Hybrid optothermal and acoustic manipulations of microbubbles for precise and on-demand handling of micro-objects

摘要

Manipulating specific micro-objects (e.g., colloidal particles and microorganisms) precisely and selectively in liquid medium is of great importance in myriad engineering fields. We here develop a hybrid technique for micromanipulation of micro-objects by incorporating optothermally and acoustically excited bubble on-demand. The integrated strategy combines strengths of optothermal (e.g., precise size control in bubble creation and easy delivery of micro-objects into target position) and acoustical (e.g., on-demand capturing and precise sorting of micro-objects) strategies. Microbubbles can be optothermally generated, and their size can be regulated by tuning the illumination time and power of a laser beam. The bubbles can be delivered into a preferred position an optothermocapillary flow. Sequentially, micro-objects with two different sizes can be selectively separated, and then only micro-objects with a specific size can be collected through a secondary acoustic radiation and a streaming flow generated from an acoustically oscillating bubble. To emulate on-demand manipulation of bio-objects in technological applications, we examine a full-step manipulation process of micro-objects, which consists of generating bubbles and sorting/capturing/carrying/releasing of desired micro-objects under optothermal and acoustical actuation. The hybrid manipulation technique can be a good alternative technology to conventional ones and thus can be utilized in biological applications and micro-device assembly.