TY - JOUR
T1 - High sensitivity liquid level sensor for microfluidic applications using a hollow core fiber structure
AU - Liu, Dejun
AU - Li, Wei
AU - Wu, Qiang
AU - Zhao, Haoyu
AU - Ling, Fengzi
AU - Tian, Ke
AU - Shen, Changyu
AU - Han, Wei
AU - Wei, Fangfang
AU - Farrell, Gerald
AU - Semenova, Yuliya
AU - Wang, Pengfei
N1 - Funding information:
This work was financially supported by the Guangdong Basic and Applied Basic Research Foundation (2019A1515110320); Shenzhen Basic Research Foundation (JCYJ20190808173401660, JCYJ20190808140805488, JCYJ20190808173619062); China Postdoctoral Science Foundation (2019M663025); National Natural Science Foundation of China (11874332); National major scientific research instrument development project of Natural Science Foundation of China (61727816); Department for Agriculture, Food and the Marine, Ireland (17F284).
PY - 2021/12/1
Y1 - 2021/12/1
N2 - Liquid level measurement in microfluidics is challenging, where a sensor with ultra-high sensitivity but miniature in nature is demanded. In this paper, we propose for the first time a microsized fiber sensor structure in both diameter and length for microfluidics applications, which is capable of sub-micrometer scale liquid level measurement. The sensor is simply fabricated by fusion splicing a short section of a hollow core fiber (HCF) between two singlemode fibers (SMFs). HCFs with different air core diameters (10 μm, 20 μm, 30 μm) were investigated and it is found that for a given length of HCF stronger resonant dips were excited in transmission for the HCF with a smaller air core diameter. Thus the HCF structure with an air core diameter of 10 μm (HCF-10) was used for demonstration of high sensitivity liquid level measurement in microfluidics. Simultaneous excitation of both Anti-Resonant Reflecting Optical Waveguide (ARROW) guiding mechanism and Mach-Zehnder interferometer (MZI) in transmission is demonstrated in such an HCF-10 structure when HCF-10 is longer than the critical length. A maximum sensitivity of 0.042dB/µm (corresponding to a calculated liquid level resolution of ~0.23 μm) was experimentally achieved with an HCF-10 length of ~867 μm, which is three times higher than that of the previous reported to date of the most sensitive fiber optic liquid level sensors based on intensity modulation. In addition, the proposed sensor shows good repeatability of measurement and a very low cross sensitivity to changes in the surrounding refractive index.
AB - Liquid level measurement in microfluidics is challenging, where a sensor with ultra-high sensitivity but miniature in nature is demanded. In this paper, we propose for the first time a microsized fiber sensor structure in both diameter and length for microfluidics applications, which is capable of sub-micrometer scale liquid level measurement. The sensor is simply fabricated by fusion splicing a short section of a hollow core fiber (HCF) between two singlemode fibers (SMFs). HCFs with different air core diameters (10 μm, 20 μm, 30 μm) were investigated and it is found that for a given length of HCF stronger resonant dips were excited in transmission for the HCF with a smaller air core diameter. Thus the HCF structure with an air core diameter of 10 μm (HCF-10) was used for demonstration of high sensitivity liquid level measurement in microfluidics. Simultaneous excitation of both Anti-Resonant Reflecting Optical Waveguide (ARROW) guiding mechanism and Mach-Zehnder interferometer (MZI) in transmission is demonstrated in such an HCF-10 structure when HCF-10 is longer than the critical length. A maximum sensitivity of 0.042dB/µm (corresponding to a calculated liquid level resolution of ~0.23 μm) was experimentally achieved with an HCF-10 length of ~867 μm, which is three times higher than that of the previous reported to date of the most sensitive fiber optic liquid level sensors based on intensity modulation. In addition, the proposed sensor shows good repeatability of measurement and a very low cross sensitivity to changes in the surrounding refractive index.
KW - Antiresonant
KW - Fiber sensor
KW - Hollow core fiber
KW - Liquid level
KW - Mach-Zehnder interferometer
UR - http://www.scopus.com/inward/record.url?scp=85117078704&partnerID=8YFLogxK
U2 - 10.1016/j.sna.2021.113134
DO - 10.1016/j.sna.2021.113134
M3 - Article
SN - 0924-4247
VL - 332
JO - Sensors and Actuators A: Physical
JF - Sensors and Actuators A: Physical
M1 - 113134
ER -