Time filter

Source Type

Sunnyvale, CA, United States

Hai B.,Case Western Reserve University | Tolmachev Y.V.,Kent State University | Loparo K.A.,Case Western Reserve University | Zanelli C.,Onda Corporation | Scherson D.,Case Western Reserve University
Journal of the Electrochemical Society | Year: 2011

The transient response of a series RC equivalent circuit to a staircase potential perturbation, where R represents the resistance due to the electrolyte and C a voltage dependent interfacial capacitance, has been examined theoretically using, as a model system, capacitance data believed to be characteristic of the Pt (111) 0.1 M HCl O 4 interface. Solutions to the governing algebraic differential equation were obtained by numerical techniques, which were then used to generate current versus potential curves assuming various data sampling protocols. In general, the resulting curves were not only found to be sensitive to the time at which the current was sampled within each step, but, also, quite different than those obtained by scanning the potential at a constant rate, as in conventional linear scan voltammetry (LSV). Excellent agreement between the staircase voltammetry (SCV) and LSV results could be achieved, however, based on values of the average step currents, Q step /T, where Q step represents the total charge injected during the step and T the length of the step, as well as by the postfiltering technique introduced by He [Anal. Chem., 67, 986 (1995)]. Implications of these results for studies involving electrocatalytic systems are discussed. © 2010 The Electrochemical Society.

ONDA Ltd | Date: 1987-09-01


Balachandran R.,University of Arizona | Zhao M.,University of Arizona | Yam P.,Onda Corporation | Zanelli C.,Onda Corporation | Keswani M.,University of Arizona
Microelectronic Engineering | Year: 2015

Megasonic cleaning is routinely used for removal of particulate contaminants from various surfaces in integrated circuit industry. One of the drawbacks of megasonic cleaning is that although it can achieve good particle removal efficiencies at high power densities, it also causes feature damage. The current paradigm is that damage is primarily caused by transient cavitation whereas cleaning is affected by streaming and stable cavitation. In order to develop a damage-free and effective megasonic cleaning process, it is essential to understand the acoustic bubble behavior and identify conditions that generate significant stable cavitation without any transient cavitation. In the current work, microelectrode based chronoamperometry, pressure measurements using a hydrophone and fluorescence spectroscopy studies were conducted under different acoustic frequencies (1-3 MHz) and power densities (2-8 W/cm2) to fundamentally investigate the type of cavitation produced under these conditions and also establish a correlation to the generation of hydroxyl radicals for characterization of transient cavitation. © 2014 Elsevier B.V. All rights reserved.

ONDA Ltd | Date: 1987-09-01


Howard S.,Onda Corporation | Twomey R.,NTR University of Health Sciences | Morris H.,Onda Corporation | Zanelli C.I.,Onda Corporation
AIP Conference Proceedings | Year: 2010

The objective of this work was to develop a device for ultrasound power measurement applicable over a broad range of medical transducer types, orientations and powers, and which supports automatic measurements to simplify use and minimize errors. Considering all the recommendations from standards such as IEC 61161, an accurate electromagnetic null-balance has been designed for ultrasound power measurements. The sensing element is placed in the water to eliminate errors due to surface tension and water evaporation, and the motion and detection of force is constrained to one axis, to increase immunity to vibration from the floor, water sloshing and water surface waves. A transparent tank was designed so it could easily be submerged in a larger tank to accommodate large transducers or side-firing geometries, and can also be turned upside-down for upward-firing transducers. A vacuum lid allows degassing the water and target in situ. An external control module was designed to operate the sensing/driving loop and to communicate to a local computer for data logging. The sensing algorithm, which incorporates temperature compensation, compares the feedback force needed to cancel the motion for sources in the "on" and "off" states. These two states can be controlled by the control unit or manually by the user, under guidance by a graphical user interface (the system presents measured power live during collection). Software allows calibration to standard weights, or to independently calibrated acoustic sources. The design accommodates a variety of targets, including cone, rubber, brush targets and an oil-filled target for power measurement via buoyancy changes. Measurement examples are presented, including HIFU sources operating at powers from 1 to 100. © 2010 American Institute of Physics.

Discover hidden collaborations