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https://www.readbyqxmd.com/read/29034168/quantitative-comparison-of-pzt-and-cmut-probes-for-photoacoustic-imaging-experimental-validation
#1
Maëva Vallet, François Varray, Jérôme Boutet, Jean-Marc Dinten, Giosuè Caliano, Alessandro Stuart Savoia, Didier Vray
Photoacoustic (PA) signals are short ultrasound (US) pulses typically characterized by a single-cycle shape, often referred to as N-shape. The spectral content of such wideband signals ranges from a few hundred kilohertz to several tens of megahertz. Typical reception frequency responses of classical piezoelectric US imaging transducers, based on PZT technology, are not sufficiently broadband to fully preserve the entire information contained in PA signals, which are then filtered, thus limiting PA imaging performance...
December 2017: Photoacoustics
https://www.readbyqxmd.com/read/29019249/electrochemical-atr-seiras-using-low-cost-micromachined-si-wafers
#2
Tyler A Morhart, Bipinlal Unni, Michael J Lardner, Ian J Burgess
Thin, micromachined Si wafers, designed as internal reflection elements (IREs) for attenuated total reflectance infrared spectroscopy, are adapted to serve as substrates for electrochemical ATR surface enhanced infrared absorption spectroscopy (ATR-SEIRAS). The 500 μm thick wafer IREs with groove angles of 35o are significantly more transparent at long mid-IR wavelengths as compared to conventional large Si hemisphere IREs. The appeal of greater transparency is mitigated by smaller optical throughout at larger grazing angles and steeper angles of incidence at the reflecting plane that reduce the enhancement factor...
October 11, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/29017900/neural-electrode-resilience-against-dielectric-damage-may-be-improved-by-use-of-highly-doped-silicon-as-a-conductive-material
#3
Ryan Caldwell, Rohit Sharma, Pavel Takmakov, Matthew G Street, Florian Solzbacher, Prashant Tathireddy, Loren Rieth
BACKGROUND: Dielectric damage occurring in vivo to neural electrodes, leading to conductive material exposure and impedance reduction over time, limits the functional lifetime and clinical viability of neuroprosthetics. We used silicon micromachined Utah Electrode Arrays (UEAs) with iridium oxide (IrOx) tip metallization and parylene C dielectric encapsulation to understand the factors affecting device resilience and drive improvements. NEW METHOD: In vitro impedance measurements and finite element analyses were conducted to evaluate how exposed surface area of silicon and IrOx affect UEA properties...
October 7, 2017: Journal of Neuroscience Methods
https://www.readbyqxmd.com/read/28994803/an-experimental-protocol-for-assessing-the-performance-of-new-ultrasound-probes-based-on-cmut-technology-in-application-to-brain-imaging
#4
Giulia Matrone, Alessandro Ramalli, Alessandro Stuart Savoia, Fabio Quaglia, Gloria Castellazzi, Patrizia Morbini, Marco Piastra
The possibility to perform an early and repeatable assessment of imaging performance is fundamental in the design and development process of new ultrasound (US) probes. Particularly, a more realistic analysis with application-specific imaging targets can be extremely valuable to assess the expected performance of US probes in their potential clinical field of application. The experimental protocol presented in this work was purposely designed to provide an application-specific assessment procedure for newly-developed US probe prototypes based on Capacitive Micromachined Ultrasonic Transducer (CMUT) technology in relation to brain imaging...
September 24, 2017: Journal of Visualized Experiments: JoVE
https://www.readbyqxmd.com/read/28994800/fabrication-and-validation-of-an-organ-on-chip-system-with-integrated-electrodes-to-directly-quantify-transendothelial-electrical-resistance
#5
Marinke W van der Helm, Mathieu Odijk, Jean-Philippe Frimat, Andries D van der Meer, Jan C T Eijkel, Albert van den Berg, Loes I Segerink
Organs-on-chips, in vitro models involving the culture of (human) tissues inside microfluidic devices, are rapidly emerging and promise to provide useful research tools for studying human health and disease. To characterize the barrier function of cell layers cultured inside organ-on-chip devices, often transendothelial or transepithelial electrical resistance (TEER) is measured. To this end, electrodes are usually integrated into the chip by micromachining methods to provide more stable measurements than is achieved with manual insertion of electrodes into the inlets of the chip...
