bluuebunny/crossref_metadata_2025 huggingface dataset:
Predicting Thermal Runaway in Li-Ion Battery Employing Machine Learning Framework
Authors: Ragone Marco , Yurkiv Vitaliy , Ramasubramanian Ajaykrishna , Shahbazian-Yassar Reza , Mashayek Farzad
Published: May 2020

Failures of lithium-ion batteries (LIBs) arise in both energetic and non-energetic ways. Both modes may occur due to numerous reasons such as cell manufacturing flaws, poor cell design (electrical or mechanical), external abuse of cells (thermal, mechanical, or electrical), defective protection electronics, chargers, etc. In this work, we present a machine learning (ML) study of the most severe energetic failure of the LIBs, which occurs due to the thermal runaway (TRA). In general, the TRA consists of a rapid self-heating of a cell sourced from exothermic (electro-) chemical reactions. During the TRA, the excessive heat has a detrimental influence on the electric characteristics and the state-of-charge (SOC) of the LIBs, which could lead to the accidental explosion of the battery. During the TRA, it is impossible to directly monitor the occurring events in practical operating conditions. However, the change of electric parameters during the TRA like-events could potentially indicate the existence of a failure, thus allowing to foresee the LIBs malfunction.

We propose two deep learning techniques to address the problem of predicting the TRA like-events based upon the temporal variation of electric parameters, the SOC and the thermal images in overheating conditions. First, a recurrent neural network (RNN) built upon the long-short-term memory (LSTM) scheme is used to estimate the time dependency of the SOC on the voltage, current and temperature of a cell. In the second method the objective is to predict the presence of the TRA in the LIBs subjected to internal/external heating directly from thermal images collected as sequences of video frames during the battery operation. For this purpose, a Convolutional LSTM (Conv-LSTM) network is constructed and trained to distinguish the recorded thermal images among two classes, specifically the presence or absence of the TRA like-events. Conv-LSTM is a recurrent neural network designed to extract information from sequential images in time series analysis, which combines the image processing capabilities of convolutional neural networks (CNN) and the temporal tracking potential of LSTM. The main advantage of the proposed techniques is that they do not require the physical modeling of the internal battery chemistry, which is cumbersome in the TRA scenario, but they rely only on the experimental/ modeling data and the collected thermal images,
Review of the Safety of Aged Li-Ion Batteries As a Function of Aging Protocol and Abuse Method
Authors: Preger Yuliya , Torres-Castro Loraine , Langendorf Jill , Lamb Joshua , Chalamala Babu R.
Published: May 2020

High voltage and energy density have increased the use of lithium-ion batteries (LiBs) in many applications, including consumer electronics, electric vehicles, and grid-tied energy storage systems (ESS). However, with increasing energy density and installation size come heightened concerns about safety, including the risk of thermal runaway and serious fires. To understand the risks and outcomes of LiB failure, numerous studies have examined the response of fresh cells to mechanical, electrical, and thermal abuse. However, given the expected lifetime of LiBs, it is critical to consider the abuse response of aged cells. In this presentation, we review previous results on the abuse of aged cells to facilitate understanding of how aging conditions (such as temperature and cycle rate) and abuse methodology (including calorimetry, short circuit, and overcharge) impact key metrics of safety relative to fresh cells. In general, the conditions used to produce aged cells in these studies have involved extreme temperatures. Thus, we also share more recent calorimetry of cells aged to 80% capacity by relatively mild protocols to understand the abuse response of cells from more typical device operating conditions. These results facilitate a more data-informed risk assessment of aged energy storage systems and the development and adoption of appropriate failure mitigation strategies.

Sandia National Laboratories is a multimission laboratory managed and operated by National Technology & Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525.
Parameter Identification through Physics-Based Impedance Models Using Impedance Spectra for Lithium-Ion Batteries
Authors: Teo Linnette , Kuo Jason , Hu Victor Waiman , Kolluri Suryanarayana , Pathak Manan , Schwartz Daniel T. , Subramanian Venkat R.
Published: May 2020

Electrochemical impedance spectroscopy (EIS) is a useful characterization tool due to its ability to separate physicochemical processes by their intrinsic time constants. EIS is extensively used to study diffusion1 and kinetic2 processes, investigate passive layer growth3, and characterize aging4 in lithium-ion batteries. However, experimental EIS data is traditionally fit using equivalent circuit models with circuit elements that are representative of the physical processes happening inside a battery. Such models may lose physical meaning and interpretability as processes and parameters are lumped together.

Physics-based impedance models mathematically describe physicochemical processes based on fundamentally derived equations and are thus better alternatives for providing direct insight than their equivalent circuit analogs5. These models are often highly coupled and complex, and traditional solution methods make it difficult to solve them in a reasonable time frame suited for multi-parameter identification. Recent work on a hybrid analytical-collocation approach demonstrated significant reduction in computation time (two orders of magnitude improvement compared to commercial software), making multi-parameter estimation a more feasible optimization problem6.

