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https://www.readbyqxmd.com/read/28809682/an-optimization-and-comparative-study-of-air-coupled-cmut-cells-with-circular-and-annular-geometries
#1
Shuai Na, Zhenhao Li, Lawrence L P Wong, Albert I-H Chen, Mirek Macecek, John T W Yeow
Air-coupled capacitive micromachined ultrasonic transducers (CMUTs) with annular cell geometry have recently been reported to have a promising transmit sensitivity. This paper reports three optimization schemes, which further improve the transmit sensitivity and also help achieve a reasonable comparison between the novel annular and conventional circular cells. Lumped element models of both cell types with laminate plate structures are presented. Based on these models, a design optimization flow chart was constructed to facilitate analytical optimization on the three schemes...
August 14, 2017: IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
https://www.readbyqxmd.com/read/28796616/wireless-power-transfer-to-millimeter-sized-nodes-using-airborne-ultrasound
#2
Angad S Rekhi, Butrus T Khuri-Yakub, Amin Arbabian
We propose the use of airborne ultrasound for wireless power transfer to mm-sized nodes, with intended application in the next generation of the Internet of Things. We show through simulation that ultrasonic power transfer can deliver 50μW to a mm-sized node 0.88m away from a ~50 kHz, 25 cm2 transmitter array, with the peak pressure remaining below recommended limits in air, and with load power increasing with transmitter area. We report wireless power recovery measurements with a pre-charged capacitive micromachined ultrasonic transducer, demonstrating a load power of 5μW at a simulated distance of 1...
August 9, 2017: IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
https://www.readbyqxmd.com/read/28774143/effect-of-repetition-rate-on-femtosecond-laser-induced-homogenous-microstructures
#3
Sanchari Biswas, Adya Karthikeyan, Anne-Marie Kietzig
We report on the effect of repetition rate on the formation and surface texture of the laser induced homogenous microstructures. Different microstructures were micromachined on copper (Cu) and titanium (Ti) using femtosecond pulses at 1 and 10 kHz. We studied the effect of the repetition rate on structure formation by comparing the threshold accumulated pulse ( F Σ p u l s e ) values and the effect on the surface texture through lacunarity analysis. Machining both metals at low F Σ p u l s e resulted in microstructures with higher lacunarity at 10 kHz compared to 1 kHz...
December 19, 2016: Materials
https://www.readbyqxmd.com/read/28772683/integration-of-electrodeposited-ni-fe-in-mems-with-low-temperature-deposition-and-etch-processes
#4
Giuseppe Schiavone, Jeremy Murray, Richard Perry, Andrew R Mount, Marc P Y Desmulliez, Anthony J Walton
This article presents a set of low-temperature deposition and etching processes for the integration of electrochemically deposited Ni-Fe alloys in complex magnetic microelectromechanical systems, as Ni-Fe is known to suffer from detrimental stress development when subjected to excessive thermal loads. A selective etch process is reported which enables the copper seed layer used for electrodeposition to be removed while preserving the integrity of Ni-Fe. In addition, a low temperature deposition and surface micromachining process is presented in which silicon dioxide and silicon nitride are used, respectively, as sacrificial material and structural dielectric...
March 22, 2017: Materials
https://www.readbyqxmd.com/read/28772521/study-of-thermal-electrical-modified-etching-for-glass-and-its-application-in-structure-etching
#5
Zhan Zhan, Wei Li, Lingke Yu, Lingyun Wang, Daoheng Sun
In this work, an accelerating etching method for glass named thermal electrical modified etching (TEM etching) is investigated. Based on the identification of the effect in anodic bonding, a novel method for glass structure micromachining is proposed using TEM etching. To validate the method, TEM-etched glasses are prepared and their morphology is tested, revealing the feasibility of the new method for micro/nano structure micromachining. Furthermore, two kinds of edge effect in the TEM and etching processes are analyzed...
