Photoluminescent-Electrochromic Synergy in Passive Devices for Pressure Visualization and Multi-Level Encryption

A novel self-powered opto-electrically coupled non-pixelated electrochromic device has been presented for dynamic pressure visualization, addressing the limitations of conventional pressure sensors, such as rigid systems, high power consumption, and environmental sensitivity. The device integrates a flexible architecture with a WO 3 @Eu 3 ⁺/Ag nanowires (Ag NWs) composite layer, enabling dual-mode pressure-responsive optical modulation: electrochromism under mechanical pressure and photoluminescence for dark-environment visualization. By leveraging the redox potential difference between, and liquid metal (InSnBi) electrodes, the device achieves self-powered color switching without external energy input. An air gap design isolates the electrolyte and electrochromic layers, ensuring localized pressure-triggered color changes. Experimental results demonstrate a high spatial resolution (200 µm), a broad pressure response range (0–25 N), and stable pattern retention for 30 days. The dual-mode operation, combining pressure-induced electrochromism and rare-earth photoluminescence, enables applications in biometric authentication, dynamic art preservation, and multilevel optical encryption. This work advances flexible sensing technology by merging mechanical and optical biometric features, offering a low-power, environmentally adaptable solution for real-time pressure visualization.