Estimation of parameters is an important step to using physics-based models in battery management systems (BMS) to monitor, predict, and control batteries, since such physics-based models inherently require knowledge of specific battery parameters. This work builds on the previously developed fast simulation approach for physics-based impedance models for a full cell consisting of two porous electrodes, by conducting a parameter reduction study through clustering of physical parameters. We present a method to demonstrate the identification of parameters and explore the ability to estimate parameters for the impedance spectra at different states of charge of a cell and at various states of aging.

References

1. P. Yu, B. N. Popov, J. A. Ritter, and R. E. White, J. Electrochem. Soc., 146, 8–14 (1999).

2. K. Dokko et al., J. Electrochem. Soc., 148, 422–426 (2001).

3. E. Barsoukov, J. H. Kim, J. H. Kim, C. O. Yoon, and H. Lee, J. Electrochem. Soc., 145, 2711–2717 (1998).

4. U. Tröltzsch, O. Kanoun, and H. R. Tränkler, Electrochim. Acta, 51, 1664–1672 (2006).

5. M. Doyle, J. P. Meyers, and J. Newman, J. Electrochem. Soc., 147, 99–110 (2000).

6. M. Pathak et al., J. Electrochem. Soc., 165, A1324–A1337 (2018).
Deciphering the Role of Temperature and Thermal Gradient Magnitude on Li-Ion Battery Performance and Safety
Authors: Kingston Todd A. , Carter Rachel , Atkinson Robert W. , Love Corey T.
Published: May 2020

Lithium-ion batteries are a transformative technology that have far-reaching implications in applications from consumer electronics to vehicles. The transient environmental conditions of many of these applications combined with internal heat generation and removal from the battery during operation cause it to be subjected to various thermal profiles. It has been shown that the cell’s material properties and kinetics are temperature dependent [1-3] and that thermal gradients can modulate electrochemistry [4, 5]. Our prior studies of externally-applied thermal gradients in batteries found that a gradient of 40 °C across the cell (0 °C anode-side and 40 °C cathode-side) has profound effects on local electrochemistry. However, the sensitivity of the cell to varied local electrode temperatures and the magnitude of the anode-to-cathode thermal gradient remains uncertain. In this work, we decipher the contributions of these two thermal aspects by independently modulating the temperature of each electrode within a single-layer pouch cell. Li-ion full cells are fabricated using lithium-iron-phosphate cathodes and graphite anodes. Local temperature measurements of the electrodes are obtained using thin-film sensors embedded within the cell. Galvanostatic cycling at different current rates and electrochemical impedance spectroscopy are performed on cells with various temperature and thermal gradient magnitudes to quantify thermo-electrochemical coupling phenomena. The implications of the thermal and operating conditions on battery performance and safety are discussed. This work demonstrates the need for effective thermal management strategies that can enable desired operational conditions, such as fast charging, while maintaining safe operation.

References

[1] Ji, Y., Zhang, Y., and Wang, C.-Y., Journal of The Electrochemical Society, 2013, 160(4), A636-A649.

[2] Love, C.T., Baturina, O.A., Swider-Lyons, K.E., ECS Electrochemistry Letters, 2015, 4(2), A24-A27.

[3] Bazinski, S.J. and Wang, X., Journal of Power Sources, 2015, 293, 283-291.

[4] Carter, R. and Love, C.T., ACS Applied Materials and Interfaces, 2018, 10, 26328-26334.

[5] Atkinson, R.W., Carter, R., and Love, C.T., Energy Storage Materials, 2019, 22, 18-28.
Unveiling the Underlying Mechanism of CO2-Assisted Li–O2 Batteries in the Presence of a Br3
–/Br2 Redox Couple
Authors: Marques Mota Filipe , Byon Hye Ryung , KIM Dong Ha
Published: May 2020

A critical step towards the commercialization of Li-air batteries involves replacing O2 with air. The presence of CO2 in the air, however, has been established to substantially alter the O2 chemistry of the Li-air battery, emphasizing the need to pursue fundamental exploratory works prior to the development of practical devices [1]. In our preliminary studies, we have investigated the effect of an increasing CO2 incorporation in the O2 gas feed on the performance of the resulting devices with a tetraglyme-based electrolyte. When up to 30% CO2 was added to Li–O2 cells, CO2 acted as an O2
− scavenger, with emerging soluble discharge products (e.g., CO4
2− and C2O6
2−) being correlated with enhanced full capacity and cell cyclability of these devices. The CO2-assisted Li–air device was confirmed to suffer, however, from unpractical recharge potentials at ~4.5 V required for the decomposition of Li2CO3, equally formed during discharge [2]. In agreement, incorporating a Br3
–/Br2 redox mediator was proposed as a promising strategy to suppress the overcharge potential. Electrochemically-generated Br2 was shown in this work to remarkably hinder the overpotential during recharge (~0.5 V). In addition, the performance of the introduced redox mediator was disclosed to be a function of the introduced LiBr concentration and of the insulating Li2CO3 crystallinity and morphology. As a seminal methodology, coupled electrochemical and spectroscopic analyses were then pursued to discern involved redox shuttling steps at progressive states-of-charge. Remarkably, our work revealed here for the first time the presence of Br2···Br3
− loosely-bound anionic complexes in the electrolyte during the recharge step. As opposed to discrete polar Br2 irreversibly precipitated on the CNT surface, the facile diffusion of the soluble Br2···Br3
− complex pinpointed these species as operating redox mediators during cell cycling. These findings are believed to shed light over the rational design of efficient mobile mediators beyond an overcharge decrease in the unexplored CO2-assisted Li–O2 device.

