Composite Chitosan-TiO<sub>2</sub> Nanocrystal Optical Metasurfaces for Humidity Sensing in the Visible Spectrum
We report the fabrication and characterization of responsive dielectric metasurfaces composed of titanium dioxide (TiO2) nanocrystals (NCs) and chitosan hydrogel biopolymer composites. Chitosan is controllably introduced into aqueous TiO2 NC dispersions to formulate adaptive inks. The inks are then used in a nanoimprinting process to produce moisture-responsive metasurfaces with high quality factor (Q), quasi-guided mode (QGM) resonances. The metasurfaces function as environmental relative humidity (RH) sensors, exhibiting a 250% enhancement in sensitivity with the addition of chitosan─to a maximum of 0.29 nm/%RH. This work presents a scalable, single-step, room-temperature strategy for producing optically tunable metasurfaces in the visible, offering high sensitivity and quality factor resonances, and enabling enhanced optical humidity sensor performance.
Authors
- Akhila Mallavarapu (ORCID: https://orcid.org/0000-0001-9145-8102)
- Kai Lu (ORCID: https://orcid.org/0000-0003-2259-3882)
- Cherie R. Kagan (ORCID: https://orcid.org/0000-0001-6540-2009)
- Jonah J. Ng (ORCID: https://orcid.org/0009-0000-1363-713X)
- Chavez F. K. Lawrence (ORCID: https://orcid.org/0009-0000-5112-5987)
Institutions
- California University of Pennsylvania (US)
- University of Pennsylvania (US)
Publication Details
- Journal
- ACS Applied Nano Materials
- Published
- 2025-08-14
- DOI
- https://doi.org/10.1021/acsanm.5c02711
- Citations
- 2
- Primary Topic
- Gas Sensing Nanomaterials and Sensors
- Type
- article
- Field-Weighted Citation Impact
- 1.46
Funders
- Division of Engineering Education and Centers