February 10, 2017: Materials
https://www.readbyqxmd.com/read/28772424/scaling-up-techniques-for-the-nanofabrication-of-cell-culture-substrates-via-two-photon-polymerization-for-industrial-scale-expansion-of-stem-cells
#6
Davide Ricci, Michele M Nava, Tommaso Zandrini, Giulio Cerullo, Manuela T Raimondi, Roberto Osellame
Stem-cell-based therapies require a high number (10⁶-10⁸) of cells, therefore in vitro expansion is needed because of the initially low amount of stem cells obtainable from human tissues. Standard protocols for stem cell expansion are currently based on chemically-defined culture media and animal-derived feeder-cell layers, which expose cells to additives and to xenogeneic compounds, resulting in potential issues when used in clinics. The two-photon laser polymerization technique enables three-dimensional micro-structures to be fabricated, which we named synthetic nichoids...
January 13, 2017: Materials
https://www.readbyqxmd.com/read/28765573/all-laser-micromachining-of-ridge-waveguides-in-linbo3-crystal-for-mid-infrared-band-applications
#7
Lingqi Li, Weijie Nie, Ziqi Li, Qingming Lu, Carolina Romero, Javier R Vázquez de Aldana, Feng Chen
The femtosecond laser micromachining of transparent optical materials offers a powerful and feasible solution to fabricate versatile photonic components towards diverse applications. In this work, we report on a new design and fabrication of ridge waveguides in LiNbO3 crystal operating at the mid-infrared (MIR) band by all-femtosecond-laser microfabrication. The ridges consist of laser-ablated sidewalls and laser-written bottom low-index cladding tracks, which are constructed for horizontal and longitudinal light confinement, respectively...
August 1, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28738154/modifying-surface-chemistry-of-metal-oxides-for-boosting-dissolution-kinetics-in-water-by-liquid-cell-electron-microscopy
#8
Yue Lu, Jiguo Geng, Kuan Wang, Wei Zhang, Wenqiang Ding, Zhenhua Zhang, Shaohua Xie, Hongxing Dai, Fu-Rong Chen, Manling Sui
Dissolution of metal oxides is fundamentally important for understanding mineral evolution and micromachining oxide functional materials. In general, dissolution of metal oxides is a slow and inefficient chemical reaction. Here, by introducing oxygen deficiencies to modify the surface chemistry of oxides, we can boost the dissolution kinetics of metal oxides in water, as in situ demonstrated in a liquid environmental transmission electron microscope (LETEM). The dissolution rate constant significantly increases by 16-19 orders of magnitude, equivalent to a reduction of 0...
July 27, 2017: ACS Nano
https://www.readbyqxmd.com/read/28727563/a-low-power-high-dynamic-range-receiver-system-for-in-probe-3-d-ultrasonic-imaging
#9
Hourieh Attarzadeh, Ye Xu, Trond Ytterdal
In this paper, a dual-mode low-power, high dynamic-range receiver circuit is designed for the interface with a capacitive micromachined ultrasonic transducer. The proposed ultrasound receiver chip enables the development of an in-probe digital beamforming imaging system. The flexibility of having two operation modes offers a high dynamic range with minimum power sacrifice. A prototype of the chip containing one receive channel, with one variable transimpedance amplifier (TIA) and one analog to digital converter (ADC) circuit is implemented...
July 18, 2017: IEEE Transactions on Biomedical Circuits and Systems
https://www.readbyqxmd.com/read/28713873/wireless-strain-measurement-with-a-micromachined-magnetoelastic-resonator-using-ringdown-frequency-locking
#10
Venkatram Pepakayala, Scott R Green, Yogesh B Gianchandani
Resonant magnetoelastic devices are widely used as anti-theft tags and are also being investigated for a range of sensing applications. The vast majority of magnetoelastic devices are operated at resonance, and rely upon an external interface to wirelessly detect the resonant frequency, and other characteristics. For micromachined devices, this detection method must accommodate diminished signal strength and elevated resonant frequencies. Feedthrough of the interrogating stimulus to the detector also presents a significant challenge...
