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Currently, the only clinically utilized Phonocardiogram (PCG) is an electronic stethoscope used in a hospital or clinical environment. The availability of continuously recorded PCGs can provide a new avenue of research into chronic disease management at home. Researchers have proposed such wearable PCG devices. However, limitations exist in evaluating such devices as PCG recording devices in home-like environments. Here, we evaluate a wearable PCG system in a belt-type form factor with an embedded force sensor, accelerometer, and a single lead ECG to study the feasibility of acquiring diagnostic-grade PCGs while the wearer performs daily activities. We describe qualitative and quantitative exploratory analysis methods for cross-subject comparison of PCG signal quality, wearer comfort, and the impact of activities using Signal-to-Noise (SNR) comparisons and cross-spectral coherence between activity and PCG. The analysis of the data suggests that a common user-chosen method of donning a wearable PCG is not applicable across subjects for obtaining optimal PCG recording quality. We propose a method to calibrate wearable PCG devices using an embedded force sensor and by following a protocol involving feedback from the embedded force sensor to determine the optimal method of wearing the device. Following a similar path to precision medicine using genomic data and the extrapolation of risk, wearable devices with healthcare applications should be developed with the ability to be adapted and calibrated to each individual. In the immediate future this may involve calibration procedures such as those followed in this work, using controlled measurements performed with each patient to tune a device for them.

Wearable and Mobile Healthcare Nanosystems will be presented with a focus on the implementation of various engineering principles in the conception, design, development, analysis and operation of biomedical, biotechnological, wireless systems and applications. The primary objective of this talk is to introduce the latest research topics and techniques in biomedical and nanomedical wearable wireless technologies. This talk also discusses the development and application of mobile wearable nano-bio health monitoring systems for telemedicine. Nanomaterials-based biosensors used to measure physiological signals, such as electrocardiogram (ECG), electroencephalogram (EEG), electromyogram (EMG), and electrooculogram (EOG) will be discussed with the latest developments in Neurocardiology. Techniques and methodologies for physiological signal processing and utilizing Smartphones as base stations are discussed. Cloud computing resources used for complex computations, such as feature extraction and automatic diagnosis will be discussed.

Health and long-term care is a growth area for wearable heath monitoring systems. Wearable diagnostic and therapeutic systems can contribute to timely point-of-care (POC) for patients with chronic health conditions, especially chronic neurological disorders, cardiovascular diseases and strokes that are leading causes of mortality worldwide. Diagnostics and therapeutics for patients under timely POC can save thousands of lives. However, lack of access to minimally intrusive monitoring systems makes timely diagnosis difficult and sometimes impossible. Existing ambulatory recording equipment is incapable of performing continuous remote patient monitoring (RPM) because of the inability for conventional silver-silver-chloride-gel-electrodes to perform long-term monitoring, non-reusability, lack of scalable-standardized wireless communication platforms, and user-friendly design. Recent progress in nanotextile biosensors and mobile platforms has resulted in novel wearable health monitoring systems for neurological and cardiovascular disorders. This chapter discusses nanostructured-textile-based dry electrodes that are better suited for long-term measurement of electrocardiography (ECG), electroencephalography (EEG), electrooculography (EOG), electromyography (EMG), and bioimpedance with very low baseline noise, improved sensitivity, and seamless integration into garments of daily use. It discusses bioelectromagnetic principles of origination and propagation of bioelectric signals and nanosensor functioning, which provide a unique perspective on the development of novel wearable systems that harness their potential. Combined with state-of-the-art embedded wireless network devices and printable fractal antenna to communicate with smartphone, laptop, or directly to remote server through mobile network (GSM, 4G-LTE, GPRS), they can function as wearable wireless health diagnostic systems that are more intuitive to use.

