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Issue 14, 2012
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Ion diode logics for pH control

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Abstract

Electronic control over the generation, transport, and delivery of ions is useful in order to regulate reactions, functions, and processes in various chemical and biological systems. Different kinds of ion diodes and transistors that exhibit non-linear current versus voltage characteristics have been explored to generate chemical gradients and signals. Bipolar membranes (BMs) exhibit both ion current rectification and water splitting and are thus suitable as ion diodes for the regulation of pH. To date, fast switching ion diodes have been difficult to realize due to accumulation of ions inside the device structure at forward bias – charges that take a long time to deplete at reverse bias. Water splitting occurs at elevated reverse voltage bias and is a feature that renders high ion current rectification impossible. This makes integration of ion diodes in circuits difficult. Here, we report three different designs of micro-fabricated ion bipolar membrane diodes (IBMDs). The first two designs consist of single BM configurations, and are capable of either splitting water or providing high current rectification. In the third design, water-splitting BMs and a highly-rectifying BM are connected in series, thus suppressing accumulation of ions. The resulting IBMD shows less hysteresis, faster off-switching, and also a high ion current rectification ratio as compared to the single BM devices. Further, the IBMD was integrated in a diode-based AND gate, which is capable of controlling delivery of hydroxide ions into a receiving reservoir.

Graphical abstract: Ion diode logics for pH control

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Publication details

The article was received on 24 Jan 2012, accepted on 03 Apr 2012 and first published on 04 Apr 2012


Article type: Paper
DOI: 10.1039/C2LC40093F
Citation: Lab Chip, 2012,12, 2507-2513
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    Ion diode logics for pH control

    E. O. Gabrielsson, K. Tybrandt and M. Berggren, Lab Chip, 2012, 12, 2507
    DOI: 10.1039/C2LC40093F

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