June 2017: ISSS J Micro Smart Syst
https://www.readbyqxmd.com/read/28695944/design-and-modeling-of-electrode-networks-for-code-division-multiplexed-resistive-pulse-sensing-in-microfluidic-devices
#11
Ruxiu Liu, Waqas Waheed, Ningquan Wang, Ozgun Civelekoglu, Mert Boya, Chia-Heng Chu, A Fatih Sarioglu
A typical microfluidic device sorts, captures or fractionates sample constituents by exposing them to discriminating microenvironments. Direct electronic acquisition of such manipulation by a network of integrated sensors can provide a fast, integrated readout, replacing otherwise required microscopy. We have recently introduced a sensor technology, Microfluidic CODES, which allows us to multiplex resistive pulse sensors on a microfluidic device. Microfluidic CODES employs a network of micromachined coplanar electrodes such that particles passing over these electrodes produce distinguishable code sequences...
July 25, 2017: Lab on a Chip
https://www.readbyqxmd.com/read/28675992/a-microbolometer-system-for-radiation-detection-in-the-thz-frequency-range-with-a-resonating-cavity-fabricated-in-the-cmos-technology
#12
Aleksander Sesek, Andrej Zemva, Janez Trontelj
BACKGROUND: The THz sensors using microbolometers as a sensing element are reported as one of the most sensitive room-temperature THz detectors suitable for THz imaging and spectroscopic applications. Microbolometer detectors are usually fabricated using different types of the MEMS technology. The patent for the detection system presented in this paper describes a method for microbolometer fabrication using a standard CMOS technology with advanced micromachining techniques. The measured sensitivity of the sensors fabricated by the patented method is 1000 V/W at an optimal frequency and is determined by the performance of a double-dipole antenna and quarter-wavelength resonant cavity...
July 4, 2017: Recent Patents on Nanotechnology
https://www.readbyqxmd.com/read/28669429/hybrid-photoacoustic-ultrasound-tomograph-for-real-time-finger-imaging
#13
Milan Oeri, Wolfgang Bost, Nicolas Sénégond, Steffen Tretbar, Marc Fournelle
We report a target-enclosing, hybrid tomograph with a total of 768 elements based on capacitive micromachined ultrasound transducer technology and providing fast, high-resolution 2-D/3-D photoacoustic and ultrasound tomography tailored to finger imaging. A freely programmable ultrasound beamforming platform sampling data at 80 MHz was developed to realize plane wave transmission under multiple angles. A multiplexing unit enables the connection and control of a large number of elements. Fast image reconstruction is provided by GPU processing...
June 29, 2017: Ultrasound in Medicine & Biology
https://www.readbyqxmd.com/read/28668000/a-micromachined-piezoelectric-microgripper-for-manipulation-of-micro-nanomaterials
#14
Huaduo Shi, Weiliang Shi, Ran Zhang, Junyi Zhai, Jinkui Chu, Shuxiang Dong
Micro/nanomaterials and devices have attracted great interest in recent years because of their extensive application prospects in almost all kinds of fields. However, the manipulations of the material at the micro/nanoscale, such as the separation or transfer of a micro/nano-object in the process of assembling micro/nanodevices, are quite difficult. In this paper, we present a micromachined micro-gripper made of photoresist material (SU-8) and driven by piezoelectric Pb(Mg,Nb)O3-PbTiO3 single crystal pieces...
June 2017: Review of Scientific Instruments
https://www.readbyqxmd.com/read/28656975/light-controlled-3d-micromotors-powered-by-bacteria
#15
Gaszton Vizsnyiczai, Giacomo Frangipane, Claudio Maggi, Filippo Saglimbeni, Silvio Bianchi, Roberto Di Leonardo
Self-propelled bacteria can be integrated into synthetic micromachines and act as biological propellers. So far, proposed designs suffer from low reproducibility, large noise levels or lack of tunability. Here we demonstrate that fast, reliable and tunable bio-hybrid micromotors can be obtained by the self-assembly of synthetic structures with genetically engineered biological propellers. The synthetic components consist of 3D interconnected structures having a rotating unit that can capture individual bacteria into an array of microchambers so that cells contribute maximally to the applied torque...