This paper discusses the design, development and implementation of a plasmonic fishnet meta-structure, synthesis of TE ink and binder, fabrication of conductive ink, and printing technology to improve the overall efficiency of the hybrid PV-TE devices. Embedded fishnet meta-structure in hybrid photovoltaic-thermoelectric (PV-TE) system and, synthesis/characterization of printable nanoporous thermoelectric (TE) ink are proposed. Back passivation layer of the solar cell includes a planar fishnet structure that enhances solar radiation absorption near the infrared band of the solar spectrum. It was observed to improve the efficiency around 11 folds in the hybrid system with fishnet. Nanoporous Bi2Te3 and Sb2Te3 were used to prepare printing inks to print p-n junctions. Development of fishnet, synthesis/characterization of TE ink, binder and conductive ink are elucidated in this paper. Display Omitted We design TE device with plasmonic fishnet metastructure and nanoporous TE ink and binder to improve efficiency by 11 folds of hybrid PV-TE device.Performance of different formulations of nanoporous TE filler and nanocomposite conductive binders compared to silver based conductive binder.Application of nanoporous p-type and n-type TE inks and nanoimprinted fishnet structure enables Roll to Roll manufacturing of Hybrid TE device.

We propose embedment of a fishnet metastructure for a photovoltaic-thermoelectric (PV-TE) hybrid system to produce more electrical power of a thermoelectric generator by absorbing more solar thermal energy. The hybrid system consists of a hydrogenated amorphous silicon (a-Si:H) thin film solar cell as a top cell and a thermoelectric generator as a bottom cell. A planar fishnet structure is embedded in a back passivation layer of the solar cell to enhance solar thermal absorption near the infrared band of the solar spectrum. The absorbed thermal energy by the fishnet embedded solar cell is transferred to the TE generator, which increases temperature difference between hot and cold sides of the TE generator that enables to produce more electric power. The fishnet structure is optimized through the parametric simulation in terms of pitch, width and thickness. To calculate the total solar thermal energy of the hybrid system, the solar power spectrum is modeled by using the power spectral density of blackbody radiation. The total absorbed solar energy over infrared band is calculated by windowing absorption of the hybrid system to the modeled power spectral intensity. The hybrid system with the optimized fishnet structure absorbs more solar thermal energy than the system without fishnet by around 12 folds. This study would provide some enlightenment for the high performance of PV-TE hybrid systems. Display Omitted Embedding a fishnet metastructure in a photovoltaic-thermoelectric hybrid system is proposed.The geometry and material properties of the fishnet metastructure are the most critical parameters.Pitch, width and thickness of the fishnet metastructure should be optimized.Solar thermal absorption in the near infrared spectrum is increased.The electromagnetic response of the system is simulated with one unit cell by assuming infinite periodic extensions.

Magnetic nanotubes hold the potential for neuroscience applications because of their capability to deliver chemicals or biomolecules and the feasibility of controlling the orientation or movement of these magnetic nanotubes by an external magnetic field thus facilitating directed growth of neurites. Therefore, we sought to investigate the effects of laminin treated magnetic nanotubes and external alternating magnetic fields on the growth of dorsal root ganglion (DRG) neurons in cell culture. Magnetic nanotubes were synthesized by a hydrothermal method and characterized to confirm their hollow structure, the hematite and maghemite phases, and the magnetic properties. DRG neurons were cultured in the presence of magnetic nanotubes under alternating magnetic fields. Electron microscopy showed a close interaction between magnetic nanotubes and the growing neurites Phase contrast microscopy revealed live growing neurons suggesting that the combination of the presence of magnetic nanotubes and the alternating magnetic field were tolerated by DRG neurons. The synergistic effect, from both laminin treated magnetic nanotubes and the applied magnetic fields on survival, growth and electrical activity of the DRG neurons are currently being investigated.

Ventricular arrhythmias in the heart and the rapid heartbeat of ventricular tachycardia can lead to sudden cardiac death. This is a major health issue worldwide. What is needed is to develop a catheter based sensor and mapping approach which will provide the mechanisms of ventricular arrhythmia, and effectively prevent and treat the same, potentially save life.

