Fig. 1. Schematic of microfluidic device fabrication^［10］

Fig. 2. Working principle of （a） POM and （b） FCPM technique^［10］

Fig. 3. （a） Orientation changes of liquid crystals under different flow velocities^［54］； （b） Orientation control of liquid crystals in microfluidic channels^［55］； （c） Influence of different fabrication processes on liquid crystal molecular orientation in PDMS microchannels^［56］.

Fig. 4. （a） Top： Cross-polarized microscopy images of CLC confined in micron-sized channels with varying channel depths between 1.2 mm and 2.2 mm and widths between 3 mm and 30 mm. Bottom： Optical characterization of bubble and stripe textures^［12］. （b） Flow response of CLC in microchannels under different pressure gradients， with the pressure gradient increasing from top to bottom^［57］.

Fig. 5. （a） NLC microfluidic optical modulator based on peristaltic flow^［59］； （b） Liquid crystal microfluidic tunable color light filter^［60］.

Fig. 6. （a） Tunable optofluidic lens based on NLC birefringence effect and microfluidic technology^［61］； （b） Self-assembled microlenses from chiral liquid crystals in microchannels^［26］.

Fig. 7. （a） NLC-based microfluidic grating^［62］； （b，c） NLC-based optical waveguide devices^［63-64］.

Fig. 8. （a） Schematic of the optical setup and process for fabricating a microfluidic tunable broadband distributed Bragg reflector based on a liquid crystal polymer template； （b） Reflectance spectrum variations when a mixture of BA and MA is injected into the microchannel （left） and when MA is injected into the microchannel （right） at a flow rate of 20 µL/min^［65］.

Fig. 9. （a） Non-invasive optical flow velocity measurement technique based on NLC microfluidic system^［66］； （b） Particle-free flow field visualization method based on liquid crystal polarization^［67］.

Fig. 10. Real-time monitoring of fluid flow in microchannels by microfluidic device based on NLC birefringence^［68］

Fig. 11. Liquid crystals for surface defect detection in microchannels. （a） Orientations and optical appearance of LC in a rectangular microchannel； （b） Optical images （under a POM） of LC flowing inside a rectangular microchannel at different flow rates and Er numbers； （c） Movable disclination lines of flowing LC in the rectangular microchannel； （d） Amplification of surface defects by flowing LC in a rectangular microchannel^［69］.

Fig. 12. Liquid crystal microfluidics for biochemical molecule detection. （a） Liquid crystal microfluidic-based immunosensing system^［70］； （b） Biochemical molecular sensing using liquid crystal film microfluidic device^［71］； （c） Liquid crystal microdroplets fabricated by inkjet printing for biochemical sensing^［72］.

Fig. 13. （a） Ultra-highly sensitive and stable liquid crystal-enhanced optofluidic biosensor for protein detection^［73］； （b） Liquid crystal optofluidic biosensor for label-free biotin detection^［74］.

Fig. 14. （a） Monitoring the spatial distribution of ethanol in microfluidic channels using a thin layer of CLC^［75］； （b） CLC biosensing chip for albumin detection^［76］.

Fig. 15. Color change in cholesteric liquid crystal polymer networks induced by infiltration of organic compounds^［77］