electrode contact
Recently Published Documents


TOTAL DOCUMENTS

191
(FIVE YEARS 49)

H-INDEX

23
(FIVE YEARS 3)

2022 ◽  
Vol 9 (1) ◽  
Author(s):  
Jan Cimbalnik ◽  
Jaromir Dolezal ◽  
Çağdaş Topçu ◽  
Michal Lech ◽  
Victoria S. Marks ◽  
...  

AbstractData comprise intracranial EEG (iEEG) brain activity represented by stereo EEG (sEEG) signals, recorded from over 100 electrode channels implanted in any one patient across various brain regions. The iEEG signals were recorded in epilepsy patients (N = 10) undergoing invasive monitoring and localization of seizures when they were performing a battery of four memory tasks lasting approx. 1 hour in total. Gaze tracking on the task computer screen with estimating the pupil size was also recorded together with behavioral performance. Each dataset comes from one patient with anatomical localization of each electrode contact. Metadata contains labels for the recording channels with behavioral events marked from all tasks, including timing of correct and incorrect vocalization of the remembered stimuli. The iEEG and the pupillometric signals are saved in BIDS data structure to facilitate efficient data sharing and analysis.


PLoS ONE ◽  
2021 ◽  
Vol 16 (12) ◽  
pp. e0260162
Author(s):  
Anneke M. Frankemolle-Gilbert ◽  
Bryan Howell ◽  
Kelsey L. Bower ◽  
Peter H. Veltink ◽  
Tjitske Heida ◽  
...  

Deep brain stimulation (DBS) is an established clinical therapy, and directional DBS electrode designs are now commonly used in clinical practice. Directional DBS leads have the ability to increase the therapeutic window of stimulation, but they also increase the complexity of clinical programming. Therefore, computational models of DBS have become available in clinical software tools that are designed to assist in the identification of therapeutic settings. However, the details of how the DBS model is implemented can influence the predictions of the software. The goal of this study was to compare different methods for representing directional DBS electrodes within finite element volume conductor (VC) models. We evaluated 15 different DBS VC model variants and quantified how their differences influenced estimates on the spatial extent of axonal activation from DBS. Each DBS VC model included the same representation of the brain and head, but the details of the current source and electrode contact were different for each model variant. The more complex VC models explicitly represented the DBS electrode contacts, while the more simple VC models used boundary condition approximations. The more complex VC models required 2–3 times longer to mesh, build, and solve for the DBS voltage distribution than the more simple VC models. Differences in individual axonal activation thresholds across the VC model variants were substantial (-24% to +47%). However, when comparing total activation of an axon population, or estimates of an activation volume, the differences between model variants decreased (-7% to +8%). Nonetheless, the technical details of how the electrode contact and current source are represented in the DBS VC model can directly affect estimates of the voltage distribution and electric field in the brain tissue.


2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Adam Khalifa ◽  
Mohsen Zaeimbashi ◽  
Tony X. Zhou ◽  
Seyed Mahdi Abrishami ◽  
Neville Sun ◽  
...  

AbstractElectrical stimulation via invasive microelectrodes is commonly used to treat a wide range of neurological and psychiatric conditions. Despite its remarkable success, the stimulation performance is not sustainable since the electrodes become encapsulated by gliosis due to foreign body reactions. Magnetic stimulation overcomes these limitations by eliminating the need for a metal-electrode contact. Here, we demonstrate a novel microfabricated solenoid inductor (80 µm × 40 µm) with a magnetic core that can activate neuronal tissue. The characterization and proof-of-concept of the device raise the possibility that micromagnetic stimulation solenoids that are small enough to be implanted within the brain may prove to be an effective alternative to existing electrode-based stimulation devices for chronic neural interfacing applications.


2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Jinzhong Song ◽  
Tianshu Zhou ◽  
Zhonggang Liang ◽  
Ruoxi Liu ◽  
Jianping Guo ◽  
...  

