scholarly journals Demonstration and Experimental Validation of Plastic-Encased Resonant Ultrasonic Piezoelectric Actuator for MRI-Guided Surgical Robots

2018 ◽  
Author(s):  
Paulo A. W. G. Carvalho ◽  
Christopher J. Nycz ◽  
Katie Y. Gandomi ◽  
Gregory S. Fischer
Keyword(s):  
Metal Content ◽  
Experimental Validation ◽  
Surgical Instruments ◽  
Robotic Manipulation ◽  
Resonance Imaging ◽  
Surgical Robots ◽  
High Metal Content ◽  
Piezoelectric Elements ◽  
High Metal ◽  
Magnetic Resonance Imaging Mri

Intra-operative medical imaging based on magnetic resonance imaging (MRI) coupled with robotic manipulation of surgical instruments enables precise feedback-driven procedures. Electrically powered non-ferromagnetic motors based on piezoelectric elements have shown to be well suited for MRI robots. However, even avoiding ferrous materials, the high metal content on commercially available motors still cause distortions to the magnetic fields. We construct semi-custom piezoelectric actuators wherein the quantity of conductive material is minimized and demonstrate that the distortion issues can be partly addressed through substituting several of these components for plastic equivalents, while maintaining motor functionality. Distortion was measured by assessing the RMS change in position of 49 centroid points in a 12.5mm square grid of a gelatin-filled phantom. The metal motor caused a distortion of up to 4.91mm versus 0.55mm for the plastic motor. An additional SNR drop between motor off and motor spinning of approximately 20% was not statistically different for metal versus plastic (p = 0.36).

scholarly journals Demonstration and Experimental Validation of Plastic-Encased Resonant Ultrasonic Piezoelectric Actuator for Magnetic Resonance Imaging-Guided Surgical Robots

2019 ◽  
Vol 3 (1) ◽  
Author(s):  
Paulo A. W. G. Carvalho ◽  
Christopher J. Nycz ◽  
Katie Y. Gandomi ◽  
Gregory S. Fischer
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Signal To Noise Ratio ◽  
Surgical Instruments ◽  
Resonance Imaging ◽  
Surgical Robots ◽  
Additional Signal ◽  
High Metal Content ◽  
Piezoelectric Elements ◽  
Magnetic Resonance Imaging Mri

Abstract Intra-operative medical imaging based on magnetic resonance imaging (MRI) coupled with robotic manipulation of surgical instruments enables precise feedback-driven procedures. Electrically powered nonferromagnetic motors based on piezoelectric elements have shown to be well suited for MRI robots. However, even avoiding ferrous materials, the high metal content on commercially available motors still cause distortions to the magnetic fields. We construct semicustom piezoelectric actuators wherein the quantity of conductive material is minimized and demonstrate that the distortion issues can be partly addressed through substituting several of these components for plastic equivalents, while maintaining motor functionality. Distortion was measured by assessing the root-mean-squared (RMS) change in position of 49 centroid points in a 12.5 mm square grid of a gelatin-filled phantom. The metal motor caused a distortion of up to 4.91 mm versus 0.55 mm for the plastic motor. An additional signal-to-noise-ratio (SNR) drop between motor off and motor spinning of approximately 20% was not statistically different for metal versus plastic (p = 0.36).

MR-Safe Pneumatic Rotation Stepping Actuator

2012 ◽  
Vol 24 (5) ◽  
pp. 820-827 ◽  
Author(s):  
Hiroyuki Sajima ◽  
◽  
Hiroki Kamiuchi ◽  
Kenta Kuwana ◽  
Takeyoshi Dohi ◽  
...  
Keyword(s):  
Surgical Navigation ◽  
Safety Evaluation ◽  
Surgical Instruments ◽  
Resonance Imaging ◽  
Surgical Robots ◽  
Maximum Torque ◽  
Pneumatic Actuators ◽  
Magnetic Resonance Imaging Mri ◽  
Mr Safe ◽  
Direct Acting

