Portable Electronic Systems Research Articles

Guest Editorial: Special Section on Circuit and System Design Methodologies for Emerging Technologies

The demand for ever smaller, portable, energy-efficient and high-performance electronic systems has been the primary driver for CMOS technology scaling. As CMOS scaling approaches physical limits, it has been fraught with challenges that required introduction of newer materials, manufacturing processes and device structures. High- $\kappa$ oxide and metal-gate stack was introduced to mitigate oxide leakage which became a significant concern for sub-65nm CMOS technologies. Thin body, undoped channels, and multiple-gate structures were introduced to mitigate subthreshold leakage as battery life for mobile devices rose to prominence. 3D transistors such as double-gate FinFET and trigate transistors have been introduced to improve ON current and reduce subthreshold leakage without compromising layout efficiency that is crucial for device density which leads to lower costs. These innovations have allowed sustained scaling of CMOS technology which will continue to dominate semiconductor manufacturing for reasons that are both technological and financial. In CMOS technology, charge conveys logic information. Movement of charge is central to computation and storage, which entails a minimum energy dissipation of the order kB $\ast$ T per switching event. It has been argued that energy dissipation defines the fundamental limit of CMOS scaling.

Low Power 10T XOR based 1 Bit Full Adder

The popularity and necessity of portable electronic systems by users have strongly influenced VLSI designers to make great effort for reduced silicon area, improved speeds, long duration battery life, and great reliability. The VLSI designers always try to save power consumption while designing a system. In this paer, an efficient methodology is presented to improve the output swing level of GDI gates. New designs of GDI based basic digital (AND, OR, XOR, XNOR) gates are presented using single pass transistors to improve swing level of GDI gates. The new design of basic gates with combination of GDI logic and pass transistor logic is called hybrid GDI technique. Compared to existing GDI technique with buffer restoration circuits, hybrid GDI implementation provides full swing output voltage in all digital circuits. Also it shows less power and less delay with about 60% area increase as compared to basic GDI.

Effect of Thermal Treatment of Poly(amide imide) Binder on Cycling Performance of Silicon Alloy-Based Anode for Lithium-Ion Battery

The growing demand for high-performance rechargeable lithium-ion batteries for applications such as portable electronic devices, electric vehicles and energy storage systems requires remarkable improvement in the energy density. It has led to the search for advanced materials with high theoretical specific capacities, which should be abundantly available for large-scale applications. Silicon-based anode materials with high theoretical capacity, low reduction potential and low cost satisfy these requirements for next-generation lithium-ion batteries. However, the silicon materials undergo large volume changes during the alloying/de-alloying reaction, resulting in pulverization of the electrode. In addition, the large volume expansion results in the continuous breakdown and formation of solid-electrolyte interphase (SEI) layer during the repeated cycling. To mitigate the volume change, many studies have been carried out by different approaches such as fabricating thin films, reducing particle size, employing Si alloy materials and using strong binder. It is well known that binders are critical to maintain the electrode structure and capacity retention. Different binders for Si-based anodes developed to date include carboxymethyl cellulose (CMC), poly(acrylic acid) (PAA), poly(vinyl alcohol) (PVA), poly(amide imide)(PAI) and polyimide (PI). Among them, thermally-treated PAI has high mechanical strength and good adhesion, enhancing the electric contact with current collector. In this study, we report electrochemical characterization of Si alloy materials with thermally-treated PAI as a binder. Furthermore, we analyzed binding mechanism of PAI, with changing heat treatment temperature. A detailed investigation and evaluation of cycling performances are performed by XPS, FT-IR, electrochemical impedance spectroscopy, peel test and galvanostatic cycling test.

Graphene-Coated Silicon Alloy with High Capacity and Good Cycling Stability for Lithium-Ion Batteries

