Autonomous microfluidic sensing device employing liquid crystal for detection of biological interactions

We report the design of an autonomous sensing device, which employs a thermotropic nematic liquid crystal (LC) to conduct chemical or biological sensing tasks. The development of highly reproducible methods to create uniform LC thin film is critical for utilizing LCs for sensing. Herein, we describe the use of shear forces generated by the laminar flow of liquid within a microfluidic channel to create thin LC films stabilized within microfabricated structures. The orientational response of the supported LC films to targeted analytes in aqueous phases was observed through changes in the optical birefringence of the LC thin films. Experiments employing two systems are reported: (i) dodecyl trimethylammonium bromide (DTAB) dissolved in aqueous solution, and (ii) the hydrolysis of phospholipids by the enzyme phospholipase A₂ (PLA₂).