Fabrication and performance of a miniaturized 64-element high-frequency endoscopic phased array

Abstract

We have developed a 40-MHz, 64-element phased-array transducer packaged in a 2.5 x 3.1 mm endoscopic form factor. The array is a forward-looking semi-kerfed design based on a 0.68Pb(Mg(1/3)Nb(2/3))O(3) - 0.32PbTiO3 (PMN-32%PT) single-crystal wafer with an element-to-element pitch of 38 µm. To achieve a miniaturized form factor, a novel technique of wire bonding the array elements to a polyimide flexible circuit board oriented parallel to the forward looking ultrasound beam and perpendicular to the array was developed. A technique of partially dicing into the back of the array was also implemented to improve the directivity of the array elements. The array was fabricated with a single-layer P(VDF-TrFE)-copolymer matching layer and a polymethylpentene (TPX) lens for passive elevation focusing to a depth of 7 mm. The two-way -6-dB pulse bandwidth was measured to be 55% and the average electromechanical coupling (k(eff)) for the individual elements was measured to be 0.62. The one-way -6-dB directivities from several array elements were measured to be ±20°, which was shown to be an improvement over an identical kerfless array. The -3-dB elevation focus resulting from the TPX lens was measured to be 152 µm at the focal depth, and the focused lateral resolution was measured to be 80 µm at a steering angle of 0°. To generate beam profiles and images, the probe was connected to a commercial ultrasound imaging platform which was reprogrammed to allow for phased array transmit beamforming and receive data collection. The collected RF data were then processed offline using a numerical computing script to generate sector images. The radiation pattern for the beamformed transmit pulse was collected along with images of wire phantoms in water and tissue-equivalent medium with a dynamic range of 60 dB. Finally, ex vivo tissue images were generated of porcine brain tissue.

The Emergence of Egalitarianism in a Model of Early Human Societies

“…All simulations were performed on a personal computer using custom-written software in the Julia programming language [44,45]. To obtain a truncated exponential distribution, values were drawn using the formula 0.05*10 RN where RN is a random number between -2 and 0, yielding a range from 0.005 to 0.5 with a median of 0.05.…”

The emergence of egalitarianism in a model of early human societies

“…All simulations were performed on a personal computer using custom-written software in the Julia programming language [ 44 , 45 ]. To obtain a truncated exponential distribution, values were drawn using the formula 0.1*10 RN where RN is a random number between −2 and 0, yielding a range from 0.01 to 1.0 with a median of 0.1.…”

Flexible Ultrasonic Transducer Array with Bulk PZT for Adjuvant Treatment of Bone Injury

“…Ultrasound is widely used in the field of medicine, especially in elderly rehabilitation [1][2][3], because of its excellent mechanical effects. This includes kidney stone lithotripsy with ultrasonic diagnostic technology and noninvasive tumor therapy with high-intensity focused ultrasound (HIFU) [4][5][6][7][8][9][10]. Recent research on the effect of ultrasound on chondrocyte proliferation and matrix production of human articular cartilage has shown the potential of low-intensity pulsed ultrasound (LIPU) for adjuvant treatment of bone injury [11,12].…”