Browsing by Subject "Device"

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    Design of a novel MRI compatible manipulator for image guided prostate interventions
    (IEEE, 2005-02) Krieger, A.; Susil, R. C.; Ménard, C.; Coleman, J. A.; Fichtinger, G.; Atalar, Ergin; Whitcomb, L. L.
    This paper reports a novel remotely actuated manipulator for access to prostate tissue under magnetic resonance imaging guidance (APT-MRI) device, designed for use in a standard high-field MRI scanner. The device provides three-dimensional MRI guided needle placement with millimeter accuracy under physician control. Procedures enabled by this device include MRI guided needle biopsy, fiducial marker placements, and therapy delivery. Its compact size allows for use in both standard cylindrical and open configuration MRI scanners. Preliminary in vivo canine experiments and first clinical trials are reported.
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    In vivo magnetic resonance imaging of mesenchymal stem cells in myocardial infarction
    (Lippincott Williams & Wilkins, 2003) Kraitchman, D. L.; Heldman, A. W.; Atalar, Ergin; Amado, L. C.; Martin, B. J.; Pittenger, M. F.; Hare, J. M.; Bulte, J. W. M.
    Background - We investigated the potential of magnetic resonance imaging (MRI) to track magnetically labeled mesenchymal stem cells (MR-MSCs) in a swine myocardial infarction (MI) model. Methods and Results - Adult farm pigs (n=5) were subjected to closed-chest experimental MI. MR-MSCs (2.8 to 16×107 cells) were injected intramyocardially under x-ray fluoroscopy. MRIs were obtained on a 1.5T MR scanner to demonstrate the location of the MR-MSCs and were correlated with histology. Contrast-enhanced MRI demonstrated successful injection in the infarct and serial MSC tracking was demonstrated in two animals. Conclusion - MRI tracking of MSCs is feasible and represents a preferred method for studying the engraftment of MSCs in MI.
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    Intravascular extended sensitivity (IVES) MRI antennas
    (John Wiley & Sons, Inc, 2003) Susil, R. C.; Yeung, C. J.; Atalar, Ergin
    The design and application of an intravascular extended sensitivity (IVES) MRI antenna is described. The device is a loopless antenna design that incorporates both an insulating, dielectric coating and a winding of the antenna whip into a helical shape. Because this antenna produces a broad region of high SNR and also allows for imaging near the tip of the device, it is useful for imaging long, luminal structures. To elucidate the design and function of this device, the effects of both insulation and antenna winding were characterized by theoretical and experimental studies. Insulation broadens the longitudinal region over which images can be collected (i.e., along the lumen of a vessel) by increasing the resonant pole length. Antenna winding, conversely, allows for imaging closer to the tip of the antenna by decreasing the resonant pole length. Over a longitudinal region of 20 cm, the IVES imaging antenna described here produces a system SNR of approximately 40,000/r (mL-1Hz1/2), where r is the radial distance from the antenna axis in centimeters. As opposed to microcoil antenna designs, these antennas do not require exact positioning and allow for imaging over broad tissue regions. While focusing on the design of the IVES antenna, this work also serves to enhance our overall understanding of the properties and behavior of the loopless antenna design. © 2003 Wiley-Liss, Inc.
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    Plasmonics: merging photonics and electronics at nanoscale dimensions
    ((AAAS) American Association for the Advancement of Science, 2006) Özbay, Ekmel
    Electronic circuits provide us with the ability to control the transport and storage of electrons. However, the performance of electronic circuits is now becoming rather limited when digital information needs to be sent from one point to another. Photonics offers an effective solution to this problem by implementing optical communication systems based on optical fibers and photonic circuits. Unfortunately, the micrometer-scale bulky components of photonics have limited the integration of these components into electronic chips, which are now measured in nanometers. Surface plasmon-based circuits, which merge electronics and photonics at the nanoscale, may offer a solution to this size-compatibility problem. Here we review the current status and future prospects of plasmonics in various applications including plasmonic chips, light generation, and nanolithography.
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    Random sized plasmonic nanoantennas on Silicon for low-cost broad-band-near-infrared photodetection
    (Nature Publishing Group, 2014-11-19) Nazirzadeh, M. A.; Atar, F. B.; turgut, B. B.; Okyay, Ali Kemal
    In this work, we propose Silicon based broad-band near infrared Schottky barrier photodetectors. The devices operate beyond 1200 nm wavelength and exhibit photoresponsivity values as high as 3.5 mA/W with a low dark current density of about 50 pA/mu m(2). We make use of Au nanoislands on Silicon surface formed by rapid thermal annealing of a thin Au layer. Surface plasmons are excited on Au nanoislands and this field localization results in efficient absorption of sub-bandgap photons. Absorbed photons excite the electrons of the metal to higher energy levels (hot electron generation) and the collection of these hot electrons to the semiconductor results in photocurrent (internal photoemission). Simple and scalable fabrication makes these devices suitable for ultra-low-cost NIR detection applications.