Hydrodynamic channeling as a controlled flow reversal mechanism for bidirectional AC electroosmotic pumping using glassy carbon microelectrode arrays

2019 ◽  
Vol 29 (7) ◽  
pp. 075007 ◽  
Author(s):  
Matias Vazquez-Pinon ◽  
Bidhan Pramanick ◽  
Felipe G Ortega-Gama ◽  
Victor H Perez-Gonzalez ◽  
Lawrence Kulinsky ◽  
...  
Keyword(s):  
Glassy Carbon ◽  
Microelectrode Arrays ◽  
Flow Reversal ◽  
Electroosmotic Pumping ◽  
Reversal Mechanism ◽  
Controlled Flow

Comparison of Two-Dimensional and Three-Dimensional Carbon Electrode Geometries Affecting Bidirectional Electroosmotic Pumping

2019 ◽  
Vol 7 (2) ◽  
Author(s):  
Matías Vázquez-Piñón ◽  
Hyundoo Hwang ◽  
Marc J. Madou ◽  
Lawrence Kulinsky ◽  
Sergio O. Martínez-Chapa
Keyword(s):  
Flow Behavior ◽  
Fluid Velocity ◽  
Three Dimensional ◽  
Electrode System ◽  
Flow Reversal ◽  
Peak Voltage ◽  
Velocity Magnitude ◽  
Electroosmotic Pumping ◽  
Coplanar Electrodes ◽  
Asymmetric Electrodes

This study compares fluid velocity magnitude and direction for three different glassy carbon (GC) electrode systems effecting alternating current (AC) electroosmotic pumping. The flow behavior is analyzed for electroosmotic pumping performed with asymmetric coplanar electrodes. Subsequently, effects of adding microposts array of two different heights (40 μm and 80 μm) are studied. Experimental results demonstrate that as peak-to-peak voltage is increased above 10 V peak-to-peak, the flow reversal is achieved for planar electrodes. Utilization of microposts-enhanced asymmetric electrodes blocks the flow reversal and alters the magnitude of the fluid velocity at the application of larger voltages (above 10 V peak-to-peak). Understanding of the consequences of three-dimensional geometry of asymmetric electrodes would allow designing the electrode system for AC electroosmotic pumping and mixing, as well as bidirectional fluid driving with equal forward and backward flow velocities.

scholarly journals Glassy Carbon Microelectrode Arrays Enable Voltage-Peak Separated Simultaneous Detection of Dopamine and Serotonin Using Fast Scan Cyclic Voltammetry

The Analyst ◽  
2021 ◽  
Author(s):  
Elisa Castagnola ◽  
Sanitta Thongpang ◽  
Mieko Hirabayashi ◽  
Giorgio Nava ◽  
Surabhi Nimbalkar ◽  
...  
Keyword(s):  
Cyclic Voltammetry ◽  
Electrochemical Detection ◽  
Glassy Carbon ◽  
Simultaneous Detection ◽  
Microelectrode Arrays ◽  
Fast Scan Cyclic Voltammetry ◽  
In Vivo Detection ◽  
Neuroscience Research ◽  
Voltage Peak

Progress in real-time, simultaneous in vivo detection of multiple neurotransmitters will help accelerate advances in neuroscience research. The need for development of probes capable of stable electrochemical detection of rapid...

scholarly journals In Vivo Dopamine Detection and Single Unit Recordings Using Intracortical Glassy Carbon Microelectrode Arrays

MRS Advances ◽  
2018 ◽  
Vol 3 (29) ◽  
pp. 1629-1634 ◽  
Author(s):  
Elisa Castagnola ◽  
Nasim Winchester Vahidi ◽  
Surabhi Nimbalkar ◽  
Srihita Rudraraju ◽  
Marvin Thielk ◽  
...  
Keyword(s):  
Glassy Carbon ◽  
Neural Activity ◽  
Microelectrode Array ◽  
Flexible Substrate ◽  
Microelectrode Arrays ◽  
European Starling ◽  
Dopamine Detection ◽  
Vertical Spacing

ABSTRACTIn this study, we present a 4-channel intracortical glassy carbon (GC) microelectrode array on a flexible substrate for the simultaneous in vivo neural activity recording and dopamine (DA) concentration measurement at four different brain locations (220µm vertical spacing). The ability of GC microelectrodes to detect DA was firstly assessed in vitro in phosphate-buffered saline solution and then validated in vivo measuring spontaneous DA concentration in the Striatum of European Starling songbird through fast scan cyclic voltammetry(FSCV). The capability of GC microelectrode arrays and commercial penetrating metal microelectrode arrays to record neural activity from the Caudomedial Neostriatum of European starling songbird was compared. Preliminary results demonstrated the ability of GC microelectrodes in detecting neurotransmitters release and recording neural activity in vivo. GC microelectrodes array may, therefore, offer a new opportunity to understand the intimate relations linking electrophysiological parameters with neurotransmitters release.