The growing demand for high-performance energy storage devices for applications in portable electronic devices, electric vehicles and energy storage systems requires dramatic improvement in the energy density and cycle life. Silicon-based anode materials hold promise for these applications due to their high theoretical capacity and abundant availability for large-scale applications. However, silicon anodes are known to have problems such as electrode pulverization due to its high volume expansion during repeated cycling and poor cycle life due to unstable solid-electrolyte interphase (SEI) layer. To solve these problems, many studies have been carried out in terms of thin film, nanostructure, alloy and composites. In this work, we synthesized Si-based alloy materials with high specific capacity. To improve their cycling stability, the silicon alloy materials were surface modified with reduced graphene oxide (rGO). The rGO layer formed on the Si alloy played as a flexible confinement for accommodating volume changes during cycling. And also, its high mechanical strength prevented the pulverization of the electrode. In addition, its 2-dimensional structure enabled to electronically connect the individual Si alloy particles to the current collector. Their interfacial studies and cycling performances are investigated by electrochemical impedance spectroscopy, XPS, FE-SEM, HR-TEM and cycling test. Detailed characterization of the rGO-coated silicon alloy materials along with their electrochemical performance will be presented.

전기방사를 이용한 슈퍼캐퍼시터용 금속산화물/탄소나노섬유 복합체

Abstract The hybridization of carbon nano-materials enhances the efficiency of each function of the resulting structure or composites. Also, the addition of non-carbon elements to nanomaterials modifies the electrochemical properties. Electrodes combining po-rous carbon nanofibers (CNFs) and metal oxides benefit from the combination of the double-layer capacitance of the CNFs and the pseudocapacitive character associated with the surface redox-type reactions. Consequently, they demonstrate superior supercapacitor performance in terms of high capacitance, high energy/power efficiency and high rate capability. This paper presents a comprehensive review of the latest advances made in the development and application of various metal oxide/CNF composites (CNFCs) to supercapacitor electrodes. Keywords : Electrospinning, Carbon nanofiber composite, Metal oxide, Supercapacitor 1. Introduction 1) The increasing demand for clean energy and the growing concern re-garding air pollution and global warming have stimulated intense re-search into energy storage and conversion from alternative energy sources[1-4]. For this reason, electrochemical capacitors (ECs) are con-sidered promising power sources for portable electronic systems and automotive applications, because of their practical applications as high power devices owing to their large capacitance, long cycling life, and lack of toxic materials[5-9]. To obtain satisfactory performance, ECs must display high electrical conductivity, high surface area for optimal charge accumulation, sufficient pore diameter and good pore con-

BIT EFFICIENT RESIDUE NUMBER SYSTEM BASED LOW POWER RECONFIGURABLE DSP PROCESSOR

In modern era of advanced computing and high end multimedia there is a need for low power reliable and portable electronic systems. Even though many techniques have been proposed to reduce power over the years, out of all, the best possible solution, so far has been to over scale the power supply. When a system is over scaled the power reduces drastically but this also increases the complexity of the design. The other alternate is to replace the conventional binary number systems with Residue Number System. The residue number system is a non-weighted number system which speeds up arithmetic operations by dividing them into smaller parallel operations and provides carry-free addition, multiplication and borrow-free substraction operations. In this paper we propose a technique to reduce power based on bit efficient Residue Number System with a proper choice of prime moduli . Here we consider a Digital Signal Processor that can be reconfigured as a case study. The technique proposed can reduce power upto 34 percent thn a conventional binary number system based DSP Processor

Bendable All‐Solid‐State Asymmetric Supercapacitors based on MnO2 and Fe2O3 Thin Films

AbstractThe growing interest in portable and consumable electronics demands efficient and low‐cost energy storage devices with excellent flexibility and of light weight. We demonstrate flexible high‐performance all‐solid‐state thin‐film asymmetric supercapacitors (ASSTF‐ASCs) using α‐MnO2 and α‐Fe2O3 thin films as positive and negative electrodes, respectively. The as‐fabricated ASSTF‐ASC devices have excellent electrochemical performance with extended potential window of 2.0 V and excellent cycling stability for 2500 cycles. Impressively, an MnO2//Fe2O3 asymmetric cell demonstrates high specific capacitance of 145 F g−1 with a high energy density of 41 Wh kg−1 while maintaining a power density of 2.1 kW kg−1. A parallel combination of two MnO2//Fe2O3 asymmetric cells is able to illuminate a panel of 31 light emitting diodes (LEDs). These findings may offer new opportunities for the use of asymmetric configurations in energy storage devices for various portable electronic systems.

