Air-coupled micro-disk resonator

Trace phosphate in 10 min

Air-spaced coupling region with liquid-immersed sensing zone offers higher Q and stability than conventional fully immersed designs.

Li, Houchang · Liu, Bin · Liu, Juan · Zefeng, Li · Yuze, Gao · Haili, Ma · Pu, Shengli · Rao, Lan · Zhou, Xian · Yuan, Jinhui · Farrell, Gerald · Wu, Qiang

Sensors and Actuators, B: Chemical 2026

Specifications

Limit of detection

{'zh': '4.30 × 10⁻⁶', 'en': '4.30 × 10⁻⁶'} mg/L

Linear range

{'zh': '5 × 10⁻⁶–1 × 10⁻²', 'en': '5 × 10⁻⁶–1 × 10⁻²'} mg/L

Spiked recovery

{'zh': '96%–104%', 'en': '96%–104%'} %

Assay time

{'zh': '10', 'en': '10'} min

Advantages

High Q maintained

The coupling region is in air, avoiding liquid-induced coupling losses; only the sensing region contacts liquid, yielding a much higher Q than fully immersed designs.

Accurate in real samples

Spiked recoveries of 96%–104% in tap water and biological fluids demonstrate reliable quantitation in complex matrices.

Applications

• Environmental water quality monitoring：On-site phosphate screening in tap water without lab pretreatment
• Clinical biomarker detection：Direct trace phosphate quantitation in biological fluids for diagnosis
• Optical microcavity sensing：Air-coupled architecture boosts Q and stability for microcavity sensing