Flexible Microswimmer Manipulation in Multiple Microfluidic Systems Utilizing Thermal Buoyancy-Capillary Convection

Abstract

Flexible and accurate control of microswimmers is significant for lots of applications. Herein, we present a method for effective microswimmer manipulation in multiple microfluidic systems by thermal buoyancy−capillary convection. In the microdevice, four strips of microheaters arranged at the bottom of the microchannel are used to unevenly heat microfluids, and the convection flow forms under the influence of gravity and interfacial tension gradient. By adjusting the DC signals applied on these four heating elements, the intensity and direction of convection flow can be flexibly adjusted. Accordingly, granular samples dispersed in liquid buffer can be controllably driven to the target position by the Stokes drag. The swimming behavior of polystyrene (PS) microspheres at the solid−liquid interface of the device is first investigated. It shows that the PS microswimmers can migrate along various geometrical patterns by powering the microheaters with designed voltage combinations, and the migration velocity is positively affected by the increased voltage. Then, the butyl acrylate (BA) microswimmers are manipulated at the gas−liquid interface of the microchip. It turns out that the BA microswimmers migrate oppositely compared with PS swimmers under the same energization strategy. Additionally, the translation direction of BA swimmers can be changed over a 360°range by different voltage combinations. The multifunctionality of our approach is further demonstrated by conveniently driving the trimethylolpropane triacrylate microswimmers at the liquid−liquid interface of the microplatform along different directions and pathlines. Therefore, this technique can be promising for many cases needing granular sample control, such as cargo delivery and sensing.

Dielectric Characterization and Multistage Separation of Various Cells via Dielectrophoresis in a Bipolar Electrode Arrayed Device

“…Electric properties of separation buffer, involving conductivity and dielectric permittivity, will have an evident response for varying local temperatures , as a result of Joule heating in the buffer. A dielectric gradient generates in the buffer, giving rise to a volume force on the bulk liquid , where T indicates the temperature, and σ­( T ) and ε­( T ) are the fluid conductivity and permittivity at different temperatures, respectively. Consequently, bulk electroconvection occurs in the channel.…”

Multimodal bubble microrobot near free liquid surface

“…The swimming microrobots using biomimetic swimming strategies and microscale uid dynamics have recently made great progress [1][2][3][4][5][6][7][8] . These untethered microtools can establish exible interactions between the macro world and the micro uid environment [9][10][11] , and have shown important applications in various elds where precise micromanipulation is needed, e.g., drug delivery [12][13][14][15][16][17][18] , single cell manipulation 19,20 and micromotor navigation 21 .…”

On-Chip Arbitrary Manipulation of Single Particles by Acoustic Resonator Array

“…Based on this, better-performing materials could be obtained, and targeted individuals could be isolated. In the search for universal, arbitrary, and precise manipulation of micro/nanoparticles and cells, various manipulation methods have been developed based on different principles, which include acoustic tweezers, − optical tweezers, , magnetic tweezers, , electrophoresis, , thermophoresis, , and dielectrophoresis . These methods have been utilized in many applications and have helped promote the lab-on-a-chip (LOC) technology.…”