An implantable pressure sensing system with electromechanical interrogation scheme

Albert Kim, Charles Powell, Babak Ziaie

Research output: Contribution to journalArticle

18 Citations (Scopus)

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 H-2O is achieved with minimal misalignment sensitivity (26% drop at 90° misalignment between the implanted device and acoustic source; 60% drop at 90° misalignment between the implanted device and RF receiver coil).

Original languageEnglish
Article number6807758
Pages (from-to)2209-2217
Number of pages9
JournalIEEE Transactions on Biomedical Engineering
Volume61
Issue number7
DOIs
StatePublished - 2014

Fingerprint

Pressure
Vibration
Acoustics
Vibrations (mechanical)
Acoustic receivers
Natural frequencies
Cable cores
Electric charge
Equipment and Supplies
Pressure sensors
Ferrite
Capacitors
Acoustic waves
Wire
Urinary Bladder
Swine
Radiation

Keywords

  • Acoustic powering
  • Bladder pressure
  • Implantable pressure sensor
  • Mechanical vibration

ASJC Scopus subject areas

  • Biomedical Engineering
  • Medicine(all)

Cite this

An implantable pressure sensing system with electromechanical interrogation scheme. / Kim, Albert; Powell, Charles; Ziaie, Babak.

In: IEEE Transactions on Biomedical Engineering, Vol. 61, No. 7, 6807758, 2014, p. 2209-2217.

Research output: Contribution to journalArticle

@article{4daef560603e49dd97d0d1cacdb15263,
title = "An implantable pressure sensing system with electromechanical interrogation scheme",
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 H-2O is achieved with minimal misalignment sensitivity (26{\%} drop at 90° misalignment between the implanted device and acoustic source; 60{\%} drop at 90° misalignment between the implanted device and RF receiver coil).",
keywords = "Acoustic powering, Bladder pressure, Implantable pressure sensor, Mechanical vibration",
author = "Albert Kim and Charles Powell and Babak Ziaie",
year = "2014",
doi = "10.1109/TBME.2014.2318023",
language = "English",
volume = "61",
pages = "2209--2217",
journal = "IEEE Transactions on Biomedical Engineering",
issn = "0018-9294",
publisher = "IEEE Computer Society",
number = "7",

}

TY - JOUR

T1 - An implantable pressure sensing system with electromechanical interrogation scheme

AU - Kim, Albert

AU - Powell, Charles

AU - Ziaie, Babak

PY - 2014

Y1 - 2014

N2 - 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 H-2O is achieved with minimal misalignment sensitivity (26% drop at 90° misalignment between the implanted device and acoustic source; 60% drop at 90° misalignment between the implanted device and RF receiver coil).

AB - 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 H-2O is achieved with minimal misalignment sensitivity (26% drop at 90° misalignment between the implanted device and acoustic source; 60% drop at 90° misalignment between the implanted device and RF receiver coil).

KW - Acoustic powering

KW - Bladder pressure

KW - Implantable pressure sensor

KW - Mechanical vibration

UR - http://www.scopus.com/inward/record.url?scp=84903195058&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84903195058&partnerID=8YFLogxK

U2 - 10.1109/TBME.2014.2318023

DO - 10.1109/TBME.2014.2318023

M3 - Article

VL - 61

SP - 2209

EP - 2217

JO - IEEE Transactions on Biomedical Engineering

JF - IEEE Transactions on Biomedical Engineering

SN - 0018-9294

IS - 7

M1 - 6807758

ER -