Disordered-nanoparticle-based etalon for ultrafast humidity-responsive colorimetric sensors and anti-counterfeiting displays

The development of real-time and sensitive humidity sensors is in great demand from smart home automation and modern public health. We hereby proposed an ultrafast and full-color colorimetric humidity sensor that consists of chitosan hydrogel sandwiched by a disordered metal nanoparticle layer and reflecting substrate. This hydrogel-based resonator changes its resonant frequency to external humidity conditions because the chitosan hydrogels are swollen under wet state and contracted under dry state. The response time of the sensor is similar to 10(4) faster than that of the conventional Fabry-Perot design. The origins of fast gas permeation are membrane pores created by gaps between the metal nanoparticles. Such instantaneous and tunable response of a new hydrogel resonator is then exploited for colorimetric sensors, anti-counterfeiting applications, and high-resolution displays.

Automated summary

This study proposes an ultrafast and full-color humidity sensor that utilizes the expansion and contraction of chitosan hydrogel to change its resonant frequency, resulting in a response time 10(4) times faster than traditional designs. The sensor achieves fast gas permeation through gaps between metal nanoparticles. It can be applied in various fields, including colorimetric humidity sensors, anti-counterfeiting applications, and high-resolution displays.