The Experts below are selected from a list of 27423 Experts worldwide ranked by ideXlab platform
Shizhi Qian - One of the best experts on this subject based on the ideXlab platform.
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a cell electrofusion microfluidic chip with micro cavity Microelectrode array
Microfluidics and Nanofluidics, 2013Co-Authors: Xiaoling Zhang, Jun Yang, Sang W. Joo, Shizhi QianAbstract:A new cell electrofusion microfluidic chip with 19,000 pairs of micro-cavity structures patterned on vertical sidewalls of a serpentine-shaped microchannel has been designed and fabricated. In each micro-cavity structure, the two sidewalls perpendicular to the microchannel are made of SiO2 insulator, and that parallel to the microchannel is made of silicon as the Microelectrode. One purpose of the design with micro-cavity Microelectrode array is to obtain high membrane voltage occurring at the contact point of two paired cells, where cell fusion takes place. The device was tested to electrofuse NIH3T3 and myoblast cells under a relatively low voltage (~9 V). Under an AC electric field applied between the pair of Microelectrodes positioned in the opposite micro-cavities, about 85–90 % micro-cavities captured cells, and about 60 % micro-cavities are effectively capable of trapping the desired two-cell pairs. DC electric pulses of low voltage (~9 V) were subsequently applied between the micro-cavity Microelectrode arrays to induce electrofusion. Due to the concentration of the local electric field near the micro-cavity structure, fusion efficiency reaches about 50 % of total cells loaded into the device. Multi-cell electrofusion and membrane rupture at the end of cell chains are eliminated through the present novel design.
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a high throughput dielectrophoresis based cell electrofusion microfluidic device
Electrophoresis, 2011Co-Authors: Jun Yang, Zhengqin Yin, Irina Svir, Shizhi Qian, Bin Xia, Jiawen Yan, Wensheng Hou, Xiaolin ZhengAbstract:A high-throughput cell electrofusion microfluidic chip has been designed, fabricated on a silicon-on-insulator wafer and tested for in vitro cell fusion under a low applied voltage. The developed chip consists of six individual straight microchannels with a 40-μm thickness conductive highly doped Si layer as the microchannel wall. In each microchannel, there are 75 pairs of counter protruding Microelectrodes, between which the cell electrofusion is performed. The entire highly doped Si layer is covered by a 2-μm thickness aluminum film to maintain a consistent electric field between different protruding Microelectrode pairs. A 150-nm thickness SiO₂ film is subsequently deposited on the top face of each protruding Microelectrode for better biocompatibility. Owing to the short distance between two counter protruding Microelectrodes, a high electric field can be generated for cell electrofusion with a low voltage imposed across the electrodes. Both mammalian cells and plant protoplasts were used to test the cell electrofusion. About 42-68% cells were aligned to form cell-cell pairs by the dielectrophoretic force. After cell alignment, cell pairs were fused to form hybrid cells under the control of cell electroporation and electrofusion signals. The averaged fusion efficiency in the paired cells is above 40% (the highest was about 60%), which is much higher than the traditional polyethylene glycol method (<5%) and traditional electrofusion methods (∼12%). An individual cell electrofusion process could be completed within 10 min, indicating a capability of high throughput.
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a cell electrofusion microfluidic device integrated with 3d thin film Microelectrode arrays
Biomicrofluidics, 2011Co-Authors: Jun Yang, Sang W. Joo, Shizhi Qian, Xiaolin ZhengAbstract:A microfluidic device integrated with 3D thin film Microelectrode arrays wrapped around serpentine-shaped microchannel walls has been designed, fabricated and tested for cell electrofusion. Each Microelectrode array has 1015 discrete Microelectrodes patterned on each side wall, and the adjacent Microelectrodes are separated by coplanar dielectric channel wall. The device was tested to electrofuse K562 cells under a relatively low voltage. Under an AC electric field applied between the pair of the Microelectrode arrays, cells are paired at the edge of each discrete Microelectrode due to the induced positive dielectrophoresis. Subsequently, electric pulse signals are sequentially applied between the Microelectrode arrays to induce electroporation and electrofusion. Compared to the design with thin film Microelectrode arrays deposited at the bottom of the side walls, the 3D thin film Microelectrode array could induce electroporation and electrofusion under a lower voltage. The staggered electrode arrays on opposing side walls induce inhomogeneous electric field distribution, which could avoid multi-cell fusion. The alignment and pairing efficiencies of K562 cells in this device were 99% and 70.7%, respectively. The electric pulse of low voltage (∼9 V) could induce electrofusion of these cells, and the fusion efficiency was about 43.1% of total cells loaded into the device, which is much higher than that of the convectional and most existing microfluidics-based electrofusion devices.