References

1. Takechi, T. Shiga and T. Asaoka, Chem. Commun.
47, 3463 (2011).

2. Qiao, J. Yi, S. Guo, Y. Sun, S. Wu, X. Liu, S. Yang, P. Hec and H. Zhou, Energy Environ. Sci. 5, 1211 (2018).
(Invited) Three-Dimensional Porous Electrode Architecture: Impact on Electrochemistry
Authors: Takeuchi Esther S , Wang Lei , Takeuchi Kenneth J , Marschilok Amy C.
Published: May 2020

Effective utilization of the electroactive material in thick electrodes could enable scalable batteries to be developed with higher energy densities while simultaneously reducing the overall cost of the battery. The challenges for thick electrodes include limited ion diffusion resulting in increased polarization and the inability to fully access the active material.

As part of the overall effort, the Center for Mesoscale Transport Properties is exploring alternative electrode architectures. A 3-dimensional porous electrode design was created through the deliberate incorporation of acicular carbon as part of the design strategy to enable an electrode with minimal active material agglomeration in a thick electrode (~400 µm). This design approach was explored with several active materials including high capacity conversion materials as well as layered insertion materials. In all cases, effective utilization of the active material was achieved. Further, examination of the electrode homogeneity under operando conditions was conducted using synchrotron x-ray techniques. Spatial and temporal resolution gained from the measurements provided insight into the effective electrochemical utilization.
Enabling Longer-Lasting Rechargeable Batteries Via Synchronizing Lithium and Lithium-Ion Batteries
Authors: Manikandan P. , Parekh Mihit , Pol Vilas G.
Published: May 2020

Synchronized lithium metal and lithium-ion battery (SLLIB) exhibits high energy storage device and longer-lasting rechargeable batteries through reservoir-replenishment and reservoir-boost processes. In SLLIB, lithium-electrode acts as a reservoir and booster-electrode to mitigate the formation cycle capacity loss in LiFePO4 cathode vs. mesocarbon microbeads (MCMB) anode. The recovered specific charge-discharge capacities of 146/ 144 mAh g–1 at 0.2 C was achieved for SLLIB, as compared to half-cell capacities 142/ 143 mAh g–1 at 0.2 C. The irreversible capacity compensation from the reservoir, offered to a renewed flat-voltage profile at 3.3/ 3.2 V and renewed electrode characteristics of 144 mAh g–1 for LiFePO4 and 390 mAh g–1 for MCMB. The energy reduced cell (due to formation cycles) was replenished/ boosted to increased energy density of 455 Wh kg–1 with retained flat-voltage profile through Li+ ion replenishment from the lithium-electrode to MCMB anode. Further, reservoir-reserved mode yielded the charge-discharge capacities of 126/ 124 mAh g–
1 at 0.2 C for lithium battery associated with the Li+ ion transport from reservoir-electrode to LiFePO4 cathode, confirmed by Li+ ion diffusion path through MCMB electrode. Eventually, the reservoir-replenishment, reservoir-boost and reservoir-reserved mode cycling processes of synchronized lithium and lithium-ion battery pointed out towards longer-lasting rechargeable batteries for advanced storage applications.

Figure 1
Li-Ion Pouch Cells Made with a Scalable Nanosilicon-Graphite Composite Anode
Authors: Toupin Mathieu , Yim Chae-Ho , Niketic Svetlana , Laforgue Alexis , Abu-Lebdeh Yaser
Published: May 2020

Nanosilicon can be dropped-in the battery-graphite processing flow to form a composite having enhanced specific capacity and improved capacity retention. The resulting active material was used to fabricate pouch cell using a pilot scale semi-automated battery manufacturing line without any special treatment or processing. This demonstrated that such a technological platform could be transparent to cell manufacturers. The electrochemistry of the composite active material will be evaluated in half-cells against Li metal and in full cells against NMC 532 by polarization curves, differential capacity analysis (dQ/dV) and rate mapping to evaluate the performance. Further characterization by in-operando X-ray diffraction, focused ion-beam x-section images made with a scanning electron microscope will be showed and discussed in an attempt to better understand the structure of the composite. This opens the door to the evaluation of numerous promising nanomaterials and graphite feeds in a rather simple fashion, most importantly a scalable one.
(Invited) Enzymatic Metal Oxide Electrolyte-Gated Field-Effect Transistors for Non-Invasive Glucose Biosensor
Authors: Kim Hojoong , Chung Kwun-Bum , Kwon Jang-Yeon
Published: May 2020

