Electrochromic devices (ECDs) have been widely applied to smart windows, mirrors, gas sensors, and low-power displays. Dynamic application of color tunable devices from Visual Gas Sensors
to Robust Flexible Electrochromic Device (FECD) using Solvent-Free and Maskless Patterning
system, is presented in this study.  We present two solvent-free, dry-deposition routes that broaden
the color-tunable device platform. First, a Cu-doped ZnO/TiO₂ film deposited by the
nanoparticle deposition system (NPDS) detects NO gas at room temperature (25 °C) and, coupled
with a viologen-based ECD, converts the electrical gas signal directly into a visible color change.
Second, the aerodynamically focused nanoparticle (AFN) system patterns WO₃ nanopowders
into maskless, ink- and solvent-free micro-scale lines far narrower than the nozzle diameter. These
dry-patterned devices switch stably over 500 cycles, and extension to flexible ITO-PET substrates
yields robust flexible ECDs withstanding thousands of cycles and repeated bending. We expect these dry deposition and patterning platforms to broaden the design space of electrochromic displays toward wearable devices and environmental monitoring.

Nanoparticle deposition system; room-temperature sensing; aerodynamically focused nanoparticle system;,electrochromism