Wireless electrochemiluminescence at functionalised gold microparticles using 3D titanium electrode arrays

2021 ◽  
Author(s):  
Samantha F. Douman ◽  
David Collins ◽  
Loanda R. Cumba ◽  
Stephen Beirne ◽  
Gordon G. Wallace ◽  
...  
Keyword(s):  
Active Transport ◽  
Electric Fields ◽  
Electrode Arrays ◽  
Titanium Electrode ◽  
3D Printed

Wireless electrochemiluminescence is generated from functionalised gold microparticles using interdigitated, 3D printed, titanium arrays as feeder electrodes. Active transport and intense electric fields leads to bright electrochemiluminescence.

scholarly journals SCIDOT-52. IN SITU DELIVERY OF TUMOR TREATING FIELDS THERAPY IN GLIOBLASTOMA PATIENTS

2019 ◽  
Vol 21 (Supplement_6) ◽  
pp. vi282-vi282
Author(s):  
Jeffrey Arle ◽  
Eric Wong ◽  
Anders Korshoej ◽  
Socrates Dokos ◽  
Ze’ev Bomzon ◽  
...  
Keyword(s):  
Field Strength ◽  
Electric Fields ◽  
Large Scale ◽  
Cell Damage ◽  
Human Head ◽  
Tumor Control ◽  
Electrode Arrays ◽  
Tumor Treating Fields ◽  
Newly Diagnosed Glioblastoma

Abstract The efficacy of Tumor-Treating Fields (TTFields) rests on the result of a large-scale clinical trial that demonstrated an increase in the survival of newly diagnosed glioblastoma patients when combined with temozolomide chemotherapy. Overall survival now extends to over 60 months in some of our patients when dexamethasone, which we suspected of interference with TTFields effects, is replaced with celecoxib to control tumor-associated inflammation. The transcranial method of delivering TTFields has not changed in light of ongoing advances in deep brain stimulation (DBS) and transcranial electric stimulation (TES), notably that the resistivity of the skull is the principle obstacle to placing therapeutic electric field strength of 2 V/cm into target tumor sites and variation in skull thickness is the main difference in TES efficiency across individuals. Realistic human head finite element modeling (FEM) predicted that surgical craniectomy beneath TTFields’ electrodes would enhance field strength at target tumor sites. Here we show that 2 V/cm can be reliably delivered to tumor sites using minimally-invasive DBS cylindrical leads or ribbon electrode arrays, pre- or post-resection. Two objections arise to the in situ method: 1) Will TTFields stimulate axons in situ? 2) Will field strength exceed safety limits for cell damage? Neural stimulation modeling and experiments show that TTFields’ frequency of 200 kHz, 1–3 orders of magnitude higher than ion channel time constants, is too high to stimulate them. Furthermore, 2 V/cm is well below cell damage limits of 700 V/mm. Thus we propose a new delivery method to improve tumor control in glioblastoma patients and to provide valuable information on TTFields’ effects via cell studies using in situ electric fields at 200 kHz.

scholarly journals Controlled Phase Interactions Between Pulsed Electric Fields, Ultrasonic Motion, and Magnetic Fields in an Anodic Dissolution Cell

2018 ◽  
Vol 140 (4) ◽  
Author(s):  
Curtis Bradley ◽  
Johnson Samuel
Keyword(s):  
Magnetic Field ◽  
Anodic Dissolution ◽  
Electric Fields ◽  
High Frequency ◽  
Performance Metrics ◽  
Removal Rate ◽  
Ultrasonic Transducer ◽  
Three Dimensional ◽  
Electrochemical Machining ◽  
3D Printed

This paper presents the design of a novel testbed that effectively combines pulsed electric field waveforms, ultrasonic velocity, and magnetic field waveforms in an anodic dissolution electrochemical machining (ECM) cell. The testbed consists of a custom three-dimensional (3D)-printed flow cell that is integrated with (i) a bipolar-pulsed ECM circuit, (ii) an ultrasonic transducer, and (iii) a custom-built high-frequency electromagnet. The driving voltages of the ultrasonic transducer and electromagnet are calibrated to achieve a timed workpiece velocity and magnetic field, respectively, in the machining area. The ECM studies conducted using this testbed reveal that phase-controlled waveform interactions between the three assistances affect both the material removal rate (MRR) and surface roughness (Ra) performance metrics. The triad-assisted ECM case involving phase-specific combinations of all three high-frequency (15.625 kHz) assistance waveforms is found to be capable of achieving a 52% increase in MRR while also simultaneously yielding a 78% improvement in the Ra value over the baseline pulsed-ECM case. This result is encouraging because assisted ECM processes reported in the literature typically improve only one of these performance metrics at the expense of the other. In general, the findings reported in this paper are expected to enable the realization of multifield assisted ECM testbeds using phase-specific input waveforms that change on-the-fly to yield preferential combinations of MRR and surface finish.

