Recent advances in liquid crystal droplet-based biosensors

Liquid crystals (LCs), as stimuli-responsive soft materials with optical anisotropy, have shown great potential in the development of LC-based photonic devices. In recent years, the intriguing optical properties of LCs have aroused enormous interest in biosensing fields. LC droplets have received particular attention recently due to their large surface area-to-volume ratio and rich topographic information. Herein, the recent advances of LC droplet-based biosensors, including nematic LC, cholesteric LC and whispering gallery mode-based LC droplets, are introduced. The optical properties, detection principles, as well as fabrication methods of the three types of LC droplets are summarized. Representative examples of LC droplet-biosensors, with an emphasis on the design strategies of the biosensing interfaces for various biological analytes, are then discussed in detail. Finally, perspectives on future challenges and opportunities of LC droplet-based biosensors are discussed.