A review is presented of the present status of the theory, the developed technology and the current applications of dielectrophoresis (DEP). Over the past 10 years around 2000 publications have addressed these three aspects, and current trends suggest that the theory and technology have matured sufficiently for most effort to now be directed towards applying DEP to unmet needs in such areas as biosensors, cell therapeutics, drug discovery, medical diagnostics, microfluidics, nanoassembly, and particle filtration. The dipole approximation to describe the DEP force acting on a particle subjected to a nonuniform electric field has evolved to include multipole contributions, the perturbing effects arising from interactions with other cells and boundary surfaces, and the influence of electrical double-layer polarizations that must be considered for nanoparticles. Theoretical modelling of the electric field gradients generated by different electrode designs has also reached an advanced state. Advances in the technology include the development of sophisticated electrode designs, along with the introduction of new materials (e.g., silicone polymers, dry film resist) and methods for fabricating the electrodes and microfluidics of DEP devices (photo and electron beam lithography, laser ablation, thin film techniques, CMOS technology). Around three-quarters of the 300 or so scientific publications now being published each year on DEP are directed towards practical applications, and this is matched with an increasing number of patent applications. A summary of the US patents granted since January 2005 is given, along with an outline of the small number of perceived industrial applications (e.g., mineral separation, micropolishing, manipulation and dispensing of fluid droplets, manipulation and assembly of micro components). The technology has also advanced sufficiently for DEP to be used as a tool to manipulate nanoparticles (e.g., carbon nanotubes, nano wires, gold and metal oxide nanoparticles) for the fabrication of devices and sensors. Most efforts are now being directed towards biomedical applications, such as the spatial manipulation and selective separation/enrichment of target cells or bacteria, high-throughput molecular screening, biosensors, immunoassays, and the artificial engineering of three-dimensional cell constructs. DEP is able to manipulate and sort cells without the need for biochemical labels or other bioengineered tags, and without contact to any surfaces. This opens up potentially important applications of DEP as a tool to address an unmet need in stem cell research and therapy.

/pdf/review-article-dielectrophoresis-status-of-the-theory-99vmv2147w.pdf

Review Article—Dielectrophoresis: Status of the theory, technology, and applications

During the last few years, graphene's unusual friction and wear properties have been demonstrated at nano to micro scales but its industrial tribological potential has not been fully realized. The macroscopic wear resistance of one atom thick graphene coating is reported by subjecting it to pin-on-disc type wear testing against most commonly used steel against steel tribo-pair. It is shown that when tested in hydrogen, a single layer of graphene on steel can last for 6400 sliding cycles, while few-layer graphene (3–4 layers) lasts for 47 000 cycles. Furthermore, these graphene layers are shown to completely cease wear despite the severe sliding conditions including high contact pressures (≈0.5 GPa) observed typically in macroscale wear tests. The computational simulations show that the extraordinary wear performance originates from hydrogen passivation of the dangling bonds in a ruptured graphene, leading to significant stability and longer lifetime of the graphene protection layer. Also, the electronic properties of these graphene sheets are theoretically evaluated and the improved wear resistance is demonstrated to preserve the electronic properties of graphene and to have significant potential for flexible electronics. The findings demonstrate that tuning the atomistic scale chemical interactions holds the promise of realizing extraordinary tribological properties of monolayer graphene coatings.

Extraordinary Macroscale Wear Resistance of One Atom Thick Graphene Layer

Graphene is an ultra-thin material, which has received broad interest in many areas of science and technology because of its unique physical, chemical, mechanical and thermal properties. Synthesis of high quality graphene in an inexpensive and eco-friendly manner is a big challenge. Among various methods, chemical synthesis is considered the best because it is easy, scalable, facile, and inexpensive. Different kinds of chemical reducers have been used to produce graphene sheets. However, some chemicals are toxic, corrosive, and hazardous. For this reason, researchers have been using different environmentally friendly substances (termed green reducers) to produce functional graphene sheets. This paper presents an overview and discussion of the green reduction of graphene oxide (GO) to graphene. It also reviews the characterization of GO and its oxide reduction through the analysis of different spectroscopic and microscopic techniques such as Raman spectroscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, transmission electron microscopy, scanning electron microscopy, and atomic force microscopy.

The green reduction of graphene oxide

The durability of electrode materials is a limiting parameter for many electrochemical energy conversion systems. In particular, electrocatalysts for the essential oxygen reduction reaction (ORR) present some of the most challenging instability issues shortening their practical lifetime. Here, we report a mesostructured graphitic carbon support, Hollow Graphitic Spheres (HGS) with a specific surface area exceeding 1000 m2 g–1 and precisely controlled pore structure, that was specifically developed to overcome the long-term catalyst degradation, while still sustaining high activity. The synthetic pathway leads to platinum nanoparticles of approximately 3 to 4 nm size encapsulated in the HGS pore structure that are stable at 850 °C and, more importantly, during simulated accelerated electrochemical aging. Moreover, the high stability of the cathode electrocatalyst is also retained in a fully assembled polymer electrolyte membrane fuel cell (PEMFC). Identical location scanning and scanning transmission elect...

Toward Highly Stable Electrocatalysts via Nanoparticle Pore Confinement

Polymeric dielectrics play a key role in the realization of flexible organic electronics, especially for the fabrication of scalable device arrays and integrated circuits. Among a wide variety of polymeric dielectric materials, aromatic polyimides (PIs) are flexible, lightweight, and strongly resistant to high-temperature processing and corrosive etchants and, therefore, have become promising candidates as gate dielectrics with good feasibility in manufacturing organic electronic devices. More significantly, the characteristics of PIs can be conveniently modulated by the design of their chemical structures. Herein, from the perspective of structure optimization and interface engineering, a brief overview of recent progress in PI-based dielectrics for organic electronic devices and circuits is provided. Also, an outlook of future research directions and challenges for polyimide dielectric materials is presented.

