Sustaining redox-magnetohydrodynamics (R-MHD) microfluidics by switching oppositely-polarized permanent magnets: Synchronized activation and automation

SENSORS AND ACTUATORS B-CHEMICAL

卷:346

Article

Khan, Foysal Z.¹  Tello, Miguel Abrego¹  Parette, David N.¹  Fritsch, Ingrid¹ 

[1] Univ Arkansas, Dept Chem & Biochem, Fayetteville, AR 72701 USA

关键词: Microfluidics;    Magnetohydrodynamics;    Permanent magnets;    Electrode chips;    Poly(3;    4-ethylenedioxythiophene);   

DOI  :  10.1016/j.snb.2021.130415

来源: Elsevier

【 摘 要 】

A transformative advance in redox-magnetohydrodynamics (R-MHD) microfluidics is demonstrated that indefinitely extends its pumping duration with a miniaturizable approach, while preserving its uniqueness as an internal, self-contained, on-device, active and versatile pump that can also propel fluid in a loop. R-MHD can address the need for fine-tuning microfluidics in micro total analysis systems (mu TAS) for multiple functions in an automated fashion that conventional external pumps with channels and/or valves that determine direction cannot fulfill. In MHD, a body force produced by the cross product of ionic current between strategically activated electrodes and magnetic flux from a permanent magnet or electromagnet drives the fluid. Conducting-polymer-modified electrodes (e.g. with poly(3,4-ethylenedioxythiophene), PEDOT), involve faradaic processes to convert electronic current in the external circuit to ionic current in solution, overcoming bubble generation and electrode corrosion that limited previous MHD microfluidic applications. PEDOT-R-MHD pumping operates with a wider variety of solution compositions and without redox additives. However, pumping stops after complete oxidation/reduction of redox sites in the PEDOT films. The new advance reverses current between PEDOT-modified electrodes to discharge/recharge the polymer while simultaneously swapping permanent magnets of opposite polarities to sustain a constant, unidirectional pumping speed interrupted with brief pauses and without inductive heating. Factors affecting fluid velocities are described, including positions across the magnet assembly, current magnitudes and synchrony with current reversal. A model system (microbeads in biologically-compatible phosphate-buffered saline) is used, which can be generalized more broadly to biological and environmental applications, where starting, stopping, and indefinitely sustaining pumping of a sample are important.

【 授权许可】

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