Neurocardiology is the pathophysiological interplay of nervous and cardiovascular systems. The communication between the heart and brain has revealed various methodologies in healthcare that could be investigated to study the heart-brain interactions and other cardiovascular and neurological diseases. A textile based wearable nanosensor system in the form of e-bra, e-shirt, e-headband, e-brief, underwear etc, was presented in this SPIE conferences earlier for noninvasive recording of EEG and EKG, and showing the correlation between the brain and heart signals. In this paper, the technology is expanded further using fractal based geometries using 3D printing system for low cost and flexible wearable sensor system for healthcare.

Congestive Heart Failure (CHF) is a cardiovascular disease that affects about 5.7 million people in the US. The most prevalent comorbidity to CHF is Atrial Fibrillation (AF). These two pathologies present in a mutually worsening manner in that patients diagnosed with CHF are more likely to develop AF and patients who are diagnosed with AF are more likely to develop CHF. The underlying pathophysiological mechanisms have been studied for several years and the most recent efforts are in the cellular and molecular basis. In this paper, we focus on manifestation of CHF and AF symptoms as influenced by the posture assumed by a patient. We consider three postures – Left lateral decubitus, right lateral decubitus and supine. We review the clinical evidence gathered thus far relating enhanced sympathetic activity to the left lateral decubitus and supine positions with equivalent evidence on the enhanced vagal activity when the right lateral decubitus posture is assumed. We conclude with a compilation of all the hypotheses on the mechanism by which the right lateral decubitus posture alleviates the symptoms of CHF and AF, and future avenues for investigation.

Neurocardiology is the exploration of neurophysiological, neurological and neuroanatomical facets of neuroscience’s influence in cardiology. The paraphernalia of emotions on the heart and brain are premeditated because of the interaction between the central and peripheral nervous system. This is an investigative attempt to study emotion based neurocardiology and the factors that influence this phenomenon. The factors include: interaction between sleep EEG (electroencephalogram) and ECG (electrocardiogram), relationship between emotion and music, psychophysiological coherence between the heart and brain, emotion recognition techniques, and biofeedback mechanisms. Emotions contribute vitally to the mundane life and are quintessential to a numerous biological and everyday-functional modality of a human being. Emotions are best represented through EEG signals, and to a certain extent, can be observed through ECG and body temperature. Confluence of medical and engineering science has enabled the monitoring and discrimination of emotions influenced by happiness, anxiety, distress, excitement and several other factors that influence the thinking patterns and the electrical activity of the brain. Similarly, HRV (Heart Rate Variability) widely investigated for its provision and discerning characteristics towards EEG and the perception in neurocardiology.

This review focusses on introducing the mechanics in carbon nanotubes (CNT), and the major applications of CNT and its composites in biomedicine. It emphasizes the nanomechanics of these materials by reviewing the widely followed experimental methods, theoretical models, simulations, classification, segregation and applications the aforementioned materials. First, several mechanical properties contributing to the classification of the CNT, for various biomedicine applications, are discussed in detail to provide a cursory glance at the uses of CNT. The mechanics of CNT discussed in this paper include: elasticity, stress, tension, compression, nano-scale mechanics. In addition to these basic properties, a brief introduction about nanoscale composites is given. Second, a brief review on some of the major applications of CNT in biomedicine including drug delivery, therapeutics, diagnostics and regenerative medicine is given.

