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Yingchun Peng, Zhiyu Wen, Dongling Li, Zhengguo Shang
Contact time is one of the most important properties for inertial micro-switches. However, it is usually less than 20 μs for the switch with rigid electrode, which is difficult for the external circuit to recognize. This issue is traditionally addressed by designing the switch with a keep-close function or flexible electrode. However, the switch with keep-close function requires an additional operation to re-open itself, causing inconvenience for some applications wherein repeated monitoring is needed. The switch with a flexible electrode is usually fabricated by electroplating technology, and it is difficult to realize low-g switches (<50 g) due to inherent fabrication errors...
February 16, 2017: Sensors
Marco Sautto, Alessandro Stuart Savoia, Fabio Quaglia, Giosue Caliano, Andrea Mazzanti
A formal comparison between fundamental RX amplifier configurations for Capacitive Micromachined Ultrasonic Transducers (CMUT) is proposed in this paper. The impact on both RX and the pulse-echo frequency response and on the output SNR are thoroughly analysed and discussed. It is shown that the resistive-feedback amplifier yields a band-pass RX frequency response, while both open-loop voltage and capacitivefeedback amplifiers exhibit a low-pass frequency response. For a given power dissipation, it is formally proved that a capacitivefeedback amplifier provides a remarkable SNR improvement against the commonly adopted resistive feedback stage, achieved at the expense of a reduced pulse-echo center frequency, making its use convenient in low and mid-frequency ultrasound imaging applications...
February 13, 2017: IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
Yahui Yang, Siyuan Xing, Zecong Fang, Ruya Li, Helen Koo, Tingrui Pan
The latest development in wearable technologies has attracted much attention. In particular, collection and analysis of body fluids has been a focus. In this paper, we have reported a wearable microfluidic platform made using conventional fabric materials and laser micromachining to measure the flow rate on a patterned fabric surface, referred to as digital droplet flowmetry (DDF). The proposed wearable DDF is capable of collecting and measuring continuous perspiration with high precision (96% on average) in a real-time fashion over a defined area of skin...
February 15, 2017: Lab on a Chip
Miao Sun, Yanbo Xie, Jihong Zhu, Jun Li, Jan C T Eijkel
Breaking through technical barriers and cost reduction are critical issues for the development of microfluidic devices, and both rely greatly on the innovation of fabrication techniques and use of new materials. The application of 3D printing definitely accelerated the prototyping of microfluidic chips by its versatility and functionality. However, the resolution of existing 3D printing techniques is still far below that of lithography, which makes it difficult to work on the scale of single cells and near impossible for single molecule work...
February 7, 2017: Analytical Chemistry
Kyle John Bachus, Lili Mats, Heeyoon W Choi, Graham T T Gibson, Richard David Oleschuk
The deposition of nanoliter and sub-nanoliter volumes is important in chemical and biochemical droplet-based microfluidic systems. There are several techniques that have been established for the deposition/generation of small volumes including the use of surfaces with patterned differences in wettability. Many such methods require complex and time-consuming lithographic techniques. Here, we present a facile method for the fabrication of superhydrophobic surfaces with patterned hydrophilic regions by laser micromachining...
February 7, 2017: ACS Applied Materials & Interfaces
Giovanni Lenguito, Deborah Chaimov, Jonathan R Weitz, Rayner Rodriguez-Diaz, Siddarth A K Rawal, Alejandro Tamayo-Garcia, Alejandro Caicedo, Cherie L Stabler, Peter Buchwald, Ashutosh Agarwal
We report the design and fabrication of a robust fluidic platform built out of inert plastic materials and micromachined features that promote optimized convective fluid transport. The platform is tested for perfusion interrogation of rodent and human pancreatic islets, dynamic secretion of hormones, concomitant live-cell imaging, and optogenetic stimulation of genetically engineered islets. A coupled quantitative fluid dynamics computational model of glucose stimulated insulin secretion and fluid dynamics was first utilized to design device geometries that are optimal for complete perfusion of three-dimensional islets, effective collection of secreted insulin, and minimization of system volumes and associated delays...
February 3, 2017: Lab on a Chip
Xuepeng Zhan, Huailiang Xu, Chunhao Li, Hongwei Zang, Chang Liu, Jihong Zhao, Hongbo Sun
We report an approach for remote and rapid fabrication of a broadband low-reflectivity black silicon surface by ablating crystalline silicon with femtosecond laser filaments in air. Porous microstructures on the processed silicon surface are formed, resulting in a significantly enhanced light trapping efficiency in a broadband (UV-IR) spectral range. It is found that the air filament can significantly reduce the average number of adopted pulses in a normalized fabrication area and enables the processing remotely, which opens a way toward remote and rapid micromachining of optoelectronic materials by femtosecond laser filaments...
February 1, 2017: Optics Letters
Hayrettin Koymen, Abdullah Atalar, A Sinan Tasdelen
We introduce the large-signal and small-signal equivalent circuit models for a capacitive micromachined ultrasonic transducer (CMUT) cell, which has radiating plates on both sides. We present the diffraction coefficient of baffled and unbaffled CMUT cells. We show that the substrate can be modeled as a very thick radiating plate on one side, which can be readily incorporated in the introduced model. In the limiting case, the reactance of this backing impedance is entirely compliant for substrate materials with a Poisson's ratio less than 1/3...
February 2017: IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
Yuanyu Yu, Sio Pun, Peng Un Mak, Ching-Hsiang Cheng, Jiujiang Wang, Pui In Mak, Mang I Vai
Capacitive micromachined ultrasonic transducers (CMUTs) have emerged as a competitive alternative to piezoelectric ultrasonic transducers, especially in medical ultrasound imaging and therapeutic ultrasound applications which require high output pressure. However, as compared with piezoelectric ultrasonic transducers, the output pressure capability of CMUTs remains to be improved. In this paper, a novel structure is proposed by forming an embossed vibrating membrane on a CMUT cell operating in the collapse-mode to increase the maximum output pressure...
April 15, 2016: IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
Benjamin Greenlay, Roger Zemp
The microfabrication processes for sacrificial-release based capacitive micromachined ultrasound transducer (CMUT) arrays are provided with an emphasis on top-orthogonal-to-bottom electrode (TOBE) 2D arrays. These arrays have significant promise for high-quality 3D imaging with reduced wiring complexity compared to 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.
October 24, 2016: IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
Ryan K W Chee, Peiyu Zhang, Mohammad Maadi, Roger J Zemp
Multifrequency capacitive micromachined ultrasound transducers (CMUTs) are introduced consisting of interlaced 82- [Formula: see text] (low frequency) and 36- [Formula: see text] (high frequency) membranes. The membranes have been interlaced on a scale smaller than the shortest wavelength of operation allowing several advantages over other multifrequency transducer designs including aligned beam profiles, optimal imaging resolution, and minimal grating lobes. The low- and high-frequency CMUTs operate at 1.74 and 5...
February 2017: IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
Hyo-Seon Yoon, Chienliu Chang, Ji Hoon Jang, Anshuman Bhuyan, Jung Woo Choe, Amin Nikoozadeh, Ronald Watkins, Doug Stephens, Kim Butts Pauly, Butrus 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-mm2, 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...
September 5, 2016: IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
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 biomicromachines by using diatom frustules as integrated active components, including the assembling, operation, and performance characterization. We further investigate and demonstrate unique applications of the biomicromachines 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...
February 7, 2017: ACS Applied Materials & Interfaces
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