3.6.2. Particle trapping
Particle trapping and enrichment have tremendous applications in clinical diagnostics (Hammarström, Nilson, Laurell, Nilsson, & Ekström, 2014), water quality management (Zeng, Chen, Vedantam, Tzeng, & Xuan, 2013) and drug development (Collins et al., 2015). The ICEK flow has also been utilized for particle/cell trapping. Yalcin et al. (Yalcin, Sharma, Qian, Joo, & Baysal, 2011) were the first to demonstrate the capability in particle trapping under DC electric field using the ICEO MVs around the floating electrodes placed on the microchannel wall. The trapping of particles down to 500 nm in diameter was demonstrated under induced MVs. Ren et al. (Ren et al., 2015) developed a particle enrichment device in which the particles were trapped at the desired location within the microchannel by applying an electric field around a floating electrode (Fig. 6A ). Tao et al. (Tao et al., 2016) demonstrated that increasing in size of several floating electrodes or enlarging the width of a single floating electrode enhanced the trapping efficiency (Fig. 6B ). Harrison et al. (Harrison et al., 2015) utilized the two counter-rotating MVs generated around two dielectric corners of a reservoir–microchannel junction for concentrating the particles of 1 µm diameter. Wu et al. (Y. Wu, Ren, Tao, Hou, & Jiang, 2016) used a rotating electric field for trapping polystyrene (PS) microspheres with 5-20 μm in diameter on a central electrodes array (Fig. 6C ). Last but not the least, Zhao and Yang (Cunlu Zhao & Yang, 2018) used ICEK-based micro-vortices around a polarizable plate located on the microchannel wall for the enrichment of 50-1900 nm fluorescent particles under combined AC/DC electric field (Fig. 6D ).