Based on one simulated skin-electrode electrochemical interface, some electrochemical characteristics based on skin-electrode contact pressure (SECP) for dry biomedical electrodes were analysed and applied in this research. First, 14 electrochemical characteristics including 2 static impedance (SI) characteristics, 11 alternating current impedance (ACI) characteristics and one polarization voltage (PV), and 4 SECP characteristics were extracted in one electrochemical evaluation platform, and their correlation trends were statistically analysed. Second, dry biomedical electrode samples developed by the company and the laboratory, including textile electrodes, Apple watch, AMAZFIT rice health bracelet 1S, and stainless steel electrodes, were placed horizontally and vertically on the “skin” surface of the electrochemical evaluation platform, whose polarization voltages were quantitatively analysed. Third, electrocardiogram (ECG) collection circuits based on an impedance transformation (IT) circuit for textile electrodes were designed, and a wearable ECG acquisition device was designed, which could obtain complete ECG signals. Experimental results showed SECP characteristics for dry electrodes had good correlations with static impedance and ACI characteristics and the better correlation values among 2-10 Hz. In addition, polarization voltages in vertical state were smaller in horizontal state for dry biomedical electrodes, and polarization voltage of electrode pair (PVEP) values for Apple watch bottom was always smaller than ones for Apple watch crown and LMF-2 textile electrode. And the skin-electrode contact impedance of IT textile electrodes was less than the traditional textile electrodes.


Crystals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 964
Author(s):  
Der-Yuh Lin ◽  
Hung-Pin Hsu ◽  
Guang-Hsin Liu ◽  
Ting-Zhong Dai ◽  
Yu-Tai Shih

The 2H molybdenum telluride (MoTe2) photodetector structures were made with inserting 1T-MoTe2 interlayer contacts. The optical response properties such as photoconductivity (PC) spectroscopy, illumination intensity dependent photoresponsivity, frequency dependent photocurrent, and time-resolved photoresponse were carried out in this study. In PC spectra, a much higher photoresponsivity of 2H-MoTe2 were observed by inserting 1T-MoTe2 interlayer contact. The frequency dependent photocurrent and time-resolved photoresponse investigations explore the carrier kinetic decay process of MoTe2 with different electrode contact. The Schottky barrier heights (SBH) extracted by thermionic emission theory were also investigated by inserting 1T-MoTe2 interlayer contacts. The results show the potential applicability for photodetection devices based MoTe2 layered transition metal dichalcogenides semiconductors.


2021 ◽  
Author(s):  
Alice Le Gall ◽  
Audrey Chatain ◽  
Ralph D. Lorenz ◽  
Michel Hamelin ◽  
Grégoire Deprez ◽  
...  

