An Integrated Droplet Manipulation Platform with Photodeformable Microfluidic Channels

Abstract

Jiang et al. used the microstructure of the solid surface to make the droplet produce asymmetric wettability, which caused the droplet to flow spontaneously on the solid surface. [9] Ichimura et al. used the cis-trans isomerization of azophenyl groups to change the surface polarity, moving oil droplets by wettability gradient. [10] However, these droplet motions were limited to relative low speeds and simple linear trajectories, which were undesirable for the reactions and detections in an integrated platform (at least involving liquid transportation, fusion, separation, and mixing). [11,12] Recently, we presented a new way to manipulate droplets (liquid slugs) confined in a microtube by photo-induced asymmetric deformation. Photodeformable linear liquid crystal polymers (LLCPs) were chosen to fabricate the microtubes due to the excellent deformability and good processability for building 3D actuation structures. [13][14][15] Laplace pressure was generated when the microtubes deformed from cylinder-like to cone-like geometry attributed to the photoinduced orientation change of the liquid crystal units, [16][17][18][19] which led to the motion of the slug toward the narrower side. During the motion of the slug, mixing occurred simultaneously due to the formation of the vortex. [15] Furthermore, the fusion of two slugs was achieved in the junction of the Y-shaped tube. Although the slug transportation, mixing, and fusion have been realized individually in separated microtubes in the previous work, the integration of these operations in one platform has not been realized. The fused slug was "locked" in the junction, and was neither separated nor pro-The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/smtd.202100969.

Reliable and Low Temperature Actuation of Water and Oil Slugs in Janus Photothermal Slippery Tube

“…Actuation of liquid droplet or liquid slug is crucial for microfluidic applications. , Many liquid actuation methods have been developed, making use of forces from external stimuli, such as optical, − magnetical, − or electrical forces. , However, most of the research has been focused on the manipulation of droplets on open surfaces. Much less attention has been paid to actuate liquid in closed tubes or channels, despite the fact that most microfluidic applications are performed in microchannels.…”

“…This method exploits the capillary forces generated by the photoinduced asymmetric deformation of the microtubes. In the following studies, the authors further integrated this method in microfluidic systems. , In addition, Tian’s team adopted a similar mechanism but made use of magnetic forces to induce the asymmetric deformation . Thanks to the strong magnetic force, the droplet transport speed was significantly increased.…”

Contactless manipulation of mixed phase fluids in liquid crystal polymer microtubes assisted with light-driven vortex

“…Photodeformable liquid crystal polymers are promising candidates for smart materials to manipulate solid/liquid mixed phases via fast, tunable, and multitudinous anisotropic deformation by controlling the variation in mesogen alignment [19][20][21][22][23][24][25][26][27][28] . In previous publications, we proposed a conceptually novel strategy to propel diverse liquid phases by asymmetric photodeformation of newly designed linear liquid crystal polymers (LLCPs) [29][30][31][32] . LLCPs with excellent processability were easily processed into 3-dimensional tubular actuators and microfluidic chips with photodeformable channels [29][30][31][32] .…”

“…In previous publications, we proposed a conceptually novel strategy to propel diverse liquid phases by asymmetric photodeformation of newly designed linear liquid crystal polymers (LLCPs) [29][30][31][32] . LLCPs with excellent processability were easily processed into 3-dimensional tubular actuators and microfluidic chips with photodeformable channels [29][30][31][32] . The asymmetric photodeformation of the LLCP channels induced Laplace pressure that propelled a train of discrete droplets with controllable speed and direction.…”

Low-Cost Wearable Fluidic Sweat Collection Patch for Continuous Analyte Monitoring and Offline Analysis

“… 26 , 27 In particular, a lot of research is being executed in optimizing the sensitivity, selectivity, and durability of the electrode materials. 28 − 30 Additionally, significant progress has been achieved in sweat rate measurement 31 , 32 and design integration of the fluidic system and the sensors. 25 , 33 , 34 These novel systems may support physiologists in their research to find sweat biomarkers, but there are two major limitations.…”