Xiaolin Zheng - One of the best experts on this subject based on the ideXlab platform.
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a high throughput dielectrophoresis based cell electrofusion microfluidic device
Electrophoresis, 2011Co-Authors: Jun Yang, Zhengqin Yin, Irina Svir, Shizhi Qian, Bin Xia, Jiawen Yan, Wensheng Hou, Xiaolin ZhengAbstract:A high-throughput cell electrofusion microfluidic chip has been designed, fabricated on a silicon-on-insulator wafer and tested for in vitro cell fusion under a low applied voltage. The developed chip consists of six individual straight microchannels with a 40-μm thickness conductive highly doped Si layer as the microchannel wall. In each microchannel, there are 75 pairs of counter protruding Microelectrodes, between which the cell electrofusion is performed. The entire highly doped Si layer is covered by a 2-μm thickness aluminum film to maintain a consistent electric field between different protruding Microelectrode pairs. A 150-nm thickness SiO₂ film is subsequently deposited on the top face of each protruding Microelectrode for better biocompatibility. Owing to the short distance between two counter protruding Microelectrodes, a high electric field can be generated for cell electrofusion with a low voltage imposed across the electrodes. Both mammalian cells and plant protoplasts were used to test the cell electrofusion. About 42-68% cells were aligned to form cell-cell pairs by the dielectrophoretic force. After cell alignment, cell pairs were fused to form hybrid cells under the control of cell electroporation and electrofusion signals. The averaged fusion efficiency in the paired cells is above 40% (the highest was about 60%), which is much higher than the traditional polyethylene glycol method (<5%) and traditional electrofusion methods (∼12%). An individual cell electrofusion process could be completed within 10 min, indicating a capability of high throughput.
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a cell electrofusion microfluidic device integrated with 3d thin film Microelectrode arrays
Biomicrofluidics, 2011Co-Authors: Jun Yang, Sang W. Joo, Shizhi Qian, Xiaolin ZhengAbstract:A microfluidic device integrated with 3D thin film Microelectrode arrays wrapped around serpentine-shaped microchannel walls has been designed, fabricated and tested for cell electrofusion. Each Microelectrode array has 1015 discrete Microelectrodes patterned on each side wall, and the adjacent Microelectrodes are separated by coplanar dielectric channel wall. The device was tested to electrofuse K562 cells under a relatively low voltage. Under an AC electric field applied between the pair of the Microelectrode arrays, cells are paired at the edge of each discrete Microelectrode due to the induced positive dielectrophoresis. Subsequently, electric pulse signals are sequentially applied between the Microelectrode arrays to induce electroporation and electrofusion. Compared to the design with thin film Microelectrode arrays deposited at the bottom of the side walls, the 3D thin film Microelectrode array could induce electroporation and electrofusion under a lower voltage. The staggered electrode arrays on opposing side walls induce inhomogeneous electric field distribution, which could avoid multi-cell fusion. The alignment and pairing efficiencies of K562 cells in this device were 99% and 70.7%, respectively. The electric pulse of low voltage (∼9 V) could induce electrofusion of these cells, and the fusion efficiency was about 43.1% of total cells loaded into the device, which is much higher than that of the convectional and most existing microfluidics-based electrofusion devices.
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electric field simulation of high throughput cell electrofusion chip
Chinese Journal of Analytical Chemistry, 2008Co-Authors: Yi Cao, Jun Yang, Zhengqin Yin, Xiaolin Zheng, Wensheng Hou, H U Ning, Jing Yang, X U Rong, Ruiqiang ZhangAbstract:Abstract The electric field profile within a cell-fusion chip is of great significance for cell manipulation and cell-fusion efficiency, which is a main factor considered in chip design. This profile is mainly decided by the channel geometry and Microelectrode structure. In the cell-fusion chip, the Microelectrode array which was composed of a large number of Microelectrodes was used to obtain high cell-fusion efficiency. Its simulation was difficult because there were many electrodes, complex channel geometry and Microelectrode structure on this chip. ANSYS software was used in this study to simulate the electric field profile (strength and gradient) in the cell fusion chip. Comparison between different designs, the layout of electrodes was optimized and an interdigital, pectinate, rectangular Microelectrode arrays were selected as the main components of the cell-electrofusion chip. In the preliminary experiments on this chip prototype, many plant protoplasts could be fused simultaneously. The fusion efficiency (about 40%) was much larger than those in traditional chemical induced fusion (
Luciano Fadiga - One of the best experts on this subject based on the ideXlab platform.