Fabrication of nano-scaled biosensors with high sensing performance is essential demand for a future biological sensing system. Detection of biomolecules is conducted in terms of change in electrical properties of the biosensor so that the consideration of semiconductor material becomes more crucial. Although a lot of attractive attentions are attempted such as utilizing silicon nanowire or carbon nanotube, studies for investigating the highly reliable and biocompatible materials still have been progressed. Metal oxide material for biosensing application has an advantages of relatively high electrical characteristics and provides environmental condition for immobilizing an enzyme. InGaZnO (IGZO) has high electron mobility and reliability which leads a high sensitivity for detecting biomolecules. Adapting field effect transistor (FET) structure is additional approach to enhance the signal response of the sensor. The fundamental principle of the FET biosensor relies on its sensitive response to the variation of electric field or potential at the sensor surface resulting from the electrical interaction between the semiconductor and glucose molecules captured at the glucose oxidase (GOx). The FET biosensor also could be effectively integrated with other application circuits through conventional photolithography technologies. In addition, electrolyte-gated FET structure, utilizing an electrolyte as a gate insulator, shows a high sensitivity to the glucose concentration originated from a large capacitance of the electrolyte.

IGZO based electrolyte-gated FET (IGZO-EGFET) biosensor is fabricated. The pH sensing is tested for predicting the biosensing performance of IGZO-EGFET. The pH sensitivity is measured as 52.5 mV/pH within 3 to 9 pH range, which is comparable to other nano material pH sensors. Immobilization of GOx on the IGZO surface is conducted via crosslinking modification with (3-aminopropyl)triethoxysilane (APTES) and glutaraldehyde treatment. Finally, the variation of glucose concentration is successfully identified on the GOx immobilized IGZO-EGFET. This study shows the IGZO-EGFET biosensor could lead to the applications of portable and real-time detecting sensor.
Fabrication of Heavy Metal Ion FET Based Sensor for Detecting Arsenite
Authors: Tatavarthi Sai Sudheer , Wang Yu-Lin
Published: May 2020

Arsenic is one of the toxic chemical among heavy metals. It is mostly present in ground waters at higher levels. The long term exposure of food or water to arsenic leads to cancer and heart diseases. Arsenic occurs in two oxidation states, Arsenite (As2O3, As (III)) a trivalent form and Arsenate (As2O5, As (V)) a pentavalent form. As (III) is an inorganic form which is more toxic than As (V). The detection of arsenic ion in drinking water or in any liquid form of food can be done with several laboratory equipments such as ICP-MS. The detection limit of ICP-MS for Arsenic is 0.05μg/L (10^-10M). Though these laboratory methods can be used for detecting the arsenic ion but it is very complex, costly and time consuming. In this research, we developed a methodology for detecting Arsenite ion (As2O3, As (III)). FET based ion sensor is fabricated where the gate pulse is characterized with 1500 μs pulse width and amplitude of 1 V is connected to one electrode. A steady DC bias of 2 V is applied as the drainsource voltage. The Ion Selective Membrane(ISM) is used which is immobilized on the sensing areas. This ISM contains Ionophore, Potassium tetra phenyl borate, Poly vinyl chloride, 2-Nitrophenyl octyl ether and this ISM components mixture is dissolved in Tetrahydrofuran. Sodium Arsenite (NaAsO2) is the inorganic compound which is used for detection of As (III). This solution is dropped on the sensing area which covers both ISM and gate. When Vd is supplied, we temporarily apply Vg of 0V and 1V which causes a change in current level, we define it as gain and is used as our measurement signal. The concentration range from 10^-10 M to 10^-4 M of arsenite ion can be detected. This sensor is easy to fabricate, smaller in size, high sensitivity and takes less time for detecting Arsenite. This FET based ion sensor has same detection limit comparable to ICP-MS and this sensor shows higher sensitivity than the Nernstian slope. The sensing characteristics are not affected by the interfering ions.

Figure 1
Layer-By-Layer Nanoassembly Of Polyelectrolites Engineered With Bioreceptors For High-Sensitivity Optical Label-Free Biosensing With Nanostructured Porous Silicon
Authors: Mariani Stefano , Robbiano Valentina , Strambini Lucanos M , Debrassi Aline , Egri Gabriela , Dähne L. , Barillaro Giuseppe
Published: May 2020

Here we report the layer-by-layer (LbL) nanoassembly of charged polyelectrolytes engineered with bioreceptors as an effective and robust alternative to covalent biofunctionalization (e.g., organosilanization and hydrosilylation) for affinity biosensing with porous silicon (PSi) interferometers [1]. As a proof of concept demonstration, a bi-layer of positively-charged poly(allylamine hydrochloride) (PAH) and negatively-charged biotinylated poly(methacrylic acid) (b-PMAA) is assembled onto the surface of oxidized PSi interferometers for the affinity detection of streptavidin in buffer and raw saliva. The LbL nanoassembly allows a homogenous coating of the inner PSi surface, ensuring a robust anchoring of the bioreceptors and, in turn, high sensitive and selective detection of streptavidin, also in raw saliva, down to a theoretical detection limit of 600 fM. This pushes PSi based biosensors at detection limit comparable to that of state-of-the-art nanostructured photonic and plasmonic platforms for biosensing. Further, the development and employment of polymers engineered with several bioreceptors or with stronger dissociation properties (e.g. PSS) could broaden the applications LbL nano-assembly in biosensing and in biomedical applications.

