Development and Demonstration of Measurement-Time Efficient Methods for Impedance Spectroscopy of Electrode and Sensor Arrays.

Kevin R Cooper,Matthew Smith,Derek Johnson

doi:10.3390/s8031774

Abstract

The development of impedance-based array devices is hindered by a lack ofrobust platforms and methods upon which to evaluate and interrogate sensors. One aspectto be addressed is the development of measurement-time efficient techniques forbroadband impedance spectroscopy of large electrode arrays. The objective of this workwas to substantially increase the low frequency impedance measurement throughputcapability of a large channel count array analyzer by developing true parallel measurementmethods. The goal was achieved by Fourier transform-based analysis of simultaneouslyacquiredmulti-channel time-based current and voltage data. Efficacy and quantitativeanalysis of the parallel approach at frequencies less than ca. 10 Hz as well as a combinedsequential parallel approach for efficient broadband impedance spectroscopy over 5-orders of magnitude in frequency is demonstrated through complex impedancemeasurement of arrays consisting of up to 100 elements.

Highlights

Impedance-based measurement approaches, which are non-invasive, can substantially improve the selectivity and sensitivity [1,2,3] and yield shorter response times and more stable readings [4] whenSensors 2008, 8 applied to chemiresistor and other sensor types
The second part describes experiments designed to demonstrate the efficacy of a combined sequential + parallel measurement approach on dummy cells composed of resistor-capacitor networks that mimic in their frequencydependent impedance response typical sensor and/or electrochemical systems
The results demonstrate that, in general, the large-channel count array analyzer used here was capable of accurately measuring the impedance of dummy cells designed to simulate typical chemiresistor sensors [1,2,3,4, 24, 25]

Summary

Introduction

Impedance-based measurement approaches, which are non-invasive, can substantially improve the selectivity and sensitivity [1,2,3] and yield shorter response times and more stable readings [4] whenSensors 2008, 8 applied to chemiresistor and other sensor types. Commercially-available, general purpose multi-channel analyzers capable of DC and AC impedance interrogation of arrays with up to 100 electrodes have been used to study complex electrochemical phenomenon such as metallurgical and spatiotemporal interactions in localized corrosion [7,8,9,10,11], combinatorial electrochemistry for discovery of improved corrosion inhibitors [12, 13], lithium-ion battery electrode materials [14,15,16,17], and fuel cell catalyst [18] These works employ DC electrochemical measurement methods, such as linear or cyclic polarization techniques. Only one publication [19] describes impedance spectroscopy of large-channel count arrays, i.e., where N ~ 100 electrodes

Objectives

Methods

Results

Conclusion