On-chip manipulation of objects using mobile oscillating bubbles

Abstract

This paper describes a new on-chip manipulation method for handling millimeter-and micron-sized objects using oscillating mobile bubbles. It is found that acoustically excited oscillating bubbles can attract and capture neighboring objects. A variety of objects, including hydrophilic glass beads (80 μm), polystyrene beads (100 μm), a fish egg (∼1 mm) and a live water flea (∼1 mm), are successfully captured. The capturing performance is characterized using 80 μm hydrophilic glass particles while varying the acoustic excitation frequency and amplitude. The oscillation amplitude of the bubbles is quantified using high-speed images. At the natural frequencies of the bubbles the capturing range is highest. The capturing range increases as the oscillation amplitude increases. It is also found that while the bubbles are in lateral motion the capturing force is strong enough to hold the captured objects. By integrating acoustic excitation with electrowetting-on-dielectric (EWOD) bubble transportation, it is demonstrated that oscillating mobile bubbles can capture, carry and release neighboring objects on a chip. This new manipulation method may provide an efficient tool for handling millimeter-as well as micron-sized objects such as biological cells.

Lateral air cavities for microfluidic pumping with the use of acoustic energy

“…However, recently there has been a growing trend in harnessing this byproduct for a variety of novel applications (Rife et al 2000;Tsai and Lin 2002;Hilgenfeldt 2003, 2004;Dijkink et al 2006;Marmottant et al 2006;Hettiarachchi et al 2007; Kao et al 2007; Tho et al 2007;Xu and Attinger 2007;Chung and Cho 2008;Ahmed et al 2009a, b;Chung and Cho 2009;Tovar and Lee 2009). The first practical use of trapped air bubbles in a microfluidic device utilized acoustic energy to rapidly mix two fluids within a chamber (Liu et al 2002) for the increase of DNA hybridization (Liu et al 2003a, b).…”

Bubble dynamics atop an oscillating substrate: Interplay of compressibility and contact angle hysteresis

“…Another example concerns acoustic or electrowetting-driven oscillations of a sessile bubble used to generate streaming flow in the bulk, which presents a way to manipulate small-sized objects indirectly, including capture, propulsion, and release. [23][24][25] …”

Bubble actuation by electrowetting-on-dielectric (EWOD) and its applications: A review

“…The capturing of microparticles and various objects using oscillating bubbles was intensively studied by Chung et al. 39,[74][75][76] The effects of the frequency and amplitude of acoustic excitation and AC-EWOD actuation on the capturing of microparticles are quantified with the bubble oscillation amplitude using high-speed imaging. 75 Figure 13 shows the effects of frequency on capturing by AC-EWOD actuation.…”

“…Thanks to these advantages, various applications using the principles of EWOD have been developed: lab-on-a-chips, 2,4,21 electrical switches, 17,22-24 liquid lens, [25][26][27] microprism arrays, 28,29 electrowetting displays, 30-32 and others. [33][34][35][36][37][38][39][40] In the abovementioned applications, the target fluids are mainly liquid. Accordingly, the focus of many review papers on EWOD has been on the dynamics of liquid EWOD.…”