Toward an OFDM-based Technique for Electrochemical Impedance Spectroscopy
Résumé
Fibrosis represents an open issue for medium to
long-term active implants given that this biological medium
surrounds the stimulation electrodes and can impact or
modify the performances of the system. For this reason,
Embedded Impedance Spectroscopy techniques has been
investigated these last years to sense the fibrosis. The
following article introduces a new paradigm for
Electrochemical Impedance Spectroscopy (EIS) derived from
multi-carrier digital communication methods. Due to its
properties of flat spectrum and fast generation the
Orthogonal-Frequency Division Multiplexing (OFDM)
technique for EIS seems to be a real alternative to traditional
ones. This article focuses on this approach and defines its
performances on gold electrodes used for in-vitro
experiments. An embedded implementation is also presented.
This designed prototype allows to measure a medium with an
error between 2% and 3%, when stimulating with a 16 or 32
tones multitone signal and a sampling frequency of 12KHz.