scholarly journals Silicon Carbide and MRI: Towards Developing a MRI Safe Neural Interface

Micromachines ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 126
Author(s):  
Mohammad Beygi ◽  
William Dominguez-Viqueira ◽  
Chenyin Feng ◽  
Gokhan Mumcu ◽  
Christopher Frewin ◽  
...  
Keyword(s):  
Silicon Carbide ◽  
Brain Tissue ◽  
High Field ◽  
Neural Interface ◽  
Image Artifacts ◽  
Mri Imaging ◽  
Neural Implants ◽  
Free Standing ◽  
High Field Mri ◽  
Sic Films

An essential method to investigate neuromodulation effects of an invasive neural interface (INI) is magnetic resonance imaging (MRI). Presently, MRI imaging of patients with neural implants is highly restricted in high field MRI (e.g., 3 T and higher) due to patient safety concerns. This results in lower resolution MRI images and, consequently, degrades the efficacy of MRI imaging for diagnostic purposes in these patients. Cubic silicon carbide (3C-SiC) is a biocompatible wide-band-gap semiconductor with a high thermal conductivity and magnetic susceptibility compatible with brain tissue. It also has modifiable electrical conductivity through doping level control. These properties can improve the MRI compliance of 3C-SiC INIs, specifically in high field MRI scanning. In this work, the MRI compliance of epitaxial SiC films grown on various Si wafers, used to implement a monolithic neural implant (all-SiC), was studied. Via finite element method (FEM) and Fourier-based simulations, the specific absorption rate (SAR), induced heating, and image artifacts caused by the portion of the implant within a brain tissue phantom located in a 7 T small animal MRI machine were estimated and measured. The specific goal was to compare implant materials; thus, the effect of leads outside the tissue was not considered. The results of the simulations were validated via phantom experiments in the same 7 T MRI system. The simulation and experimental results revealed that free-standing 3C-SiC films had little to no image artifacts compared to silicon and platinum reference materials inside the MRI at 7 T. In addition, FEM simulations predicted an ~30% SAR reduction for 3C-SiC compared to Pt. These initial simulations and experiments indicate an all-SiC INI may effectively reduce MRI induced heating and image artifacts in high field MRI. In order to evaluate the MRI safety of a closed-loop, fully functional all-SiC INI as per ISO/TS 10974:2018 standard, additional research and development is being conducted and will be reported at a later date.

scholarly journals Strain Tensor Imaging: Cardiac-induced brain tissue deformation in humans quantified with high-field MRI

NeuroImage ◽  
2021 ◽  
pp. 118078
Author(s):  
Jacob-Jan Sloots ◽  
Geert Jan Biessels ◽  
Alberto de Luca ◽  
Jaco J.M. Zwanenburg
Keyword(s):  
Brain Tissue ◽  
High Field ◽  
Strain Tensor ◽  
Tissue Deformation ◽  
High Field Mri

Hardness and Young's modulus of amorphous a-SiC thin films determined by nanoindentation and bulge tests

1994 ◽  
Vol 9 (1) ◽  
pp. 96-103 ◽  
Author(s):  
M.A. El Khakani ◽  
M. Chaker ◽  
A. Jean ◽  
S. Boily ◽  
J.C. Kieffer ◽  
...  
Keyword(s):  
Thin Films ◽  
Mechanical Properties ◽  
Silicon Carbide ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Chemical Vapor ◽  
Free Standing ◽  
Film Composition ◽  
Sputtering Deposition ◽  
Sic Films

Due to its interesting mechanical properties, silicon carbide is an excellent material for many applications. In this paper, we report on the mechanical properties of amorphous hydrogenated or hydrogen-free silicon carbide thin films deposited by using different deposition techniques, namely plasma enhanced chemical vapor deposition (PECVD), laser ablation deposition (LAD), and triode sputtering deposition (TSD). a-SixC1−x: H PECVD, a-SiC LAD, and a-SiC TSD thin films and corresponding free-standing membranes were mechanically investigated by using nanoindentation and bulge techniques, respectively. Hardness (H), Young's modulus (E), and Poisson's ratio (v) of the studied silicon carbide thin films were determined. It is shown that for hydrogenated a-SixC1−x: H PECVD films, both hardness and Young's modulus are dependent on the film composition. The nearly stoichiometric a-SiC: H films present higher H and E values than the Si-rich a-SixC1−x: H films. For hydrogen-free a-SiC films, the hardness and Young's modulus were as high as about 30 GPa and 240 GPa, respectively. Hydrogen-free a-SiC films present both hardness and Young's modulus values higher by about 50% than those of hydrogenated a-SiC: H PECVD films. By using the FTIR absorption spectroscopy, we estimated the Si-C bond densities (NSiC) from the Si-C stretching absorption band (centered around 780 cm−1), and were thus able to correlate the observed mechanical behavior of a-SiC films to their microstructure. We indeed point out a constant-plus-linear variation of the hardness and Young's modulus upon the Si-C bond density, over the NSiC investigated range [(4–18) × 1022 bond · cm−3], regardless of the film composition or the deposition technique.