Protein association starts with random collisions of individual proteins. Multiple collisions and rotational diffusion brings the molecules to a state of orientation. Majority of the protein associations are influenced by electrostatic interactions. To introduce: electrostatic rate enhancement, Brownian dynamics and transient complex theory has been traditionally used. Due to the recent advances in interdisciplinary sciences, an array of molecular assembly methods is being studied. Protein nanostructural assembly and macromolecular crowding are derived from the subsets of biochemistry to study protein-protein interactions and protein self-assembly. This paper tries to investigate the issue of enhancing the protein self-association rate, and bridging the gap between the simulations and experimental results. The methods proposed here include: electrostatic rate enhancement, macromolecular crowing, nanostructural protein assembly, microfluidics based approaches and magnetic force based approaches. Despite the suggestions of several methods, microfluidic and magnetic force based approaches seem to serve the need of protein assembly in a wider scale. Congruence of these approaches may also yield better results. Even though, these methods prove to be conceptually strong, to prevent the disagreement of theory and practice, a wide range of experiments is required. This proposal intends to study theoretical and experimental methods to successfully implement the aforementioned assembly strategies, and conclude with an extensive analysis of experimental data to address practical feasibility.

The development of intelligent miniaturized nano-bio-and info-tech based sensors capable of wireless communication will fundamentally change the way we monitor and treat patients with chronic disease and after surgery. These new sensors will allow the monitoring of the patients as they maintain their normal daily activities, and provide warning to healthcare workers when critical events arise. This will facilitate early discharge of patients from hospitals as well as providing reassurance to patients and family that potential problems will be detected at an early stage. The use of continuous monitoring allows both transient and progressive abnormalities to be reliably detected thus avoiding the problems of conventional diagnosis and monitoring methods where by data is captured only for a brief period during hospital/clinic visits. We have been working with a printable organic semiconductor and thin film transistor, and have fabricated and tested various biosensors that can measure important physiological signs before and after surgery. Integrated into "smart" fabrics - garments with wireless technology – and independent e-bandaid sensors, nanosensors in tattoos and socks, minimally invasive implantable devices, the sensor systems will be able to monitor a patient's condition in real time and thus provide point-of-care diagnostics to health-care professionals and greater freedom for patients.

Wearable and ultraportable electronics coupled with pervasive computing are poised to revolutionize healthcare services delivery. The potential cost savings in both treatment, as well as preventive care are the focus of several research efforts across the globe. In this review, we describe the motivations behind wearable solutions to real-time cardiovascular monitoring from a perspective of current healthcare services, as well as from a systems design perspective. We identify areas where emerging research is underway, namely: nanotechnology in textile-based wearable monitors and healthcare solutions targeted towards smart devices, like smartphones and tablets.

Partition of noble atoms is studied using a pre-twisted single-walled carbon nanotube with semi-capped end via molecular dynamic simulations. A small portion on one end of the carbon nanotube is initially twisted to form a torsion buckling state. Upon releasing the pre-twisted portion, the collapse propagates along the tube wall. The van der Waals force between the encapsulated atoms and the collapsed wall of the nanotube thus initiates a motion and a consequent separation of the atoms. A successful separation of different atoms is found to be owing to the difference in the inertia of the atoms and the barrier effect of the semi-capped tip of the nanotube. Motions of one neon atom and one xenon atom are simulated to illustrate the separation process and various effects, such as twist angle and semi-capped tip, on the effectiveness of the process are discussed. Separation of eight atoms, four neon and four xenon, is demonstrated to further show the practical potential of the proposed partition method.

A good night's sleep plays a vital role in physical and mental wellbeing by performing the recuperative function for the brain and the body. Notwithstanding the fact that, good sleep is an essential part of a person's life, an increasing number of people are experiencing sleep disorders and loss of sleep. According to the research by the National Institutes of Health (NIH), 50 to 70 million Americans suffer from sleep disorders and sleep deprivation. Although sleep disorder is a highly prevalent condition like diabetes or asthma, 80 to 90 percent of the cases remain undiagnosed. The short-term effects of sleep disorder are morning headaches, excessive daytime sleepiness, shot-term memory loss and depression, but the cumulative long-term effects result in severe health consequences like heart attacks and strokes. In addition, people suffering from sleep disorders are 7.5 times more likely to have a higher body mass index and 2.5 times more likely to have diabetes. Further, undiagnosed and untreated sleep disorders have a significant direct and indirect economic impact. The costs associated with untreated sleep disorders are far higher than the costs for adequate treatment. According to the survey, approximately 16 billion of dollars are spent on medical expenses associated with repeated doctor visits, prescriptions and medications.

