Trapping stable bubbles in hydrophobic microchannel for continuous ultrasonic microparticle manipulation

The application of bubbles in lab-on-chip devices has attracted considerable attention and is exerting an increasingly significant role in recent years due to its influential functions for fluid and particle manip-ulation. Herein, we demonstrated a simple air bubble trapping method based on the surface tension of hydrophobic chip material and demonstrated particle manipulation utilizing oscillating bubbles. The mi-crofluidic device has a T-shaped junction structure with triangular obstacles, which allows us to transfer air -pocket generated due to non-synchronized liquid filling in the microchannel to stable bubbles attached to channel wall at the desired location. The trapped bubbles can maintain stable state at a flow rate of less than 50 mu L/min. By activating bubbles with the sound wave at a specific frequency, we can achieve particle focusing, trapping, extraction and enrichment in a contact-free, label-free and continuous manner. The proposed bubble trapping method may serve as a reusable, detachable and biocompatible tool for broader bubble-based applications in chemical, biology, and engineering fields, such as drug delivery, cell focusing, as well as isolation of tumor cell. (c) 2021 Elsevier B.V. All rights reserved.

Automated summary

This study demonstrates the application of bubble manipulation in lab-on-chip devices for particle manipulation. By utilizing surface tension and oscillating bubbles, particles can be focused, trapped, extracted, and enriched in a contact-free and continuous manner. The proposed bubble trapping method shows potential for broader applications in chemical, biology, and engineering fields.