Microfluidic sensing devices employing in situ-formed liquid crystal thin film for detection of biochemical interactions

Abstract

Although biochemical sensing using liquid crystals (LC) has been demonstrated, relatively little attention has been paid towards the fabrication of in situ-formed LC sensing devices. Herein, we demonstrate a highly reproducible method to create uniform LC thin film on treated substrates, as needed, for LC sensing. We use shear forces generated by the laminar flow of aqueous liquid within a microfluidic channel to create LC thin films stabilized within microfabricated structures. The orientational response of the LC thin films to targeted analytes in aqueous phases was transduced and amplified by the optical birefringence of the LC thin films. The biochemical sensing capability of our sensing devices was demonstrated through experiments employing two chemical systems: dodecyl trimethylammonium bromide (DTAB) dissolved in an aqueous solution, and the hydrolysis of phospholipids by the enzyme phospholipase A2 (PLA2).

Non-electronic gas sensors from electrospun mats of liquid crystal core fibres for detecting volatile organic compounds at room temperature

“…The response is due to the ability of certain gas molecules, even at low concentration, to strongly influence the liquid crystal self-assembly [40,[42][43][44][45], triggering a reorientation of the liquid crystal director [32,34,43,44], a change in period of the supramolecular helix of shortpitch cholesterics [19,36,42,[46][47][48], or even complete loss of long-range ordering [11]. In particular, Abbott and his group [35,39,[43][44][45] demonstrated the capability of nematic LCs as sensors for detecting nerve agents at concentrations as low as part per billion. Recently, the group also demonstrated highly sensitive detection of toluene vapour using nematics [32].…”

“…We are currently experiencing an increasing interest in gas sensors based on liquid crystals (LCs) [32][33][34][35][36][37][38][39][40][41], functioning at room temperature, requiring no energy supply as they are powered by thermal energy alone, and delivering a strong optical response that is easily detected without complex spectroscopic equipment. The response is due to the ability of certain gas molecules, even at low concentration, to strongly influence the liquid crystal self-assembly [40,[42][43][44][45], triggering a reorientation of the liquid crystal director [32,34,43,44], a change in period of the supramolecular helix of shortpitch cholesterics [19,36,42,[46][47][48], or even complete loss of long-range ordering [11].…”

Applications of metal ions and liquid crystals for multiplex detection of DNA

“…In the past, many chemical and biomolecular sensors based on the unique properties of LCs have been developed. For example, Abbott's group reported LC sensors for detecting peptides, lipids and other chemical compounds [2][3][4][5][6][7]. Other groups also developed a series of LC sensors for the detection of DNA, proteins and small molecules including thiol, amines and metal ions [8][9][10][11].…”

Real-time monitoring of chemical reaction in microdroplet using fluorescence spectroscopy

“…These findings indicate that microfluidic devices should be considered as useful tools for the development of innovative new materials in chemical and biological research. Recently, several types of microfluidic technologies have attracted considerable attention with applications in DNA sequencing [18,19], fluorescence microscopy [20,21], and in monitoring chemical reactions using absorbance measurements [21][22][23]. A most important advantage of the microfluidic devices is an accumulated chemical reaction rate owing to the reduced mass-transfer limitation by promoting mixing and dispersion for the multiple phases [24,25], and such a high-throughput method will be a key technology for lab-on-a-chip systems in enabling more realistic predictions of behavior in reagents.…”