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Benjamin A Greenlay, Roger J Zemp
The microfabrication processes for sacrificial-release-based capacitive micromachined ultrasound transducer arrays are provided with an emphasis on top-orthogonal-to-bottom electrode 2-D arrays. These arrays have significant promise for high-quality 3-D imaging with reduced wiring complexity compared with fully wired arrays. The protocols and best practices are outlined in significant detail along with design considerations and notes of caution for pitfalls and factors impacting yield.
January 2017: IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
Ryan D Sochol, Navin R Gupta, Joseph V Bonventre
The advancement of "kidney-on-a-chip" platforms - submillimeter-scale fluidic systems designed to recapitulate renal functions in vitro - directly impacts a wide range of biomedical fields, including drug screening, cell and tissue engineering, toxicity testing, and disease modelling. To fabricate kidney-on-a-chip technologies, researchers have primarily adapted traditional micromachining techniques that are rooted in the integrated circuit industry; hence the term, "chip." A significant challenge, however, is that such methods are inherently monolithic, which limits one's ability to accurately recreate the geometric and architectural complexity of the kidney in vivo...
March 2016: Current Transplantation Reports
Leilei Shi, Tao Zhu, Dongmei Huang, Chuancan Liang, Min Liu, Shibin Liang
An in-fiber Mach-Zehnder interferometer and sphere whispering gallery mode resonator coupling structure is demonstrated by femtosecond laser micromachining. Asymmetric spectra around the resonant wavelength of the whispering gallery cavities in different coupling states are experimentally observed. An extinction ratio of ∼7  dB and a slope of 117 dB/nm can be achieved in the asymmetric spectrum of the overcoupled whispering gallery cavity, where an additional π phase shift at the resonant wavelength is introduced to the Mach-Zehnder interferometer...
January 1, 2017: Optics Letters
Daniel Bollschweiler, Miroslava Schaffer, C Martin Lawrence, Harald Engelhardt
Most halophilic Archaea of the class Halobacteriaceae depend on the presence of several molar sodium chloride for growth and cell integrity. This poses problems for structural studies, particularly for electron microscopy, where the high salt concentration results in diminished contrast. Since cryo-electron microscopy of intact cells provides new insights into the cellular and molecular organization under close-to-live conditions, we evaluated strategies and conditions to make halophilic microbes available for investigations in situ...
January 3, 2017: Extremophiles: Life Under Extreme Conditions
Alessio Tommasi, Matteo Cocuzza, Denis Perrone, Candido Fabrizio Pirri, Roberto Mosca, Marco Villani, Nicola Delmonte, Andrea Zappettini, Davide Calestani, Simone Luigi Marasso
In the sensors field the active sensing material frequently needs a controlled temperature in order to work properly. In microsystems technology, micro-machined hotplates represent a platform consisting of a thin suspended membrane where the sensing material can be deposited, usually integrating electrical stimuli and temperature readout. The micro-hotplate ensures a series of advantages such as miniaturized size, fast response, high sensitivity, low power consumption and selectivity for chemical sensing. This work compares the coplanar and the buried approach for the micro-hotplate heaters design with the aim to optimize the fabrication process and to propose a guideline for the choice of the suitable design with respect to the applications...
December 30, 2016: Sensors
Soowon Shin, Jae-Hyun Kim, Joonsoo Jeong, Tae Mok Gwon, Seung-Hee Lee, Sung June Kim
BACKGROUND: Ideally, neural probes should have channels with a three-dimensional (3-D) configuration to record the activities of 3-D neural circuits. Many types of 3-D neural probes have been developed; however, most of them were designed as an array of multiple shanks with electrodes located along one side of the shanks. NEW METHOD: We developed a novel liquid crystal polymer (LCP)-based neural probe with four-sided electrodes. This probe has electrodes on four sides of the shank, i...
December 29, 2016: Journal of Neuroscience Methods
Shuai Na, Lawrence L P Wong, Albert I H Chen, Zhenhao Li, Mirek Macecek, John T W Yeow
Air-coupled capacitive micromachined ultrasonic transducers (CMUTs) based on annular cell geometry have recently been reported. Finite element analysis and experimental studies have demonstrated their significant improvement in transmit efficiency compared with the conventional circular-cell CMUTs. Extending the previous work, this paper proposed a lumped element model of annular-cell CMUTs. Explicit expressions of the resonance frequency, modal vector, and static displacement of a clamped annular plate under uniform pressure were first derived based on the plate theory and curve fitting method...
