The orientational transition of liquid crystals (LCs) is used as a label-free detection mechanism for immunoassays developed in microfluidic systems. LCs only show bright optical textures (visible to the naked eye) in the line-line intersections in which label-free antibodies bind to their surface-immobilized antigens, suggesting the feasibility of using LCs to detect specific antigen-anti body binding events in a high-throughput and multiplexed manner.