<p>Titan, Saturn’s biggest moon, is an ocean world, covered by organic materials and therefore one of the most promising astrobiological target in the Solar System, likely holding clues on the origin of life on Earth. That is why NASA has selected the Dragonfly mission to send in 2027 a rotorcraft lander to Titan and investigate its prebiotic chemistry and habitability.</p> <p> </p> <p>Making multiple flights (up to 24 in 2.5 years, starting in 2034), Dragonfly will explore a variety of locations, from the Shangri-La dune field to the rim of the young impact crater Selk (Lorenz et al., 2018), and therefore sample materials and determine surface properties in different geologic settings. The two permittivity probes - called DIEL- on board the Geophysical and Meteorological package (DraGMet) will be especially useful to characterize Dragonfly landing site environment.</p> <p> </p> <p>DIEL<strong> </strong>consist of 2 electrodes acting as self-impedance permittivity probes. They will be mounted on each skid of the Dragonfly rotorcraft and operate independently for sake of redundancy and safety. Their objective is to measure the complex ground permittivity at several low frequencies (<10 kHz) which will provide clues on the composition, moisture and porosity of the near-subsurface of Titan as well as on the spatial and temporal variations of such properties. As a reminder, the first permittivity probe on Titan (actually the first ever planetary permittivity probe) successfully determined the complex permittivity of the Huygens landing site in 2005 (Grard et al, 2006; Hamelin et al. 2016).</p> <p> </p> <p>During this presentation, we will describe the tests that have been performed on prototypes of the DIEL electrode plates in order to estimate their sounding depth and sensitivity to composition variations. Tests were performed e.g., with the electrode lying on reference plastic slabs and natural materials (air, sand, soil, liquid water, etc.) of well-known complex permittivity, at ambient and Titan temperatures. The effect of porosity and of a bad ground-electrode contact was also investigated leading to suggestions to optimize DIEL electrode design, accommodation and performance.</p> <p> </p> <p>Indeed, the design of the DIEL experiments (size, shape, accommodation of the electrodes, modes of operation ect.) is not frozen yet and we are also conducting modelling simulations with COMSOL Multiphysics © to explore possible better designs and confirm the results obtained in laboratory.</p> <p> </p> <p>Lastly, in order to relate DIEL measurements to the ground composition, it is crucial to know the electrical properties of materials relevant to Titan’s surface. This is the purpose of the PAP (Permittivité d’Analogues Planétaires) measurement bench that have been developed at LATMOS. This bench includes a cryostat to perform measurements at Titan’s temperature (90 K). It was successfully used to investigate the complex permittivity of analogs of Titan’s organic aerosols called “tholins” (Lethuillier et al., 2018). Future measurements will focus on “eroded” tholins, that is tholins that have been modified during their descent to the surface by processes analogous to those at play in Titan’s atmosphere: UV radiations (Carrasco et al., 2018), interaction with ionosphere’s charged particles (Chatain et al., 2020), deposition of ice in the low stratosphere (Fleury et al., 2019; Dubois et al., 2020), wetting by droplets of liquid methane in the troposphere etc.</p> <p> </p> <p><strong>References</strong></p> <p>Beghin et al., <em>Icarus</em> 218 (2012)</p> <p>Carrasco et al., Nature Astronomy, Nature Publishing Group (2018)</p> <p>Chatain et al., Icarus 345 (2020)</p> <p>Dubois et al., Icarus 338 (2016)</p> <p>Hamelin et al., Icarus 270 (2016)</p> <p>Grard et al., Planet. Space Sciences 54 (2006)</p> <p>Fleury et al., Icarus 321 (2019)</p> <p>Lethuillier et al., Astronomy & Astrophysics 519 (2018)</p> <p>Lorenz et al., <em>Johns Hopkins APL Technical Digest</em> 34 (2018)</p> <p> </p>


Photonics ◽  
2021 ◽  
Vol 8 (7) ◽  
pp. 272
Author(s):  
Bingfei Dou ◽  
Rui Jia ◽  
Zhao Xing ◽  
Xiaojiang Yao ◽  
Dongping Xiao ◽  
...  

Light-trapping nanostructures have been widely used for improving solar cells’ performance, but the higher surface recombination and poor electrode contact introduced need to be addressed. In this work, silicon nanostructures were synthesized via silver-catalyzed etching to texturize solar cells. Atomic-layer-deposited Al2O3 passivated the nanotextured cells. A surface recombination velocity of 126 cm/s was obtained, much lower than the 228 cm/s of the SiNX-passivated one. Additionally, the open-circuit voltage (VOC) of the nanotextured cells improved significantly from 582 to 610 mV, as did the short-circuit current (JSC) from 25.5 to 31 mA/cm2. Furthermore, the electrode contact property was enhanced by light-induced plating. A best efficiency of 13.3% for nano-textured cells was obtained, which is higher than the planar cell’s 12%.


2021 ◽  
Vol 12 ◽  
Author(s):  
Myung Ji Kim ◽  
Kyung Won Chang ◽  
So Hee Park ◽  
Won Seok Chang ◽  
Hyun Ho Jung ◽  
...  

