scholarly journals High-Sensitivity in Dielectrophoresis Separations

Micromachines ◽  
2020 ◽  
Vol 11 (4) ◽  
pp. 391
Author(s):  
Benjamin G. Hawkins ◽  
Nelson Lai ◽  
David S. Clague
Keyword(s):  
Electrical Properties ◽  
Cell Size ◽  
Electric Fields ◽  
Cell Separation ◽  
High Sensitivity ◽  
Label Free ◽  
Phenotypic Differences ◽  
Actuation Force ◽  
Highly Sensitive ◽  
Phenotypic Variations

The applications of dielectrophoretic (DEP) techniques for the manipulation of cells in a label-free fashion within microfluidic systems continue to grow. However, a limited number of methods exist for making highly sensitive separations that can isolate subtle phenotypic differences within a population of cells. This paper explores efforts to leverage that most compelling aspect of DEP—an actuation force that depends on particle electrical properties—in the background of phenotypic variations in cell size. Several promising approaches, centering around the application of multiple electric fields with spatially mapped magnitude and/or frequencies, are expanding the capability of DEP cell separation.

Tunnel dielectrophoresis for ultra-high precision size-based cell separation

Lab on a Chip ◽  
2021 ◽  
Author(s):  
Yu-Chun Kung ◽  
Kayvan R. Niazi ◽  
Pei-Yu Chiou
Keyword(s):  
Cell Size ◽  
High Precision ◽  
Microfluidic Device ◽  
Cell Separation ◽  
Label Free

In this study, we present a microfluidic device that can achieve label-free and size-based cell separation with high size differential resolution for arbitrary cell size band filtering.

Electrokinetics-Based Microfluidic Technology for the Rapid Separation and Concentration of Bacteria/Cells/Biomolecules

2014 ◽  
Vol 911 ◽  
pp. 347-351 ◽  
Author(s):  
I Fang Cheng ◽  
Tzu Ying Chen ◽  
Hsien Chang Chang
Keyword(s):  
Cancer Cell ◽  
Electrochemical Impedance ◽  
High Sensitivity ◽  
High Specificity ◽  
Cell Detection ◽  
Label Free ◽  
Rapid Separation ◽  
Whole Cells ◽  
Highly Sensitive ◽  
Label Free Detection

Conventional techniques for detection of bacteria/cell and assessment of cancer cell typically use DNA techniques, Western blot and ELISA kits that are high cost, complicated processes and long time consuming. Our researches focus on rapid, portable, simple and highly sensitive separation and detection of cells/bacteria/biomolecules for field-use diagnosis. An ideal portable biosensor (molecular or whole cells detections) unit must have several important features: rapid detection time (<10 minutes), high sensitivity (pM level for molecular detection, 103 cells/ml for whole cell detection), high specificity, small and inexpensive instrumentation configuration. Electrochemical impedance/conductance sensing is preferred over optical detection because of cost and portability concerns. Cancer cell detection using heterogeneous medical samples require continuous isolation, sorting, and trapping of the target bioparticles and immunocolloids within a diagnostic chip. We have developed several electrokinetic strategies to rapid separation, concentration and detection of cells/bacteria/biomolecules in a microfluidic chip using such as dielectrophoresis (DEP), traveling-wave dielectrophoresis (twDEP) and electrohydrodynamics (EHD). Several key techniques we done, which on a rapid/simple/label-free detection platform for the highly sensitive on-chip separation/identification/quantification will be introduced in this paper.

Multiplexed electrochemical and SERS dual-mode detection of stroke biomarkers: rapid screening with high sensitivity

2019 ◽  
Vol 43 (34) ◽  
pp. 13381-13387 ◽  
Author(s):  
Jingyi Sun ◽  
Yi Zhao ◽  
Yajun Hou ◽  
Hanxia Li ◽  
Mingfeng Yang ◽  
...  
Keyword(s):  
Neuron Specific Enolase ◽  
High Sensitivity ◽  
Rapid Screening ◽  
Label Free ◽  
Raman Spectroscopic ◽  
Mode Detection ◽  
Β Protein ◽  
Highly Sensitive ◽  
Surface Enhanced Raman ◽  
Sers Detection

In this work, a real-time assay for a highly sensitive, label-free, multiplexed electrochemical and surface-enhanced Raman spectroscopic (SERS) detection of stroke biomarkers by neuron-specific enolase (NSE) and S100-β protein was developed using lateral flow devices.

