This paper presents power transmission performance of the ultrasound-based piezoelectric recharging system for
implantable medical devices. The efficiency of the piezoelectric ultrasonic transcutaneous energy transfer system
depends on frequency matching of the transmitter and receiver, electrical, mechanical and acoustical impedance
characteristics, distance between the transducers, and misalignment. However, it was realized that the angular
misalignment between transmitter and receiver was one of key factors to have effect on the power transmission
efficiency. As such, misalignment effect of the piezoelectric ultrasound transmitter and receiver on the power
transmission efficiency was investigated by theoretical analysis using finite-difference time-domain method. The
pressure field variation in the near field was also estimated to examine the influence of the power transfer performance
of the ultrasound-based charging system.
Analytical results indicate that the transferred power is greatly reduced by voltage cancellation on the receiver from
phase shift due to the misalignment. Furthermore, significant acoustic pressure variation in the near field makes the
effect of misalignment on power transmission dependent on the receiver location.
This paper presents experimental results that demonstrate energy generating performance of circular piezoelectric
diaphragm harvesters for use in implantable medical devices. The piezoelectric energy generators are designed to
transfer internal biomechanical forces into electrical energy that can be stored and used to power other in vivo devices.
Such energy harvesters can eliminate complicated procedures for replacement of batteries in active implants by possibly
increasing the longevity or capacity of batteries. Experimental results indicated that the PZT circular diaphragm
harvesters generated enough power to meet requirements for specific implantable medical devices. It is also found that
edge condition, thickness of bonding layer, and a degree of symmetry in fabrication for the unimorph circular
diaphragms affect the energy generating performance significantly.
This paper presents current work on a project to demonstrate the feasibility of harvesting energy for medical devices
from internal biomechanical forces using piezoelectric transducer technology based on PMN-PT. The energy harvesting
device in this study is a partially covered, simply-supported PMN-PT unimorph circular plate to capture biomechanical
energy and to provide power to implanted medical devices. Power harvesting performance for the piezoelectric energy
harvesting diaphragm structure is examined analytically. The analysis includes comprehensive modeling and parametric
study to provide a design primer for a specific application. An expression for the total power output from the devices for
applied pressure is shown, and then used to determine optimal design parameters. It is shown that the device's
deflections and stresses under load are the limiting factors in the design. While the primary material choice for energy
harvesting today is PZT, an advanced material, PMN-PT, which exhibits improved potential over current materials, is
used.
Laser-induced breakdown spectroscopy (LIBS) has been used for a variety of
applications, usually those requiring remote or in situ spectrochemical analysis.
Several beryllium monitoring instruments based on LIBS have been built. The
progress and implementation of this technique will be reviewed.
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