Research news

Droplet-based diagnostics on liquid crystal–based open surfaces

Photo: David Clode

Publish Date: 13.10.2021

Category: Interdisciplinary research, Our contribution to sustainable development goals

Sustainable development goals: 3 Good health and well-being, 9 Industry, innovation and infrastructure, 12 Responsible consumption and production (Indicators)

Uroš Tkalec, a research associate at the Institute of Biophysics of the University of Ljubljana's Faculty of Medicine, has published an article on a new class of slippery porous surfaces for liquid crystal-based microfluidic applications in the renowned journal Science Advances in co-authorship with American researchers at Ohio State University, Harvard University, the University of Waterloo and University of Michigan.

The authors report on the independent control of the mobility and chemical compositions of microlitre scale aqueous droplets on thin layers of liquid crystal with temperature-modifiable mesophases. The experiment results show that the gliding of water droplets is primarily influenced by the positional order of liquid crystal molecules at the contact layer, whereas the transfer of chemicals between two immiscible liquids depends on the orientational order of the mesophase. Through a controlled order of phase transitions between the smectic, nematic and isotropic mesophases, droplets can be selectively moved across an inclined surface, and encapsulated microparticles and ions can be released from the liquid crystal substrate into water, thus cleaning the surface. It turns out that the sliding water droplets on such surfaces can be extremely effective in removing heavy-metal ions, which promises a variety of possible future applications in biomedical diagnostics, such as the release of active substances, delivery of active ingredients and production of droplet-based microreactors.

Grafika Kapljice MF

Shown in the figure is the principle of thermally triggered release of orange microdroplets from the liquid crystal substrate into the water droplet after the phase transition from the nematic (N) to the isotropic (I) phase.

Article: Yang XU, Adil M. RATHER, Yuxing YAO, Jen-Chun FANG, Rajdeep S. MAMTANI, Robert K. A. BENNET, Richard G. ATTA, Solomon ADERA, Uroš TKALEC, Xiaoguang WANG, Liquid crystal-based open surface microfluidics manipulate liquid mobility and chemical composition on demand. Science Advances 7, eabi7607, 2021, Link to article.


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