Precisely sensing hydrofluoric acid by photonic crystal hydrogels

Area of Science:

• Materials Science
• Chemical Sensing
• Nanotechnology

Background:

• Detecting hydrofluoric acid (HF) with precision and visual readout is challenging.
• Existing methods often lack selectivity or visual feedback.
• There is a need for efficient and accessible HF sensing technologies.

Purpose of the Study:

• To develop a novel photonic crystal (PC) hydrogel sensor for visual and spectral detection of hydrofluoric acid (HF).
• To investigate the "selective etching-induced swelling" mechanism for HF sensing.
• To create a low-cost, portable, and highly selective HF sensor.

Main Methods:

• Fabrication of a PC hydrogel using silica/water/hydroxyethyl acrylate via non-close-assembling and photopolymerization.
• Utilizing the "selective etching-induced swelling" mechanism where HF etches silica, causing hydrogel swelling.
• Observing changes in reflection wavelength and structural colors for HF detection (0-10 mM).

Main Results:

• The PC hydrogel sensor demonstrated high precision and selectivity for HF detection.
• Visual and spectral changes in the hydrogel correlated with HF concentration.
• Achieved a low detection limit of 0.1 mM for HF.
• The sensor exhibited tailorable, portable, and easy-to-operate characteristics.

Conclusions:

• The developed PC hydrogel sensor provides an efficient and convenient tool for sensing HF in aqueous solutions.
• The "selective etching-induced swelling" mechanism offers a unique approach to photonic sensing.
• This work advances the understanding of photonic sensing mechanisms and offers practical applications for HF detection.