scholarly journals On the Electrical Resistance Relaxation of 3D-Anisotropic Carbon-Fiber-Filled Polymer Composites Subjected to External Electric Fields

Membranes ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 412
Author(s):  
Pei Huang ◽  
Yingze Cao ◽  
Zhidong Xia ◽  
Pengfei Wang ◽  
Shaosong Chen
Keyword(s):  
Carbon Fiber ◽  
Electric Fields ◽  
Electrical Resistance ◽  
Electrical Current ◽  
Electrical Field ◽  
Flexible Composites ◽  
3D Printed ◽  
And Migration ◽  
Small Voltage ◽  
Resistance Relaxation

Flexible composites as sensors are applied under a small voltage, but the effect of the external electrical field on the resistance is always ignored and unexplored by current research. Herein, we investigate the electrical resistance relaxation of anisotropic composites when they are subjected to an external electric field. The anisotropic composites were 3D-printed based on carbon-fiber-filled silicon rubber. Constant DC voltages were applied to the composites, and the output electrical current increased with time, namely the electrical resistance relax with time. The deflection and migration of carbon fibers are dominantly responsible for the resistance relaxation, and the angle’s evolution of a carbon fiber, under the application and removal of the electrical field, was well observed. The other factor hindering the resistance relaxation is the increased temperature originating from the Joule heating effect. This work provides a new understanding in the working duration and the static characteristics of flexible composites.

scholarly journals Alternating Electric Fields (TTFields) Activate Cav1.2 Channels in Human Glioblastoma Cells

Cancers ◽  
2019 ◽  
Vol 11 (1) ◽  
pp. 110 ◽  
Author(s):  
Eric Neuhaus ◽  
Lisa Zirjacks ◽  
Katrin Ganser ◽  
Lukas Klumpp ◽  
Uwe Schüler ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Plasma Membrane ◽  
Electric Fields ◽  
Clonogenic Survival ◽  
Phase Cell ◽  
Dependent Manner ◽  
Electrode Arrays ◽  
Human Glioblastoma ◽  
Alternating Electric Fields ◽  
Cav1.2 Channels

Tumor treating fields (TTFields) represent a novel FDA-approved treatment modality for patients with newly diagnosed or recurrent glioblastoma multiforme. This therapy applies intermediate frequency alternating electric fields with low intensity to the tumor volume by the use of non-invasive transducer electrode arrays. Mechanistically, TTFields have been proposed to impair formation of the mitotic spindle apparatus and cytokinesis. In order to identify further potential molecular targets, here the effects of TTFields on Ca2+-signaling, ion channel activity in the plasma membrane, cell cycle, cell death, and clonogenic survival were tested in two human glioblastoma cell lines in vitro by fura-2 Ca2+ imaging, patch-clamp cell-attached recordings, flow cytometry and pre-plated colony formation assay. In addition, the expression of voltage-gated Ca2+ (Cav) channels was determined by real-time RT-PCR and their significance for the cellular TTFields response defined by knock-down and pharmacological blockade. As a result, TTFields stimulated in a cell line-dependent manner a Cav1.2-mediated Ca2+ entry, G1 or S phase cell cycle arrest, breakdown of the inner mitochondrial membrane potential and DNA degradation, and/or decline of clonogenic survival suggesting a tumoricidal action of TTFields. Moreover, inhibition of Cav1.2 by benidipine aggravated in one glioblastoma line the TTFields effects suggesting that Cav1.2-triggered signaling contributes to cellular TTFields stress response. In conclusion, the present study identified Cav1.2 channels as TTFields target in the plasma membrane and provides the rationale to combine TTFields therapy with Ca2+ antagonists that are already in clinical use.

scholarly journals Electrochemical Polishing of Extruded and Laser Powder-Bed-Fused Inconel 718