September 26, 2017: Journal of Visualized Experiments: JoVE
https://www.readbyqxmd.com/read/28994785/aerosol-assisted-chemical-vapor-deposition-of-metal-oxide-structures-zinc-oxide-rods
#6
Stella Vallejos, Nade Z da Pizu Rova, Jan Čechal, Isabel Gràcia, Carles Cané
Whilst columnar zinc oxide (ZnO) structures in the form of rods or wires have been synthesized previously by different liquid- or vapor-phase routes, their high cost production and/or incompatibility with microfabrication technologies, due to the use of pre-deposited catalyst-seeds and/or high processing temperatures exceeding 900 °C, represent a drawback for a widespread use of these methods. Here, however, we report the synthesis of ZnO rods via a non-catalyzed vapor-solid mechanism enabled by using an aerosol-assisted chemical vapor deposition (CVD) method at 400 °C with zinc chloride (ZnCl2) as the precursor and ethanol as the carrier solvent...
September 14, 2017: Journal of Visualized Experiments: JoVE
https://www.readbyqxmd.com/read/28960218/3d-shape-evolution-of-microparticles-and-3d-enabled-applications-using-non-uniform-uv-flow-lithography-nufl
#7
Kenneth Choi, Mohammad Salehizadeh, Rafael Belo Da Silva, Navid Hakimi, Eric Diller, Dae Kun Hwang
The generation of microparticles with non-spherical morphologies has generated extensive interest because of their enhanced physical properties that can increase their performance in a wide variety of clinical and industrial applications. A flow lithographic technique based on stop flow lithography (SFL) recently showed the ability to fabricate particles with 3D shapes via manipulation of the UV intensity profile in a simple 2D microfluidic channel. Here, we further explore this flow lithographic method, called non-uniform flow lithography (NUFL), to investigate the 3D-shape tuning ability for the generation of 3D magnetic microparticles and their potential applications...
September 29, 2017: Soft Matter
https://www.readbyqxmd.com/read/28957259/micro-cantilever-based-fiber-optic-hydrophone-fabricated-by-a-femtosecond-laser
#8
Jie Liu, Lei Yuan, Jincheng Lei, Wenge Zhu, Baokai Cheng, Qi Zhang, Yang Song, Chuan Chen, Hai Xiao
We report an open cavity, cantilever-based fiber optic Fabry-Perot interferometer hydrophone. The hydrophone is made of fused silica material, and its micro-cantilever beam is directly fabricated by femtosecond (fs) laser micromachining. The theoretical analyses and experimental verifications of the frequency response of the sensor are presented.
July 1, 2017: Optics Letters
https://www.readbyqxmd.com/read/28930146/co%C3%A2-sensing-characteristics-of-a-la%C3%A2-o%C3%A2-sno%C3%A2-stacked-structure-with-micromachined-hotplates
#9
Tatsuya Iwata, Kyosuke Matsuda, Kazuhiro Takahashi, Kazuaki Sawada
Demand for the detection of carbon dioxide (CO 2 ) is increasing in various fields, including air-quality monitoring, healthcare, and agriculture. On the other hand, smart gas sensors, in which micromachined gas sensors are integrated with driving circuits, are desirable toward the development of the society of the internet of things. In this study, micromachined hotplate-based CO 2 sensors were fabricated and their characteristics were investigated. The sensors have La 2 O 3 /SnO 2 stacked layers as a sensing material and Pt interdigitated electrodes...
September 20, 2017: Sensors
https://www.readbyqxmd.com/read/28929363/all-in-one-low-intensity-pulsed-ultrasound-stimulation-system-using-piezoelectric-micromachined-ultrasonic-transducer-pmut-arrays-for-targeted-cell-stimulation
#10
Wonjun Lee, Seungjun Yoo, Joontaek Jung, Woojin Kang, Wei Wang, Cheil Moon, Hongsoo Choi
A novel cell-stimulation system was fabricated using 10 × 29 piezoelectric micromachined ultrasonic transducer (pMUT) arrays for targeted ultrasonic cell stimulation. Both the diameter of a single pMUT element and the edge-to-edge gap were 120 μm, and the size of a pMUT array was 2.27 × 6.84 mm, to be placed at the bottom of a Transwell. The measured resonance frequency of a single pMUT element was 1.48 ± 0.13 MHz and the measured acoustic intensity of the pMUT array was 0.15 ± 0.03 MPa at 1 mm away from the transducer...
