Title: Light-Directed Liquid Manipulation in Flexible Bilayer Microtubes

Author: Bo Xu, Chongyu Zhu, Lang Qin, Jia Wei, Yanlei Yu*

Journal: Small, 2019, 15(24), 1901847. (Cover paper)

Abstract:

Flexible microfluidic systems have potential in wearable and implantable medical applications. Directional liquid transportation in these systems typically requires mechanical pumps, gas tanks,and magnetic actuators. Herein, an alternative strategy is presented for light-directed liquid manipulation in flexible bilayer microtubes, which are composed of a commercially available supporting layer and the photodeformable layer of a newly designed azobenzene-containing linear liquid crystal copolymer. Upon moderate visible light irradiation, various liquid slugs confined in the flexible microtubes are driven in the preset direction over along distance due to photodeformation-induced asymmetric capillary forces.Several light-driven prototypes of parallel array, closed-loop channel, and multiple micropump are established by the flexible bilayer microtubes to achieve liquid manipulation.  Furthermore,an example of a wearable device attached to a finger for light-directed liquid motion is demonstrated in different gestures. These unique photo controllable flexible microtubes offer a novel concept of wearable microfluidics.

This paper was selected as cover paper for Small 24/2019.

Fulltext Link: https://onlinelibrary.wiley.com/doi/abs/10.1002/smll.201901847

Using the synergistic effect of biphenyl and azobenze moieties, we design and synthesize a photo-responsive linear liquid crystal polymer PABBP with good mechanical properties. Its elastic modulus can match with commercial EVA hose to prepare double-layer microtubule actuator. In addition, the introduction of biphenyl moieties can increase the penetration depth of light in the PABBP layer, improve the photodeformation ability, and drive the deformation of the non-responsive layer EVA tube with more than four times its own thickness. At the same time, the PABBP layer has self-healing performance. After damage and fracture, photo-fluidization occurs under ultraviolet light irradiation, which can rebond PABBP layer with the EVA layer to restore the liquid transport function and effectively improve the stability of the double-layer microtubule actuator and its service life.