The current state of novel technology, surface microfabricated ultrasonic transducers, is reported. Experiments demonstrating both air and water transmission are presented. Air-coupled longitudinal wave through aluminum demonstrated, implying a 110 dB dynamic range for transducers at 2.3 MHz in air. Water experiments from 1 to 20 performed, with measured 60 SNR 3 MHz. A theoretical model proposed that agrees well observed transducer behavior. Most significantly, the used demonstrate...

Piezoelectric materials have dominated the ultrasonic transducer technology. Recently, capacitive micromachined transducers (CMUTs) emerged as an alternative technology offering advantages such wide bandwidth, ease of fabricating large arrays, and potential for integration with electronics. The aim this paper is to demonstrate viability CMUTs ultrasound imaging. We present first pulse-echo phased array B-scan sector images using a 128-element, one-dimensional (1-D) linear CMUT array....

Photoacoustic imaging is an emerging modality that overcomes to a great extent the resolution and depth limitations of optical while maintaining relatively high-contrast. However, since many diseases will not manifest endogenous photoacoustic contrast, it essential develop exogenous contrast agents can target diseased tissue(s). Here we present novel agent, Indocyanine Green dye-enhanced single walled carbon nanotube (SWNT-ICG). We conjugated this agent with cyclic Arg-Gly-Asp (RGD) peptides...

Capacitive micromachined ultrasonic transducers (CMUTs) have been subject to extensive research for the last two decades. Although they were initially developed air-coupled applications, today their main application space is medical imaging and therapy. This paper first presents a brief description of CMUTs, basic structure, operating principles. Our progression developing several generations fabrication processes discussed with an emphasis on advantages disadvantages each process....

Photoacoustic imaging is a unique modality that overcomes to great extent the resolution and depth limitations of optical while maintaining relatively high contrast. However, since many diseases will not manifest an endogenous photoacoustic contrast, it essential develop exogenous contrast agents can target diseased tissue(s). Here we present family novel are based on binding small dyes single-walled carbon nanotubes (SWNT-dye). We synthesized five different SWNT-dye using dyes, creating...

Focused ultrasound is a promising noninvasive technology for neural stimulation. Here we use the isolated salamander retina to characterize effect of on an intact circuit and compared these effects with those visual stimulation same retinal ganglion cells. Ultrasound stimuli at acoustic frequency 43 MHz focal spot diameter 90 μm delivered from piezoelectric transducer evoked stable responses temporal precision equal strong but shorter latency. By presenting together, found that ultrasonic...

Airborne ultrasound has many applications such as, ranging, nondestructive evaluation, gas flow measurement, and acoustic microscopy. This paper investigates the generation detection of in air at a few MHz. Conventional plane piston lead zirconium titanate (PZT) based transducers perform poorly for this application due to lack proper matching layer materials. Electrostatic, or capacitive, promise higher efficiency broader bandwidth performance. The device structure work consists capacitor...

Introduces a new method for fabricating capacitive micromachined ultrasonic transducers (CMUTs) that uses wafer bonding technique. The transducer membrane and cavity are defined on an SOI (silicon-on-insulator) prime wafer, respectively. Then, using silicon direct in vacuum environment, the two wafers bonded together to form transducer. This technique, capable of large CMUTs, offers advantages over traditionally CMUTs. First, forming vacuum-sealed is relatively easy since performed chamber....

This paper presents a microfluidic mixer that uses acoustic stirring created by ultrasonic waves. The ultrasound is introduced into the channel integrated piezoelectric transducers. transducers are made of zinc oxide thin film, which deposited on bottom surface quartz substrate. poly(dimethylsiloxane) aligned to top designed for operation around 450 MHz. main mechanism mixing fluid perpendicular flow direction. radiation pressure generated transducer causes inside channel. performance...

Capacitive micromachined ultrasonic transducer (cMUT) technology is a prime candidate for next generation imaging systems. Medical and underwater the nondestructive evaluation (NDE) societies have expressed growing interest in cMUTs over years. expected to make strong impact on technologies, especially volumetric imaging, appear commercial products near future. This paper focuses fabrication technologies reviews compares variations production processes. We developed two main approaches of...

