspired polydopamine (PDA) coating. It has been realized that dopamine (DA), the precursor, can be coated virtually on any substrates in presence of a buffer of pH ~ 8.5. Over the past 20 years, an overwhelming interest has been noticed around cellulose based materials specially nanofibers (CNFs) shown due to its many unique characteristics including high stiffness and modulus, great transparency well biodegradability, biocompatibility and low production cost. Despite of the facts, pristine cellulose often suffers from certain characteristic limitations in biomaterial applications due to the lack of appropriate surface functionalities. This research therefore aims to develop cellulose based composite materials suitable for biomedical applications, precisely electrode material for biosensors. The electrodes were made of controlled amount of polydopamine treated cellulose nanofiber composite. When investigated the mechanical properties of the composites, significant improvement was observed. Moreover, the composites exhibited good sensing behaviors under electrochemical investigations, leading them to be a promising material for biosensing applications.

Electronic skin are devices that mimic the tactile sensing functionalities of human skin, which a wide variety of applications in touch screens, wearable electronics, prosthetic, and robotics. Important characteristics of electronic skin are high sensitivity, large dynamic range, low hysteresis, high spatial and temporal resolution, large area processability, and the ability to differentiate between various tactile inputs. We herein present various materials selection and architectural design principles to tune these properties to achieve high performance electronic skin devices.

Heart disease is the most common cause of death, so there is a great need for non-invasive continuous monitoring of heart activities in daily life for early diagnosis and treatment. However, existing devices are not suitable for long-term use since they are uncomfortable to wear and heavy due to rigid plastics and thick metals. Here, we introduce a low-profile, comfortable, skin-wearable multifunctional biopatch, capable of wireless monitoring of heart and motion activities. The combination of a thin, tacky elastomeric membrane, skin-like stretchable electrodes, and a small form factor flexible circuit ensures the intimate integration of the device on the skin in adhesive and gel electrolyte-free environment. The results are not only enhanced user comfort and minimized motion artifacts during normal activities but also accurate classifications for various arrhythmias based on R-R interval and ST-segment analysis. In addition, the integrated motion sensor is available to track human activities and alert an emergency when a fall event occurs. This multifunctional soft wearable system would serve as a new wearable tool to advance human healthcare.

Implanted neural sensing is important to unravel the complexity of neuronal circuitries and understand brain function. Implanted neural devices can capture neurochemical signals in the brain real time. During chronic implantation, micromotion between the neural implant and brain tissue is considered as one of key drivers for immune response and astroglial sheath formation around implants. Therefore, micromotion during in-vivo experiments interfere electrochemical sensing signals and longevity in the brain. This research presents experimental design and results of electrochemical and mechanical coupling of micromotion in a brain-like phantom simulating the brain. A piezoelectric actuator was used to generate motion of an electrode implanted in a phantom while applying potentials for cyclic voltammetry. Electrochemical signal analysis of neurotransmitter sensing was performed to identify motional effects varying experimental conditions such as the frequency and amplitude of mechanical motion, and the chemical and mechanical properties of the brain-like phantom changing the concentration of gelatin. The mechanical effect on neural sensing was also analyzed using DFT. We also introduced a computational model of micromotion in the brain to simulate and analyze mechanical effects on electrochemical neural sensing. The experiment and simulation results show mechanical motion affects the current level in the redox peaks of CV the most, and also shifts the peak voltages.

The high mortality rate in developing countries stemming from poverty and diseases, and the pressure on healthcare budgets in developed countries have evoked a major concern in healthcare delivery. The need for less costly and patientcentered healthcare delivery brings point-of-care (POC) testing to the fore. POC devices help to eliminate the overhead associated with centralized bench-top laboratory instruments. Although handheld devices such as glucose biosensor strip exist, POC devices for molecular techniques such as Polymerase Chain Reaction (PCR) are new and emerging. PCR makes it possible to replicate DNA and generate millions of copies from a single strand. This finds applications in the medical field to identify and detect infectious diseases. Conventional PCR equipment is expensive and requires a significant amount of personnel time and space to setup and run in the laboratory. We have recently demonstrated a rapid and low-cost PCR thermocycler based on laser heating of gold nanoparticles suspended in the PCR tube. A critical aspect of PCR systems is the need to detect amplified products in real time. Here we show that by measuring the optical absorption of the suspended gold nanoparticles at a single wavelength during thermocycling, it is possible to detect amplified PCR products in real time. We investigate several different signal processing approaches in order to determine the most sensitive monitoring technique. This method makes it possible to distinguish between negative and positive PCRs with starting copy numbers as low as 10,000 genome copies per microliter.

