Sensor Selectivity Enhancement via Electrochemical Shielding in a Recessed Microelectrode Array: The Gatekeeper Geometry
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- 作者：David A. Finkelstein
- 刊名：ACS Sensor
- 出版年：2016
- 出版时间：October 28, 2016
- 年：2016
- 卷：1
- 期：10
- 页码：1217-1221
- 全文大小：501K
- ISSN：2379-3694
文摘
Selectivity in direct electrochemical sensors is difficult to achieve since Pt, the primary catalyst used for detecting analytes key to workplace safety (NH3, H2S, CO), has cross-sensitivity for a number of interferents. Recent advances in recessed microelectrode arrays readily lend themselves to enhancing selectivity in direct sensors via electrochemical shielding. However, all geometries presented to date are optimized for signal amplification, which requires a reversibly reducible or oxidizable analyte. Indeed, while 50-fold improvements in selectivity have been shown, they are a product of 10-fold enhancements via signal amplification and just 5-fold enhancements via shielding. The theoretical study presented herein demonstrates that recessed microelectrode geometries can provide 34- to 260-fold improvements in selectivity via shielding alone for measurements lasting 10 to 140 s. These order-of-magnitude improvements in selectivity via electrochemical shielding thus (1) outpace selectivity via signal amplification and (2) greatly broaden the application space of direct electrochemical sensors by improving selectivity for irreverisble analytes, which cannot benefit from signal amplification. This use of electrochemical shielding coupled with the confined dimensions of a recessed microelectrode array is termed the Gatekeeper Geometry.