Maximizing fluid delivered by bubble‐free electroosmotic pump with optimum pulse voltage waveform

Abstract

In generating high electroosmotic (EO) flows for use in microfluidic pumps, a limiting factor is faradaic reactions that are more pronounced at high electric fields. These reactions lead to bubble generation at the electrodes and pump efficiency reduction. The onset of gas generation for high current density EO pumping depends on many parameters including applied voltage, working fluid, and pulse duration. The onset of gas generation can be delayed and optimized for maximum volume pumped in the minimum time possible. This has been achieved through the use of a novel numerical model that predicts the onset of gas generation during EO pumping using an optimized pulse voltage waveform. This method allows applying current densities higher than previously reported. Optimal pulse voltage waveforms are calculated based on the previous theories for different current densities and electrolyte molarity. The electroosmotic pump performance is investigated by experimentally measuring the fluid volume displaced and flow rate.

Induced-charge electrokinetics in microfluidics: a review on recent advancements

“…Theoretical modeling of the frequency-dependent pumping was further developed [49] and used to simulate different aspects of the ACEO pumping [50,51]. Furthermore, the effect of several parameters and pumping configurations were investigated, such as studying the effect of channel height, electrochemical reactions, and non-linear surface capacitance of the Debye layer [52]; controlling the pumping direction by switching the voltage using an inclined electrode array [53,54], pumping of two different electrolytes simultaneously through microchannels [55], bubble-free pumping [56,57] as well as ACEO pumping using biased AC/DC signals [48,[58][59][60][61], pulse voltage waveforms [57], square pole-slit electrode arrays [62], and arrays of asymmetric ring electrode pairs in the cylindrical microchannels [63]. Also, the comparison between fluid velocity on arrays of identical electrodes with AC voltage and a traveling-wave potential demonstrated that traveling-wave potential resulted in a higher fluid velocity [64,65].…”

Induced-charge electrokinetic (ICEK) development and applications in microfluidics

“…Theoretical modeling of the frequencydependent pumping was further developed (Ramos, Gonzalez, Castellanos, Green, & Morgan, 2003) and used to simulate different aspects of the ACEO pumping (Debesset, Hayden, Dalton, Eijkel, & Manz, 2004;Vincent Studer, Pépin, Chen, & Ajdari, 2004). Furthermore, the effect of several parameters and pumping configurations were investigated, such as studying the effect of channel height, electrochemical reactions, and non-linear surface capacitance of the Debye layer (Olesen, Bruus, & Ajdari, 2006); controlling the pumping direction by switching the voltage using an inclined electrode array (Hilber, Weiss, Saeed, Holly, & Jakoby, 2009;Loucaides, Ramos, & Georghiou, 2007), pumping of two different electrolytes simultaneously through microchannels (Morgan, Green, Ramos, & García-Sánchez, 2007), bubble-free pumping (Kuo & Liu, 2008;Tawfik & Diez, 2017) as well as ACEO pumping using biased AC/DC signals (Islam & Reyna, 2012;Lian & Wu, 2009;Piñón et al, 2017;Jie Wu, 2008;Yang Ng, Ramos, Cheong Lam, & Rodriguez, 2012), pulse voltage waveforms (Tawfik & Diez, 2017), square pole-slit electrode arrays (Yoshida, Sato, Eom, Kim, & Yokota, 2017), and arrays of asymmetric ring electrode pairs in the cylindrical microchannels (Gao & Li, 2018). Also, the comparison between fluid velocity on arrays of identical electrodes with AC voltage and a traveling-wave potential demonstrated that traveling-wave potential resulted in a higher fluid velocity (Ramos et al, 2005;Yang, Jiang, Ramos, & García-Sánchez, 2009).…”