Neurocardiology is the exploration of neurophysiological, neurological and neuroanatomical facets of neuroscience’s influence in cardiology. The paraphernalia of emotions on the heart and brain are premeditated because of the interaction between the central and peripheral nervous system. This is an investigative attempt to study emotion based neurocardiology and the factors that influence this phenomena. The factors include: interaction between sleep EEG (electroencephalogram) and ECG (electrocardiogram), relationship between emotion and music, psychophysiological coherence between the heart and brain, emotion recognition techniques, and biofeedback mechanisms. Emotions contribute vitally to the mundane life and are quintessential to a numerous biological and everyday-functional modalities of a human being. Emotions are best represented through EEG signals, and to a certain extent, can be observed through ECG and body temperature. Confluence of medical and engineering science has enabled the monitoring and discrimination of emotions influenced by happiness, anxiety, distress, excitement and several other factors that influence the thinking patterns and the electrical activity of the brain. Similarly, HRV (Heart Rate Variability) widely investigated for its provision and discerning characteristics towards EEG and the perception in neurocardiology.

Football players are more to violent impacts and injuries more than any athlete in any other sport. Concussion or mild traumatic brain injuries were one of the lesser known sports injuries until the last decade. With the advent of modern technologies in medical and engineering disciplines, people are now more aware of concussion detection and prevention. These concussions are often overlooked by football players themselves. The cumulative effect of these mild traumatic brain injuries can cause long-term residual brain dysfunctions. The principle of concussion is based the movement of the brain in the neurocranium and viscerocranium. The brain is encapsulated by the cerebrospinal fluid which acts as a protective layer for the brain. This fluid can protect the brain against minor movements, however, any rapid movements of the brain may mitigate the protective capability of the cerebrospinal fluid. In this paper, we propose a wireless health monitoring helmet that addresses the concerns of the current monitoring methods - it is non-invasive for a football player as helmet is not an additional gear, it is efficient in performance as it is equipped with EEG nanosensors and 3D accelerometer, it does not restrict the movement of the user as it wirelessly communicates to the remote monitoring station, requirement of individual monitoring stations are not required for each player as the ZigBee protocol can couple multiple transmitters with one receiver. A helmet was developed and validated according to the above mentioned parameters.

Detection of sleepiness and drowsiness in human beings has been a daunting task for both engineering and medical technologies. Accuracy, precision and promptness of detection have always been an issue that has to be dealt by technologists. Generally, the bio potential signals – ECG, EOG, EEG and EMG are used to classify and discriminate sleep from being awake. However, the potential drawbacks may be high false detections, low precision, obtrusiveness, aftermath analysis, etc. To overcome the disadvantages, this paper reviews the design aspects of a wireless and a real time monitoring system to track sleep and detect fatigue. This concept involves the use of EOG and EEG to measure the blink rate and asses the person’s condition. In this user friendly and intuitive approach, EOG and EEG signals are obtained by the textile based nanosensors mounted on the inner side of a flexible headband. The acquired signals are then electrically transmitted to the data processing and transmission unit, which transmits the processed data to the receiver/monitoring module through ZigBee communication. This system is equipped with a software program to process, feature extract, analyze, display and store the information. Thereby, immediate detection of a person falling asleep is made feasible and, tracking the sleep cycle continuously provides an insight about the fatigue level. This approach of using a wireless, real time, dry sensor on a flexible substrate mitigates obtrusiveness that is expected from a wearable system. We have previously presented the results of the aforementioned wearable systems. This paper aims to extend our work conceptually through a review of engineering and medical techniques involved in wearable systems to detect drowsiness.