Xurography for 2D and multi-level glucose/O2 microfluidic biofuel cell

This work reports on a simple and original method for constructing a multi-level microfluidic biofuel cell (BFC) by using the xurography technique. Microfluidic BFCs have attractive properties for converting chemical energy into electrical energy via specific enzymes as catalysts and are now considered as microsources able to supply power for portable electronic systems. As a proof-of-concept demonstration, we construct 2D and multi-level microfluidic BFCs that consist of an array of microchannels and gold electrodes designed in series or parallel configuration, and we demonstrate its operation from glucose and oxygen solutions. The fabrication process of the multi-level microfluidic device involves the stacking of alternating layers of double-sided adhesive tape and transparent sheets patterned with holes to provide connections between the channels. This process of stacking provides a reproducible method for building devices with a distribution of the fluids both vertically and laterally without mixing. The efficiency of the multi-level microfluidic device is confirmed in the presence of the enzymes laccase and glucose oxidase in solution. The proposed technique offers an alternative to construct microfluidic BFCs that deliver power output in a minimum volume, favorable to scale-up the manufacture of compact micropower sources.

The p-EVES study design and methodology: a randomised controlled trial to compare portable electronic vision enhancement systems (p-EVES) to optical magnifiers for near vision activities in visual impairment.

To describe the study design and methodology for the p-EVES study, a trial designed to determine the effectiveness, cost-effectiveness and acceptability of portable Electronic Vision Enhancement System (p-EVES) devices and conventional optical low vision aids (LVAs) for near tasks in people with low vision. The p-EVES study is a prospective two-arm randomised cross-over trial to test the hypothesis that, in comparison to optical LVAs, p-EVES can be: used for longer duration; used for a wider range of tasks than a single optical LVA and/or enable users to do tasks that they were not able to do with optical LVAs; allow faster performance of instrumental activities of daily living; and allow faster reading. A total of 100 adult participants with visual impairment are currently being recruited from Manchester Royal Eye Hospital and randomised into either Group 1 (receiving the two interventions A and B in the order AB), or Group 2 (receiving the two interventions in the order BA). Intervention A is a 2-month period with conventional optical LVAs and a p-EVES device, and intervention B is a 2-month period with conventional optical LVAs only. The study adopts a mixed methods approach encompassing a broad range of outcome measures. The results will be obtained from the following primary outcome measures: Manchester Low Vision Questionnaire, capturing device 'usage' data (which devices are used, number of times, for what purposes, and for how long) and the MNRead test, measuring threshold print size, critical print size, and acuity reserve in addition to reading speed at high (≈90%) contrast. Results will also be obtained from a series of secondary outcome measures which include: assessment of timed instrumental activities of daily living and a 'near vision' visual functioning questionnaire. A companion qualitative study will permit comparison of results on how, where, and under what circumstances, p-EVES devices and LVAs are used in daily life. A health economic evaluation will provide results on: the incremental cost-effectiveness of p-EVES compared to optical magnifiers; cost-effectiveness; and cost-utility. The evidence base in low vision rehabilitation is modest and further high quality clinical trials are required to inform decisions on healthcare provision. The p-EVES study findings are anticipated to contribute to this broader evidence requirement, with the methodological issues evident here being relevant to other trials within the field.

Modified empirical fitting of the discharge behavior of LiFePO\(_4\) batteries under various conditions