Controlled flow reversal column reactor for microcapsules

1985 ◽  
Vol 7 (10) ◽  
pp. 759-764 ◽  
Author(s):  
Kaoru Obuchi ◽  
Hidekatsu Maeda
Keyword(s):  
Flow Reversal ◽  
Column Reactor ◽  
Controlled Flow

Electrokinetic Propulsion of Polymer Microparticulates Along Glassy Carbon Electrode Array

2020 ◽  
Vol 8 (2) ◽  
Author(s):  
Jennifer Cortez ◽  
Kimia Damyar ◽  
Runtian Gao ◽  
Tuo Zhou ◽  
Lawrence Kulinsky
Keyword(s):  
Electric Field ◽  
Glassy Carbon ◽  
Microelectrode Arrays ◽  
Electrode Array ◽  
In Vitro Diagnostics ◽  
Dc Offset ◽  
Lithographic Patterning ◽  
Interdigitated Microelectrode ◽  
And Control

Abstract Dielectrophoresis (DEP) is a force applied to microparticles in nonuniform electric field. This study discusses the fabrication of the glassy carbon interdigitated microelectrode arrays using lithography process based on lithographic patterning and subsequent pyrolysis of negative SU-8 photoresist. Resulting high-resistance electrodes would have the regions of high electric field at the ends of microarray as demonstrated by simulation. The study demonstrates that combining the alternating current (AC) applied bias with the direct current (DC) offset allows the user to separate subpopulations of microparticulates and control the propulsion of microparticles to the high field areas such as the ends of the electrode array. The direction of the movement of the particles can be switched by changing the offset. The demonstrated novel integrated DEP separation and propulsion can be applied to various fields including in vitro diagnostics as well as to microassembly technologies.

Domains and domain nucleation in magnetron-sputtered CoCr thin films

1993 ◽  
Vol 51 ◽  
pp. 1046-1047
Author(s):  
B. G. Demczyk
Keyword(s):  
Thin Films ◽  
Domain Structure ◽  
Magnetic Domain ◽  
Domain Size ◽  
Film Plane ◽  
Magnetic Domain Structure ◽  
Perpendicular Magnetization ◽  
Columnar Grains ◽  
Reversal Mechanism ◽  
Lorentz Transmission Electron Microscopy

CoCr thin films have been of interest for a number of years due to their strong perpendicular anisotropy, favoring magnetization normal to the film plane. The microstructure and magnetic properties of CoCr films prepared by both rf and magnetron sputtering have been examined in detail. By comparison, however, relatively few systematic studies of the magnetic domain structure and its relation to the observed film microstructure have been reported. In addition, questions still remain as to the operative magnetization reversal mechanism in different film thickness regimes. In this work, the magnetic domain structure in magnetron sputtered Co-22 at.%Cr thin films of known microstructure were examined by Lorentz transmission electron microscopy. Additionally, domain nucleation studies were undertaken via in-situ heating experiments.It was found that the 50 nm thick films, which are comprised of columnar grains, display a “dot” type domain configuration (Figure 1d), characteristic of a perpendicular magnetization. The domain size was found to be on the order of a few structural columns in diameter.

Electron-diffraction studies of amorphous carbon thin films

1993 ◽  
Vol 51 ◽  
pp. 1100-1101
Author(s):  
David A. Muller
Keyword(s):  
Thin Films ◽  
Electron Diffraction ◽  
Amorphous Carbon ◽  
Glassy Carbon ◽  
Spherical Structure ◽  
Local Ordering ◽  
Carbon Arc ◽  
Similar Appearance ◽  
Carbon Thin Films ◽  
Large Spherical

The sp2 rich amorphous carbons have a wide variety of microstructures ranging from flat sheetlike structures such as glassy carbon to highly curved materials having similar local ordering to the fullerenes. These differences are most apparent in the region of the graphite (0002) reflection of the energy filtered diffracted intensity obtained from these materials (Fig. 1). All these materials consist mainly of threefold coordinated atoms. This accounts for their similar appearance above 0.8 Å-1. The fullerene curves (b,c) show a string of peaks at distance scales corresponding to the packing of the large spherical and oblate molecules. The beam damaged C60 (c) shows an evolution to the sp2 amorphous carbons as the spherical structure is destroyed although the (220) reflection in fee fcc at 0.2 Å-1 does not disappear completely. This 0.2 Å-1 peak is present in the 1960 data of Kakinoki et. al. who grew films in a carbon arc under conditions similar to those needed to form fullerene rich soots.

Role of the Cilia Membrane in Control of Microtubule Sliding

1980 ◽  
Vol 38 ◽  
pp. 612-615
Author(s):  
Edna S. Kaneshiro
Keyword(s):  
Control Mechanism ◽  
Beat Frequency ◽  
Surface Membrane ◽  
Ciliary Membrane ◽  
Ciliary Beating ◽  
Ciliary Reversal ◽  
Voltage Dependent ◽  
Reversal Mechanism ◽  
And Function

It is currently believed that ciliary beating results from microtubule sliding which is restricted in regions to cause bending. Cilia beat can be modified to bring about changes in beat frequency, cessation of beat and reversal in beat direction. In ciliated protozoans these modifications which determine swimming behavior have been shown to be related to intracellular (intraciliary) Ca2+ concentrations. The Ca2+ levels are in turn governed by the surface ciliary membrane which exhibits increased Ca2+ conductance (permeability) in response to depolarization. Mutants with altered behaviors have been isolated. Pawn mutants fail to exhibit reversal of the effective stroke of ciliary beat and therefore cannot swim backward. They lack the increased inward Ca2+ current in response to depolarizing stimuli. Both normal and pawn Paramecium made leaky to Ca2+ by Triton extrac¬tion of the surface membrane exhibit backward swimming only in reactivating solutions containing greater than IO-6 M Ca2+ Thus in pawns the ciliary reversal mechanism itself is left operational and only the control mechanism at the membrane is affected. The topographic location of voltage-dependent Ca2+ channels has been identified as a component of the ciliary mem¬brane since the inward Ca2+ conductance response is eliminated by deciliation and the return of the response occurs during cilia regeneration. Since the ciliary membrane has been impli¬cated in the control of Ca2+ levels in the cilium and therefore is the site of at least one kind of control of microtubule sliding, we have focused our attention on understanding the structure and function of the membrane.

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