High sensitivity liquid level sensor for microfluidic applications using a hollow core fiber structure

Liquid level measurement in microfluidics is challenging, where a sensor with ultra-high sensitivity but miniature nature demanded. In this paper, we propose for the first time microsized fiber structure both diameter and length applications, which capable of sub-micrometer scale liquid measurement. The simply fabricated by fusion splicing short section hollow core (HCF) between two singlemode fibers (SMFs). HCFs different air diameters (10 µm, 20 30 µm) were investigated it found that given HCF stronger resonant dips excited transmission smaller diameter. Thus an 10 µm (HCF-10) was used demonstration high microfluidics. Simultaneous excitation Anti-Resonant Reflecting Optical Waveguide (ARROW) guiding mechanism Mach-Zehnder interferometer (MZI) demonstrated such HCF-10 when longer than critical length. A maximum 0.042 dB/µm (corresponding to calculated resolution ~0.23 experimentally achieved ~867 three times higher previous reported date most sensitive optic sensors based on intensity modulation. addition, proposed shows good repeatability very low cross changes surrounding refractive index. ● Light principles small are discussed.