Applications of Microfluidics in Liquid Crystal-Based Biosensors

Abstract

Liquid crystals (LCs) with stimuli-responsive configuration transition and optical anisotropic properties have attracted enormous interest in the development of simple and label-free biosensors. The combination of microfluidics and the LCs offers great advantages over traditional LC-based biosensors including small sample consumption, fast analysis and low cost. Moreover, microfluidic techniques provide a promising tool to fabricate uniform and reproducible LC-based sensing platforms. In this review, we emphasize the recent development of microfluidics in the fabrication and integration of LC-based biosensors, including LC planar sensing platforms and LC droplets. Fabrication and integration of LC-based planar platforms with microfluidics for biosensing applications are first introduced. The generation and entrapment of monodisperse LC droplets with different microfluidic structures, as well as their applications in the detection of chemical and biological species, are then summarized. Finally, the challenges and future perspectives of the development of LC-based microfluidic biosensors are proposed. This review will promote the understanding of microfluidic techniques in LC-based biosensors and facilitate the development of LC-based microfluidic biosensing devices with high performance.

Liquid crystal-assisted optical biosensor for early-stage diagnosis of mammary glands using HER-2

“…LCs are a prospective branch of excellent sensing and phase transition materials that exist between isotropic liquids and highly ordered solid crystals, hence LCs are mentioned as intermediate phases or mesophases 44 – 46 . They have the ability to flow like fluids and also exhibit anisotropic peculiarities such as the birefringence of crystalline materials 47 , 48 .…”

“…LCs have very weak anchoring energy on surfaces (in nematic LCs from 10 –3 to 10 –7 mJ/m 2 48 ) which makes them ultra-sensitive to external variables 52 at the interface and topography changes. These responsive materials can disturb the preferred orientation of LC molecules.…”

Anisotropic microfluidics and flow monitoring with a microchannel towards soft-matter sensing

“…Microfluidics, 1 which is commonly used in various forms in biology, 2 chemistry, 3 physics, 4 and other subjects, has played a dominating role in bioanalysis systems, 5,6 chemical analysis and synthesis, the formation of droplets and bubbles, [7][8][9][10] flow manipulation, and other areas of development. Anisotropic microfluids [11][12][13] and microparticles 14,15 have attracted extensive scientific interest in recent years, since the inherent anisotropy of these molecules provides unique flow field responsiveness, which can visually reflect flow rates. Accurate flow monitoring is especially critical for systems based on anisotropic as well as isotropic microfluids, which are generally integrated in a complex flow sensor framework to obtain accurate flow rates.…”

Sensitive Electrochemical Detection of Phosphorylated-Tau Threonine 231 in Human Serum Using Interdigitated Wave-Shaped Electrode

“…In the field of visible macroscopic optical signals, liquid crystals (LCs) are materials in a state between the isotropic liquid and the crystalline state with stimuli-responsive and optically anisotropic properties; therefore, LCs have been used in developing LC-based biosensors for biomolecule detection and protein–protein binding events. An electrical field is applied to adjust the ordering of LCs between two electrodes to manipulate the light passing through the LCs and, thus, the optical appearance [ 7 , 8 , 9 , 10 ]. In the field of electrochemical detection, the advantages and importance of electrochemical biosensors for the determination of acceptable concentrations of biomolecules, drugs, and biomarkers have been reported recently because of their reliability, rapid response, high selectivity, and low cost [ 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 ].…”