http://ieeexplore.ieee.org/iel5/5/31047/01444179.pdf

Fundamentals of acoustics

Advantages and Challenges of Relaxor-PbTiO3 Ferroelectric Crystals for Electroacoustic Transducers- A Review.

Continuous monitoring of the central-blood-pressure waveform from deeply embedded vessels, such as the carotid artery and jugular vein, has clinical value for the prediction of all-cause cardiovascular mortality. However, existing non-invasive approaches, including photoplethysmography and tonometry, only enable access to the superficial peripheral vasculature. Although current ultrasonic technologies allow non-invasive deep-tissue observation, unstable coupling with the tissue surface resulting from the bulkiness and rigidity of conventional ultrasound probes introduces usability constraints. Here, we describe the design and operation of an ultrasonic device that is conformal to the skin and capable of capturing blood-pressure waveforms at deeply embedded arterial and venous sites. The wearable device is ultrathin (240 μm) and stretchable (with strains up to 60%), and enables the non-invasive, continuous and accurate monitoring of cardiovascular events from multiple body locations, which should facilitate its use in a variety of clinical environments.

/pdf/monitoring-of-the-central-blood-pressure-waveform-via-a-205q4e1ldq.pdf

Monitoring of the central blood pressure waveform via a conformal ultrasonic device.

Recent progress in flexible and stretchable piezoelectric devices for mechanical energy harvesting, sensing and actuation

Advances in Piezoelectric Polymer Composites for Energy Harvesting Applications: A Systematic Review

In this study, a novel 1–3 composite three-row dual frequency ultrasound transducer was designed and fabricated for image-guided drug delivery. A novel dicing and filling method was used to fabricate 1–3 composite. The electrodes was fabricated by magnetron sputtering method, a NiCr film was sputtered with piezoelectric composite and electrode of Au to improve the adhesion between composite and electrode. Al 2 O 3 powder and tungsten powder were used to fabricate matching and backing layers with epoxy. And flexible circuits were used for interconnect. The middle row was a 128-element 1D array and the outer two rows were 64-element 1.5D arrays. The outer rows were assembled at an angle of 8.75° with the middle row in a mold and fixed using epoxy. A prototype transducer was successfully fabricated and tested. The average center frequency estimated from the measured pulse-echo responses of the middle row elements was 5.22 MHz and the -6dB fractional bandwidth was 79.9%. And the average center frequency of the outer rows was 1.4MHz, the −6dB fractional bandwidth was 52.1%.

Design and fabrication of a novel three-row dual frequency ultrasound transducer for image-guided drug delivery

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/pdf/development-of-novel-imaging-systems-and-techniques-for-2kf4l2gpsg.pdf

Development of novel imaging systems and techniques for micro-ultrasound

Disclosed is a microfluidic system based on an artificially structured acoustic field, comprising a microcavity and a ultrasonic emission device, wherein the microcavity is used to accommodate a solution containing particles, the ultrasonic emission device is used to emit ultrasound, and characterized in further comprising a phononic crystal plate placed in the microcavity, wherein the phononic crystal plate has an artificial cycle structure, and is used to modulate the acoustic field so as to control the particles. Also disclosed is a method of controlling microfluid particles based on an artificially structured acoustic field. In the particular embodiments, since a microcavity, an ultrasonic emission device and a phononic crystal plate are comprised, the ultrasonic emission device is used to emit ultrasound, and the phononic crystal plate has an artificial cycle structure, and is used to modulate the acoustic field so as to control the particles. The method provides a new means for drug delivery, and offers technical support for drug research and development.

Microfluidic system and method of controlling particles based on artificially structured acoustic field

The invention belongs to the field of medical imaging, and provides a method and a device for processing uniformity and contrast of ultrasonic images, in order to improve imaging quality of the ultrasonic images and meet medical imaging requirements. The method includes preprocessing input ultrasonic image data to acquire the preprocessed ultrasonic image data; partitioning the preprocessed ultrasonic image data into a characteristic region and a non-characteristic region to acquire a partitioned image; selecting different gray-scale mapping curves to perform grey scale adjustment on the characteristic region and the non-characteristic region in the partitioned image, and outputting the partitioned image to a display device for display. Compared with the prior, the method and the device have the advantages that images can be partitioned effectively,, and contrast of characteristic information can be increased; due to symmetry of a grey-scale mapping curve group, the contrast of the characteristic region and the uniformity of the non-characteristic region can be fused perfectly, and good image effect is achieved on the premise of low dependence on image partition.

Method and device for processing uniformity and contrast of ultrasonic images

The diameter of an intravascular ultrasound (IVUS) catheter is always less than 1 mm, because it must be inserted into a blood vessel to obtain ultrasound images. Owing to this requisite small size, it is difficult to perform geometric focusing on the surface of an IVUS transducer to improve the spatial resolution of the image. This study proposes a high frequency transducer with a Fresnel zone plate (FZP) for intravascular ultrasound imaging. Through theoretical calculations, the parameters and structure of the transducer are optimized for high-frequency ultrasound. The acoustic beam is simulated using COMSOL software. The aperture size of the ultrasound element is 0.778 × 0.9 mm2. Transducers with or without the FZP layer are designed and fabricated in this study. The center frequency and –6 dB bandwidth of the FZP transducer are 52.5 MHz and 42%, respectively. Meanwhile, the center frequency and –6 dB bandwidth of the plane-shape transducer are 51.3 MHz and 58%, respectively. Wire phantom and porcine artery imaging experiments were performed to evaluate the performance of the designed transducers. The spatial resolution of the FZP transducer is 46.8 μm axially and 183.6 μm laterally, and the resolution of the plane-shape transducer is 44.3 μm axially and 313.5 μm laterally. The results demonstrate that the FZP transducer provides superior lateral imaging resolution for IVUS applications.

Weibao Qiu

Papers

Design and fabrication of a novel three-row dual frequency ultrasound transducer for image-guided drug delivery

Development of novel imaging systems and techniques for micro-ultrasound

Microfluidic system and method of controlling particles based on artificially structured acoustic field

Method and device for processing uniformity and contrast of ultrasonic images

High frequency focal transducer with a Fresnel zone plate for intravascular ultrasound