Fabrication of visualized NO gas sensing system operable at near room temperature

Abstract

A chemiresistive gas sensor capable of sensing NO gas at near-room temperature (50 °C) is fabricated by depositing ZnO film using the dry-deposition method, Nano-Particle Deposition System (NPDS). We aim to overcome the limitations of conventional NO gas sensors that require high operating temperature of approximately 300 °C. A gas-sensing visualization system is developed to provide instant information of target gas. The gas sensor with viologen-based electrochromic device, is connected via Arduino to demonstrate a sensing system. The ZnO gas sensor exhibits high surface roughness of 0.583 μm. Due to oxygen vacancies on the surface, the sensor demonstrates a response of 14 % to 200-ppm NO gas under low temperature of 50 °C. The viologen-based electrochromic device displays various colors depending on the applied voltage, while maintaining stability over 100 cycles. Using this gas-sensing visualization system, the electrochromic device changes to a yellow state upon exposure to 200-ppm NO gas at 50 °C and switches to a green state when exposed to air. Cycling tests confirm that this response is maintained for 40 cycles. This demonstrates the feasibility of the proposed gas-sensing visualization system operable near room temperature, offering potential alternative to chemiresistive sensors that are more reactive at high temperatures. © 2025 Elsevier B.V.