[1] S. Mariani et al., Nature Communications. 2018, 9, 5256, 1-13.
(Invited) Plasmonic Nanoarchitectures for Label-Free Molecular Detections
Authors: Choi Dukhyun , Park Yongtae
Published: May 2020

Nanoscale periodic material design and fabrication are essentially fundamental requirement for basic scientific researches and industrial applications of nano-science and engineering. Innovative, effective, reproducible, large-area uniform, tunable and robust nanostructure/material syntheses are still challenging. Here, I would like to introduce the large-area, cost-effective and high-throughput nanofabrications based on wet chemistry. Plasmonic nanostructures with a localized surface plasmon resonance (LSPR), which is generated by the coupling of light to the collective oscillation of electrons on the nano-sized metallic surface, have generated considerable interest with the development of nanotechnology due to its ability to enhance the weak physical process such as the absorption of light. By adopting such a plasmonic nanostructure inside/onto/beneath a photoactive layer, a power conversion efficiency of solar cells could be improved because an electromagnetic (EM) field is greatly enhanced by plasmonic “hot spots”. Furthermore, optical biosensors such as surface-enhanced Raman scattering (SERS) could be designed with an ultrahigh sensitivity through a local field enhancement from the “hot spots”. A variety of optoelectronic devices and optical biosensors integrated with plasmonic nanostructures thus have been explosively studied and developed. In this study, we report large-area periodic plasmonic nanostructures based on nanotemplates. The surface morphology and optical properties are characterized by SEM and UV-vis. spectroscopy. Furthermore, their enhancement factor is evaluated by using SERS signals.
(Invited) Active Molecularization of Terahertz Meta-Atoms for Bio and Medical Sensing Applications
Authors: Lee Hojin , Kim Do Hwan
Published: May 2020

Active control of metamaterial properties is critical for advanced THz applications especially for bio and medical sensors. However, the tunability of THz properties, such as the resonance frequency and phase of the wave, remains challenging. Here, we provide a new device design for extensively tuning the resonance properties of THz metamaterials. Unlike previous approaches, the design is intended to control the electrical interconnections between the metallic unit structures of metamaterials. This strategy is referred to as the molecularization of the meta-atoms and is accomplished by placing graphene bridges between metallic unit structures whose conductivity is modulated by electrolyte gating. Because of the scalable nature of the molecularization, the resonance frequency of the terahertz metamaterials can be tuned as a function of the number of meta-atoms constituting an unit meta-molecule. At the same time, the voltage-controlled molecularization allows delicate control on the phase shift of the transmitted THz, without changing the high transmission of the materials significantly.

In this study, we propose selectively reconfigurable terahertz meta-molecules by controlling the micro-patterned ion-gel gate structures to change the conductance of graphene bridges between adjacent meta-atoms. Moreover, we experimentally verify that the proposed structures can change the resonance frequency of metamaterial device to define resonance properties from 1.40, 1.10, to 0.74 THz, by changing the metamaterial unit cell from the individual atom to dimeric and tetrameric molecules, respectively.
Ultrasensitive and Label-Free Detection of Mercury Ions Using a Highly Efficient Solid-Liquid Triboelectric Nanosensor
Authors: Roy Barman Snigdha , Wu Hua-Shan , Lin Zong-Hong
Published: May 2020

In the recent years, mercury pollution in the world have increased tremendously due to both natural and anthropogenic reasons. The mercury ions (Hg2+) after being released from the industrial wastes into the environment is transformed into the highly toxic form of methylmercury (CH3Hg+) by the microorganisms present, which further accumulates in the human body via drinking water and food, ultimately causing irreversible damage to reproductive, immune and nervous system. Currently, analytical tools such as ICP-MS, X-ray fluorescence spectroscopy, AES etc are employed for detection of the Hg2+ ions but their utility is overshadowed by certain limitations like complicated sample preparation steps, time-consuming protocol, non-portable nature, requirement of trained professionals etc. Therefore, in this work we propose a highly sensitive and selective sensing method for Hg2+ ions using the concept of solid-liquid contact electrification. This triboelectric nanosensor was developed employing modified Copper(II) oxide nanowires (CuO NWs) as the solid-triboelectric layer and deionized water as the liquid- triboelectric layer. Due to the highly specific reaction between the modified CuO NWs surface and Hg2+ ions, the as-developed sensor can detect the Hg2+ ion concentrations as low as 0.1 nM with a good linear range of 1nM-10 μM. In addition, the unrivalledly flexible nanosensor is coupled with the robotic fingertips for highly automated on-site monitoring of Hg2+ ions, making it possible to track the heavy metal pollution in inaccessible and remote locations. We believe that this work will be a stepping stone towards designing a reusable, portable, low-cost and stand-alone sensing systems which can be adapted into different environmental settings for detection of Hg2+ ion levels.
Melanin-Based Thin Films for Sustainable Electronic Devices
Authors: Saini Pooja , Santato Clara
Published: May 2020

Melanin is a natural (bio-sourced) and bio compatible material, attracting attention because of its physicochemical properties. Melanin is a family of pigments and the brown-black eumelanin pigment is part of this. It can be found in skin, hair, eyes, and brain [1-2]. Considering its quinone-based and conjugated molecular structure, eumelanin is an interesting candidate for bioelectronics. Transport physics in eumelanin-based thin films and pellets need to be better understood to optimize its technological applications. The main challenge for the use of eumelanin in bioelectronics is to increase the conductivity and detailed study is required to clarify and quantify the electronic and protonic contribution to charge transport.