November 23, 2016: Ultrasonics
Kwanoh Kim, Zexi Liang, Minliang Liu, Donglei Emma Fan
In this work, we report an innovative type of rotary bio-micromachines by using diatom frustules as integrated active components, including the assembling, operation, and performance characterization. We further investigate and demonstrate unique applications of the bio-micromachines in achieving individually reconfigurable micromachine arrays and microfluidic mixing. Diatom frustules are porous cell walls of diatoms made of silica. We assembled rotary micromachines consisting of diatom frustules serving as rotors and patterned magnets serving as bearings in electric fields...
December 29, 2016: ACS Applied Materials & Interfaces
Pradeep K Gupta, Chandra P Singh, Amarjeet Singh, Sunil K Sharma, Pranab K Mukhopadhyay, Kushvinder S Bindra
We report, for what we believe is the first time, generation of stable chair-like pulses (a pulse shape with an initial long flat portion followed by a short high peak power portion resembling the shape of a chair) by mode locking of a Ytterbium (Yb)-doped fiber laser. Chair-like pulse shapes are achieved by implementing dual saturable absorbers, one based on a nonlinear optical loop mirror (NOLM) and the other based on nonlinear polarization rotation (NPR) inside the cavity. The transmission characteristics of the NOLM-NPR pair leading to the formation of chair-like pulses are numerically investigated...
December 10, 2016: Applied Optics
Ronald W Boutte, Steve Blair
Borrowing from the wafer-level fabrication techniques of the Utah Electrode Array, an optical array capable of delivering light for neural optogenetic studies is presented in this paper: the Utah Optrode Array. Utah Optrode Arrays are micromachined out of sheet soda-lime-silica glass using standard backend processes of the semiconductor and microelectronics packaging industries such as precision diamond grinding and wet etching. 9 × 9 arrays with 1100μ m × 100μ m optrodes and a 500μ m back-plane are repeatably reproduced on 2i n wafers 169 arrays at a time...
December 2016: Biomedical Microdevices
Stanislao Rizzo, Gualtiero Fantoni, Giovanni de Santis, Jaw-Chyng Lormen Lue, Jonathan Ciampi, Michele Palla, Federica Genovesi Ebert, Alfonso Savastano, Carmelo De Maria, Giovanni Vozzi, Rodrigo A Brant Fernandes, Francesco Faraldi, Giuseppe Criscenti
PURPOSE: Thorough this experimental study, the physic features of a modified 23-gauge vitrectomy probe were evaluated in vitro. METHODS: A modified vitrectomy probe to increase vitreous outflow rate with a small-diameter probe, that also minimized tractional forces on the retina, was created and tested. The "new" probe was created by drilling an opening into the inner duct of a traditional 23-gauge probe with electrochemical or electrodischarge micromachining. Both vitreous outflow and tractional forces on the retina were examined using experimental models of vitreous surgery...
December 7, 2016: Retina
Hyo-Seon Yoon, Chienliu Chang, Ji Hoon Jang, Anshuman Bhuyan, Jung Woo Choe, Amin Nikoozadeh, Ronald D Watkins, Douglas N Stephens, Kim Butts Pauly, Butrus T Khuri-Yakub
High-intensity focused ultrasound (HIFU) has been used as noninvasive treatment for various diseases. For these therapeutic applications, capacitive micromachined ultrasonic transducers (CMUTs) have advantages that make them potentially preferred transducers over traditional piezoelectric transducers. In this paper, we present the design and the fabrication process of an 8 ×8 -mm (2) 32 ×32 -element 2-D CMUT array for HIFU applications. To reduce the system complexity for addressing the 1024 transducer elements, we propose to group the CMUT array elements into eight HIFU channels based on the phase delay from the CMUT element to the targeted focal point...
December 2016: IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
Risheng Cheng, Xiang Guo, Xiaosong Ma, Linran Fan, King Y Fong, Menno Poot, Hong X Tang
We describe a micromachining process to allow back-side coupling of an array of single-mode telecommunication fibers to individual superconducting nanowire single photon detectors (SNSPDs). This approach enables a back-illuminated detector structure which separates the optical access and electrical readout on two sides of the chip and thus allows for compact integration of multi-channel detectors. As proof of principle, we show the integration of four detectors on the same silicon chip with two different designs and their performances are compared...