This paper presents a method to provide continuous real-time condition monitoring of track health on an autonomous rail system. We use stretchable capacitive sensors installed on rolling stock (train carriages). The capacitive sensor was stretched between two points of the train with relative motion during operation, for instance, the current collector device (or shoe). Any change in relative motion signals, picked up by the capacitance change of the sensor, would indicate operational anomaly. We use our sensor to detect and differentiate between localized track wear, track misalignment and abnormal impact force. For train systems with a rigid legacy of train location detection systems, we propose a system of RFID transmitters and receivers to be lined at regular intervals along the train track and to be mounted on the train carriage, respectively. We propose a strategy to enhance the sensitivity of the capacitive sensor, and adopt Butterworth or wavelet for signal processing.

Surface plasmon resonance is widely studied and used for chemical and biological sensing. Current technology is based on angle resolved resonance detection at specific optical wavelengths. That is, changes in the reflectivity at the resonant angles are correlated to the chemical or biological substance at the surface of the sensor. In this work, we discuss the modeling and numerical techniques used to analyze a method to characterize plasmon resonances through surface acoustic wave (SAW) coupling of the incident light. The design strategies used to optimize the sensing performance of layered structures is described for several materials that are typically used as substrates and thin films.

Additive manufacturing (AM) is a crucial component of smart manufacturing systems that disrupts traditional supply chains. However, the parts built using the state-of-the-art powder-bed 3D printers have noticeable unpredictable mechanical properties. In this paper, we propose a closed-loop machine learning algorithm as a promising way of improving the underlying failure phenomena in 3D metal printing. We employ machine learning approach through a Deep Convolutional Neural Network to automatically detect the defects in printing the layers, thereby turning metal 3D printers into essentially their own inspectors. By comparing three deep learning models, we demonstrate that transfer learning approach based on Inception-v3 model in Tensorflow framework can be used to retrain our images data set consisting of only 200 image samples and achieves a classification accuracy rate of 100 % on the test set. This will generate a precise feedback signal for a smart 3D printer to recognize any issues with the build itself and make proper adjustments and corrections without operator intervention. The closed-loop ML algorithm can enhance the quality of the AM process, leading to manufacturing better parts with fewer quality hiccups, limiting waste of time and materials.

Hydrogen gas is a common byproduct in industrial and chemical processes. It is also frequently used in transportation applications such as fuel cell vehicles. It has no smell and no taste, but it may pose immediate safety risks because it is combustible in air. Multi-modal hydrogen sensors are developed by depositing nanofibers on quartz tuning forks (QTF). Near field electrospinning (NFES) was used to produce flexible, semi-conductive nanofibers that can be integrated into electronic systems as environmental gas sensors. The electrospinning parameters, especially tip-to-collector distance, were optimized to increase sensor performance. Treated multi-walled carbon nanotubes, camphorsulfonic acid doped polyaniline and platinum nanoparticles were used as the sensing materials with polyethylene oxide being used as an electrospinning guide. Intense pulsed light and sputter coating were used to maximize adhesion of the fibers onto the devices. The QTF sensor combines mechanical and electrochemical sensing methodologies. Changes in the resonance frequency were used to determine gas adsorption. Changes in the electrical resistance were used to determine the gas properties. As a result, the sensors were selective to hydrogen versus other gases and vapors including methane, hexane, toluene, ammonia, ethanol and carbon dioxide. Furthermore, the sensors can detect ppm levels of hydrogen even in the presence of high humidity.

Magnetic-driven micro-robotic devices have shown promising potential in enabling applications in micromanipulation, biosensing, targeted drug delivery, and minimally invasive surgery. However, the fabrication of miniaturized magnetic structures with complex geometries has remained the major technical obstacle. In this study, we report the development of a new magnetically-active photopolymerizable resin comprises poly (ethylene glycol) diacrylate monomer, Fe₃O₄ magnetic nanoparticles, photoinitiator, and other functional additives. Micro-continuous liquid interface production (micro-CLIP) 3D printing process was employed to realize high-resolution and high-speed fabrication of complex structures. The key characteristic properties of resin along with the matching process conditions were investigated experimentally, which allows for establishing the set of optimal fabrication conditions in fabricating magnetic microactuators towards potential applications.

