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Eletrochemically Actuated Stop–Go Valves for Capillary Force‐Operated Diagnostic Microsystems
Author(s) -
Washe Alemayehu P.,
Lozano Pablo,
Bejarano Diego,
Katakis Ioanis
Publication year - 2013
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.201300042
Subject(s) - microsystem , capillary action , task force , nanotechnology , materials science , composite material , public administration , political science
Lateral‐flow immunosensing devices continue to be the most successful commercial realization of analytical microdevices. They owe their success to their simplicity, which significantly depends on the capillary‐driven flow and versatile technological platform that lends itself to fast and low‐cost product development. To compete with such a convenient product, microsystems can benefit from simple‐to‐operate fluid manipulation. We show that the capillary‐driven flow in microchannels can be manipulated with electrochemically activated valves with no moving parts. These valves consist of screen‐printed electrode pairs that are transversal to the flow. One of the electrodes is solvent‐etched to produce a superhydrophobic surface that provides passive stopping and facilitates low‐voltage (∼1 V) actuation of the flow via electrowetting. The operation of such valves in the stop–go mode, with a response time between 2 and 45 sec depending on the type and concentration of salt, is demonstrated. Mechanistic investigations indicated that the response depends on at least three phenomena that contribute to electrocapillarity: the electrochemical double‐layer capacitance, specific counterion adsorption, and possible electrohydrodynamic effects.