T wave alternans (TWA) is the variation of the T-wave in electrocardiogram that is observed between periodic beats. TWA is one of the important precursors used to diagnose sudden cardiac death (SCD). Several clinical studies have tried to determine the significance of using TWA analysis to detect abnormalities that may lead to Ventricular Arrhythmias, as well as establish metrics to perform risk stratification for cardiovascular patients with prior cardiac episodes. The statistical significance of TWA in predicting ventricular arrhythmias has been established in patients across several diagnoses. Studies have also shown the significance of the predictive value of TWA analysis in post myocardial infarction patients, risk of SCD, congestive heart failure, ischemic cardiomyopathy, and Chagas disease.

Additive manufacturing or 3D printing techniques are being vigorously investigated as a replacement to the traditional and conventional methods in fabrication to bring forth cost and time effective approaches. Introduction of 3D printing has led to printing micro and nanoscale structures including tissues and organelles, bioelectric sensors and devices, artificial bones and transplants, microfluidic devices, batteries and various other biomaterials. Various microfabrication processes have been developed to fabricate micro components and assemblies at lab scale. 3D Fabrication processes that can accommodate the functional and geometrical requirements to realize complicated structures are becoming feasible through advances in additive manufacturing. This advancement could lead to simpler development mechanisms of novel components and devices exhibiting complex features. For instance, development of microstructure electrodes that can penetrate the epidermis of the skin to collect the bio potential signal may prove very effective than the electrodes that measure signal from the skin’s surface. The micro and nanostructures will have to possess extraordinary material and mechanical properties for its dexterity in the applications. A substantial amount of research being pursued on stretchable and flexible devices based on PDMA, textiles, and organic electronics. Despite the numerous advantages these substrates and techniques could solely offer, 3D printing enables a multi-dimensional approach towards finer and complex applications. This review emphasizes the use of 3D printing to fabricate micro and nanostructures for that can be applied for human healthcare.

This article discusses the use and benefits of e-Nanoflex that combines nanostructured sensors, smart phones, and cloud computing and promises a new platform for everyday medical monitoring. At the University of Arkansas, a team of surgeons, engineers, and computer scientists has developed a personal heart monitor based on e-Nanoflex nanostructured sensors. The sensors can be embedded in clothing that can be worn and washed just like any other garment. The e-Nanoflex can also monitor recovery from surgery, medical compliance, and neurological diseases, or help athletes optimize their training routines. The nanostructured sensors developed at the University of Arkansas make true portable, wearable electrocardiograph (EKG) systems possible. They consist of tiny metal nanowires growing outwards from the surface of the electrodes. Sophisticated software can monitor data from e-Nanoflex sensors about heart rate consistency and other factors to ensure that patients comply with their prescriptions. The combination of wearable nanostructured sensors, smart phones, and cloud computing makes wearable EKGs possible.

Field-controllable pentacene-semiconductor-based strain sensors were fabricated with hybrid gate dielectrics using polyvinyl phenol (PVP) and high-k inorganic tantalum pentoxide (Ta2O5) onto polyethylene naphthalate films. The Ta2O5 gate-dielectric layer combined with a thin PVP layer to form very smooth and hydrophobic surfaces turns out to improve the molecular structures of pentacene films significantly. The PVP-Ta2O5 hybrid-gate-dielectric films exhibit a high dielectric constant of 19.27 and a leakage-current density of as low as 100 nA/cm2 . The sensors employing a thin-film-transistor-like Wheatstone bridge configuration able to operate at reduced voltage (~ 4 V) show good device characteristics with a field-effect mobility of 1.89 cm2/V · s and a threshold voltage of -0.5 V. The strain sensor characterized with bending at 45° with respect to the bridge bias direction with different bending radii of 50-, 40-, 30-, 20-, and 8-mm displays output signals improved in linearity in a low range of operating voltages.