Resection Control in Trans-sphenoidal Surgery of Pituitary Macroadenoma by Intraoperative High-Field MRI

Skull Base ◽  
2005 ◽  
Vol 15 (S 2) ◽  
Author(s):  
Boris von Keller ◽  
R. Fahlbusch ◽  
O. Ganslandt ◽  
C. Nimsky
Keyword(s):  
High Field ◽  
Pituitary Macroadenoma ◽  
High Field Mri ◽  
Resection Control ◽  
In Trans

Grading lumbar disc degeneration: a comparison between low- and high-field MRI

2019 ◽  
Vol 60 (12) ◽  
pp. 1636-1642 ◽  
Author(s):  
Bjarke B Hansen ◽  
Urszula M Ciochon ◽  
Charlotte R Trampedach ◽  
Anders F Christensen ◽  
Zoreh Rasti ◽  
...  
Keyword(s):  
Disc Degeneration ◽  
High Field ◽  
Lumbar Disc ◽  
Lumbar Disc Degeneration ◽  
High Field Mri

scholarly journals Comparison of T1wFLAIR and T1wTSE sequences in imaging the brain of small animals using high-field MRI

2019 ◽  
Vol 72 (1) ◽  
Author(s):  
Chiara Bergamino ◽  
Séamus Hoey ◽  
Kenneth Waller ◽  
Cliona Skelly
Keyword(s):  
High Field ◽  
Small Animals ◽  
High Field Mri ◽  
The Brain

scholarly journals Effect of radiofrequency shield diameter on signal‐to‐noise ratio at ultra‐high field MRI

2021 ◽  
Vol 85 (6) ◽  
pp. 3522-3530
Author(s):  
Bei Zhang ◽  
Gregor Adriany ◽  
Lance Delabarre ◽  
Jerahmie Radder ◽  
Russell Lagore ◽  
...  
Keyword(s):  
High Field ◽  
Signal To Noise Ratio ◽  
Signal To Noise ◽  
Ultra High Field ◽  
High Field Mri ◽  
Ultra High Field Mri ◽  
Noise Ratio

CT and high-field MRI in septic thrombosis of the cavernous sinuses

1992 ◽  
Vol 34 (1) ◽  
pp. 22-24 ◽  
Author(s):  
E. Ellie ◽  
B. Houang ◽  
C. Louail ◽  
V. Legrain-Lifermann ◽  
F. Laurent ◽  
...  
Keyword(s):  
High Field ◽  
High Field Mri ◽  
Septic Thrombosis

Residual Stress Measurement and Simulation of 3C-SiC Single and Poly Crystal Cantilevers

2010 ◽  
Vol 645-648 ◽  
pp. 865-868 ◽  
Author(s):  
Ruggero Anzalone ◽  
Massimo Camarda ◽  
Daniel Alquier ◽  
M. Italia ◽  
Andrea Severino ◽  
...  
Keyword(s):  
Experimental Data ◽  
Theoretical Study ◽  
Stress Measurement ◽  
Bulk Material ◽  
Raman Shift ◽  
Silicon Substrates ◽  
Free Standing ◽  
Element Analysis ◽  
Micro Fabrication ◽  
Sic Films

The fabrication of SiC MEMS-based sensors requires new processes able to realize microstructures on either bulk material or on the SiC surface. The hetero-epitaxial growth of 3C-SiC on silicon substrates allows one to overcome the traditional limitations of SiC micro-fabrication. In this work a comparison between single crystal and poly crystal 3C-SiC micro-machined structures will be presented. The free-standing structures realized (cantilevers and membrane) are also a suitable method for residual field stress investigation in 3C-SiC films. Measurement of the Raman shift indicates that the mono and poly-crystal 3C-SiC structures release the stress in different ways. Finite element analysis was performed to determine the stress field inside the films and provided a good fit to the experimental data. A comprehensive experimental and theoretical study of 3C-SiC MEMS structures has been performed and is presented.

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