scholarly journals Materials Matter in Microfluidic Devices

MRS Bulletin ◽  
2006 ◽  
Vol 31 (2) ◽  
pp. 95-99 ◽  
Author(s):  
Xunli Zhang ◽  
Stephen J. Haswell
Keyword(s):  
High Surface ◽  
Volume Ratio ◽  
Microfluidic Devices ◽  
Surface Characteristics ◽  
Microfluidic System ◽  
Substrate Material ◽  
Material Choice ◽  
Overall Performance ◽  
The Common ◽  
Selection Of

AbstractAs more micro- and nanofluidic methodologies are developed for a growing number of diverse applications, it becomes increasingly apparent that the choice of substrate material can have a profound effect on the eventual performance of a device. This is due mostly to the high surface-to-volume ratio that exists within such small structures. In addition to the obvious limitations related to the choice of solvent, operating temperatures, and pressure, the method of fluidic pumping—in particular, an electrokinetics-based methodology using a combination of electro-osmotic and electrophoresis flows—can further complicate material choice. These factors, however, are only part of the problem; once chemicals or biological materials (e.g., proteins or cells) are introduced into a microfluidic system, surface characteristics will have a profound influence on the activity of such components, which will subsequently influence their performance. This article reviews the common types of materials that are currently used to fabricate microfluidic devices and considers how these materials may influence the overall performance associated with chemical and biological processing. Consideration will also be given to the selection of materials and surface modifications that can aid in exploiting the high surface properties to enhance process performance.

scholarly journals Rapid Multianalyte Microfluidic Homogeneous Immunoassay on Electrokinetically Driven Beads

Biosensors ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 212
Author(s):  
Pierre-Emmanuel Thiriet ◽  
Danashi Medagoda ◽  
Gloria Porro ◽  
Carlotta Guiducci
Keyword(s):  
High Surface ◽  
Three Dimensional ◽  
Microfluidic Channel ◽  
Kidney Injury ◽  
Volume Ratio ◽  
Microfluidic System ◽  
Performance Standard ◽  
Neutrophil Gelatinase Associated Lipocalin ◽  
Life Threatening ◽  
Analyte Detection

The simplicity of homogeneous immunoassays makes them suitable for diagnostics of acute conditions. Indeed, the absence of washing steps reduces the binding reaction duration and favors a rapid and compact device, a critical asset for patients experiencing life-threatening diseases. In order to maximize analytical performance, standard systems employed in clinical laboratories rely largely on the use of high surface-to-volume ratio suspended moieties, such as microbeads, which provide at the same time a fast and efficient collection of analytes from the sample and controlled aggregation of collected material for improved readout. Here, we introduce an integrated microfluidic system that can perform analyte detection on antibody-decorated beads and their accumulation in confined regions within 15 min. We employed the system to the concomitant analysis of clinical concentrations of Neutrophil Gelatinase-Associated Lipocalin (NGAL) and Cystatin C in serum, two acute kidney injury (AKI) biomarkers. To this end, high-aspect-ratio, three-dimensional electrodes were integrated within a microfluidic channel to impart a controlled trajectory to antibody-decorated microbeads through the application of dielectrophoretic (DEP) forces. Beads were efficiently retained against the fluid flow of reagents, granting an efficient on-chip analyte-to-bead binding. Electrokinetic forces specific to the beads’ size were generated in the same channel, leading differently decorated beads to different readout regions of the chip. Therefore, this microfluidic multianalyte immunoassay was demonstrated as a powerful tool for the rapid detection of acute life-threatening conditions.

A Novel Formaldehyde Gas Sensor Based on Ag-LaFeO3 Using Molecular Imprinting Technique

2016 ◽  
Vol 847 ◽  
pp. 287-293
Author(s):  
Yu Min Zhang ◽  
Chang Yi Hu ◽  
Jin Zhang ◽  
Qing Ju Liu ◽  
Qin Zhu ◽  
...  
Keyword(s):  
Gas Sensor ◽  
Molecular Imprinting ◽  
High Selectivity ◽  
High Surface ◽  
Volume Ratio ◽  
Substrate Material ◽  
Small Dimension ◽  
Molecular Imprinting Technique ◽  
First Time

A novel gas sensor for the determination of formaldehyde was developed based on molecular imprinting technique (MIT). MIT was for the first time used to recognize small organic molecule by our group. The molecular imprinting nanoparticles (MINs) with a small dimension which possess extremely high surface-to-volume ratio were synthesized using imprinting polymerization with formaldehyde as template and Ag-LaFeO3 as substrate material. The structure of the MINs is orthogonal perovskite. And then the MINs were printed onto an alumina tube. Subsequently, a high selectivity molecular imprinting gas sensor for detection of formaldehyde was achieved. At 86°C, the response to 0.5 ppm formaldehyde based on the sensor is 16, and the response is lower than 2 for the other test gases. The response time and recovery time are 55 s and 40 s, respectively.