A mathematical model is developed by fitting the discharge curve of a new LiFePO\(_4\) battery and then used to investigate the relationship between the discharge time and the closed-circuit voltage. This model consists of exponential and polynomial terms where the exponential term dominates the discharge time of a battery and the polynomial term dominates the change in the closed-circuit voltage. Time shift and time scale processes modify the exponential and polynomial terms, respectively, so that the model is suitable for batteries under various conditions. References W. Su, H. Eichi, W. Zeng and M.-Y. Chow, A survey on the electrification of transportation in a smart grid environment, IEEE Intl. Conf. Ind. I. 8:1–10, 2012. doi:10.1109/TII.2011.2172454 J. Wang, Z. Sun and X. Wei, Performance and characteristic research in LiFePO\(_4\) battery for electric vehicle applications, IEEE Vehicle Power 1657–1661, 2009. doi:10.1109/VPPC.2009.5289664 A. Shafiei, A. Momeni and S. S. Williamson, Battery modeling approaches and management techniques for plug-in hybrid electric vehicles, IEEE Vehicle Power 1–5, 2011. doi:10.1109/VPPC.2011.6043191 P. Bai, D. A. Cogswell and M. Z. Bazant, Suppression of phase separation in LiFePO\(_4\) nanoparticles during battery discharge, Nano Lett. 11:4890–4896, 2011. doi:10.1021/nl202764f H. L. Chan and D. Sutanto, A new battery model for use with battery energy storage systems and electric vehicle power systems, IEEE Power Eng. Soc. 1:470–475, 2000. doi:10.1109/PESW.2000.850009 T. Kim and W. Qiao, A hybrid battery model capable of capturing dynamic circuit characteristics and nonlinear capacity effects, IEEE T. Energy Conver. 26:1172–1180, 2011. doi:10.1109/TEC.2011.2167014 D. N. Rakhmatov and S. B. K. Vrudhula, An analytical high-level battery model for use in energy management of portable electronic systems, IEEE ICCAD 488–493, 2001. doi:10.1109/ICCAD.2001.968687 V. Srinivasan and J. Newman, Discharge model for the lithium iron-phosphate electrode, J. Electrochem. Soc. 151:A1517–A1529, 2004. doi:10.1149/1.1785012 V. Rao, G. Singhal, A. Kumar and N. Navet, Battery model for embedded systems, VLSI Des. 105–110, 2005. doi:10.1109/ICVD.2005.61 S. Dargavillez and T. W. Farrell, Predicting active material utilization in LiFePO\(_4\) electrodes using a multiscale mathematical model, J. Electrochem. Soc. 157:A830–A840, 2010. doi:10.1149/1.3425620 R. Rao, S. Vrudhula and D. N. Rakhmatov, Battery modeling for energy-aware system design, Computer 36:77–87, 2003. doi:10.1109/MC.2003.1250886 M. Chen and G. A. Rincon-Mora, Accurate electrical battery model capable of predicting runtime and i-v performance, IEEE T. Energy Conver. 21:504–511, 2006. doi:10.1109/TEC.2006.874229 L. Gao, S. Liu and R. A. Dougal, Dynamic lithium-ion battery model for system simulation, IEEE T. Compon. Pack. T. 25:495–505, 2002. doi:10.1109/TCAPT.2002.803653 V. Agarwal, K. Uthaichana, R. A. DeCarlo and L. H. Tsoukalas, Development and validation of a battery model useful for discharging and charging power control and lifetime estimation, IEEE T. Energy Conver. 25:821–835, 2010. doi:10.1109/TEC.2010.2043106 B. Schweighofer, K. M. Raab and G. Brasseur, Modeling of high power automotive batteries by the use of an automated test system, IEEE T. Instrum. Meas. 52:1087–1091, 2003. doi:10.1109/TIM.2003.814827

Lithium-Air Cells Assembled with Nitrogen and Sulfur Co-Doped Graphene Electrode

Rechargeable lithium-ion batteries are widely used as the power source for portable electronic devices, electric vehicles and energy storage systems. However, their energy density cannot fulfill the requirements of applications for electric vehicles. In this respect, lithium-air batteries have been in focus due to their higher energy density than the currently commercialized Li-ion batteries. Recently, diverse approaches on air electrode have been reported to enhance the cycling performance of Li-air batteries, such as nanostructured metal oxide, superfine platinum particles, bi-functional catalyst loaded onto carbon and metal free graphene nanosheets [1]. Graphene has been receiving a lot of attention for energy storage applications because of its high electronic conductivity, high surface area, chemical stability and good mechanical strength. Furthermore, chemical doping in graphene materials showed a considerable increase in electrochemical activity relative to pristine carbon materials [2]. In this study, we synthesized nitrogen and sulfur co-doped graphene to improve the electrochemical performance of lithium-air cell. The cycling performance of lithium-air cells assembled with N,S-doped graphene cathode was investigated and compared to that of a cell with carbon-based air electrode. The detailed investigation was carried out using electrochemical impedance spectroscopy, FE-SEM, HR-TEM, RDE and XPS analyses.