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highly stable glassy carbon interfaces for long term neural stimulation and low noise recording of brain activity
Scientific Reports, 2017Co-Authors: Maria Vomero, Emma Maggiolini, Elisa Castagnola, Luciano Fadiga, Francesca Ciarpella, Noah Goshi, Elena Zucchini, Stefano CarliAbstract:We report on the superior electrochemical properties, in-vivo performance and long term stability under electrical stimulation of a new electrode material fabricated from lithographically patterned glassy carbon. For a direct comparison with conventional metal electrodes, similar ultra-flexible, micro-electrocorticography (μ-ECoG) arrays with platinum (Pt) or glassy carbon (GC) electrodes were manufactured. The GC Microelectrodes have more than 70% wider electrochemical window and 70% higher CTC (charge transfer capacity) than Pt Microelectrodes of similar geometry. Moreover, we demonstrate that the GC Microelectrodes can withstand at least 5 million pulses at 0.45 mC/cm2 charge density with less than 7.5% impedance change, while the Pt Microelectrodes delaminated after 1 million pulses. Additionally, poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT-PSS) was selectively electrodeposited on both sets of devices to specifically reduce their impedances for smaller diameters (<60 μm). We observed that PEDOT-PSS adhered significantly better to GC than Pt, and allowed drastic reduction of electrode size while maintaining same amount of delivered current. The electrode arrays biocompatibility was demonstrated through in-vitro cell viability experiments, while acute in vivo characterization was performed in rats and showed that GC Microelectrode arrays recorded somatosensory evoked potentials (SEP) with an almost twice SNR (signal-to-noise ratio) when compared to the Pt ones.
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carbon nanotube composite coating of neural Microelectrodes preferentially improves the multiunit signal to noise ratio
Journal of Neural Engineering, 2011Co-Authors: Gytis Baranauskas, Emma Maggiolini, Elisa Castagnola, Alberto Ansaldo, Alberto Mazzoni, Gian Nicola Angotzi, Alessandro Vato, Davide Ricci, Stefano Panzeri, Luciano FadigaAbstract:Extracellular metal Microelectrodes are widely used to record single neuron activity in vivo. However, their signal-to-noise ratio (SNR) is often far from optimal due to their high impedance value. It has been recently reported that carbon nanotube (CNT) coatings may decrease Microelectrode impedance, thus improving their performance. To tease out the different contributions to SNR of CNT-coated Microelectrodes we carried out impedance and noise spectroscopy measurements of platinum/tungsten Microelectrodes coated with a polypyrrole–CNT composite. Neuronal signals were recorded in vivo from rat cortex by employing tetrodes with two recording sites coated with polypyrrole–CNT and the remaining two left untreated. We found that polypyrrole–CNT coating significantly reduced the Microelectrode impedance at all neuronal signal frequencies (from 1 to 10 000 Hz) and induced a significant improvement of the SNR, up to fourfold on average, in the 150–1500 Hz frequency range, largely corresponding to the multiunit frequency band. An equivalent circuit, previously proposed for porous conducting polymer coatings, reproduced the impedance spectra of our coated electrodes but could not explain the frequency dependence of SNR improvement following polypyrrole–CNT coating. This implies that neither the neural signal amplitude, as recorded by a CNT-coated metal Microelectrode, nor noise can be fully described by the equivalent circuit model we used here and suggests that a more detailed approach may be needed to better understand the signal propagation at the electrode–solution interface. Finally, the presence of significant noise components that are neither thermal nor electronic makes it difficult to establish a direct relationship between the actual electrode noise and the impedance spectra.
Jun Yang - One of the best experts on this subject based on the ideXlab platform.