High quality thin films of eumelanin material on substrates such as ITO (Indium Tin Oxide) and FTO (Fluorine Tin Oxide) substrates were prepared to study the electronic transport properties of the biopigment. The electrodeposition method, spray pyrolysis, and spin coating were used for the preparation of uniform thin films. The structural, optical, and morphological properties of these thin films were studied using X-ray diffraction (XRD), atomic force microscopy (AFM), field emission electron microscopy (FESEM) and transmission electron microscopy (TEM). For the metal contacts both top contacts using a through shadow masking and photolithography were used. Preliminary results on the dependence of electronic transport on temperature, relative humidity, and interelectrode distance range were collected.

Reference

[1] Julia Wunsche, Yingxin Deng, Prajwal Kumar, Eduardo Di Mauro, Erik Josberger, Jonathan Sayago, Alessandro Pezzella, Francesca Soavi, Fabio Cicoira, Marco Rolandi, and Clara Santato, Chem. Mater. 2015,27, 436−442.

[2] Prajwal Kumar, Eduardo Di Mauro, Shiming Zhang, Alessandro Pezzella, Francesca Soavi, Clara Santato and Fabio Cicoira, J. Mater. Chem. C, 2016, 4, 9516.
(Invited) Nanomaterial Assemblies for Chemical and Energy Transformation: From Reactors, Sensors, to Integrated Systems
Authors: Gao Pu-Xian
Published: May 2020

Three-dimensional (3-D) assemblies of nanomaterials into applicable platforms or devices represent the need for meeting the practical requirements in cost-effectiveness, structure sophistication, multi-function enabling, and efficient operations. Such an integration process involves a diverse array of dissimilar building-blocks such as nanoparticles, nanowires, and nanofilms made of metals, ceramics, or polymers. In this talk, I will review our decade-long research effort in the assemblies and integrations of various ceramics and metals in the forms of nanostructures or nanostructure arrays (nanoarrays) onto different macroscale surfaces as function-carrying ensembles. Departing from catalytic converters, sensors, water electrolysis, to CO2-methanol conversion, a unique nanomaterials roadmap is being drawn with function-enabling, manufacturing capability, system integratability, and economic affordability as the underlying bases. Modular, multifunctional, and scalable nanoarray devices and systems are being designed and enabled for conversion, monitoring, production, and redistribution of fuels and chemicals such as hydrogen and methanol.
(Invited) Self-Powered Wearable and Implantable Electrical Stimulation Devices for Biomedical Applications
Authors: Wang Xudong
Published: May 2020

Electrical stimulation (ES) is a widely used therapeutic treatment strategy. It showed significantly positive results in treating a variety of diseases, biological disorders, and neurological problems. Today, the emergence of wearable devices is rapidly reshaping the development of medical devices, pushing them from conventional bulky and rigid silicon electronics to flexible and primarily polymer-based systems. Among many types of functions, nanogenerators are developed as a unique device for converting biomechanical energy into electrical pulses. This talk will fist introduce the application of flexible nanogenerators as an implantable power source and its biosafety and compatibility. In addition, the pulsed electricity from nanogenerators can be applied directly as a ES signal for therapeutic treatment. In our recent research, we successfully implemented such an electromechanical system for skin wound healing, hair growth, and vagus nerve stimulation for obesity control. An electrical stimulation bandage was developed by integrating a flexible nanogenerator and a pair of dressing electrodes on a flexible substrate. Rat studies demonstrated rapid closure of a full-thickness rectangular skin wound within 3 days as compared to 12 days of usual contraction-based healing processes in rodents. From in vitro studies, the accelerated skin wound healing was attributed to the electric field-facilitated fibroblast migration, proliferation and transdifferentiation. Via a similar design, the electrical pulses were applied to stimulate hair growth. Significantly facilitated hair regeneration results were obtained from Sprague-Dawley rats and nude mice, which was attributed to the improved secretion of vascular endothelial growth factor and keratinocyte growth factor. In another work, an implanted vagus nerve stimulation system was developed. The device comprises a flexible and biocompatible nanogenerator that is attached on the surface of stomach. It generates biphasic electric pulses in responsive to the peristalsis of stomach. The electric signals generated by this device stimulates the vagal afferent fibers to reduce food intake and achieve weight control. This strategy is successfully demonstrated on rat models. Within 100 days, the average body weight is controlled at 350 g, 38% less than the control groups. All the results bring a new concept in electrical therapeutic technology that is battery-free, self-activated and directly responsive to body activities.

