Construction and electrochemical characterization of microelectrodes for improved sensitivity in paper-based analytical devices

Anal Chem. 2013 May 21;85(10):5233-9. doi: 10.1021/ac400728y. Epub 2013 May 1.

Abstract

This work presents a simple, low cost method for creating microelectrodes for electrochemical paper-based analytical devices (ePADs). The microelectrodes were constructed by backfilling small holes made in polyester sheets using a CO2 laser etching system. To make electrical connections, the working electrodes were combined with silver screen-printed paper in a sandwich type two-electrode configuration. The devices were characterized using linear sweep voltammetry, and the results are in good agreement with theoretical predictions for electrode size and shape. As a proof-of-concept, cysteine was measured using cobalt phthalocyanine as a redox mediator. The rate constant (k(obs)) for the chemical reaction between cysteine and the redox mediator was obtained by chronoamperometry and found to be on the order of 10(5) s(-1) M(-1). Using a microelectrode array, it was possible to reach a limit of detection of 4.8 μM for cysteine. The results show that carbon paste microelectrodes can be easily integrated with paper-based analytical devices.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Carbon / chemistry
  • Catalysis
  • Cysteine / analysis
  • Cysteine / chemistry
  • Electrochemistry / instrumentation*
  • Indoles / chemistry
  • Microelectrodes
  • Organometallic Compounds / chemistry
  • Paper*

Substances

  • Indoles
  • Organometallic Compounds
  • cobalt phthalocyanine
  • Carbon
  • Cysteine