Biological monitoring technology based on pressure sensing is a very useful for human diagnosis method as an assistive equipment, which should be comfortable on wearing position for user as well as and patient. Especially, pressure monitoring for prosthetic arm and artificial leg is the critical element to maintain the safety of the amputees. In this research, the fabrication and characterization of a novel flexible pressure sensor was done to measure the actual working pressure between the surface of human body and assistive device for biomechanical techniques. The ultimate goal of the sensor design is targeted for use in robotic and prosthetic limb, where feedback and ability to detect forces associated with slip is crucial point. To fabricate the capacitive type pressure sensor, finite element method (FEM), additive manufacturing (3D-printing) and signal processing were used. FEM simulation was performed with Comsol S/W for optimal structure design to evaluate with the structural deformation and maximum capacitance value up to 500 kPa in sensor range. Sensor with a full scale volume thickness under 10 mm were produced using FDM 3D-printingtechnique. A passive two-terminal electrical component part of capacitive pressure sensor was fabricated with conductive thermoplastic material and medium side of dielectric layer to keep soft and flexible structure. The output signal from the pressure sensor and related signal processing system was connected to a voltage divider circuit to amplifying the signal, multiplexer, microcontroller unit included analog to digital converter and indicating program. As a result, capacitive pressure sensing technology embedded in 3D printed structure can be considered for maintenance of stability and comfortability to amputees.

Many polar gas molecules possess distinct transitions in the terahertz frequency range. In this work, we present the design and fabrication of foam based THz gas sensor. This foam structure is auspicious for use as an effective sensing material owing to its high porosity, greatly reduction in its transmission loss in the Terahertz regime. To optimize the efficacy of cellulose in gas detection, we evaluate the properties of these porosities constructed by different fabrication process.

Recently, an increasing trend has been noticed towards synthesizing superhydrophobic surface with a water contact angle (WCA) higher than 150° due to its many potential applications including water repellency, oil spill recovery, self-cleaning, antifouling, anti-icing-deicing and so on. Unfortunately, most of the cases the superhydrophobic surface was achieved utilizing either fluorinated materials or organic-inorganic nanoparticles as the water–solid contact angle varies with the surface chemistry and roughness of the solid surface. Herein, we presented a novel approach for preparation of superhydrophobic coating without involving any such hazardous chemicals with the oath to create sustainable world. The superhydrophobic coating was prepared using cellulose nanofibers (CNFs) via a new one step surface modification process. The as-synthesized cellulose surface shows water contact angle (WCA) value of 161°(±2°). When used this material to coat other substrates such as tissue paper, sponge and fabrics, etc., to test the water repellent capacity, the WCA values were found to be between 136-150°(±3°) for the above surfaces. Moreover, the excellent durability of the coating made it very promising for efficient oil/water separation process to self-cleaning textile.

Nanocellulose-based long fiber (NLF) is a key element of natural fiber-reinforced polymer composites which have ultimate impact for the future technology, owing to its merits in terms of high specific modulus, high strength, environmentally-friendliness and low cost. In this study, NLF is made by aligning cellulose nanofibers (CNFs), which are isolated from wood pulp by a chemical and physical methods. A high degree of alignment of the CNFs leads to increased number of hydrogen bonds among CNFs with enhanced mechanical properties of NLF. In this study, wet spinning, mechanical stretching, electric field and magnetic fields are used simultaneously or continuously to align CNFs effectively. To fabricate strong NLF, the process parameters are experimentally investigated, and their effects are evaluated by using the tensile test, scanning electron microscope.

Nanocellulose has a great potential as a renewable material due to its high mechanical strength, high Young’s modulus, low density and eco-friendliness. Once a bulk material is made with it, then the bulk material made with nanocellulose can be a renewable bulk material, which is eco-friendly, lightweight and strong. Furthermore, it is known fact that cellulose has piezoelectricity due to its ordered domain of cellulose including crystal domains of cellulose. Thus, by aligning cellulose domains in the renewable bulk material made by nanocellulose, an eco-friendly and smart material can be developed. This paper aims at testing the feasibility of bulk material processing by using nanocellulose, specifically cellulose nanocrystal (CNC). The fabrication was carried out through steam with high temperature and high pressure to form hydrogen bonds between CNCs, followed by a heat and pressure molding. Its crystalline structure and physical interactions are investigated by using X-ray diffraction. Morphology and mechanical properties are investigated by scanning electron microscope and dynamic mechanical analysis.