Design of Photonic Crystals Waveguide Using Microfluidic Infiltration

2014 ◽  
Vol 492 ◽  
pp. 301-305 ◽  
Author(s):  
Faida Bougriou ◽  
Touraya Boumaza ◽  
Mohamed Bouchemat
Keyword(s):  
Photonic Crystals ◽  
Fdtd Method ◽  
High Sensitivity ◽  
Slab Waveguide ◽  
Label Free ◽  
Single Chip ◽  
Photonic Crystal Slab ◽  
Sensing Applications ◽  
Highly Sensitive ◽  
Label Free Detection

The use of photonic crystals (PCS) in biosensor applications has lead to the development of highly sensitive and selective microfluidic sensor elements. Two main advantages of these devices for sensing applications are their high sensitivity and their reduced size, which makes it possible, in one hand, to detect very small analytes without the need of markers (label-free detection), and to integrate many of these devices on a single chip to perform a multi-parameter detection on the other hand. In the present paper, we analyze the design of a highly sensitive microfluidic sensors based on 2D photonic crystal slab waveguide formed by increasing the radii of air holes localized at each side of the line defect and filling with homogenous de-ionized water (nc =1.33). The transmission spectrum of the sensor has been obtained with the use of Finite Difference Time Domain (FDTD) method and it has been observed that a 306 nm wavelength position of the lower band edge shift was observed corresponding to a sensitivity of more than 927 nm per refractive index unit (RIU). Development of microfluidic sensor designs that enhance sensitivity is especially important because it allows detection of lower concentrations of analytes.

scholarly journals Highly Sensitive Electrochemical Aptasensor for Detecting the VEGF165 Tumor Marker with PANI/CNT Nanocomposites

Biosensors ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 114
Author(s):  
Yunjeong Park ◽  
Min-Sung Hong ◽  
Woo-Hyuk Lee ◽  
Jung-Gu Kim ◽  
Kyunghoon Kim
Keyword(s):  
Tumor Marker ◽  
Limit Of Detection ◽  
Biological Fluid ◽  
Low Cost ◽  
High Sensitivity ◽  
Label Free ◽  
Electrochemical Aptasensor ◽  
Promising Tool ◽  
Highly Sensitive ◽  
Endothelial Growth Factor

Sensing targeted tumor markers with high sensitivity provides vital information for the fast diagnosis and treatment of cancer patients. A vascular endothelial growth factor (VEGF165) have recently emerged as a promising biomarker of tumor cells. The electrochemical aptasensor is a promising tool for detecting VEGF165 because of its advantages such as a low cost and quantitative analysis. To produce a sensitive and stable sensor electrode, nanocomposites based on polyaniline (PANI) and carbon nanotube (CNT) have potential, as they provide for easy fabrication, simple synthesis, have a large surface area, and are suitable in biological environments. Here, a label-free electrochemical aptasensor based on nanocomposites of CNT and PANI was prepared for detecting VEGF165 as a tumor marker. The nanocomposite was assembled with immobilized VEGF165 aptamer as a highly sensitive VEGF165 sensor. It exhibited stable and wide linear detection ranges from 0.5 pg/mL to 1 μg/mL, with a limit of detection of 0.4 pg/mL because of the complementary effect of PANI/CNT. The fabricated aptasensor also exhibited good stability in biological conditions, selectivity, and reproducibility after several measurement times after the dissociation process. Thus, it could be applied for the non-invasive determination of VEGF, in biological fluid diagnosis kits, or in an aptamer-based biosensor platform in the near future.

Label-free and highly sensitive electrochemiluminescence biosensing using quantum dots/carbon nanotubes in ionic liquid

The Analyst ◽  
2015 ◽  
Vol 140 (8) ◽  
pp. 2603-2607 ◽  
Author(s):  
Wenwen Tu ◽  
Xuelin Fang ◽  
Jing Lou ◽  
Zhihui Dai
Keyword(s):  
Carbon Nanotubes ◽  
Quantum Dots ◽  
Ionic Liquid ◽  
High Sensitivity ◽  
Label Free ◽  
Highly Sensitive

A universal and label-free electrochemiluminescence biosensing platform with high sensitivity was developed based on quantum dots/carbon nanotubes in ionic liquid.

scholarly journals Size and dielectric properties of skeletal stem cells change critically after enrichment and expansion from human bone marrow: consequences for microfluidic cell sorting

2017 ◽  
Vol 14 (133) ◽  
pp. 20170233 ◽  
Author(s):  
Miguel Xavier ◽  
María C. de Andrés ◽  
Daniel Spencer ◽  
Richard O. C. Oreffo ◽  
Hywel Morgan
Keyword(s):  
Stem Cells ◽  
Bone Marrow ◽  
Dielectric Properties ◽  
Electrical Properties ◽  
Cell Size ◽  
Membrane Capacitance ◽  
Label Free ◽  
Biophysical Parameter ◽  
Mean Size