Lithium-Ion Batteries Assembled with Electrospun Hybrid Polymer Membrane Containing Reactive Silica Nanoparticles

Lithium-ion batteries have been rapidly expanding in portable electronic devices, electric vehicles (EVs) and energy storage systems. In lithium-ion batteries, a separator is a critical component which prevents physical contact of the positive and negative electrodes while permitting free ionic transport within the cell. Most of the separators currently used in lithium-ion batteries are based on microporous polyolefin membranes. Although these separators offer excellent mechanical strength and chemical stability, they shrink, soften and even melt at high temperature, which cause short circuiting between electrodes. Furthermore, the large difference in polarity between the non-polar polyolefin separator and the polar organic electrolyte leads to poor wettability. As a result, there is a high resistance when the pores in the separator are not completely filled with liquid electrolyte. In our previous studies, we synthesized silica nanoparticles with vinyl groups, which permitted the surface reaction with vinyl monomers by radical polymerization [1-3]. With the goal of developing high performance separators with high thermal stability, good transport properties and enhanced wettability for non-aqueous liquid electrolytes, we prepared electrospun hybrid polymer membrane based on polyacrylonitrile (PAN) and reactive SiO2 nanoparticles. Due to the presence of reactive silica particles, it could be thermally cross-linked, resulting in good thermal stability and improved wettability for liquid electrolyte. Using the cross-linked electrospun hybrid polymer membranes, we assembled lithium-ion cell composed of carbon anode and LiNi0.6Co0.2Mn0.2O2 cathode. The cycling performances of the cells with cross-linked hybrid polymer membrane were evaluated, and the results were compared to those obtained with a pristine PE separator.

All Solid-State Lithium Batteries Assembled with Hybrid Solid Electrolytes

Lithium-ion batteries have rapidly become the dominant power sources for portable electronic devices, electric vehicles and energy storage systems, due to their high energy density and long cycle life [1,2]. However, safety issues still prevent full utilization of these batteries. One of the most efficient methods to enhance the battery safety is to use solid electrolyte [3-5]. Solid inorganic electrolytes present potential advantages, such as a wide electrochemical stability window, enhanced thermal stability, absence of solvent leakage and high resistance to shocks, which are important safety assets. However, sheet manufacturing, especially using thin-film technologies for making large-scale batteries, is considered to be difficult because of brittle characteristics of ceramic materials. In this work, the hybrid solid electrolytes composed of lithium aluminum germanium phosphate (LAGP) and poly(ethylene oxide)(PEO) were prepared in the form of flexible thin film, and their electrochemical properties were investigated. Their morphological properties studied using SEM, EDS and XRD. The ionic conductivities and electrochemical stability of hybrid solid electrolytes were much higher than those of PEO-based polymer electrolyte. All solid-state lithium batteries assembled with hybrid solid electrolyte exhibited high discharge capacity and excellent capacity retention with a coulombic efficiency exceeding 99.5% at 55 oC.

Electrochemical Sensing Methodology for Antibiogram Assays

We report an electrochemical method of determining antibiotic susceptibility by detecting the electrochemical oxidation peak signature of the hydrolyzed fluorescein ester. Conventionally, antibiotic susceptibility studies are conducted using optical techniques. However, an electrochemical approach used in conjunction with the popular antibiogram assay offers an avenue to move away from these expensive and time consuming colorimetric techniques. Tests were conducted using a conventional three-electrode system in samples of E.coli incubated with fluorescein diacetate, with and without the antibiotic Penicillin and Streptomycin. A peak/no-peak signature observed in a voltammetric scan indicated the presence/absence of fluorescein in the sample, suggesting that the antibiotic may/may not be considered effective. In the future, this electrochemical approach could be miniaturized onto portable electronic systems such as point-of-care antibiogram apparatus for rapid antibiotic tests.

마이크로 개질기 개발을 위한 박막형 Cu/ZnO 나노구조 촉매 합성

In this work, thin film type Cu/ZnO nanostructure catalysts were fabricated by several synthetic routes in order to maximize the performance of the micro reforming system. For this work, various Cu/ZnO nanostructure catalysts could be synthesized by means of four approaches which are chemical vapor method, wet solution method and their hybrid method. The reforming performance of these as-synthetic catalysts was evaluated as compared to the conventional catalysts. Among the as-synthetic nanostructures, sphere type catalysts with specific surface of <TEX>$18.6m^2/g$</TEX> showed the best performance of hydrogen production rate of 30ml/min at the feed rate of 0.2ml/min. This work will give the first insight on thin film type Cu/ZnO nanostructure catalyst for micro reforming system for hydrogen production of portable electronic systems.