2021 ◽  
Vol 6 (4) ◽  
pp. 284-298
Author(s):  
Srishti Jain ◽  
James Hyder ◽  
Mike Corliss ◽  
Wayne NP Hung
Keyword(s):  
Surface Finish ◽  
Inconel 718 ◽  
Surface Defects ◽  
Electrochemical Polishing ◽  
Powder Bed ◽  
Titanium Electrode ◽  
Powder Particles ◽  
3D Printed ◽  
Processing Defects ◽  
Carbide Particles

ABSTRACT Electro-chemical polishing (ECP) was utilized to produce sub-micron surface finish on Inconel 718 parts manufactured by Laser Powder-Bed-Fusion (L-PBF) and extrusion methods. The L-PBF parts had very rough surfaces due to semi-welded powder particles, surface defects, and difference layer steps that were generally not found on surfaces of extruded and machined components. This study compared the results of electro-polishing of these differently manufactured parts under the same conditions. Titanium electrode was used with an acid-based electrolyte to polish both the specimens at different combinations of pulsed current density, duty cycle, and polishing time. Digital 3D optical profiler was used to assess the surface finish, while optical and scanning electron microscopy was utilized to observe the microstructure of polished specimens. At optimal condition, the ECP successfully reduced the surface of L-PBF part from 17 µm to 0.25 µm; further polishing did not improve the surface finish due to different removal rates of micro-leveled pores, cracks, nonconductive phases, and carbide particles in 3D-printed Inconel 718. The microstructure of extruded materials was uniform and free of processing defects, therefore can be polished consistently to 0.20 µm. Over-polishing of extruded material could improve its surface finish, but not for the L-PBF material due to defects and the surrounding micro-strain.

Multiple-Channel Stimulation of the Cochlear Nucleus

1989 ◽  
Vol 101 (6) ◽  
pp. 651-657 ◽  
Author(s):  
David E. Evans ◽  
John K. Niparko ◽  
Josef M. Miller ◽  
Robert W. Jyung ◽  
David J. Anderson
Keyword(s):  
Electric Fields ◽  
Cochlear Nucleus ◽  
Growth Function ◽  
Auditory Brainstem ◽  
Auditory Prosthesis ◽  
Electrode Arrays ◽  
Multiple Channel ◽  
Middle Latency Response ◽  
Latency Response ◽  
Middle Latency

To further test the feasibility of a central nervous system auditory prosthesis, the characteristics of the electrically evoked middle latency response were studied in a series of acutely anesthetized pigmented guinea pigs, with multi-channel penetrating cochlear nucleus electrodes placed into the cochlear nucleus under direct visualization. These stimulating electrodes consisted of a silicone substrate, with five stimulating pads each, sputtered with Iridium. Monopolar and bipolar stimulation were used. Threshold, latency, and input-output functions of the electrically evoked middle latency response were studied. Systematic differences were observed, depending on the site and parameters of stimulation. Principally, higher currents were required to produce waves of equal amplitude when the electrodes were closely spaced. For near electrode pairs, the maximum wave amplitudes obtainable within the limits of tissue safety were much lower than for distant electrode pairs. The slope of the growth function curve was steeper for widely spaced electrodes than for adjacent sites. Monopolar stimulation demonstrated maximum wave amplitudes with the lowst current Intensity, implying current spread to the entire cochlear nucleus with this stimulation montage. In some cases, threshold differences were observed, higher thresholds being associated with closely spaced elecrodes. These findings are consistent with simple models of the electric fields expected to be generated by these electrode arrays. The results support the hypothesis that activtalon of subpopulations of auditory brainstem neurons with multi-channel penetrating microelectrodes is possible.

Abstract 15818: Three-dimensional Electroanatomic Mapping of Human Ventricular Tachycardia

Circulation ◽  
2020 ◽  
Vol 142 (Suppl_3) ◽  
Author(s):  
Terrence Pong ◽  
Kevin J Cyr ◽  
Joy Aparicio Valenzuela ◽  
Meghedi Babakhanian ◽  
Paul J Wang ◽  
...  
Keyword(s):  
Ventricular Tachycardia ◽  
Ex Vivo ◽  
Three Dimensional ◽  
Electroanatomic Mapping ◽  
Electrode Arrays ◽  
Epicardial Mapping ◽  
Spatiotemporal Resolution ◽  
Flexible Electrode ◽  
3D Printed ◽  
Mapping Arrays

