Opto-Microfluidic Fabry-Perot Sensor with Extended Air Cavity and Enhanced Pressure Sensitivity.

Pengfei Zhang,Zixiong Qin,Chao Wang,Zidan Gong,Qianqian Zhang,Liuwei Wan,Chi Chiu Chan

doi:10.3390/mi13010019

Pengfei Zhang, Zixiong Qin + Show 5 more

Open Access

https://doi.org/10.3390/mi13010019

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Abstract

An opto-microfluidic static pressure sensor based on a fiber Fabry-Perot Interferometer (FPI) with extended air cavity for enhancing the measuring sensitivity is proposed. The FPI is constructed in a microfluidic channel by the combination of the fixed fiber-end reflection and floating liquid surface reflection faces. A change of the aquatic pressure will cause a drift of the liquid surface and the pressure can be measured by detecting the shift of the FPI spectrum. Sensitivity of the sensor structure can be enhanced significantly by extending the air region of the FPI. The structure is manufactured by using a common single-mode optical fiber, and a silica capillary with the inner wall coated with a hydrophobic film. A sample with 3500 μm air cavity length has demonstrated the pressure sensitivity of about 32.4 μm/kPa, and the temperature cross-sensitivity of about 0.33 kPa/K.

Highlights

Optical fiber pressure sensors are miniature in size, immune to electromagnetic interference and enable remote detection, which is suitable for the applications in biomedical, industrial and environmental safety monitoring [1–3]
Another type of pressure sensor is based on cavity-length change, where the membrane with large size and small thickness is usually used as the reflective surface of the FP interferometer (FPI) for achieving a higher sensitivity
The main contribution to the high sensitivity is by the introduction of an extendedp sure measurement of the sensor significantly within a smaller dynamic cavity (EAC) in thesensitivity normal Fabry−Perot sensing structure

Summary

Introduction

Optical fiber pressure sensors are miniature in size, immune to electromagnetic interference and enable remote detection, which is suitable for the applications in biomedical, industrial and environmental safety monitoring [1–3]. The simultaneously apply the RI change and the cavity length change to obtain a high cav pressure sensors with large area and nano-thickness membrane are fragile to surface defects length sensitivity influences, of 6.9 μm/kPa pressure [18]. A compressible micro-FP cavity pressure sensor can simultaneously apply the RI change by using a combination of a common single mode fiber (SMF), a silica capillary tube a and the cavity length change to obtain a high cavity-length sensitivity of 6.9 μm/kPa for a small section of liquid. Different from the cavity between the UV-adhesive (ergo 8500) and the fiber-end, which will enhance sensors reported in [18], this sensing structure possesses an additional air cavity between measuring sensitivity significantly.

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