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Precision Plating of Human Electrogenic Cells on Microelectrodes Enhanced with Precision Electrodeposited Nano-Porous Platinum for Cell-Based Biosensing Applications
摘要： Microelectrode Arrays are established platforms for biosensing applications; however, limitations in electrode impedance and cell-electrode coupling still exist. In this paper, the SNR of 25 μm diameter gold (Au) microelectrodes was improved by decreasing the impedance with precision electrodeposition. SEM determined that N-P Pt. microelectrodes had nano-porous structures that filled the insulation cylinders. EIS, CV, and RMS noise measurements concluded that the optimized electrodeposition of N-P Pt. led to a lowered impedance of 18.36 kΩ ± 2.6 kΩ at 1 kHz, a larger double layer capacitance of 73 nF, and lowered RMS noise of 2.08 ± 0.16 μV as compared to the values for Au of 159 kΩ ± 28 kΩ at 1 kHz, 17nF, and 3.14 ± 0.42 μV, respectively. Human motoneurons and human cardiomyocytes were cultured on N-P Pt. devices to assess their biocompatibility and signal quality. In order to improve the cell-electrode coupling, a precision plating technique was used. Both cell types were electrically active on devices for up to 10 weeks, demonstrated improved SNR, and expected responses to precision chemical and electrical stimulation. The modification of Au microelectrodes with nanomaterials in combination with precision culturing of human cell types provides cost effective, highly sensitive, well coupled and relevant biosensing platforms for medical and pharmaceutical research.
关键词： Biosensing,human motoneurons,precision plating of cells,MEA,human cardiomyocytes,nano-porous platinum,precision plating of nanomaterials,microelectrodes,human electrogenic cells
更新于2025-09-23 15:22:29
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Electrical activation of degenerated photoreceptors in blind mouse retina elicited network-mediated responses in different types of ganglion cells
摘要： Electrical (e-) stimulation is explored in schemes to rescue the vision of blind people, e.g. those affected by Retinitis Pigmentosa (RP). We e-activated subretinally the surviving degenerated photoreceptors (d-Phrs) of the rd1 mouse (RP model) and evoked visual responses in the blind retina. The e-stimulation was applied with a single platinum/iridium electrode. The d-Phrs (calcium-imaging) and ganglion cells (GC) activity (MEA-recording) were recorded in simultaneous multilayer recordings. The findings of this study confirm that the d-Phrs responded to e-stimulation and modulated the retinal network-activity. The application of blockers revealed that the synaptic interactions were dependent on voltage-gated calcium channels and mediated by the transmitters glutamate and GABA. Moreover, the gap junctions coupled networks promoted the lateral-spread of the e-evoked activity in the outer (~60 μm) and inner (~120 μm) retina. The activated GCs were identified as subtypes of the ON, OFF and ON-OFF classes. In conclusion, d-Phrs are the ideal interface partners for implants to elicit enhanced visual responses at higher temporal and spatial resolution. Furthermore, the retina’s intact circuity at the onset of complete blindness makes it a tempting target when considering the implantation of implants into young patients to provide a seamless transition from blinding to chip-aided vision.
关键词： blind retina,MEA recording,subretinal implant,gap junctions,glutamate,rd1 mouse,calcium imaging,ganglion cells,GABA,electrical stimulation,Retinitis Pigmentosa,degenerated photoreceptors
更新于2025-09-19 17:15:36
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[Institution of Engineering and Technology 7th Brunei International Conference on Engineering and Technology 2018 (BICET 2018) - Bandar Seri Begawan, Brunei (12-14 Nov. 2018)] 7th Brunei International Conference on Engineering and Technology 2018 (BICET 2018) - Impact of RF and leds on plants growth
摘要： In this paper, we present a concept for a compact ultra-wideband multielement antenna (MEA) for massive MIMO indoor base stations. The antenna concept is based on the simultaneous excitation of different characteristic modes on each element of the MEA. This enables an effective 484 port antenna using only 121 physical antenna elements. Thereby, a size reduction of 54% compared to a generic MEA based on crossed dipoles is achieved. The antenna operates in the ultra-wide frequency band of 6–8.5 GHz with a re?ection coef?cient of sii < ?10 dB and the interelement and intraelement mutual coupling of the antenna ports is sji ≤ ?20 dB.
关键词： multielement antenna (MEA),massive multiple-input multiple-output (MIMO),correlation,Characteristic modes
更新于2025-09-19 17:13:59
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Influence of <i>Opa1</i> Mutation on Survival and Function of Retinal Ganglion Cells
摘要： PURPOSE. Mutations in the OPA1 gene cause autosomal dominant optic atrophy (ADOA), a visual disorder associated with degeneration of retinal ganglion cells (RGCs). Here, we characterized the disease progression in a homologous mouse model B6;C3-Opa1329-355del and asked whether the pronounced cell death affects certain RGC types more than others. METHODS. The in?uence of the Opa1 mutation was assessed by morphologic (retina and optic nerve histology) and functional (multielectrode array) methods. RESULTS. The RGC loss of approximately 50% within 18 months was signi?cantly more pronounced in RGCs with small-caliber axons. Small-caliber axon RGCs comprise a variety of functional RGC types. Accordingly, electrophysiological analyses of RGCs did not show a dropout of distinct functional RGC subgroups. However, the response properties of RGCs were affected signi?cantly by the mutation. Surprisingly, these functional changes were different under different luminance conditions (scotopic, mesopic, and photopic). Finally, melanopsin cells are known to be less susceptible to retinal insults. We found that these cells are also spared in the Opa1 mouse model, and demonstrated for the ?rst time that this resistance persisted even when the melanopsin gene had been knocked-out. CONCLUSIONS. Small-caliber axons show a higher vulnerability to the Opa1 mutation in our mouse model for ADOA. Luminance-dependent functional changes suggest an in?uence of the Opa1 mutation on the retinal circuitry upstream of RGCs. Photoresponsive RGCs are protected against cell death due to the Opa1 mutation, but not by melanopsin expression itself.
关键词： retinal ganglion cells,optic nerve,melanopsin,MEA recordings,optic neuropathy
更新于2025-09-04 15:30:14
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Characterization of Retinal Functionality at Different Eccentricities in a Diurnal Rodent
摘要： Although the properties of the neurons of the visual system that process central and peripheral regions of the visual field have been widely researched in the visual cortex and the LGN, they have scarcely been documented for the retina. The retina is the first step in integrating optical signals, and despite considerable efforts to functionally characterize the different types of retinal ganglion cells (RGCs), a clear account of the particular functionality of cells with central vs. peripheral fields is still wanting. Here, we use electrophysiological recordings, gathered from retinas of the diurnal rodent Octodon degus, to show that RGCs with peripheral receptive fields (RF) are larger, faster, and have shorter transient responses. This translates into higher sensitivity at high temporal frequencies and a full frequency bandwidth when compared to RGCs with more central RF. We also observed that imbalances between ON and OFF cell populations are preserved with eccentricity. Finally, the high diversity of functional types of RGCs highlights the complexity of the computational strategies implemented in the early stages of visual processing, which could inspire the development of bio-inspired artificial systems.
关键词： retina,central vs. periphery,MEA,RGCs,spatiotemporal analysis,receptive field properties
更新于2025-09-04 15:30:14