Introduction: The localization of sources responsible for erratic ventricular tachycardia signaling can be facilitated by high-resolution epicardial mapping. Here, we describe an approach for epicardial mapping using 3D printed electrode mapping arrays. We utilize these mapping arrays to perform global beat-to-beat epicardial mapping of ex vivo Langendorff perfused human hearts and demonstrate the ability to identify sources of ventricular tachycardia. Hypothesis: The identification of ventricular tachycardia sources can be facilitated by epicardial mapping with 3D printed flexible mapping arrays. Methods: Epicardial shells were printed using a stereolithography 3D printer using flexible photopolymer resin followed by coupling with custom-designed flexible electrode arrays. Global electroanatomic maps were obtained from Langendorff perfused human hearts during sinus rhythm and after extra stimulus pacing induced ventricular tachycardia. Results: We demonstrate the use of 3D-printed electrode mapping arrays to perform global electroanatomic mapping of the human ventricular epicardium. Flexible 3D printed electrode arrays facilitate high spatial-temporal capture of electrophysiological data in Langendorff perfused human hearts and are capable of identifying epicardial sites of ventricular tachycardia. Conclusions: We report on flexible electrode mapping arrays shaped to match the epicardial contours of the human left and right ventricle. We demonstrate the ability to perform high spatiotemporal resolution mapping of human epicardial signals and demonstrate beat-to-beat global capture of ventricular tachycardia.

scholarly journals Electrochemiluminescence at 3D Printed Titanium Electrodes

2021 ◽  
Vol 9 ◽  
Author(s):  
Samantha F. Douman ◽  
Miren Ruiz De Eguilaz ◽  
Loanda R. Cumba ◽  
Stephen Beirne ◽  
Gordon G. Wallace ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Electrode Array ◽  
Active Surface ◽  
Active Surface Area ◽  
Linear Diffusion ◽  
Titanium Electrode ◽  
Heterogeneous Electron Transfer ◽  
A Value ◽  
3D Printed ◽  
The Individual

The fabrication and electrochemical properties of a 3D printed titanium electrode array are described. The array comprises 25 round cylinders (0.015 cm radius, 0.3 cm high) that are evenly separated on a 0.48 × 0.48 cm square porous base (total geometric area of 1.32 cm2). The electrochemically active surface area consists of fused titanium particles and exhibits a large roughness factor ≈17. In acidic, oxygenated solution, the available potential window is from ~-0.3 to +1.2 V. The voltammetric response of ferrocyanide is quasi-reversible arising from slow heterogeneous electron transfer due to the presence of a native/oxidatively formed oxide. Unlike other metal electrodes, both [Ru(bpy)3]1+ and [Ru(bpy)3]3+ can be created in aqueous solutions which enables electrochemiluminescence to be generated by an annihilation mechanism. Depositing a thin gold layer significantly increases the standard heterogeneous electron transfer rate constant, ko, by a factor of ~80 to a value of 8.0 ± 0.4 × 10−3 cm s−1 and the voltammetry of ferrocyanide becomes reversible. The titanium and gold coated arrays generate electrochemiluminescence using tri-propyl amine as a co-reactant. However, the intensity of the gold-coated array is between 30 (high scan rate) and 100-fold (slow scan rates) higher at the gold coated arrays. Moreover, while the voltammetry of the luminophore is dominated by semi-infinite linear diffusion, the ECL response is significantly influenced by radial diffusion to the individual microcylinders of the array.

Separation of Particles Employing Travelling-Wave Electrokinetic Phenomena and Inclined Gravity

2011 ◽  
Vol 222 ◽  
pp. 52-55
Author(s):  
Masanori Eguchi ◽  
Toshitaka Yamakawa ◽  
Takeshi Yamakawa
Keyword(s):  
Electric Fields ◽  
Mass Density ◽  
Travelling Wave ◽  
Electrode Arrays ◽  
Electrokinetic Phenomena ◽  
Micro Particles ◽  
Propulsion Force ◽  
Selective Retention ◽  
Size Of Particles ◽  
Inclined Angle

In travelling-wave electric fields, particles are propelled along electrode arrays by a propulsion force. The propulsion force depends on an applied frequency, voltage and size of particles. In this paper, we present the separation method of micro particles using the propulsion force and inclined gravity. The suspensions of polystyrene beads were used as the method to demonstrate the general application for the selective retention or transportation of particles. The efficiency of the method depends on the size of particles and mass density of particles. Additionally the method can measure the propulsion force on particles by adjusting the inclined angle.

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