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An implantable pressure sensing system with electromechanical interrogation
scheme.
Authors Kim A, Powell CR, Ziaie B
Submitted By Charles Powell on 10/13/2014
Status Published
Journal IEEE transactions on bio-medical engineering
Year 2014
Date Published 7/1/2014
Volume : Pages 61 : 2209 - 2217
PubMed Reference
Abstract In this paper, we report on the development of an implantable pressure sensing
system that is powered by mechanical vibrations in the audible acoustic
frequency range. This technique significantly enhances interrogation range,
alleviates the misalignment issues commonly encountered with inductive powering,
and simplifies the external receiver circuitry. The interrogation scheme
consists of two phases: a mechanical vibration phase and an electrical radiation
phase. During the first phase, a piezoelectric cantilever acts as an acoustic
receiver and charges a capacitor by converting sound vibration harmonics
occurring at its resonant frequency into electrical power. In the subsequent
electrical phase, when the cantilever is not vibrating, the stored electric
charge is discharged across an LC tank whose inductor is pressure sensitive;
hence, when the LC tank oscillates at its natural resonant frequency, it
radiates a high-frequency signal that is detectable using an external receiver
and its frequency corresponds to the measured pressure. The pressure sensitive
inductor consists of a planar coil (single loop of wire) with a ferrite core
whose distance to the coil varies with applied pressure. A prototype of the
implantable pressure sensor is fabricated and tested, both in vitro and in vivo
(swine bladder). A pressure sensitivity of 1 kHz/cm H2O is achieved with minimal
misalignment sensitivity (26% drop at 90掳 misalignment between the implanted
device and acoustic source; 60% drop at 90掳 misalignment between the implanted
device and RF receiver coil).


Investigators with authorship
NameInstitution
Charles PowellIndiana University-Purdue University-Indianapolis

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