September 19, 2017: Biomedical Microdevices
https://www.readbyqxmd.com/read/28900104/geometrically-controlled-polarisation-processing-in-femtosecond-laser-written-photonic-circuits
#11
Ioannis Pitsios, Farid Samara, Giacomo Corrielli, Andrea Crespi, Roberto Osellame
Polarisation of light is a powerful and widely used degree of freedom to encode information, both in classical and quantum applications. In particular, quantum information technologies based on photons are being revolutionised by the use of integrated photonic circuits. It is therefore very important to be able to manipulate the polarisation of photons in such circuits. We experimentally demonstrate the fabrication by femtosecond laser micromachining of components such as polarisation insensitive and polarising directional couplers, operating at 1550 nm wavelength, where the two opposite behaviours are achieved just by controlling the geometric layout of the photonic circuits, being the waveguides fabricated with the same irradiation recipe...
September 12, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28844120/development-of-a-biodegradable-flow-resisting-polymer-membrane-for-a-novel-glaucoma-microstent
#12
Stefan Siewert, Karen Falke, Frank Luderer, Thomas Reske, Wolfram Schmidt, Sylvia Pfensig, Michael Stiehm, Ulf Hinze, Boris Chichkov, Niels Grabow, Rudolf Guthoff, Klaus-Peter Schmitz
Within this paper we analyzed the technical feasibility of a novel microstent for glaucoma therapy. For lowering of intraocular pressure, the flexible polyurethane (PUR) implant is designed to drain aqueous humour from the anterior chamber of the eye into subconjunctival, or alternatively suprachoroidal, space. The microstent includes a biodegradable, flow resisting polymer membrane serving as temporary flow resistance for the prevention of early postoperative hypotony. A biodegradable local drug delivery (LDD)-device was designed to prevent fibrous encapsulation...
August 26, 2017: Biomedical Microdevices
https://www.readbyqxmd.com/read/28831196/assembly-of-a-functional-and-responsive-microstructure-by-heat-bonding-of-dna-grafted-colloidal-brick
#13
Yuki Sakamoto, Shoichi Toyabe
A micromachine constructed to possess various chemical and mechanical functions is one of the ultimate targets of technology. Conventional lithographic processes can be used to form complicated structures. However, they are basically limited to rigid and static structures with poor surface properties. Here, we demonstrate a novel method for assembling responsive and functional microstructures from diverse particles modified with DNA strands. The DNA strands are designed to form hairpins at room temperature and denature when heated...
August 22, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28827785/a-highly-sensitive-plasma-based-amyloid-%C3%AE-detection-system-through-medium-changing-and-noise-cancellation-system-for-early-diagnosis-of-the-alzheimer-s-disease
#14
Yong Kyoung Yoo, Jinsik Kim, Gangeun Kim, Young Soo Kim, Hye Yun Kim, Sejin Lee, Won Woo Cho, Seongsoo Kim, Sang-Myung Lee, Byung Chul Lee, Jeong Hoon Lee, Kyo Seon Hwang
We developed an interdigitated microelectrode (IME) sensor system for blood-based Alzheimer's disease (AD) diagnosis based on impedimetric detection of amyloid-β (Aβ) protein, which is a representative candidate biomarker for AD. The IME sensing device was fabricated using a surface micromachining process. For highly sensitive detection of several tens to hundreds of picogram/mL of Aβ in blood, medium change from plasma to PBS buffer was utilized with signal cancellation and amplification processing (SCAP) system...
August 21, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28809682/an-optimization-and-comparative-study-of-air-coupled-cmut-cells-with-circular-and-annular-geometries
#15
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/28804141/a-capacitive-ultrasonic-transducer-based-on-parametric-resonance
#16
Sushruta Surappa, Sarp Satir, F Levent Degertekin
A capacitive ultrasonic transducer based on a parametric resonator structure is described and experimentally demonstrated. The transducer structure, which we call capacitive parametric ultrasonic transducer (CPUT), uses a parallel plate capacitor with a movable membrane as part of a degenerate parametric series RLC resonator circuit with a resonance frequency of fo. When the capacitor plate is driven with an incident harmonic ultrasonic wave at the pump frequency of 2fo with sufficient amplitude, the RLC circuit becomes unstable and ultrasonic energy can be efficiently converted to an electrical signal at fo frequency in the RLC circuit...
July 24, 2017: Applied Physics Letters
https://www.readbyqxmd.com/read/28796616/wireless-power-transfer-to-millimeter-sized-nodes-using-airborne-ultrasound
#17
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 (IoT). We show through simulation that ultrasonic power transfer can deliver 50 [Formula: see text] to a mm-sized node 0.88 m away from a ~ 50-kHz, 25-cm(2) 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 precharged capacitive micromachined ultrasonic transducer, demonstrating a load power of 5 [Formula: see text] at a simulated distance of 1...
October 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
#18
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
#19
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
#20
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
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