What is it about?
This is about a fiber Bragg grating (FBG) sensor for pressure (and temperature) measurements for applications requiring high pressure sensitivity (~200 pm/kPa) over dynamic range of 10-20kPa. The sensor is rugged and compatible with harsh environments. It can be daisy chained and standard FBG interrogator can probe up to ten sensors per channel. We tested three of these sensors in a artificial embankment in Delft, at the Flood Proof Holland facility.
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Why is it important?
The sensor relies on the integration of FBGs into a 3D-printed transducer and, therefore, range and sensitivity can be tuned by design to some extent. It can be easily daisy chained and it is minimally invasive (it fit s inside Casagrande tubes or it can be wrapped into geotextile sockets and buried). It has large sensitivity and shows reduced hysterisis. Most importantly, we tested the sensors in the field with positive results.
Perspectives
Pressure sensing is a tough affair. One needs to tackle the intrinsic low optical fiber sensitivity by using transducing mechanism. This brings, unfortunately, other issues, such as dealing with glues, materials properties, etc, that compromise the reapeatibility (hysterisis) and sturdiness of the sensor. In this work, we spent a lot of effort to deal with these issues and, I believe, we proved that measuring pressure with optical fiber sensor in real soil-applications is possible.
Dr Luca Schenato
National Research Council Italy
Read the Original
This page is a summary of: Design and field testing of a fiber optic pressure sensor for underground water level monitoring, August 2019, SPIE,
DOI: 10.1117/12.2540812.
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