For three-dimensional (3D) ultrasound imaging, connecting elements of a two-dimensional (2D) transducer array to the imaging system's front-end electronics is challenge because large number and small element size. To compactly connect with electronics, we flip-chip bond 2D 16 times 16-element capacitive micromachined ultrasonic (CMUT) custom-designed integrated circuit (IC). Through-wafer interconnects are used CMUT on top side pads back side. The IC provides 25-V pulser transimpedance...

The electromechanical coupling coefficient is an important figure of merit ultrasonic transducers. transducer bandwidth determined by the efficiency. is, definition, ratio delivered mechanical energy to stored total in transducer. In this paper, we present calculation and measurement for capacitive micromachined transducers (CMUTs). finite element method (FEM) used our calculations, FEM results are compared with analytical obtained parallel plate approximation. effect series capacitances...

We report the use of focused acoustic beams to eject discrete droplets controlled diameter and velocity from a free-liquid surface. No nozzles are involved. Droplet formation has been experimentally demonstrated over frequency range 5–300 MHz, with corresponding droplet diameters 300 5 μm. The physics is essentially unchanged this range. For focusing elements having similar geometries, found scale inversely frequency. A simple model used obtain analytical expressions for key parameters their...

Capacitive micromachined ultrasonic transducers (CMUTs), introduced about a decade ago, have been shown to be good alternative conventional piezoelectric in various aspects, such as sensitivity, transduction efficiency, and bandwidth. In this paper, we discuss the principles of capacitive transducer operation that underlie these aspects. Many key features are enabled with micromachining technology. Micromachining allows us miniaturize device dimensions produce perform comparably their...

Photoacoustic tomography is a rapidly growing imaging modality that can provide images of high spatial resolution and contrast at depths up to 5 cm. We report here the design, synthesis, evaluation an activatable probe shows great promise for enabling detection cleaved in presence levels nonactivated, uncleaved probe, difficult task attain absorbance-based modality. Before cleavage by its target, proteolytic enzyme MMP-2, cell-penetrating peptide, Ceeee[Ahx]PLGLAGrrrrrK, labeled with two...

Absfmet-It is demonstrated that the reflectance function R(@) of a liquid-solid interface can be obtained by inverting complex V(z) data collected with an acoustic microscope. The inversion algorithm based on nonparaxial formulation integral, which establishes Fourier transform relation between and V(z). Examples are given to show this measurement technique, phase velocities propagating modes in solid medium easily determined material losses estimated. same technique also used for...

An important criterion in the design of transducer array elements for acoustic imaging is angular response, or far-field radiation pattern, a single element. In this letter, we show that widely accepted formula response function inadequate and must be multiplied by cosϑ. Good agreement with experiment then obtained.

In real-time ultrasonic 3-D imaging, in addition to difficulties fabricating and interconnecting 2-D transducer arrays with hundreds of elements, there are also challenges acquiring processing data from a large number ultrasound channels. The coarray (spatial convolution the transmit receive arrays) can be used find efficient array designs that capture all spatial frequency content (a transmit-receive element combination corresponds frequency) reduced active channels firing events....

A small-signal equivalent circuit model and FEM often guide CMUT design. The is usually derived using a combination of numerical analysis. strictly analytical approach to design desired because it provides intuition efficient In this paper, we show that the mass-spring-damper used for many MEMS structures accurately captures behavior with circular plate. We provide equations CMUT's parameters, pull-in point, parameters. Comparison shows wide range designs. Using model, can derive simple...

State-of-the-art 3-D medical ultrasound imaging requires transmitting and receiving using a 2-D array of transducers with hundreds or thousands elements. A tight combination the transducer integrated circuitry eliminates bulky cables connecting elements to separate system electronics. Furthermore, preamplifiers located close can lead improved receive sensitivity. combined IC portable, high-performance, inexpensive system. This paper presents an flip-chip bonded 16times16-element capacitive...

We developed a photoacoustic ocular imaging device and demonstrated its utility in the deeper layers of eye including retina, choroid, optic nerve. Using safe laser intensity, system was able to visualize blood distribution an enucleated pig's living rabbit. Ultrasound images, which were simultaneously acquired, overlaid on images eye's anatomy. Such may be used future for early detection improved management neovascular diseases, wet age-related macular degeneration proliferative diabetic...