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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...
November 27, 2016: 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
Ayhan Bozkurt, G Goksenin Yaralioglu
This paper presents an analysis of thermal (Johnson) noise received from the radiation medium by otherwise noiseless capacitive micromachined ultrasonic transducer (CMUT) membranes operating in their fundamental resonance mode. Determination of thermal noise received by multiple numbers of transducers or a transducer array requires the assessment of cross-coupling through the radiation medium, as well as the self-radiation impedance of the individual transducer. We show that the total thermal noise received by the cells of a CMUT has insignificant correlation, and is independent of the radiation impedance, but is only determined by the mass of each membrane and the electromechanical transformer ratio...
November 2016: IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
Bernard Shieh, Karim G Sabra, F Levent Degertekin
A boundary element model provides great flexibility for the simulation of membrane-type micromachined ultrasonic transducers (MUTs) in terms of membrane shape, actuating mechanism, and array layout. Acoustic crosstalk is accounted for through a mutual impedance matrix that captures the primary crosstalk mechanism of dispersive-guided modes generated at the fluid-solid interface. However, finding the solution to the fully populated boundary element matrix equation using standard techniques requires computation time and memory usage that scales by the cube and by the square of the number of nodes, respectively, limiting simulation to a small number of membranes...
November 2016: IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
K Yin, Y X Song, X R Dong, C Wang, J A Duan
Reported here is the bio-inspired and robust function of underwater superoleophobic, anti-oil metallic surfaces with ultra-broadband enhanced optical absorption obtained through femtosecond laser micromachining. Three distinct surface structures are fabricated using a wide variety of processing parameters. Underwater superoleophobic and anti-oil surfaces containing coral-like microstructures with nanoparticles and mount-like microstructures are achieved. These properties of the as-prepared surfaces exhibit good chemical stability when exposed to various types of oils and when immersed in water with a wide range of pH values...
November 7, 2016: Scientific Reports
Giosue Caliano, Giulia Matrone, Alessandro Stuart Savoia
Capacitive Micromachined Ultrasonic Transducers (CMUTs) represent an effective alternative to piezoelectric transducers for medical ultrasound imaging applications. They are micro-electromechanical (MEMS) devices fabricated using silicon micromachining techniques, developed in the last two decades in many laboratories. The interest for this novel transducer technology relies in its full compatibility with standard integrated circuit technology that makes it possible to integrate on the same chip the transducers and the electronics, thus enabling the realization of extremely low-cost and highperformance devices, including both one- or two-dimensional arrays...
October 28, 2016: IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
Staci Hill, Weiyi Qian, Weiqiang Chen, Jianping Fu
Polydimethylsiloxane (PDMS) elastomer has emerged as one of the most frequently applied materials in microfluidics. However, precise and large-scale surface micromachining of PDMS remains challenging, limiting applications of PDMS for microfluidic structures with high-resolution features. Herein, surface patterning of PDMS was achieved using a simple yet effective method combining direct photolithography followed by reactive-ion etching (RIE). This method incorporated a unique step of using oxygen plasma to activate PDMS surfaces to a hydrophilic state, thereby enabling improved adhesion of photoresist on top of PDMS surfaces for subsequent photolithography...
September 2016: Biomicrofluidics
John Sinsheimer, Nathalie Bouet, Sanjit Ghose, Eric Dooryhee, Ray Conley
A new system of slits called `spiderweb slits' have been developed for depth-resolved powder or polycrystalline X-ray diffraction measurements. The slits act on diffracted X-rays to select a particular gauge volume of sample, while absorbing diffracted X-rays from outside of this volume. Although the slit geometry is to some extent similar to that of previously developed conical slits or spiral slits, this new design has advantages over the previous ones in use for complex heterogeneous materials and in situ and operando diffraction measurements...
November 1, 2016: Journal of Synchrotron Radiation
Martin Pekař, Wendy U Dittmer, Nenad Mihajlović, Gijs van Soest, Nico de Jong
The information in an ultrasound image depends on the frequency that is used. In a clinical examination it may therefore be beneficial to generate ultrasound images acquired at multiple frequencies, which is difficult to achieve with conventional transducers. Capacitive micromachined ultrasonic transducers (CMUTs) offer a frequency response that is tunable by the bias voltage. In this study we investigate this frequency tunability for ultrasonic imaging. We characterized a CMUT array operated at bias voltages up to three times higher than the collapse-voltage...
February 2017: Ultrasonics
Tae Soup Shim, Zaki G Estephan, Zhaoxia Qian, Jacob H Prosser, Su Yeon Lee, David M Chenoweth, Daeyeon Lee, So-Jung Park, John C Crocker
Active materials that respond to physical and chemical stimuli can be used to build dynamic micromachines that lie at the interface between biological systems and engineered devices. In principle, the specific hybridization of DNA can be used to form a library of independent, chemically driven actuators for use in such microrobotic applications and could lead to device capabilities that are not possible with polymer- or metal-layer-based approaches. Here, we report shape changing films that are powered by DNA strand exchange reactions with two different domains that can respond to distinct chemical signals...
October 24, 2016: Nature Nanotechnology
Boqian Sun, Shunyue Wang, Haixia Li, Xiaoxia He
A micromachined gyroscope in which a high-speed spinning rotor is suspended electrostatically in a vacuum cavity usually functions as a dual-axis angular rate sensor. An inherent coupling error between the two sensing axes exists owing to the angular motion of the spinning rotor being controlled by a torque-rebalance loop. In this paper, a decoupling compensation method is proposed and investigated experimentally based on an electrostatically suspended micromachined gyroscope. In order to eliminate the negative spring effect inherent in the gyroscope dynamics, a stiffness compensation scheme was utilized in design of the decoupled rebalance loop to ensure loop stability and increase suspension stiffness...
October 20, 2016: Sensors
Joshua Giltinan, Eric Diller, Metin Sitti
At the sub-millimeter scale, capillary forces enable robust and reversible adhesion between biological organisms and varied substrates. Current human-engineered mobile untethered micromanipulation systems rely on forces which scale poorly or utilize gripper-part designs that promote manipulation. Capillary forces, alternatively, are dependent upon the surface chemistry (which is scale independent) and contact perimeter, which conforms to the part surface. We report a mobile capillary microgripper that is able to pick and place parts of various materials and geometries, and is thus ideal for microassembly tasks that cannot be accomplished by large tethered manipulators...
October 21, 2016: Lab on a Chip
Frances J Harding, Salvatore Surdo, Bahman Delalat, Chiara Cozzi, Roey Elnathan, Stan Gronthos, Nicolas H Voelcker, Giuseppe Barillaro
Ordered arrays of silicon nano- to microscale pillars are used to enable biomolecular trafficking into primary human cells, consistently demonstrating high transfection efficiency can be achieved with broader and taller pillars that reported to date. Cell morphology on the pillar arrays is often strikingly elongated. Investigation of the cellular interaction with the pillar reveals that cells are suspended on pillar tips and do not interact with the substrate between the pillars. While cells remain suspended on pillar tips, acute local deformation of the cell membrane was noted, allowing pillar tips to penetrate the cell interior, while retaining cell viability...
October 17, 2016: ACS Applied Materials & Interfaces
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