A cost-effective label-free biosensor for rapid detection of multiple viral respiratory infections base on liquid crystals: Fabrication and modeling

The high transmission rate and incurability of recurrent Herpes Simplex Virus (HSV) infection require an accurate and fast detection approach for its efficient prevention. In an attempt to find a novel sensitive and simple optical diagnostic technique which enables on-spot testing, here we developed label-free biosensors based on E7 nematic liquid crystals (LCs) for specific detection of HSV DNA. For this purpose, homeotropically oriented LCs as smart materials are spread on the textile grid to make their both upper and lower surfaces be in contact with ambient air. HSV DNA of concentration between 1.4 nM and 5.5 nM is added to the platform, and DNA elution buffer is used as a control. Then, the reorientation of LCs occurs due to the coupling of electrical dipoles between LCs and DNA molecules. Creating a unique pattern that is projected onto CCD by putting the sample in a crosspolarizer and using white light. To model the LC's director distribution, LC's free energy equation is solved using the variational method and finite difference method (FDM). Overall, our LC-based sensor is a user-friendly, costeffective, highly sensitive, and fast way for specific detection of HSV without the need for experts and expensive equipment.