Groundwater level monitoring using a plastic optical fiber

Abstract

The present work describes the testing and application of a low cost plastic optical fiber sensor on the monitoring of groundwater levels. Two sensors with different grove depth (½ and ¼ of the core thickness) and a resolution of 20 cm along 2 m of the optical fiber were produced and tested. The sensors were tested under two experimental setups: water level variation (increasing and decreasing of the water level) and groundwater increase simulation, in a soil column. The analysis of the optical signal's amplitude and its variations due to the increasing or decreasing of water level showed that both tested sensors presented an appropriate performance and adequate sensibility to groundwater level variation and, therefore, can be used for in situ applications of monitoring.

Polymer optical fiber sensors in human life safety

“…To date, PMMA is the most used material in POF fabrication, although the use of some alternative plastics, such as CYTOP [12,24], TOPAS [10,11,25], and polycarbonate (PC) fibers [26] have recently been investigated. PMMA POFs [1,3,[5][6][7][8][9]13,[16][17][18][19][20][21][22][27][28][29][30][31] present a response of the sensors dependent on both temperature and humidity [27][28][29][30][31]. This fact, together with the issue of high loss and low operating temperature, has been hindering the application of polymer sensors in key strain sensing and biosensing areas [32].…”

“…There is a myriad of applications where POF technology is used such as geophysical surveying and security [14,15], groundwater level monitoring [16], water detection in fuel [17], healthcare [18], optoacoustic endoscopic imaging [19], central arterial pressure monitoring [20], on-line remote dosimetry [21], structural health monitoring [22], decubitus prevention [23], among others. As we can observe, all these applications are closely related to human safety.…”

An Optical Fiber Liquid Level Sensor Based on Side Coupling Induction Technology

“…The structure is simple and the measurement range is large enough. For example, the operational range of the multipoint liquid level sensor could exceed 2 m, which is achieved by engraving grooves on a vertical POF [7,8], bending and polishing POFs [9] or aligning a group of POF segments coaxially [10], and so on. The maximum range among them is 2.8 m but the resolution is 350 mm.…”

A Multipoint Liquid Level Sensor Based on Two Twisted Polymer Optical Fibers in a Race-Track Helical Structure

“…Nowadays, the liquid level measurement has attracted great interests because of the high demand in the applications of flood early warning [1,2], fuel supply system [3,4], structural monitoring [5], and so on. In the fields where the liquid level monitoring of several specific points is needed or liquids of different refractive index (RI) are required to be differentiated, many discrete or multipoint liquid level sensors are proposed [6][7][8][9][10].…”

“…The measurement range is 250 cm, but the resolution is 25 cm. Mesquita et al utilized a vertical POF with grooves spaced at every 20 cm and realized the liquid level measurement of 200 cm [5]. Jing et al twined a POF around a race-track column, and the macrobend losses change with the liquid level [15].…”