Keywords: Nanogenerator; Implantable medical devices; Wearable devices; Self-powered systems; Electrical stimulation;
Bio-Electrochemical Analysis of L-Ascorbic Acid Concentration in between Glaucoma/Cataract Patients Aqueous Humor
Authors: Wang Hung Ru , Ko Mei-Lan , Wang Yu-Lin , Chen Jung-Chih
Published: May 2020

Glaucoma is the second leading causes of vision loss in the world after cataract and irreversible, particularly among the elderly, several years past, most of the molecular mechanisms leading to primary open angle glaucoma (POAG) are still unknown, however scientists discovered ascorbic acid (AA) concentration is reduced in cataract and glaucomatous patients aqueous humor compared with healthy eyes.For understand relationship between AA concentration and glaucoma, we try to develop a simple, sensitive and accurate sensor device for detection in AA . Electrochemical sensor featured with short analytical time, low cost, high sensitivity compared with other methods, in this work, a new electrochemical aptamer sensor for detecting AA was fabricated based on AA specific aptamer linked with polydopmine (PD) layer and immobilized on screen printed carbon electrode (SPCE). Cyclic voltammetry (CV) was used to investigate AA concentration dropped on modified electrode .Both analyze real human aqueous humor sample or commercial AA solution , aptamer electrode performed a good accuracy compared with high performance liquid chromatography (HPLC).
(Invited) A Reconfigurable Remotely Epitaxial VO2 Electrical Heterostructure
Authors: Shi Jian
Published: May 2020

VO2 has been regarded as an archetypal phase transition building block with superior metal-insulator transition characteristics. However, reconfigurable VO2-based heterostructure and the associated devices are rare due to the fundamental challenge in integrating high quality VO2 in technologically important substrates. In this report, for the first time, we show the remote epitaxy of VO2 and the demonstration of a vertical diode device in graphene/epitaxial VO2/single crystalline BN/graphite structure with VO2 as a reconfigurable phase change material and hexagonal boron nitride (h-BN) as an insulating layer. By diffraction and electrical transport studies, we show that the remote epitaxial VO2 films exhibits higher structural and electrical quality than direct epitaxial one. By high resolution transmission electron microscopy and Cs-corrected scanning transmission electron microscopy we show that graphene buffered substrate leads to less strained VO2 film than bare substrate. In the reconfigurable diode, we find that the Fermi level change and spectral weight shift along with metal-insulator transition of VO2 could modify the transport characteristics. The work suggests the feasibility of developing single crystalline VO2-based reconfigurable heterostructure with arbitrary substrates and sheds light on designing novel adaptive photonics and electrical devices and circuits.
(Invited) Development of the High Performance Triboelectric Nanogenerator with a Mechanical Mediator for Its Practical Utilization
Authors: Choi Dongwhi
Published: May 2020

As technology regarding the wearable electronic devices has rapidly developed, the triboelectric nanogenerator (TENG), which utilizes contact electrification with electrical induction as operation principle to generate electricity, is considered as a promising wearable energy harvester to power the portable and wearable devices. One of the abundant energy sources to be harvested by using the TENG is a human body movement, which entirely depends on joint movements with exclusive characteristics of limited displacement with a high degree of directional freedom. In this study, we focus on development of the high performance TENG with the help of adoption of the rationally designed power transmission unit, which is called as a mechanical mediator enabling highly effective power transmission from human body to the TENG. The effective and universal energy harvesting performance with multi-directional and multi-displacement movements are demonstrated with the developed lightweight TENG. This study would broaden the applicability of the TENG with its extremely enhanced electrical output performance.
Development of Wear-Resistant Energy Harvesting Devices and Self-Powered Systems Based on Bionic Design
Authors: Huang Ming-Zheng , Lin Zong-Hong
Published: May 2020

Triboelectric nanogenerator（TENG）is a novel technology that converts mechanical energy into electrical energy and in recent years has shown great potential in promoting green energy. Interestingly, sliding mode operation of the TENG is one of the most effective method for harvesting low-frequency energy. However, the stability of the electrical output of the TENG during operation and long-term mechanical action are critical challenges. Therefore, improving the device life-time of a sliding mode TENG is an important issue that needs to be addressed urgently. In this study, we incorporate a bio-inspired structure based on the evolution of snake scales, where the unique surface structure protects snakes from being harmed from ground friction during movement. We first proposed to examine the structure and composition of the biological scales. As the structure and composition were studied, we verified that it has better charge transfer ability and better wear resistance than general commercial films. Therefore, a wear-resistant energy harvesting device was developed and demonstrated for use in daily life. The incorporation of a bio-inspired design thus has great potential and commercial value in improving life-time of TENG devices.
(Invited) Flexible Organic Photonic Sensor and Imager
Authors: Yokota Tomoyuki
Published: May 2020

In this talk, I will introduce our recent activity of conformable organic photonic systems. We have developed ultra-flexible and lightweight highly efficient, ultra-flexible, air-stable, three-color, organic light-emitting diodes (OLEDs). The total thickness of the devices, including the substrate and encapsulation layer, is only three micrometers, which is one order of magnitude thinner than the epidermal layer of the human skin. Due to the very thin substrate and neutral position, our device shows the highly flexibility and conformability. The OLEDs are directly laminated on the surface of skin and are used as indicators/displays. Furthermore, we have developed ultra-flexible organic imager which consists with a monolithically processed rectifying pixel and an organic photo diode. Our organic imager has pixel pitches as small as 50 µm, with resolutions of up to 262 ppi. Using our ultra-flexible organic imager, we succeed to measure the spatial photoplethysmography (PPG) mapping.
A Biomechanical Energy Based Wearable Sensor System for Real Time Human Gait Phase Detection and Postoperative Trauma Monitoring
Authors: Yeh Cheng , Wu Hua-Shan , Lin Zong-Hong
Published: May 2020

