Recent Progress in Nanostructured Zinc Oxide Grown on Fabric for Wearable Thermoelectric Power Generator with UV Shielding

Traditional materials for thermoelectric such as bismuth telluride have been studied and utilized commercially for the last half century, but recent advancements in materials selection are one of the principal function of the active thermoelectric device as it determines the reliability of the fabrication regarding technical and economic aspects. Recently, many researcher’s efforts have been made to utilize oxide nanomaterials for wearable thermoelectric power generator (WTPG) applications which may provide environmental stable, mechanical flexibility, and light weight with low cost of manufacturing. In precise, fabric containing oxide metals have shown great promise as P−/N-type materials with improved transport and UV shielding properties. On the other hand, we have focused on ZnO nanostructures as a high-efficiency WTPG material because they are non-toxic to skin, inexpensive and easy to obtain and possess attractive electronic properties, which means that they are available for clothing with low-cost fabrication. To our observation, we are chaptering about the thermoelectric properties of ZnO and their composite nanostructures coated cotton fabric via the solvothermal method for the first time

Theoretical Power Output of Thermoelectric Power Generator based on Metal Oxide Semiconductor

Optimizing the structure and material combination of thermoelectric power generators (TEGs) is essential to their efficiency. In order to develop an efficient TEG based on an oxide semiconductor, we theoretically simulated the power output of a TEG based on potential oxide semiconductors (ZnO, TiO2, and CuO) combined with electrode materials (Au, Ag, Cu, graphene, graphite, ITO, IZO, and AZO), and determined the influence of this material combination on the TEG’s power output. In this study, the power output was evaluated from simulated heat distribution and output voltage of a single leg and thermopiles using a simulator. The combination of ZnO and graphene showed the highest power output. This is likely due to the high thermal conductivity of graphene which allowed a high temperature difference in the ZnO. Moreover, the power output increased with decreasing electrode thickness, which allowed high output voltage to be generated by the thermoelectric material. The power density of the TEG consisting of several thermopiles based on ZnO and graphene materials was 29 mW/cm2, which was comparable with that of the\ud reported TEG consisting of Te-based materials. Thus, a TEG based on oxide semiconductor materials could be developed to reduce the use of harmful thermoelectric materials

紫外線防御作用を持ったウェアラブル熱電発電のための布上に成長した酸化物半導体ナノ構造の研究

textversion:none甲第967号創造科学技術大学院doctoral博士(工学)静岡大

Quantitative ECG based emotion state recognition using Detrended Fluctuation Analysis

Wearable emotion recogniton system is essential in identifying mental health disorders by early detection and continuous monitoring of human emotions to provide proper treatment care. Electrocardiogram (ECG) signals can be used for emotion recognition for its noninvasiveness and easy usability. In this study, Detrended Fluctuation Analysis (DFA) and Extreme Gradient Boost (XG Boost) classifier is used to classify the scary and boring emotion from the ECG signals. For this, ECG signal corresponding to these emotions are obtained from public database. The preprocessing is performed by adding the video IDs to the signal and annotating it. This preprocessed signal is subjected to DFA to understand the power-law correlations and similarity property. Further, from the power law correlations, features namely Hurst exponent and DFA intercept are extracted. These features are subjected to XG Boost classifier to differentiate the two emotions. Results shows that the log-log plot of power law correlation is linear in nature which indicates that ECG signals of both the emotions have long range correlations and self-similarity property. The extracted scaling exponent indicates variations between scary and boring with a mean and standard deviation of 0.81±0.13 and 0.68±0.07 respectively. Similarly, DFA intercept provides mean and standard deviation for scary and boring 0.15±0.06 and 0.17±0.07 respectively, showing less variability in the ECG signal. XG Boost classifier gives accuracy of 80.5% for classifying scary and boring emotion. Thus, the proposed approach can be used for wearable emotion recognition system to differentiate scary and boring emotion

Exploration of Wedelia chinensis leaf-assisted silver nanoparticles for antioxidant, antibacterial and in vitro cytotoxic applications

Green synthetic route of silver nanoparticles (AgNPs) has already been proved to be an advantageous over other physico-chemical approaches due to its simplicity, cost effectiveness, ecofriendly and nontoxicity. In this finding, aqueous Wedelia chinensis leaf extract (WLE) mediated synthesis of AgNPs was approached. Surface plasmon resonance (SPR) band at 408 nm preliminary indicated the formation of AgNPs, while TEM and XRD characterization confirmed the formation of spherically shaped and crystalline AgNPs with an average size of 31.68 nm, respectively. The plausible biomolecules in the aqueous leaf extract responsible for the reduction and stabilization of AgNPs were identified by FTIR analysis and found to be polyphenolic groups in flavonoid. Further, synthesized AgNPs was explored for different biological applications. Biosynthesized AgNPs showed significant free radical scavenging activity as compared to Wedelia leaf extract and antibacterial activity against clinically isolated test pathogens where Gram-negative bacteria were found more susceptible to AgNPs than Gram-positive one. In addition, in vitro cytotoxic response was also evaluated on hepatocellular carcinoma Hep G2 cell lines and showed a dose-dependent cytotoxic response with an IC50 value of 25 μg/mL. Keywords: Wedelia chinensis, AgNPs, Antioxidant, Antibacterial, Cytotoxicit

Thermal-based Zinc-Oxide-Coated Smart Fabric for Thermochromic Applications

The present study focuses on developing a thermochromic device with a flexible substrate through the coating of cotton fabric with ZnO (Zinc oxide) by solvothermal synthesis technique. Here, ZnO is used as the thermochromic layer for the fabrication work, and it is suitable for textile and wearable applications as it is non-toxic to human skin. This device is designed and fabricated in order to gain better insight into the role of ZnO in thermochromic applications. Here, 3D nanostructures of ZnO are grown on the surface of cotton fabric using a simple and cost-effective solvothermal synthesis approach. The coated fabrics are investigated to determine their structure, morphology, composition, electrical, optical and emissivity properties using an X-ray diffraction (XRD), field-emission scanning electron microscope (FE-SEM), current-voltage (I-V) characteristics, ultraviolet protection factor (UPF) etc. From the morphology study, uniformly packed ZnO nanorods with growth in the c -axis direction are observed. The ZnO nanostructures are known to have excellent UPF when exposed to solar radiation and showed UPF value of 112.48. It is found that coated fabrics have increased electrical conductivity under optical excitations and also enhanced the reflectance. Moreover, based on the emissivity analysis coated ZnO cotton fabric showed the emissivity of 0.95, which is higher and has greater radiation protection than that of bare cotton fabric. Hence, the developed thermochromic device has potential for use in the future in textile and wearable based thermochromic application

Seebeck Coefficient of Flexible Carbon Fabric for Wearable Thermoelectric Device

publishe