This paper describes a double-layered foam filled THz split ring resonator gas sensor. The study of resonant shifts and damping (inverse of Q-factor) of a foam filled metamaterial is conducted for the concentration measurement of acetone gas. A nanoporous cellulose foam is used for its good adsorption of gas molecules. Different dielectric inserts and multilayer metamaterials are being investigated. Results from experiment and simulation generated from the CST Studio Suite 3D EM analysis are presented. In addition, porosity of the foam optimized by fine tuning the fabrication procedure to improve the measurement is also discussed.

This paper presents the new G-Fresnel lens-based μ-spectrometer with an image-processing algorithm, such as a color space conversion, in the range of visible light. The proposed μ-spectrometer is developed by using the cost-effective and compact G-Fresnel lens, which diffuses the mixed visible light into the spectrum image, and an image processing algorithm. The RGB color space commonly used in the image signal from CMOS type image sensor is converted into the HSV color space, which is one of the most popular methods to express the color as the numeric value, Hue (H), Saturation (S), and Value (V), using the color space conversion algorithm. Because the HSV color space has the advantages of expressing not only the three primary color of light as the H-value, but also its intensity as the V-value, it was possible to obtain both the wavelength and intensity information of the visible light from its spectrum image. The proposed μ-spectrometer yielded an inverse linear sensitivity (hue vs. the wavelength). We demonstrated the potential of G-Fresnel lens-based μ-spectrometer for the wavelength measurement of visible light such as mechanoluminescence (ML), typically green light across the region of 500 nm.

Cellulose nanofiber (CNF) is known to have high mechanical strength, high Young’s modulus, optical transparency, low thermal expansion coefficient and low density, which are beneficial for flexible display substrates and optical films. The purposes of this study is to fabricate ultrathin CNF film and to explore its physical properties. CNF suspension is extracted by 2,2,6,6-tetramethylpiperidin-1-oxyl (TEMPO) oxidation combined with aqueous counter collision (ACC) treatment from bleached hardwood pulp. The CNF suspension is cast on a thin positive photoresist (PR) layer by a doctor blade casting method followed by removing PR layer and drying on a polytetrafluoroethylene (PTFE) sheet to obtain ultrathin CNF film. Morphology of ultrathin CNF film is characterized by atomic force microscopy and the thickness of the film was characterized by FE-SEM. Transparency and birefringence of the prepared ultrathin CNF film are tested by using an UV-visible spectrometer and a digital camera. The piezoelectric response microscopy (PFM) is utilized to analysis the piezoelectric properties of ultrathin CNF film.

With the advance of soft electronic industry, soft electro-ionic artificial muscles based on electro-active polymer have been actively investigated from the practical viewpoint. However, due to the few drawbacks of the soft electro-ionic artificial muscles, they have not yet been applied to the practical applications until know. Herein, we report soft electro-ionic artificial muscles based on three dimensional graphene-carbon nanotube-nickel nanostructures (G-CNT-Ni). The G-CNT-Ni were blended in both polymeric electrodes and ionic membranes to fabricate a strong and large-bending soft electro-ionic artificial muscle. Importantly, the G-CNT-Ni exhibited remarkable electrochemical reactivity due to the synergistic effects of large specific surface area, three-dimensionally networked structures, and no restacking phenomena. Moreover, reinforcement of the G-CNT-Ni makes significantly improved blocking force and bending actuation of soft electro-ionic artificial muscle. This investigation can opens up a new way to apply soft electro-ionic artificial muscles to practical applications in next-generation electronic devices.

Materials engineering has greatly contributed to improving the performance of soft active materials, but these improvements have seldom met the compelling needs of science and engineering applications. Here, we demonstrate, for the first time, a new approach to the design of soft active materials, which embraces the complexity of multiphysics phenomena across electrostatics and electrochemistry. Through principled experiments and physically-based models we investigate the integration of electrostatic actuation in ionic polymer-metal composites (IPMCs).

