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Miniature Gigahertz Acoustic Resonator and On-Chip Electrochemical Sensor: An Emerging Combination for Electroanalytical Microsystems

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Miniature Gigahertz Acoustic Resonator and On-Chip Electrochemical Sensor: An Emerging Combination for Electroanalytical Microsystems

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Abstract

Performance of electroanalytical lab-on-a-chip devices is often limited by the mass transfer of electroactive species towards the electrode surface, due to the difficulty in applying external convection. This article describes the powerful signal enhancement attained with a 2.54 GHz miniature acoustic resonator integrated with an electrochemical device in a miniaturized cell. Acoustic resonator and an on-chip gold thin-film three-electrode electrochemical cell were arranged facing each other inside a structured polymethyl methacrylate chamber. Cyclic voltammetric and chronoamperometric responses of 1 mM ferrocene-methanol were recorded under resonator’s actuation at powers ranging from 0 to 1 W. Finite element analysis was carried out to study the sono-electroanalytical process. Acoustic resonator’s actuation greatly enhances the mass transport of electroactive species towards the electrode surface. The diffusion limited cyclic voltammetric and chronoamperometric currents increase around 10 and 20 times respectively with an input power of 1 W compared to those recorded under stagnant condition. The improvement in electroanalytical process is mainly associated with acoustic resonator’s vibration induced fluid streaming. The advantages of miniaturized acoustic resonator, including the submillimeter small size, amenability for mass fabrication, cost effectiveness, low energy consumption, as well as outstanding enhancement of coupled electrochemical processes, will enable the production of highly-sensitive compact electroanalytical devices.

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... Its acoustic nature as well as gigahertz working frequency (around ten thousand times higher than commonly used ultrasound waves (26)) enables agitating liquid and amazingly generates extremely strong steady state acoustic streaming but not cavitation ( Fig. 1(D)). Also its submillimeter size makes it extremely compatible with miniature platform (27). ...
... The propagation of vibration from the resonator to the fluid induces directional fluid flow in the chamber and the resultant flow profile is mathematically calculatable. Specific calculation details can be referred to our previous publication (27). Fig. 3(A) schematically draws a two-dimensional (2D) diagram of our assembled sono-electrochemical platform. ...
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Surface Acoustic Wave Enhanced Electroanalytical Sensors
  • E Kaplan