Tiberius Brastaviceanu

Publications (8) View all

• Article: Micro-displacement sensors based on plastic photonic bandgap Bragg fibers

  H. Qu, T. Brastaviceanu, F. Bergeron, J. Olesik, M. Skorobogatiy
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  ABSTRACT: We demonstrate an amplitude-based micro-displacement sensor that uses a plastic photonic bandgap Bragg fiber with one end coated with a silver layer. The reflection intensity of the Bragg fiber is characterized in response to different displacements (or bending curvatures). We note that the Bragg reflector of the fiber acts as an efficient mode stripper for the wavelengths near the edge of the fiber bandgap, which makes the sensor extremely sensitive to bending or displacements at these wavelengths. Besides, by comparison of the Bragg fiber sensor to a sensor based on a regular multimode fiber with similar outer diameter and length, we find that the Bragg fiber sensor is more sensitive to bending due to presence of mode stripper in the form of the multilayer reflector. Experimental results show that the minimum detection limit of the Bragg fiber sensor can be smaller than 5 um for displacement sensing.
  04/2013;
• Article: Publisher's Note: "Optical detection system for probing cantilever deflections parallel to a sample surface" [Rev. Sci. Instrum. 82, 013701 (2011)].

  A Labuda, T Brastaviceanu, I Pavlov, W Paul, D E Rassier
  The Review of scientific instruments 01/2011; 82(1):019902. · 1.52 Impact Factor
• Article: Optical detection system for probing cantilever deflections parallel to a sample surface.

  A Labuda, T Brastaviceanu, I Pavlov, W Paul, D E Rassier
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  ABSTRACT: To date, commercial atomic force microscopes have been optimized for measurements of forces perpendicular to the sample surface. In many applications, sensitive parallel force measurements are desirable. These can be obtained by positioning the cantilever with its long axis perpendicular to the sample: the so-called pendulum geometry. We present a compact optical beam deflection system which solves the geometrical constraint problems involved in focusing a light beam onto a cantilever in the pendulum geometry. We demonstrate the performance of the system on measurements of forces imparted by a muscle myofibril, which is in-plane to a high-magnification objective of an optical microscope.
  The Review of scientific instruments 01/2011; 82(1):013701. · 1.52 Impact Factor
• Source

  Available from: Cecile M Perrault

  Article: Integrated microfluidic probe station.

  C M Perrault, M A Qasaimeh, T Brastaviceanu, K Anderson, Y Kabakibo, D Juncker
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  ABSTRACT: The microfluidic probe (MFP) consists of a flat, blunt tip with two apertures for the injection and reaspiration of a microjet into a solution--thus hydrodynamically confining the microjet--and is operated atop an inverted microscope that enables live imaging. By scanning across a surface, the microjet can be used for surface processing with the capability of both depositing and removing material; as it operates under immersed conditions, sensitive biological materials and living cells can be processed. During scanning, the MFP is kept immobile and centered over the objective of the inverted microscope, a few micrometers above a substrate that is displaced by moving the microscope stage and that is flushed continuously with the microjet. For consistent and reproducible surface processing, the gap between the MFP and the substrate, the MFP's alignment, the scanning speed, the injection and aspiration flow rates, and the image capture need all to be controlled and synchronized. Here, we present an automated MFP station that integrates all of these functionalities and automates the key operational parameters. A custom software program is used to control an independent motorized Z stage for adjusting the gap, a motorized microscope stage for scanning the substrate, up to 16 syringe pumps for injecting and aspirating fluids, and an inverted fluorescence microscope equipped with a charge-coupled device camera. The parallelism between the MFP and the substrate is adjusted using manual goniometer at the beginning of the experiment. The alignment of the injection and aspiration apertures along the scanning axis is performed using a newly designed MFP screw holder. We illustrate the integrated MFP station by the programmed, automated patterning of fluorescently labeled biotin on a streptavidin-coated surface.
  The Review of scientific instruments 11/2010; 81(11):115107. · 1.52 Impact Factor
• Source

  Available from: Benoit Paquette

  Article: Cancer radiotherapy based on femtosecond IR laser-beam filamentation yielding ultra-high dose rates and zero entrance dose

  Ridthee Meesat, Hakim Belmouaddine, Jean-François Allard, Catherine Tanguay-Renaud, Rosalie Lemay, Tiberius Brastaviceanu, Luc Tremblay, Benoit Paquette, J. Richard Wagner, Jean-Paul Jay-Gerin, Martin Lepage, Michael A. Huels, Daniel Houde
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  ABSTRACT: Since the invention of cancer radiotherapy, its primary goal has been to maximize lethal radiation doses to the tumor volume while keeping the dose to surrounding healthy tissues at zero. Sadly, conventional radiation sources (γ or X rays, electrons) used for decades, including multiple or modulated beams, inevitably deposit the majority of their dose in front or behind the tumor, thus damaging healthy tissue and causing secondary cancers years after treatment. Even the most recent pioneering advances in costly proton or carbon ion therapies can not completely avoid dose buildup in front of the tumor volume. Here we show that this ultimate goal of radiotherapy is yet within our reach: Using intense ultra-short infrared laser pulses we can now deposit a very large energy dose at unprecedented microscopic dose rates (up to 1011 Gy/s) deep inside an adjustable, well-controlled macroscopic volume, without any dose deposit in front or behind the target volume. Our infrared laser pulses produce high density avalanches of low energy electrons via laser filamentation, a phenomenon that results in a spatial energy density and temporal dose rate that both exceed by orders of magnitude any values previously reported even for the most intense clinical radiotherapy systems. Moreover, we show that (i) the type of final damage and its mechanisms in aqueous media, at the molecular and biomolecular level, is comparable to that of conventional ionizing radiation, and (ii) at the tumor tissue level in an animal cancer model, the laser irradiation method shows clear therapeutic benefits.
  Proceedings of the National Academy of Sciences 09/2012; 109(38):E2508-E2513. · 9.68 Impact Factor