There is ongoing uncertainty about the best way to mitigate the complication strategy in the development of varifocal lenses. Many efforts are being focused on the fabrication of adaptive focus lenses by a simple technique. Since the adaptive focus lenses change its curvature in response to the applied voltage; there has been a multitude of research is actively under progress. In this paper, we propose a compliant, highly transparent, and electroactive polymers based selfdeformable microlens for smart optical devices. Especially, a non-ionic PVC gel among electroactive polymers was selected to develop self-deformable microlens to avoid the solvent leakage because its actuation mechanism is not based on solvent-drag deformation but on creep deformation in an electric field, unlike ionic gel electrolytes. To make the convex shape on an actuation area of the proposed module, we put a rigid annular electrode on the electroactive PVC gel and apply pressure input by the rigid annular electrode. Later, we measure the focal length variations of the proposed varifocal lens with various thicknesses of electroactive gels. The resulting focal length values, obtained for the proposed module being large enough to use in small and compact optic devices.

Our understanding of the physics of air ows may benefit from direct full-field pressure measurement. In this work, we demonstrate the possibility of simultaneous planar velocity and pressure measurement of an air flow using pressure-sensitive tracer particles. Specifically, polystyrene microparticles embedded with pressure-sensitive dye PtOEP are fabricated and used to quantify the velocity and pressure variations of an air flow. The velocity field is obtained by particle tracking and the pressure field is inferred from the emission lifetime of the dye. Our experiment offers preliminary evidence for the possibility of simultaneous velocity and pressure measurement of an airflow using pressure-sensitive tracer particles.

Rechargeable power management system (RPMS) is significantly necessary to monitor the performance of power storage in biomedical devices. Failure of power storage device due to the battery pack, in a medical device, can entail dire consequences such as respiratory devices defibrillators and severe trembling. During charging and discharging the cell might become overstressed or underutilized, of which former may degrade the cell's lifespan. We applied an active balancing technique to distribute charges uniformly into the cell and thus increasing its efficiency and lifespan. In this technique, cells in the stack are monitored at regular intervals for their state of charge (SOC) and the average charge among them is calculated. The cell having the lowest voltage is charged by the series combination of the rest of the cells, by using switching device through isolation transformer which acts as the charge transferring device. In this research, the amount of charge transferred to the low voltage cell was controlled by controlling the frequency of the switching ranging from 100-500kHz. This RPMS includes modules for data acquisition and data logger by which the history of battery pack can be checked for any possible future breakdown and prediction of available run time for the battery pack. RPMS also features cell temperature monitoring to keep it within its safe limits. In this presentation, we will discuss the circuit simulation results using Multisim™ and hardware implementation in progress.

This study developed the feedforward control strategy of the piezoelectric micro-stage integrated with a bridge-type compliant mechanism. The micro-stage was assembled with three actuator legs and a moving plate. The actuator leg was consisted of four piezoelectric actuators with compliant mechanism. However, the complex nonlinear coupling between piezo-actuators and the compliant mechanism caused the hysteresis which can obstruct the precise control. The hysteresis of the piezoelectric micro-stage was realized by the 3rd order polynomial model in this study. Furthermore, the polynomial model was revised to consider the hysteresis change depending on the rate of input voltage. The compensator based on the revised polynomial model was designed for the feedforward control. The performance of the compensator was evaluated while changing the input voltage rate. Experiment results show that the tracking error of the compensator with the rate-dependent model quite decreases in compared with the rate-independent model. The feedforward control based on the revised polynomial model can be successfully utilized to the piezoelectric micro-stage regardless of the input voltage rate.

Purpose/Aim

It is known from literature that several electrical characteristics such as Partial Discharge (PD) Resistance of Polypropylene (PP) Films can be improved by homogeneous dispersion of Nanofillers into the polymer matrix. In this work, effect of variation in aging voltage on PD characteristics of PP and its remnant breakdown strength (BDS) is investigated for unfilled (PP+0%) and natural Nanofilled PP (PP+2% and PP+6%)

Experimental/Modeling methods.

