The manipulation of small amounts of liquids has applications ranging from biomedical devices to liquid transfer. Direct light-driven manipulation of liquids, especially when triggered by light-induced capillary forces, is of particular interest because light can provide contactless spatial and temporal control. However, existing light-driven technologies suffer from an inherent limitation in that liquid motion is strongly resisted by the effect of contact-line pinning. Here we report a strategy to manipulate fluid slugs by photo-induced asymmetric deformation of tubular microactuators, which induces capillary forces for liquid propulsion. Microactuators with various shapes (straight, 'Y'-shaped, serpentine and helical) are fabricated from a mechanically robust linear liquid crystal polymer. These microactuators are able to exert photocontrol of a wide diversity of liquids over a long distance with controllable velocity and direction, and hence to mix multiphase liquids, to combine liquids and even to make liquids run uphill. We anticipate that this photodeformable microactuator will find use in micro-reactors, in laboratory-on-a-chip settings and in micro-optomechanical systems.

Photocontrol of fluid slugs in liquid crystal polymer microactuators

Numerical study on turbulent heat transfer and pressure drop of nanofluid in coiled tube-in-tube heat exchangers

Numerical prediction of turbulent flow and heat transfer in helically coiled pipes

Liquid-liquid extraction system with microstructured coiled flow inverter and other capillary setups for single-stage extraction applications

Utilization of milli-scale coiled flow inverter in combination with phase separator for continuous flow liquid-liquid extraction processes

The potential industrial applications of curved tubes for single- and two-phase flow are reviewed within the context of physics of flow, trends in the development of technology, and its laboratory to industrial-scale commercialization. Comparison of the performance of curved tube configurations demonstrates its edge over the conventional motionless mixers, heat exchangers, and reactors. Alongside, their respective advantages and limitations are also highlighted. Further, a compendium of the available correlations for single- and two-phase friction factor and heat- and mass-transfer coefficient in curved tubes has also been presented. Key issues regarding the design parameters governing the performance of the curved tubes for mixing and heat- and mass-transfer that impact the research, development, and scale-up or scale-down of such devices are also analyzed. Emerging trends for the development of a new class of curved tubes, namely, inverters and serpentine and chaotic devices are also presented.

and Vimal Kumar

Papers

A Review on the Potential Applications of Curved Geometries in Process Industry