Variations in concentrations of ions in biological systems can be important events in the onset of a physiological disorder. In an episode of myocardial ischemia, acidosis and elevation of potassium ion concentration has been observed in the extra-cellular matrix of the myocardium. As a spectrum of markers, they can help detect onset of ischemia as well as infarctions. In this study, Flexible Organic Ion-Sensitive Field-Effect Transistors (ISFETs) have been characterized to detect Ischemia-like variations in pH and potassium ion concentration. Detection capabilities, of the sensors, have been shown as pure chemical concentration to current signal transduction of the ISFET. Independent of peripheral amplifier-converter circuits, they are standalone sensors. The sensors have been evaluated for their sensitivity and signal resolution. Calibration expression, following a thermo-electric model for device operation, represents an explicit relations between transistor drain current and ion concentrations. Signal conditioning, by normalization, has been attempted to make the calibration expression explicit in ion-concentration. Finally a reliable detection strategy, in differential mode, is proposed for a reference electrode free device.

A high-order continuum model is developed to study wave propagation in nanowires. By using the model, heterogeneous nanostructure effects can be captured especially for high wave frequency cases. Surface stress effects are also included by using the incremental deformation approach. The governing equations of motion in the nanowire are derived including both the strain-independent and strain-dependent surface stresses. For simplicity and clarity, specific attention will be paid to the effects of strain-independent surface stress in this study. The accuracy of the proposed model is validated by comparing dispersion curves of longitudinal wave propagation from the current model with those from the exact solution. By conducting a reduced formulation, the results predicted by the current model will be compared with those based on existed high-order models to show capability of the current model. Numerical simulations are then conducted to study both longitudinal and flexural wave propagation in nanowires. The surface stress effects upon both longitudinal and flexural wave propagation in nanowires are demonstrated, from which the size dependent wave information in nanowires can be observed. Some new physical wave phenomena related to the surface stress effects are discussed.

Multiwalled carbon nanotube (CNT) arrays were grown by catalytic thermal decomposition of acetylene, over Fe-catalyst deposited on Si-wafer in the temperature range 700–750 °C. The growth parameters were optimized to obtain dense arrays of multiwalled CNTs of uniform diameter. The vertical cross-section of the grown nanotube arrays reveals a quasi-vertical alignment of the nanotubes. The effect of varying the thickness of the catalyst layer and the effect of increasing the growth duration on the morphology and distribution of the grown nanotubes were studied. A scotch-tape test to check the strength of adhesion of the grown CNTs to the Si-substrate surface reveals a strong adhesion between the grown nanotubes and the substrate surface. Transmission electron microscopy analysis of the grown CNTs shows that the grown CNTs are multiwalled nanotubes with a bamboo structure, and follow the base-growth mechanism.

γ-Manganese dioxide nanorods were prepared using a simple hydrothermal method based on redox reactions between S2O82− and Mn2+ and decoration of silver nanoparticles was performed by a wet impregnation method. The as-prepared materials were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD). Electrochemical discharging capacity of Ag/MnO2, MnO2/multi-walled carbon nanotubes (MWNTs), and Ag/MnO2/MWNTs electrodes were determined at 0.1 C discharging rate. The results showed that utility efficiency of MnO2 was greatly enhanced when silver particles were introduced and there was strong interaction between silver nanoparticles and bulk MnO2 materials. Electrochemical impedance spectroscopy (EIS) measurements were performed to investigate the discharging mechanism of the Ag/MnO2/MWNTs electrodes. Silver nanoparticles not only enhanced electronic conductivity of the network, but also improved proton diffusion process.

Postannealing effects on pentacene thin film transistors (TFTs) are discussed correlating the pentacene film morphology, the crystalline polymorph, and the electronic transport. The bulk phase thermally induced in pentacene during postannealing treatment is found to be another main cause detrimental to the carrier transport of TFTs. In addition, it turns out that encapsulation of the TFTs using polyvinyl alcohol helps to improve the thermal stability by retarding the onset of the bulk phase in pentacene.