Evaluation of a portable MOS electronic nose to detect root rots in shade tree species

The early detection of wood decays in high-value standing trees is very important in urban areas because mitigating control measures must be implemented long before tree failures result in property damage or injuries to citizens. Adverse urban environments increase physiological stresses in trees, causing greater susceptibility to attacks by pathogenic decay fungi. The detection of fungal root rots in urban trees is particularly difficult because conventional detection tools, currently used for diagnosis of wood decays, are not feasible below ground level. Portable electronic olfactory systems or electronic noses (e-noses), currently used in many different scientific fields and industries, previously have been tested for the early diagnosis of wood decay fungi and wood rots. We evaluated the accuracy and effectiveness of the portable PEN3 electronic nose to discriminate between healthy and decayed root segments of five shade trees species, artificially inoculated separately with three species of root-rot fungi and incubated in different soil types under laboratory conditions. The PEN3 e-nose discriminated between healthy and inoculated root fragments and between different decay fungi in different soil types for most host-fungus combinations, but the discrimination power of this e-nose varied depending on tree species and strain of root-rot fungus analyzed. We provide explanations for the ineffectiveness of the e-nose to detect low levels of decay for certain host-fungus combinations. The advantages of e-nose detection over conventional wood decay detection tools also are discussed.

Design of a 75‐nW, 0.5‐V subthreshold complementary metal–oxide–semiconductor operational amplifier

ABSTRACTThis work focuses on the subthreshold design of ultra low‐voltage low‐power operational amplifiers. A well‐defined procedure for the systematic design of subthreshold operational amplifiers (op‐amps) is introduced. The design of a 0.5‐V two‐stage Miller‐compensated amplifier fabricated with a 0.18‐µm complementary metal–oxide–semiconductor process is presented. The op‐amp operates with all transistors in subthreshold region and achieves a DC gain of 70 dB and a gain–bandwidth product of 18 kHz, dissipating just 75 nW. The active area of the chip is ≈0.057 mm2. Experimental results demonstrate that well‐designed subthreshold op‐amps are a very attractive solution to implement sub‐1‐V energy‐efficient applications for modern portable electronic systems. A comparative analysis with low‐voltage, low‐power op‐amp designs available in the literature highlights that subthreshold op‐amps designed according to the proposed design procedure achieve a better trade‐off among speed, power, and load capacitance. Copyright © 2013 John Wiley &amp; Sons, Ltd.

Research on Tropical Agricultural Products Quality Recognition and Detection System Based on Electronic Nose Technology

This article describes the invention and development of electronic nose technology. According to the International and domestic technology development situation in recent years and based on the basis of the electronic nose technology for mango, banana, papaya and other the typical tropical crops products, for example, to have the quality identification detection experiment with Agricultural and sideline products .Compare PCA-BP the LDA-BP neural network recognition effect Design a conceived program. which is a professional portable electronic nose technology systems, Specifically for Hainan's tropical agricultural products quality inspection.

Design and Layout of a High-Performance PWM Control Class D Amplifiers IC Systems

This paper presents the design and implementation of a novel pulse width modulation control class D amplifiers chip. With high-performance, low-voltage, low-power and small area, these circuits are employed in portable electronic systems, such as the low-power circuits, wireless communication and high-frequency circuit systems. This class D chip followed the chip implementation center advanced design flow, and then was fabricated using Taiwan Semiconductor Manufacture Company 0.35-μm 2P4M mixed-signal CMOS process. The chip supply voltage is 3.3 V which can operate at a maximum frequency of 100 MHz. The total power consumption is 2.8307 mW, and the chip area size is 1.1497×1.1497 mm2. Finally, the class D chip was tested and the experimental results are discussed. From the excellent performance of the chip verified that it can be applied to audio amplifiers, low-power circuits, etc.

Micro-supercondensateurs : enjeux technologiques et applications

The miniaturization of portable electronic systems, as well as the emergence of wireless sensors networks, raise an essential issue : how to implement a sustainable source of energy of appropriate size ? Powering may be assured by small batteries (called mini- or micro-batteries depending). These components are however limited in power, lifetime and temperature range. The integration of low-profile, miniaturized supercapacitors could satisfy in this sense a variety of micro-power demands. However, it is still an emerging field of research. The main challenge is the development of IC-compatible technological processes for the deposition of the active material.