Using PD measurement set up several AC voltages (multiple of inception voltage, Vi) are applied on each sample for a duration of two hours and PD parameters such as average discharge; maximum discharge, Weibull Scale (α) and Shape Factor (β) of PD distribution etc. are continuously acquired. After the completion PD measurement experiments, surface erosion of aged PP samples was measured using Profilometer to investigate effects of change in applied voltage and Nanofillers concentrations on the PD Resistance of PP samples. Using microscopic analyses degradation of PP samples were evaluated. At the end, Breakdown Strength Measurement experiment of all unaged and aged PP samples were conducted to dig into the effect of degree of aging of PP samples on their breakdown strengths when the samples contained different amounts of nanofillers.

Results/discussion

Variation of applied voltage influences PD characteristics because of different space charge accumulation threshold voltages for unfilled and Nanofilled PP samples. Above a threshold voltage rate of space charge accumulation is lower in Nanofilled PP than in base PP. Percolation limit of filler concentrations will also play a vital role on the variations in PD characteristics. Above a percolation limit discharges become higher because of the presence of surpassable double layers.

Conclusions

Changes in aging voltage will affect the polymer morphology changing the BDS in turn. Two parameter (Scale Factor α and Shape Factor β) Weibull Distribution were used to analyze breakdown strength of all samples. Comparison of PD characteristics of all samples (unaged and aged) were done finally and the effect of voltages on PD during aging and consequently the remnant Breakdown Strength in presence and absence of nanofillers were investigated.

Recently, cellulose fiber reinforced ecofriendly polymer composite for structural material is one of issue due to its sustainability, high mechanical properties, light weight and abundancy. For high strength and sustainable blend, a resin with sustainable, high strength and cellulose compatibility is demanded. PVA-lignin composite is one of good candidate for resin materials due to its high mechanical properties and good adhesion with cellulose. However, low waterproof ability is significant disadvantage of this material. In this paper, esterification reaction with maleic acid was adopted to enhance the mechanical properties. The esterification reaction enhanced waterproof ability and adhesion of PVA-lignin resin to cellulose material.

This paper reports an electrospinning of cellulose nanofiber (CNF) and poly(vinyl alcohol) (PVA) blend for fabricating nanocellulose based long filament in terms of experiment and simulation. To enhance spinnability, Triton X-100 and dimethyl sulfoxide (DMSO) was introduced as a surfactant and cosolvent, respectively. Parameters governing the electrospinning of CNF-PVA blend are voltage, spinning speed, nozzle diameter, the distance between the electrodes, and the viscosity of the blend. Node-based analysis of the electrospinning is performed with electrostatic field modeling via MATLAB software. With the simulation results, proper combinations of parameters are determined for CNF-PVA electrospinning. Furthermore, empirical demonstration of the CNF-PVA electrospinning is achieved. Electospun nanofiber mat is investigated by field emission scanning electron microscopy.

Being a naturally occurring biopolymer, cellulose is popular and deeply explored for its amazing mechanical properties. Cellulose nanofibers are modelled and molecular dynamics simulations conducted using GROMACS and All-Optimized Potential for Liquid Simulations (OPLS-AA) force field is used for parameterization. The mechanical properties and structural stability of the cellulose nanofibers are investigated via the simulations. We explore the hydrogen bonding disparities on the CNF structure as it is subjected to different pull forces. The results show that the hydrogen bonds decrease every time a pull force is increased, with the decrement more significant when large pull forces are applied than low pull forces.

In order to meet the environmental regulation due to global warming issues, the new energy resource such as ocean temperature between surface and deep see level or wasted heat resources from power plant have received much attentions as a renewable energy, which is not used in conventional power cycle using a water-steam phase change. Instead, organic Rankine cycle (ORC) based on a properly selected refrigerant can be used for power generation by utilizing the relatively hot source from cooling water from conventional power plants, internal combustion engines and industrial processes. To operate ORC cycle in low temperature difference, a proper selection of working fluid is very essential to design the ORC system for industrial application. However, the selection of working fluid is currently very limited due to ozone depletion by CFC as well as global warming issues by CO2 emission. Under new regulations, we should design and select appropriate refrigerants which can meet the environmental regulation for lower global warming potential (GWP) and lower ozone depletion potential (ODP). In this study, the convective heat transfer coefficients of single, binary or ternary refrigerants were studied through a pool boiling test. Also, the selected refrigerants were tested by lab scaled ORC system.