Recent Progress in Aromatic Polyimide Dielectrics for Organic Electronic Devices and Circuits.

The hydrogened diamond like carbon film (DLCH) with 1 μm thickness is made by hydrocarbon gas ion beam deposition method. The relationship between I D /I G ratio fitted from visible Raman spectra and sp 2 /sp 3 ratio done from XPS spectra of DLCH film shows a trend. The I D /I G ratio of deconvoluted visible Raman spectra shows a correlation with sp 2 /sp 3 ratio from XPS spectra as annealing temperature increases, the graphitization and the disorder increase. The I D /I G ratios fitted with two-curve Gaussian functions of Raman spectra tend to be proportional to sp 2 /sp 3 ratio fitted with three-curve with 100% Gaussian function of XPS spectra when post annealed treatment is below 400°C and without severe oxidation.

Correlation between ID⁄IG Ratio from Visible Raman Spectra and sp2/sp3 Ratio from XPS Spectra of Annealed Hydrogenated DLC Film

The hydrogenated diamond-like carbon (DLCH) film with 1-µm thickness is deposited by direct hydrocarbon gas ion beam method on silicon wafer and annealed at 400 °C. Detailed Raman spectra feature are fitted from nine sets of different peak fitting functions, including Gaussian, Lorentzian and Breit-Wigner-Fano (BWF) functions. These fitting results obtained from a two-peak combination show some specific variances on the G peak position, FWHMG and ID/IG ratio for as-deposited and as-annealed DLCH films. The most popular two-peak fitting method with full Gaussian function tends to exhibit a higher ratio of the G peak position shift and higher ID/IG ratio than others fitting methods, the drastic difference among the most popular G (G) & G (D) and B (G) & L (D) schemes also have brought out in ID/IG ratio. However, for a more complex four-peak Gaussian function fitting Raman spectra, the ID/IG ratio is close to that of a two-peak fitting function with a mixture functions of BWF (G) and L (D). Furthermore, a series of systematic peak fitting procedures and comparisons of Raman spectra have been discussed in this study. Copyright © 2009 John Wiley & Sons, Ltd.

Multipeak fitting analysis of Raman spectra on DLCH film

Effect of film thickness and interlayer on the adhesion strength of diamond like carbon films on different substrates

The bonding and crystalline structures of oil-fried fly ash collected from a power plant were analyzed by using Raman spectroscopy and X-ray diffraction (XRD), respectively. These carbon powders underwent a series of annealing treatment for graphitization and crystallization. In Raman spectra, the refined, unburned carbon contains clearly the D, G and D′ peaks under 2000 or 2700 °C treatment. The Raman spectral line shape of refined, unburned carbon heated at 2700 °C is similar to that of commercial graphite made from graphitization process. In the XRD spectra, the refined, unburned carbon contains (002), (100) and (004) diffraction peaks under heating at 2000 or 2700 °C. The XRD spectral line shape of refined, unburned carbon heated at 2700 °C is similar to that of a commercial graphite bar. The quantitative graphitization level from Raman spectra and crystallization degree from XRD spectra on refined, unburned carbon powders serve as preliminary guide for the qualitative evaluation of these unburned carbon powders. Copyright © 2009 John Wiley & Sons, Ltd.

Raman and X-ray diffraction analysis on unburned carbon powder refined from fly ash

The effect of thermal and plastic mismatch on stress distribution in diamond like carbon film under different interlayer/substrate system

Handle everyday research tasks with reliable, citation-backed results

Your personal Research Agent to handle research tasks with citation-backed results

Popular Tasks used by Researchers

How can I help with your research?

Meet SciSpace

Get more enhanced response by uploading the PDFs you want me to reference.

No relevant PDFs in your library

SciSpace is the AI research assistant for academics. Run systematic literature reviews on 280M+ papers, and write papers with cited sources. Trusted by 1M+ students, PhDs & researchers.

SciSpace | AI for Research

Analyze PDFs

Code & Manuscripts

Funding & Grants

Literature & Patents

Medical & Clinical Data

Systematic Review

Visualize & Present

Web & Data

Build a Google Scholar-like website for your research.

Build a website

Create charts and images for your research

Create a Chart

Write a paper for submission to a journal

Draft a manuscript

Patent Search

Design eye-catching scientific posters in minutes.

Scientific Poster Generation

Systematic Literature Review

One task is running at the moment. Your messages will be shown right after.

Drag and drop or click here to browse

Loved by <highlight>1 million+</highlight> researchers

Extract a list of specific topics and their sources from unstructured text

Topics

Compare and analyze relevant papers that matches with your search

Papers

Get insights from PDFs and bookmarked papers from your library

My library

Recent searches

Try searching for:

Catch AI-generated content in scholarly and non-scholarly content

{ai} Detector

Ai Writer

Get PDF Summaries, highlighted text explanations 

Chat with PDF

Effortlessly create in-text citations and bibliographies in APA and 2,500 other formats

Citation generator

Get explanations, summaries, and answers on academic papers

Ease up your research workflow with {scispace}'s cohort of exciting AI tools

Elevate your academic writing skills and convey your ideas the way you want

Paraphraser

Explore our range of reading and writing tools

Your file is being prepared and should be ready in a few minutes. If it's a large file, it might take a bit longer. You can close this window, and we'll email you the file when it's done.

You have reached a maximum limit of <strong>{limit}</strong> columns in the table. Remove at least <strong>1</strong> column to add or create another one.

Chehung Wei

Author Tools

Chat about Author