Deep brain stimulation (DBS) targeting the ventralis intermedius (VIM) nucleus of the thalamus and the posterior subthalamic area (PSA) has been shown to be an effective treatment for essential tremor (ET). The aim of this study was to compare the stimulation-induced side effects of DBS targeting the VIM and PSA using a single electrode. Patients with medication-refractory ET who underwent DBS electrode implantation between July 2011 and October 2020 using a surgical technique that simultaneously targets the VIM and PSA with a single electrode were enrolled in this study. A total of 93 patients with ET who had 115 implanted DBS electrodes (71 unilateral and 22 bilateral) were enrolled. The Clinical Rating Scale for Tremor (CRST) subscores improved from 20.0 preoperatively to 4.3 (78.5% reduction) at 6 months, 6.3 (68.5% reduction) at 1 year, and 6.5 (67.5% reduction) at 2 years postoperation. The best clinical effect was achieved in the PSA at significantly lower stimulation amplitudes. Gait disturbance and clumsiness in the leg was found in 13 patients (14.0%) upon stimulation of the PSA and in significantly few patients upon stimulation of the VIM (p = 0.0002). Fourteen patients (15.1%) experienced dysarthria when the VIM was stimulated; this number was significantly more than that with PSA stimulation (p = 0.0233). Transient paresthesia occurred in 13 patients (14.0%) after PSA stimulation and in six patients (6.5%) after VIM stimulation. Gait disturbance and dysarthria were significantly more prevalent in patients undergoing bilateral DBS than in those undergoing unilateral DBS (p = 0.00112 and p = 0.0011, respectively). Paresthesia resolved either after reducing the amplitude or switching to bipolar stimulation. However, to control gait disturbance and dysarthria, some loss of optimal tremor control was necessary at that particular electrode contact. In the present study, the most common stimulation-induced side effect associated with VIM DBS was dysarthria, while that associated with PSA DBS was gait disturbance. Significantly, more side effects were associated with bilateral DBS than with unilateral DBS. Therefore, changing active DBS contacts to simultaneous targeting of the VIM and PSA may be especially helpful for ameliorating stimulation-induced side effects.


BJPsych Open ◽  
2021 ◽  
Vol 7 (S1) ◽  
pp. S11-S11
Author(s):  
Paul M Briley ◽  
Sudheer Lankappa

AimsTo assess patient and clinician acceptability of handheld 6-lead ECG, for obtaining information about cardiac rhythm and electrical intervals, in acute general adult mental health ward inpatients who refuse traditional 12-lead ECG.BackgroundIn a previous audit of patients admitted to four acute general adult mental health wards, we found that 1 in 4 patients refused 12-lead ECG for at least two weeks, with 1 in 6 refusing throughout their entire stay. ECG refusers were significantly more likely to have a psychotic illness than non-refusers and were thus more likely to benefit from medications that carry a risk of prolonging the QT interval. Less invasive, handheld, 6-lead ECG, which includes measurement of lead II (the lead used to define traditional QT-interval cut-off values) is available on the NHS supply chain. Whilst not providing the full range of information that 12-lead ECG is able to provide, handheld 6-lead ECG might be an acceptable alternative in patients who would otherwise never have any form of ECG performed.MethodWe developed a Standard Operating Procedure for use of handheld 6-lead ECG and provided training for junior doctors on the four wards that were the subject of our original audit. These doctors were then able to offer the device to patients on their wards who refused 12-lead ECG. Doctors completed a short feedback form each time a handheld ECG was offered.ResultSo far, handheld 6-lead ECGs have been offered to 17 patients who refused 12-lead ECGs. Mean age (± SD) was 36.1 (± 12.6) years, and 4 of these patients were female. 13 patients (76%) accepted a handheld ECG. One of these attempts failed due to patient agitation. Attempts took a mean of 7 (± 5.4) minutes. 54% of recordings were described as “very easy” by clinicians, whereas 15%, 23% and 8% were described as “somewhat easy”, “intermediate”, and “somewhat difficult”, respectively. Clinician difficulties focussed on patient movement with impact on electrode contact and trace quality. Where answered (N = 10), 90% of patients stated they would recommend a handheld ECG to others. Patients liked the speed of the process, that it felt “less scary”, and that it was less invasive and did not involve removing clothing.ConclusionOur initial findings from this pilot suggest that handheld 6-lead ECG may be acceptable, both to clinicians and patients, as a means of obtaining information on cardiac rhythm and electrical intervals for patients who refuse 12-lead ECGs.


Sign in / Sign up

Export Citation Format

Share Document