The capacity of bone and cartilage to regenerate can be attributed to skeletal stem cells (SSCs) that reside within the bone marrow (BM). Given SSCs are rare and lack specific surface markers, antibody-based sorting has failed to deliver the cell purity required for clinical translation. Microfluidics offers new methods of isolating cells based on biophysical features including, but not limited to, size, electrical properties and stiffness. Here we report the characterization of the dielectric properties of unexpanded SSCs using single-cell microfluidic impedance cytometry (MIC). Unexpanded SSCs had a mean size of 9.0 µm; larger than the majority of BM cells. During expansion, often used to purify and increase the number of SSCs, cell size and membrane capacitance increased significantly, highlighting the importance of characterizing unaltered SSCs. In addition, MIC was used to track the osteogenic differentiation of SSCs and showed an increased membrane capacitance with differentiation. The electrical properties of primary SSCs were indistinct from other BM cells precluding its use as an isolation method. However, the current studies indicate that cell size in combination with another biophysical parameter, such as stiffness, could be used to design label-free devices for sorting SSCs with significant clinical impact.

scholarly journals A label-free and sensitive photoluminescence sensing platform based on long persistent luminescence nanoparticles for the determination of antibiotics and 2,4,6-trinitrophenol

RSC Advances ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 5714-5720 ◽  
Author(s):  
Xi Zhang ◽  
Na-Yan Xu ◽  
Qiong Ruan ◽  
Dan-Qing Lu ◽  
Yun-Hui Yang ◽  
...  
Keyword(s):  
High Sensitivity ◽  
Persistent Luminescence ◽  
Label Free ◽  
Low Background ◽  
Background Interference ◽  
Sensing Platform ◽  
Highly Sensitive ◽  
Visualized Detection

A highly sensitive luminescence sensor based on PLNPs for visualized detection of antibiotic and organic explosives was developed, which could eliminate the background interference, allowing low background and therefore high sensitivity.

High-sensitivity detection of gold labels by high-angle dark-field STEM imaging

1990 ◽  
Vol 48 (3) ◽  
pp. 892-893 ◽  
Author(s):  
Max T. Otten
Keyword(s):  
High Sensitivity ◽  
Dark Field ◽  
Bright Field ◽  
Backscattered Electron Imaging ◽  
Backscattered Electrons ◽  
Average Atomic Number ◽  
Highly Sensitive ◽  
Backscattered Electron ◽  
Electron Imaging ◽  
High Sensitivity Detection

Labelling of antibodies with small gold probes is a highly sensitive technique for detecting specific molecules in biological tissue. Larger gold probes are usually well visible in TEM or STEM Bright-Field images of unstained specimens. In stained specimens, however, the contrast of the stain is frequently the same as that of the gold labels, making it virtually impossible to identify the labels, especially when smaller gold labels are used to increase the sensitivity of the immunolabelling technique. TEM or STEM Dark-Field images fare no better (Figs. 1a and 2a), again because of the absence of a clear contrast difference between gold labels and stain.Potentially much more useful is backscattered-electron imaging, since this will show differences in average atomic number which are sufficiently large between the metallic gold and the stains normally used. However, for the thin specimens and at high accelerating voltages of the STEM, the yield of backscattered electrons is very small, resulting in a very weak signal. Consequently, the backscattered-electron signal is often too noisy for detecting small labels, even for large spot sizes.

Surface confinement induces the formation of solid-like insulating ionic liquid nanostructures

2017 ◽  
Author(s):  
Massimiliano Galluzzi ◽  
Simone Bovio ◽  
Paolo Milani ◽  
Alessandro Podestà
Keyword(s):  
Ionic Liquid ◽  
Electrical Properties ◽  
Electric Fields ◽  
Relative Dielectric Constant ◽  
Ionic Mobility ◽  
Electric Properties ◽  
Bulk Liquid ◽  
Structural Reorganization ◽  
Surface Confinement ◽  
Insulator Layers

We report on the modification of the electric properties of the imidazolium-based [BMIM][NTf2] ionic liquid upon surface confinement in the sub-monolayer regime. Solid-like insulating nanostructures of [BMIM][NTf2] spontaneously form on a variety of insulating substrates, at odd with the liquid and conductive nature of the same substances in the bulk phase. A systematic spatially resolved investigation by atomic force microscopy of the morphological, mechanical and electrical properties of [BMIM][NTf2] nanostructures showed that this liquid substance rearranges into lamellar nanostructures with a high degree of vertical order and enhanced resistance to mechanical compressive stresses and very intense electric fields, denoting a solid-like character. The morphological and structural reorganization has a profound impact on the electric properties of supported [BMIM][NTf2] islands, which behave like insulator layers with a relative dielectric constant between 3 and 5, comparable to those of conventional ionic solids, and significantly smaller than those measured in the bulk ionic liquid. These results suggest that in the solid-like ordered domains confined either at surfaces or inside the pores of the nanoporous electrodes of photo-electrochemical devices, the ionic mobility and the overall electrical properties can be significantly perturbed with respect to the bulk liquid phase, which would likely influence the<br>performance of the devices.<br>

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