This technical note is concerned with the buckling of single-walled carbon nanotubes with one atomic vacancy. An elastic beam theory is developed to predict the buckling strain of defective CNTs, and the strain prediction via the continuum mechanics model is verified from comparison studies by molecular dynamics simulations. The results demonstrate the effectiveness of the continuum mechanics theory for longer CNTs. In addition, a local kink is revealed in the morphology of the buckling of shorter defective CNTs via molecular dynamics.

This paper presents the fabrication of dual electrode ensembles for electrochemical sensing of dopamine. A new dual electrode ensemble consists of vertically aligned core nanowire electrodes and a shell electrode with a hemi-cylindrical nanocavity structure and submicron inter-electrode spacing between the two working electrodes. By using a 3-dimensional cavity structure of two working electrodes, collection efficiency in redox cycling of dopamine is enhanced. Initial measurement results show the ability to detect 200 μM concentration of dopamine with 69% collection efficiency on a dual electrode ensemble.

The effect of nanomaterials in platinum-decorated, multiwalled, carbon nanotube-based electrodes for amperometric glucose sensing was investigated by a comparative study with other carbon material-based electrodes such as graphite, glassy carbon, and multiwalled carbon nanotubes. Scanning and transmission electron microscopy and x-ray diffraction were used to investigate their morphologies and crystallinities. Electrochemical impedance spectroscopy was conducted to compare the electrochemical characteristics of these electrodes. The glucose-sensing results from the chronoamperometric measurements indicated that carbon nanotubes improve the linearity of the current response to glucose concentrations over a wide range, and that platinum decoration of the carbon nanotubes produces improved electrochemical performance with a higher sensitivity.

Elementary steps in heterogeneous nucleation and hierarchical nanogrowth processes, which are important in design and development of viable bottom-up nanofabrications, have been seldom exploited. We here combine new kinetic data from series of hierarchical nanosyntheses, including activation enthalpy and entropy, with FTIR results to tackle (i) elementary steps in both the nucleation and the growth of ZnO nanobranches and (ii) roles of heterogeneous nucleation directing agent and mild heating in the steps. Thus-enriched understanding of the interfacial kinetics may help solve some long-standing problems such as the lattice mismatch in the hierarchical bottom-up assembly of nanodevices from nanostructured building blocks in solution.

Continuum mechanics models for the torsional buckling of carbon nanotubes (CNTs) are developed in the Letter. The applicability of these models is investigated for CNTs with different aspect ratios. In particular, molecular dynamics simulations are conducted to verify the feasibility of the models for moderately long CNTs.

Wave propagation in carbon nanotubes (CNTs) is studied based on the proposed nonlocal elastic shell theory. Both theoretical analyses and numerical simulations have explicitly revealed the small-scale effect on wave dispersion relations for different CNT wavenumbers in the longitudinal and circumferential directions and for different wavelengths in the circumferential direction. The applicability of the proposed nonlocal elastic shell theory is especially explored and analyzed based on the differences between the wave solutions from local and nonlocal theories in numerical simulations. It is found that the newly proposed nonlocal shell theory is indispensable in predicting CNT phonon dispersion relations at larger longitudinal and circumferential wavenumbers and smaller wavelength in the circumferential direction when the small-scale effect becomes dominant and hence noteworthy. In addition, the asymptotic frequency, phase velocities and cut-off frequencies are also derived from the nonlocal shell theory. Moreover, an estimation of the scale coefficient is provided based on the derived asymptotic frequency. The research findings not only demonstrate great potential of the proposed nonlocal shell theory in studying vibration and phonon dispersion relations of CNTs but also signify limitations of local continuum mechanics in analysis of small-scale effects, and thus are of significance in promoting the development of nonlocal continuum mechanics in the design of nanostructures.