November 28, 2016: Optics Express
Evangelos Tsiambas, Christos Riziotis
Cervical cancer screening based on the Papanicolaou (Pap) test is a widely applied but not always efficient practice for detecting Human Papillomavirus (HPV) mediated lesions, partially due to a non-systematic and inadequate screening process. Our aim was to introduce an inexpensive easy-to-use direct screening platform for improved detection of abnormal cells indicative of underlying cervical neoplasia as well as persisting HPV infection. By employing a novel, efficient technique of laser-based micromachining, we achieved the fabrication of spatial grids on commercially available coverslips allowing visual segmentation of the slide for efficient screening...
January 2017: Pathology International
Yan Liu, Hai Wang, Wei Zhao, Hongbo Qin, Xuan Fang
The field of piezoresistive sensors has been undergoing a significant revolution in terms of design methodology, material technology and micromachining process. However, the temperature dependence of sensor characteristics remains a hurdle to cross. This review focuses on the issues in thermal-performance instability of piezoresistive sensors. Based on the operation fundamental, inducements to the instability are investigated in detail and correspondingly available ameliorative methods are presented. Pros and cons of each improvement approach are also summarized...
November 24, 2016: Sensors
Jing Liu, Hong-Lian Guo, Zhi-Yuan Li
Controlled propulsion of microparticles and micromachines in fluids could revolutionize many aspects of technology, such as biomedicine, microfluidics, micro-mechanics, optomechanics, and cell biology. We report the self-propelled cyclic round-trip motion of metallo-dielectric Janus particles in static line optical tweezers (LOT). The Janus particle is a 5 μm-diameter polystyrene sphere half-coated with 3 nanometer thick gold film. Both experiment and theory show that this cyclic translational and rotational motion is a consequence of the collective and fine action of the gold-face orientation dependent propulsion optical force, the gradient optical force, and the spontaneous symmetry breaking induced optical torque in different regions of the LOT...
December 1, 2016: Nanoscale
John Lehman, Andreas Steiger, Nathan Tomlin, Malcolm White, Mathias Kehrt, Ivan Ryger, Michelle Stephens, Christian Monte, Ingmar Mueller, Joerg Hollandt, Marla Dowell
The absolute responsivity of a planar cryogenic radiometer fabricated from micromachined silicon and having carbon nanotubes, as the absorber and thermistor were measured in the visible and far infrared (free-field terahertz) wavelength range by means of detector-based radiometry. The temperature coefficient of the thermistor near 4.8 K and noise equivalent power were evaluated along with independent characterization of the window transmittance and specular reflectance of the nanotube absorber. Measurements of absolute power by means of electrical substitution are compared to the German national standard and the uncertainty of the radiometer responsivity as a function of wavelength is summarized...
November 14, 2016: Optics Express
O D Supekar, J J Brown, N T Eigenfeld, J C Gertsch, V M Bright
Focused ion beam (FIB) micromachining is a powerful tool for maskless lithography and in recent years FIB has been explored as a tool for strain engineering. Ion beam induced deformation can be utilized as a means for folding freestanding thin films into complex 3D structures. FIB of high energy gallium (Ga(+)) ions induces stress by generation of dislocations and ion implantation within material layers, which create creases or folds upon mechanical relaxation enabled by motion of the material layers. One limitation on such processing is the ability to fabricate flat freestanding thin film structures...
December 9, 2016: Nanotechnology
Johannes Rebling, Omri Warshavski, Cyril Meynier, Daniel Razansky
No abstract text is available yet for this article.
April 1, 2017: Journal of Biomedical Optics
Mohsen Rezaei, Iman Hasani Nia, Alireza Bonakdar, Hooman Mohseni
A simple and compact telecentric lens based on two hemispheric optical elements arranged in a formation resembling an "hourglass" is proposed and evaluated. Our modeling and experimental results show the ability of this lens in achieving high resolution over a large field of view. A prototype with 500 μm total thickness is built using silicon micromachining methods for a center wavelength of 1500 nm. Experimental measurement shows near-diffraction-limited performance and good telecentricity over an 80° field of view at a numerical aperture of 0...
November 1, 2016: Applied Optics
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