Vibration Analysis and Evaluation of Piezoelectric Micromachined Ultrasonic Transducers Using Epitaxial Pb(Zr, Ti)O3 Thin Film

Abstract

To improve the transmitting and receiving characteristics of piezoelectric micromachined ultrasonic transducers (pMUTs), the thickness of the diaphragm material SiN x of the pMUT was investigated by vibration analysis using the finite element method (FEM). The vibration magnitudes increase 1.7-fold by changing the SiN x thickness from 1.0 to 0.5 μm as determined by the FEM results. A pMUT with a new structure that has a 0.5-μm-thick SiN x layer was fabricated and evaluated. The vibration of the pMUT was evaluated by a laser Doppler vibrometer (LDV), and the vibration magnitude of the fabricated pMUT was threefold that of our previously reported pMUT. Ultrasonic characteristics such as transmitted ultrasonic sound pressure and ultrasonic sensitivity are also evaluated and compared with those of the previous pMUT. The fabricated pMUT shows 11 times larger transmitted ultrasonic sound pressure and 5 times larger ultrasonic sensitivity than those exhibited by the previous pMUT.

Pseudo-gamma Spectrometry in Plastic Scintillators

“…Other examples were reported with zirconium oxide nanoparticles loaded in PSt for 67.4 keV X-rays [32]. Loadings up to 30 wt% have been achieved.…”

X-ray detection capability of bismuth-loaded plastic scintillators

“…For this purpose, some of the authors (the Japanese group) have evaluated novel scintillation materials, including inorganic crystals exhibiting fast self-trapped exciton emission 4) or Auger-free luminescence, 5,6) organic-inorganic hybrid compounds with quantum-well structures, 7) and plastic scintillators loaded with inorganic nanoparticles. 8,9) To complete the spectrum of available solutions, this paper focuses on plastic scintillators loaded with homogenously dispersed organometallic compounds, as plastic scintillators with enhanced detection efficiencies are promising candidates for such usage. Furthermore, this technology is very costefficient as the chemical cost is low and a very large variety of shapes and volumes is readily accessible.…”