Nanomaterials in Electrochemical Biosensor

2014 ◽  
Vol 995 ◽  
pp. 125-143 ◽  
Author(s):  
Md. Abdul Aziz ◽  
Munetaka Oyama
Keyword(s):  
High Surface ◽  
Chemical Properties ◽  
Volume Ratio ◽  
High Sensitivity ◽  
Electrochemical Biosensors ◽  
Surface Immobilization ◽  
Physico Chemical ◽  
Overall Performance ◽  
Detection Of Biomolecules ◽  
Affinity Biosensors

Nanomaterial based electrochemical method gain tremendous interest for the detection of biomolecules due to high sensitivity, selectivity, and low fabrication cost. High surface to volume ratio, excellent electrocatalytic properties of the nanomaterials plays important role for the sensitive and selective detection of biomolecules. For electrochemical biosensors, proper control of chemical, electrochemical and physical properties, as well as their functionalization and surface immobilization significantly influences the overall performance. This chapter gives an overview of the importance of the development of nanomaterials based electrochemical biosensors; particularly direct electrooxidation-or electroreduction-based biosensors, catalysis-based biosensors, and label-based affinity biosensors. In addition, fabrication methods including modification of electrode surface with nanomaterials, tailoring their physico-chemical properties, and functionalization with chemicals or biomolecules are also highlighted.

Supported Bilayer Membranes for Reducing Cell Adhesion in Microfluidic Devices

2021 ◽  
Author(s):  
Julia R Clapis ◽  
Mengqi Jonathan Fan ◽  
Michelle L Kovarik
Keyword(s):  
Cell Adhesion ◽  
Surface Area ◽  
High Surface ◽  
High Surface Area ◽  
Volume Ratio ◽  
Microfluidic Devices ◽  
Microfluidic Channels ◽  
Bilayer Membranes ◽  
Supported Bilayer

The high surface area-to-volume ratio of microfluidic channels makes them susceptible to fouling and clogging when used for biological analyses,including cell-based assays. We evaluated the role of electrostatic and van...

Electric Field Driven Control and Manipulation of Particles in Multiple Designs of Microfluidic Devices Including the Electrothermal Effects

2006 ◽  
Author(s):  
Vishwanath Mulukutla ◽  
Boris Khusid ◽  
Hongjun Song ◽  
Dawn J. Bennett ◽  
Conrad James
Keyword(s):  
Electric Field ◽  
Particle Motion ◽  
High Surface ◽  
Volume Ratio ◽  
Microfluidic Devices ◽  
Biological Warfare ◽  
Electric Field Gradients ◽  
Field Gradients ◽  
Research Corporation ◽  
Electrothermal Effects

Micro-total-analytical systems for analyzing chemical/biological substances are now used across a wide variety of applications ranging from biological warfare agent detection to the healthcare industry. The first step in the operation of such systems consists of concentrating and separating the analytes of interest from the background matrix and positioning these analytes into selected locations for subsequent analysis. Electro-kinetic and electro-hydrodynamic techniques for manipulating particles in suspension are highly used in microsystems eliminating the need for movable parts. In addition, because of the high surface to volume ratio there is efficient dissipation of Joule heating. Here, we analyze the electric field distribution and particle motion in microfluidic devices with a variety of electrode configurations. First, we consider the particle motion and electric field gradient in our recently developed technique of dielectric gating. We consider the particle motion and numerical simulation results using the Computational Fluid Dynamics Research Corporation (CFDRC) code in 2D designs. In addition, the electrothermal effects within the channel are examined. Next, we consider triangular and trapezoidal electrode configurations as well as single stream particle delivery. We study the particle motion, electric field gradients, and electrothermal effects in these designs. Computer simulations and experimental results are compared.