June 28, 2017: Nature Communications
https://www.readbyqxmd.com/read/28655276/modified-random-sequential-adsorption-model-for-understanding-kinetics-of-proteins-adsorption-at-a-liquid-solid-interface
#16
Hwall Min, Eugene Freeman, Weiwei Zhang, Chowdhury Ashraf, David Allara, Adri C T van Duin, Srinivas Tadigadapa
In this Article, we experimentally measure the adsorption kinetics of human serum albumin (HSA) on a hydrophobic hexadecanethiolated gold surface. We use micromachined quartz crystal resonators with fundamental frequency of 83 MHz to accomplish these measurements in real time. In this work, we focus on two key results: (i) asymptotic behavior of the sensor responses upon HSA adsorption and (ii) the jamming limit of adsorbed layer formed by both single-injection and multi-injection experiments with the same value of final concentration...
July 12, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28645796/preclinical-testing-of-frequency-tunable-capacitive-micromachined-ultrasonic-transducer-probe-prototypes
#17
Martin Pekař, Alexander F Kolen, Harm Belt, Frank van Heesch, Nenad Mihajlović, Imo E Hoefer, Tamas Szili-Török, Hendrik J Vos, Johan G Bosch, Gijs van Soest, Antonius F W van der Steen
In intracardiac echocardiography (ICE) it may be beneficial to generate ultrasound images acquired at multiple frequencies, having the possibility of high penetration or high-resolution imaging in a single device. The objective of the presented work is to test two frequency-tunable probe prototypes in a preclinical setting: a rigid probe having a diameter of 11 mm and a new flexible and steerable 12-Fr ICE catheter. Both probes feature a forward-looking 32-element capacitive micromachined ultrasonic transducer array (aperture of 2 × 2 mm(2)) operated in collapse mode, which allows for frequency tuning in the 6-MHz-18-MHz range...
June 20, 2017: Ultrasound in Medicine & Biology
https://www.readbyqxmd.com/read/28632157/development-of-a-novel-transparent-flexible-capacitive-micromachined-ultrasonic-transducer
#18
Da-Chen Pang, Cheng-Min Chang
This paper presents the world's first transparent flexible capacitive micromachined ultrasonic transducer (CMUT) that was fabricated through a roll-lamination technique. This polymer-based CMUT has advantages of transparency, flexibility, and non-contacting detection which provide unique functions in display panel applications. Comprising an indium tin oxide-polyethylene terephthalate (ITO-PET) substrate, SU-8 sidewall and vibrating membranes, and silver nanowire transparent electrode, the transducer has visible-light transmittance exceeding 80% and can operate on curved surfaces with a 40 mm radius of curvature...
June 20, 2017: Sensors
https://www.readbyqxmd.com/read/28613242/design-and-fabrication-of-piezoelectric-micromachined-ultrasound-transducer-pmut-with-partially-etched-zno-film
#19
Junhong Li, Wei Ren, Guoxiang Fan, Chenghao Wang
A square piezoelectric composite diaphragm was analyzed by the finite element method to enhance the sensitivity of a piezoelectric micromachined ultrasound transducer (pMUT). The structures of electrode and piezoelectric film were optimized and a centric electrode was designed to avoid the counteraction of stress in the centre and edges. In order to further improve the sensitivity; a pMUT with partially-etched piezoelectric film was adopted. The receive and transmit sensitivities of the pMUT were analyzed in details...
June 14, 2017: Sensors
https://www.readbyqxmd.com/read/28605185/soft-matter-printed-circuit-board-with-uv-laser-micropatterning
#20
Tong Lu, Eric J Markvicka, Yichu Jin, Carmel Majidi
When encapsulated in elastomer, micropatterned traces of Ga-based liquid metal (LM) can function as elastically deformable circuit wiring that provides mechanically robust electrical connectivity between solid-state elements (e.g., transistors, processors, and sensor nodes). However, LM-microelectronics integration is currently limited by challenges in rapid fabrication of LM circuits and the creation of vias between circuit terminals and the I/O pins of packaged electronics. In this study, we address both with a unique layup for soft-matter electronics in which traces of liquid-phase Ga-In eutectic (EGaIn) are patterned with UV laser micromachining (UVLM)...
June 23, 2017: ACS Applied Materials & Interfaces
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