Interfacially stabilized microfluidic core-shell cholesteric liquid-crystal droplets integrated with an...

Conventional liquid-crystal (LC)-based anti-counterfeiting labels often rely on passive optical or thermal responses, which limits information capacity and access control. Herein, we report a flexible electro-optical-thermal multiresponsive LC encryption device based on a vertically integrated two-layer architecture. The upper layer is a magnesium oxide nanoparticle (MgO NP)-doped polymer-dispersed liquid crystal (PDLC) film that functions as an electrically switchable optical gate, while the lower layer consists of microfluidically generated core-shell cholesteric liquid crystal (CLC) droplets doped with spiropyran (SP). By tuning the concentration of the chiral dopant S811, the CLC formulation exhibited a thermochromic reflection shift of 236 nm over 28-32 °C. The isolated core-shell droplets retained 86.1% of their UV-triggered optical signal after 60 photochromic cycles. In the integrated device, repeated electrical-optical-thermal decoding identified the thermochromic channel as the lifetime-limiting component, mainly due to poly(vinyl alcohol) (PVA)matrix dehydration, droplet aggregation, and disruption of CLC helical order. The MgO NP-doped PDLC layer achieved a threshold voltage of 14 V and a saturation voltage of 38 V, enabling active gating of the lower encrypted droplet array. By assembling seven types of functional droplets, three encrypted patterns, "CSU", "596", and "930", were sequentially decoded through a prescribed electrical-optical-thermal stimulus sequence. No single stimulus could reveal the complete information. The device further showed recognizable information readout over 30°-90°. This work provides a proof-of-concept access-controlled colloidal LC platform for multilevel flexible information encryption.