A Comparison of Four Adolescent Language Tests

1987 ◽  
Vol 18 (3) ◽  
pp. 250-266 ◽  
Author(s):  
R. Jane Lieberman ◽  
Ann Marie C. Heffron ◽  
Stephanie J. West ◽  
Edward C. Hutchinson ◽  
Thomas W. Swem
Keyword(s):  
Test Performance ◽  
Sixth Grade ◽  
Significant Discrepancy ◽  
Language Impaired ◽  
Language Functions ◽  
Language Tests ◽  
Significant Difference ◽  
Sixth Grade Students ◽  
Overall Performance ◽  
Selection Of

Four recently developed adolescent language tests, the Fullerton Test for Adolescents (FLTA), the Test of Adolescent Language (TOAL), the Clinical Evaluation of Language Functions (CELF), and the Screening Test of Adolescent Language (STAL), were compared to determine: (a) whether they measured the same language skills (content) in the same way (procedures); and (b) whether students performed similarly on each of the tests. First, respective manuals were reviewed to compare selection of subtest content areas and subtest procedures. Then, each of the tests was administered according to standardized procedures to 30 unselected sixth-grade students. Despite apparent differences in test content and procedures, there was no significant difference in students' performance on three of the four tests, and correlations among test performance were moderate to high. A comparison of the pass/fail rates for overall performance on the tests, however, revealed a significant discrepancy between the proportions of students identified in need of further evaluation on the STAL (20%) and the proportion diagnosed as language impaired on the three diagnostic tests (60-73%). Clinical implications are discussed.

Kesulitan Mahasiswa Pembelajar Pemula Bahasa Perancis dalam Memahami Gramatika

Metahumaniora ◽  
2017 ◽  
Vol 7 (3) ◽  
pp. 354
Author(s):  
Ferli Hasanah
Keyword(s):  
French Literature ◽  
French Language ◽  
First Year ◽  
The Common ◽  
French Grammar ◽  
Bahasa Indonesia ◽  
Selection Of

ABSTRAKGramatika pada setiap bahasa memiliki kekhasannya masing-masing.Mahasiswa Program Studi Sastra Perancis tahun pertama sebagai pembelajar pemulasering mengalami kesulitan dalam memahami gramatika bahasa. Kesulitan mereka tidakterlepas dari perbedaan-perbedaan mendasar pada struktur bahasa Indonesia sebagaibahasa ibu mereka dan bahasa Perancis yang tengah dipelajari. Penelitian ini dilaksanakandengan tujuan untuk mengetahui hambatan yang dimiliki mahasiswa pembelajar pemuladi Program Studi Sastra Perancis Universitas Padjadjaran dalam memahami gramatikabahasa Perancis. Metode yang digunakan dalam penelitian ini adalah metode simak dancatat. Hasil analisis ini menunjukkan bahwa kesalahan-kesalahan yang umum dilakukanpembelajar pemula ada pada penggunaan accent, konjugasi verba, partikel défini maupunindéfini, accord penanda feminin atau jamak, serta pemilihan preposisi.Kata kunci: gramatika, bahasa Perancis, konjugasiABST RACTThe grammar in every language has its own particularities. French literaturestudents in the first year as a beginner learners often have problem in understandingFrench grammar which is frequently considered difficult. Their struggle is inseparablefrom the fundamental differences between Indonesian structure as their mother tongueand the French language which being studied. This research aims to know the obstaclesof the students of beginner learners in the French Literature of Padjadjaran university inunderstanding the basic French grammar. The method used in this research is referringand taking notes method. The results of the analysis shows that the common mistakes oflearners are in the use of accents, verb conjugations, particles défini or indéfini, markeraccord feminine or plural, and the selection of prepositions.Keywords: grammar, French, conjugation

Philosophcal review of h. white̕s tropological theory in the context of the new philosophy of history

2020 ◽  
Vol 3 (152) ◽  
pp. 92-99
Author(s):  
S. M. Geiko ◽  
◽  
O. D. Lauta
Keyword(s):  
Modern Science ◽  
Historical Knowledge ◽  
Text Organization ◽  
The Social ◽  
History Of ◽  
Actual Material ◽  
The Common ◽  
Historical Nature ◽  
Selection Of