Real time sensitive monitoring of gait phase has important applications for medical treatment and diagnostics. Time periods composing walking phase of gait can be clinically meaningful parameters to reveal differences between normal and pathological gait. In this study, biomechanical energy harvesting have been reported as a feasible solution for directly driving wearable sensors for gait phase monitoring. This not only can save the original space of battery in the sensors but also can avoid environmental pollution caused by waste batteries. Here, we have developed a flexible and wearable sensor with a broader range for pressure detection using triboelectric nanogenerators (TENG) to acquire human walking gait phase signals. According to previous studies, if people have trauma on their foot, the walking gait phase will become unusual compared to normal people. In addition, fewer cases of trauma like Anterior Cruciate Ligament Tear and Ankle muscle injury have also been analyzed with the developed sensor systems. The obtained time point of gait phase signal and the amplitude of peak can help patient understand their recovery situation precisely. We believed this wearable gait phase system not only expands the applications of biomechanical energy harvesters for wearable sensors, but also provides possible approaches for wearable human motion monitoring which is of great importance in many fields such as sports science and medical diagnostics.
(Invited) Detection of Cancer Biomarkers By Scanning Electrochemical Microscopy
Authors: Lin Tzu-En , Darvishi Sorour , Lesch Andreas , Girault Hubert H.
Published: May 2020

Scanning electrochemical microscopy (SECM) is a scanning probe technique that is composed of a micro- or nanoelectrode that can be scanned in close proximity to an interface. Faradaic current signals can be recorded due to the flux of redox active species between the sample and an amperometric SECM probe. SECM can be used to image the topography and reactivity of biological specimens for mapping localized biochemical activity. Although SECM has been applied to different biological systems, SECM studies of tissues are still under exploration. The reason is due to the shape and high roughness of such real samples and requires overcoming major drawbacks in conventional SECM instrumentation when scanning large, i.e. square centimeter sized, areas with irregular surface keeping a constant working distance.

My research aims to develop various reliable SECM bioimaging techniques for the study of the distribution of biomarkers in tape-stripping cancer samples and human melanoma tumor samples. Melanoma is the most lethal form of skin cancer striking thousands of people around the world. The survival rate depends on the stage of the cancer when it is diagnosed. SECM could improve the diagnosis and understanding of different melanoma stages based on highly resolved maps of the tyrosinase distribution in tumor sections. [1]

Furthermore, the increasing levels of tyrosinase were recorded in cells that were collected from the skin of melanoma mouse models representing three different stages of tumor growth. [2] Additionally, SECM results of tape-stripped different human melanoma cell lines were confirmed by previous studies based on traditionally fixed and permeabilized cells. The presented electrochemical tyrosinase detection approach can potentially be integrated into point of-care testing (POCT) devices. SECM scanning parameters, such as microelectrode size and step size can be used to determine experimentally the best design before fabricating microelectrode array prototypes. [1]

1. Lin TE, Lu YJ, Sun CL, Pick H, Chen JP, Lesch A, Girault H. Soft electrochemical probes for mapping the distribution of biomarkers and injected nanomaterials in animal and human tissues Angew. Chem. Int. Ed. 2017;56:16498–16502.

2. Darvishi S, Pick H, Lin TE, Zhu Y, Li X, Ho PC, Girault HG, Lesch A. Tape-Stripping Electrochemical Detection of Melanoma Anal. Chem. 2019, 91, 12900–12908
Improved Sensing Capability of Hg-Ion Selective Membrane(ISM)-Coated FET Sensors with PBS Conditioning
Authors: Chiang Chen-Wei , Wang Shin-Li , Wu Chang-Run , Wu Sung-Yu , Wang Yu-Lin
Published: May 2020

In this work, phosphate buffered saline (PBS) conditioned PVC-based mercury ion selective membranes (Hg-ISM) were used to fabricate ion-selective extended gate FET mercury ion sensor. At pH 7.4 phosphate buffer solution, a detection limit below 10-12M and a linear response ranging from 10-12M to 10-7M were obtained. The excellent selectivity of the PBS-conditioned mercury ion selective membrane were demonstrated by the selectivity experiment of the membrane. It has been shown that PBS-conditioned mercury ion selective membrane possesses superb selectivity toward Pb and Cd. X-ray photoelectron spectroscopy were successfully applied in the surface characterization of the mercury ion selective membrane coated extended gate field effect transistor. The X-ray photoelectron spectroscopy confirmed that mercury ion were captured in the membrane structure after testing with mercury standard solution. This PBS-conditioned mercury ion selective membrane coated extended gate FET provides the detection limit lower than the conventional ion-selective electrode (10-6M), and the detection limit is comparable to the laboratory-based instrument such as ICP-MS. Our sensor can enable us to conduct facile, instant and accurate test of the mercury ion in the daily diet.

Figure 1