Paper-based potentiometric ion sensing

Wen Jie Lan, Xu U. Zou, Mahiar M. Hamedi, Jinbo Hu, Claudio Parolo, E. Jane Maxwell, Philippe Bühlmann, George M. Whitesides

Research output: Contribution to journalArticlepeer-review

133 Scopus citations


This paper describes the design and fabrication of ion-sensing electrochemical paper-based analytical devices (EPADs) in which a miniaturized paper reference electrode is integrated with a small ion-selective paper electrode (ISPE) for potentiometric measurements. Ion-sensing EPADs use printed wax barriers to define electrochemical sample and reference zones. Single-layer EPADs for sensing of chloride ions include wax-defined sample and reference zones that each incorporate a Ag/AgCl electrode. In EPADs developed for other electrolytes (potassium, sodium, and calcium ions), a PVC-based ion-selective membrane is added to separate the sample zone from a paper indicator electrode. After the addition of a small volume (less than 10 μL) of sample and reference solutions to different zones, ion-sensing EPADs exhibit a linear response, over 3 orders of magnitude, in ranges of electrolyte concentrations that are relevant to a variety of applications, with a slope close to the theoretical value (59.2/z mV). Ion-selective EPADs provide a portable, inexpensive, and disposable way of measuring concentrations of electrolyte ions in aqueous solutions.

Original languageEnglish (US)
Pages (from-to)9548-9553
Number of pages6
JournalAnalytical Chemistry
Issue number19
StatePublished - Oct 7 2014

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Publisher Copyright:
© 2014 American Chemical Society.


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