The article provides a philosophical analysis of the tropological theory of the history of H. White. The researcher claims that history is a specific kind of literature, and the historical works is the connection of a certain set of research and narrative operations. The first type of operation answers the question of why the event happened this way and not the other. The second operation is the social description, the narrative of events, the intellectual act of organizing the actual material. According to H. White, this is where the set of ideas and preferences of the researcher begin to work, mainly of a literary and historical nature. Explanations are the main mechanism that becomes the common thread of the narrative. The are implemented through using plot (romantic, satire, comic and tragic) and trope systems – the main stylistic forms of text organization (metaphor, metonymy, synecdoche, irony). The latter decisively influenced for result of the work historians. Historiographical style follows the tropological model, the selection of which is determined by the historian’s individual language practice. When the choice is made, the imagination is ready to create a narrative. Therefore, the historical understanding, according to H. White, can only be tropological. H. White proposes a new methodology for historical research. During the discourse, adequate speech is created to analyze historical phenomena, which the philosopher defines as prefigurative tropological movement. This is how history is revealed through the art of anthropology. Thus, H. White’s tropical history theory offers modern science f meaningful and metatheoretically significant. The structure of concepts on which the classification of historiographical styles can be based and the predictive function of philosophy regarding historical knowledge can be refined.

Peculiarities of the juvenile period of the native Chechen genotypes of willow leaf pear (Pyrus salicifolia Pall.)

2020 ◽  
Vol 62 ◽  
pp. 32-38
Author(s):  
E. A. Dolmatov ◽  
R. B. Borzayev ◽  
A. N. Shaipov
Keyword(s):  
Chestnut Soil ◽  
Crop Breeding ◽  
Juvenile Period ◽  
Period 2 ◽  
Russian Research Institute ◽  
The Common ◽  
One Year ◽  
First Time ◽  
Selection Of ◽  
Creative Cooperation

The results of the study of the duration of the juvenile period of indigenous Chechen willow leaf pear genotypes (Pyrus salicifolia Pall.) are given in connection with the acceleration of the breeding process and the use of selected forms in pear breeding for high precocity. The studies were carried out in 2016-2019 at OOO “Orchards of Chechnya” in accordance with the Agreement on creative cooperation with the Russian Research Institute of Fruit Crop Breeding. The work was carried out in accordance with generally accepted programs and methods. The objects of the study were one-year and two-year-old pear seedlings obtained from sowing seeds of selected dwarf and low-growing local Chechen forms of willow pear (P. salicifolia Pall.), laying fruit buds on annual growths and seedlings of Caucasian pear (P. caucasica Fed.), 20 500 pcs. of each specie. The aim of the research was to study the potential of precocity of willow pear seedlings and to reveal of selected forms with the greatest degree of this trait. Stratified seeds were sown in the sowing department of the OOO “Orchards of Chechnya” production nursery in April, 2017. The seedlings were grown according to the common technology in dryland conditions on the plot with chestnut soil. The first fl owering of plants was noted in the spring, 2019. As a result of the research, for the first time on a large number of the experimental material it was found that in the off spring of the indigenous Chechen willow leaf pear genotypes, the selection of a little more than 2% of seedlings with a very short juvenile period (2 years) was possible. They are of great interest in accelerating the breeding process and in the selection of new pear varieties with high precocity. 20 willow leaf pear genotypes were selected for the further use in breeding for high precocity and as sources of the trait of short juvenile period.

scholarly journals Electrospun Nanofibers for Sensing and Biosensing Applications—A Review

2021 ◽  
Vol 22 (12) ◽  
pp. 6357
Author(s):  
Kinga Halicka ◽  
Joanna Cabaj
Keyword(s):  
High Surface ◽  
High Surface Area ◽  
Toxic Metal ◽  
Volume Ratio ◽  
Electrospun Nanofibers ◽  
Clinical Diagnostics ◽  
Loading Capacity ◽  
Electrospun Nanofiber ◽  
Sensing Platforms ◽  
Different Types

Sensors and biosensors have found applications in many areas, e.g., in medicine and clinical diagnostics, or in environmental monitoring. To expand this field, nanotechnology has been employed in the construction of sensing platforms. Because of their properties, such as high surface area to volume ratio, nanofibers (NFs) have been studied and used to develop sensors with higher loading capacity, better sensitivity, and faster response time. They also allow to miniaturize designed platforms. One of the most commonly used techniques of the fabrication of NFs is electrospinning. Electrospun NFs can be used in different types of sensors and biosensors. This review presents recent studies concerning electrospun nanofiber-based electrochemical and optical sensing platforms for the detection of various medically and environmentally relevant compounds, including glucose, drugs, microorganisms, and toxic metal ions.

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