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a cell electrofusion microfluidic chip with micro cavity Microelectrode array
Microfluidics and Nanofluidics, 2013Co-Authors: Xiaoling Zhang, Jun Yang, Sang W. Joo, Shizhi QianAbstract:A new cell electrofusion microfluidic chip with 19,000 pairs of micro-cavity structures patterned on vertical sidewalls of a serpentine-shaped microchannel has been designed and fabricated. In each micro-cavity structure, the two sidewalls perpendicular to the microchannel are made of SiO2 insulator, and that parallel to the microchannel is made of silicon as the Microelectrode. One purpose of the design with micro-cavity Microelectrode array is to obtain high membrane voltage occurring at the contact point of two paired cells, where cell fusion takes place. The device was tested to electrofuse NIH3T3 and myoblast cells under a relatively low voltage (~9 V). Under an AC electric field applied between the pair of Microelectrodes positioned in the opposite micro-cavities, about 85–90 % micro-cavities captured cells, and about 60 % micro-cavities are effectively capable of trapping the desired two-cell pairs. DC electric pulses of low voltage (~9 V) were subsequently applied between the micro-cavity Microelectrode arrays to induce electrofusion. Due to the concentration of the local electric field near the micro-cavity structure, fusion efficiency reaches about 50 % of total cells loaded into the device. Multi-cell electrofusion and membrane rupture at the end of cell chains are eliminated through the present novel design.
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a high throughput dielectrophoresis based cell electrofusion microfluidic device
Electrophoresis, 2011Co-Authors: Jun Yang, Zhengqin Yin, Irina Svir, Shizhi Qian, Bin Xia, Jiawen Yan, Wensheng Hou, Xiaolin ZhengAbstract:A high-throughput cell electrofusion microfluidic chip has been designed, fabricated on a silicon-on-insulator wafer and tested for in vitro cell fusion under a low applied voltage. The developed chip consists of six individual straight microchannels with a 40-μm thickness conductive highly doped Si layer as the microchannel wall. In each microchannel, there are 75 pairs of counter protruding Microelectrodes, between which the cell electrofusion is performed. The entire highly doped Si layer is covered by a 2-μm thickness aluminum film to maintain a consistent electric field between different protruding Microelectrode pairs. A 150-nm thickness SiO₂ film is subsequently deposited on the top face of each protruding Microelectrode for better biocompatibility. Owing to the short distance between two counter protruding Microelectrodes, a high electric field can be generated for cell electrofusion with a low voltage imposed across the electrodes. Both mammalian cells and plant protoplasts were used to test the cell electrofusion. About 42-68% cells were aligned to form cell-cell pairs by the dielectrophoretic force. After cell alignment, cell pairs were fused to form hybrid cells under the control of cell electroporation and electrofusion signals. The averaged fusion efficiency in the paired cells is above 40% (the highest was about 60%), which is much higher than the traditional polyethylene glycol method (<5%) and traditional electrofusion methods (∼12%). An individual cell electrofusion process could be completed within 10 min, indicating a capability of high throughput.
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a cell electrofusion microfluidic device integrated with 3d thin film Microelectrode arrays
Biomicrofluidics, 2011Co-Authors: Jun Yang, Sang W. Joo, Shizhi Qian, Xiaolin ZhengAbstract:A microfluidic device integrated with 3D thin film Microelectrode arrays wrapped around serpentine-shaped microchannel walls has been designed, fabricated and tested for cell electrofusion. Each Microelectrode array has 1015 discrete Microelectrodes patterned on each side wall, and the adjacent Microelectrodes are separated by coplanar dielectric channel wall. The device was tested to electrofuse K562 cells under a relatively low voltage. Under an AC electric field applied between the pair of the Microelectrode arrays, cells are paired at the edge of each discrete Microelectrode due to the induced positive dielectrophoresis. Subsequently, electric pulse signals are sequentially applied between the Microelectrode arrays to induce electroporation and electrofusion. Compared to the design with thin film Microelectrode arrays deposited at the bottom of the side walls, the 3D thin film Microelectrode array could induce electroporation and electrofusion under a lower voltage. The staggered electrode arrays on opposing side walls induce inhomogeneous electric field distribution, which could avoid multi-cell fusion. The alignment and pairing efficiencies of K562 cells in this device were 99% and 70.7%, respectively. The electric pulse of low voltage (∼9 V) could induce electrofusion of these cells, and the fusion efficiency was about 43.1% of total cells loaded into the device, which is much higher than that of the convectional and most existing microfluidics-based electrofusion devices.