Magnetic Resonance Imaging (MRI) is widely used not only for diagnosis but also for surgical navigation, etc. Surgeons and surgery-support systems can conduct surgeries less invasively because they derive accurate positional relationships between surgical instruments and anatomical regions of interest from preoperative or intraoperative MRI images. Many surgical robots intended for use within MRI gantries have been developed. Some of them use pneumatic actuators that are difficult to control accurately or that have many components, however, causing high fabrication cost, low durability and low sterilizability. To solve these problems, we have developed a φ30-mm pneumatic rotation stepping actuator. The actuator consists of three Direct Acting gears (D.A. gears) and a Rotation gear (R gear). When all of the D.A. gears are pushed sequentially up by compressed air, the R gear rotates because it engages all of them. In a fundamental performance experiment, the maximum angular error was 2.1° and maximum torque was approximately 150 mNm using 0.6 MPaG. Additionally, in an MR safety evaluation, the actuator was not found to cause any distortion or artifacts in MRI images. The actuator can therefore be applied to MR-safe positioning or puncturing robots.

Demetallization of Heavy Oils of High Metal Content through Pyrolysis under Supercritical Water Environment

2020 ◽  
Vol 34 (3) ◽  
pp. 2861-2869 ◽  
Author(s):  
Xu-Quan Tang ◽  
Jing-Cao Pu ◽  
Hong-Bing Zheng ◽  
Xu-De Yu ◽  
Xue-Feng Chen ◽  
...  
Keyword(s):  
Supercritical Water ◽  
Metal Content ◽  
Water Environment ◽  
Heavy Oils ◽  
High Metal Content ◽  
High Metal

Preparation of high metal content nanoporous carbon

2013 ◽  
Vol 115 ◽  
pp. 115-121 ◽  
Author(s):  
Miguel Molina-Sabio ◽  
Mateus Carvalho Monteiro de Castro ◽  
Manuel Martinez-Escandell ◽  
Francisco Rodríguez-Reinoso
Keyword(s):  
Metal Content ◽  
Nanoporous Carbon ◽  
High Metal Content ◽  
High Metal

Sea sediments contaminated with heavy metals: metal speciation and removal

1995 ◽  
Vol 32 (9-10) ◽  
pp. 65-73 ◽  
Author(s):  
C. Savvides ◽  
A. Papadopoulos ◽  
K. J. Haralambous ◽  
M. Loizidou
Keyword(s):  
Heavy Metals ◽  
Industrial Waste ◽  
Metal Content ◽  
Metal Speciation ◽  
Acid Solutions ◽  
Significant Percentage ◽  
High Metal Content ◽  
Residual Phase ◽  
High Metal ◽  
Partitioning Procedure

The contamination of sediments with heavy metals may lead to serious environmental problems and in some cases action has to take place for their decontamination. In this work, studies were performed on sediments near the outfall of domestic and industrial waste. The metals examined were Cu, Cr, Ni, Pb, Zn and Fe. Indeed, high metal content was found in the sediments and the contamination factors were quite high, indicating the effect of the nearby discharge of effluents. The results of the application of a sequential extraction partitioning procedure indicated that an important part of the metal content is carried by the residual phase but also a significant percentage is found in the organic and reducible fractions, i.e. in potentially available fractions. Batch extraction experiments using acid solutions of various concentrations and different acid-sediment contact times were performed in order to remove heavy metals from the sediments. For most metals studied, a satisfactory percentage was extracted at low contact times.

scholarly journals High Metal Content of Highly Accreting Quasars

2021 ◽  
Vol 910 (2) ◽  
pp. 115
Author(s):  
Marzena Śniegowska ◽  
Paola Marziani ◽  
Bożena Czerny ◽  
Swayamtrupta Panda ◽  
Mary Loli Martínez-Aldama ◽  
...  
Keyword(s):  
Metal Content ◽  
High Metal Content ◽  
High Metal

scholarly journals Synthesis and properties of metal-carbon nanocomposites Ni/C, Co/C AND Cu/C with high metal content

Surface ◽  
2017 ◽  
Vol 9(24) ◽  
pp. 136-144 ◽  
Author(s):  
V. M. Bogatyrov ◽  
◽  
M. V. Borysenko ◽  
O. I. Oranska ◽  
M. V. Galaburda ◽  
...  
Keyword(s):  
Metal Content ◽  
Carbon Nanocomposites ◽  
High Metal Content ◽  
High Metal
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