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electric field simulation of high throughput cell electrofusion chip
Chinese Journal of Analytical Chemistry, 2008Co-Authors: Yi Cao, Jun Yang, Zhengqin Yin, Xiaolin Zheng, Wensheng Hou, H U Ning, Jing Yang, X U Rong, Ruiqiang ZhangAbstract:Abstract The electric field profile within a cell-fusion chip is of great significance for cell manipulation and cell-fusion efficiency, which is a main factor considered in chip design. This profile is mainly decided by the channel geometry and Microelectrode structure. In the cell-fusion chip, the Microelectrode array which was composed of a large number of Microelectrodes was used to obtain high cell-fusion efficiency. Its simulation was difficult because there were many electrodes, complex channel geometry and Microelectrode structure on this chip. ANSYS software was used in this study to simulate the electric field profile (strength and gradient) in the cell fusion chip. Comparison between different designs, the layout of electrodes was optimized and an interdigital, pectinate, rectangular Microelectrode arrays were selected as the main components of the cell-electrofusion chip. In the preliminary experiments on this chip prototype, many plant protoplasts could be fused simultaneously. The fusion efficiency (about 40%) was much larger than those in traditional chemical induced fusion (
Urs Frey - One of the best experts on this subject based on the ideXlab platform.
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revealing neuronal function through Microelectrode array recordings
Frontiers in Neuroscience, 2015Co-Authors: Marie Engelene J Obien, Urs Frey, Kosmas Deligkaris, Torsten Bullmann, Douglas J BakkumAbstract:Microelectrode arrays and microprobes have been widely utilized to measure neuronal activity, both in vitro and in vivo. The key advantage is the capability to record and stimulate neurons at multiple sites simultaneously. However, unlike the single-cell or single-channel resolution of intracellular recording, Microelectrodes detect signals from all possible sources around the sensor. Here, we review the current understanding of Microelectrode signals and the techniques for analyzing them. We introduce the ongoing advancements in Microelectrode technology, with focus on achieving higher resolution and quality of recordings by means of monolithic integration with on-chip circuitry. We show how recent advanced Microelectrode array measurement methods facilitate the understanding of single neurons as well as network function.
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growing cells atop microelectronic chips interfacing electrogenic cells in vitro with cmos based Microelectrode arrays
Proceedings of the IEEE, 2011Co-Authors: Andreas Hierlemann, Urs Frey, S Hafizovic, F HeerAbstract:Complementary semiconductor-metal-oxide (CMOS) technology is a very powerful technology that can be more or less directly interfaced to electrogenic cells, like heart or brain cells in vitro. To this end, the cells are cultured directly atop the CMOS chips, which usually undergo dedicated postprocessing to obtain a reliable bidirectional interface via noble-metal Microelectrodes or high-k dielectrics. The big advantages of using CMOS integrated circuits (ICs) include connectivity, the possibility to address a large number of Microelectrodes on a tiny chip, and signal quality, the possibility to condition small signals right at the spot of their generation. CMOS will be demonstrated to constitute an enabling technology that opens a route to high-spatio-temporal-resolution and low-noise electrophysiological recordings from a variety of biological preparations, such as brain slices, or cultured cardiac and brain cells. The recording technique is extracellular and noninvasive, and the CMOS chips do not leak out any toxic compounds, so that the cells remain viable for extended times. In turn, the CMOS chips have been demonstrated to survive several months of culturing while being fully immersed in saline solution and being exposed to cellular metabolic products. The latter requires dedicated passivation and packaging techniques as will be shown. Fully integrated, monolithic Microelectrode systems, which feature large numbers of tightly spaced Microelectrodes and the associated circuitry units for bidirectional interaction (stimulation and recording), will be in the focus of this review. The respective dense Microelectrode arrays (MEAs) with small pixels enable subcellular-resolution investigation of regions of interest in, e.g., neurobiological preparations, and, at the same time, the large number of electrodes allows for studying the activity of entire neuronal networks . Application areas include neuroscience, as the devices enable fundamental neurophysiological insights at the cellular and circuit level, as well as medical diagnostics and pharmacology.
