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Development of a Frugal, In Situ Sensor Implementing a Ratiometric Method for Continuous Monitoring of Turbidity in Natural Waters

Authors :
Raul Sanchez
Michel Groc
Renaud Vuillemin
Mireille Pujo-Pay
Vincent Raimbault
Équipe MICrosystèmes d'Analyse (LAAS-MICA)
Laboratoire d'analyse et d'architecture des systèmes (LAAS)
Université Toulouse Capitole (UT Capitole)
Université de Toulouse (UT)-Université de Toulouse (UT)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse)
Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université Toulouse - Jean Jaurès (UT2J)
Université de Toulouse (UT)-Université Toulouse III - Paul Sabatier (UT3)
Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP)
Université de Toulouse (UT)-Université Toulouse Capitole (UT Capitole)
Université de Toulouse (UT)
Observatoire océanologique de Banyuls (OOB)
Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)
Laboratoire d'Océanographie Microbienne (LOMIC)
Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)
CNRS 80|PRIME OpenProbe
MultiFAB - FEDER European Regional Funds and French Région Occitanie - grant agreement number 16007407/MP0011594
Econect - FEDER European Regional Funds and French Région Occitanie - grant agreement number MP00021763
ANR-21-ESRE-0014,TERRA-FORMA,Concevoir et tester l'observatoire intelligent des territoires à l'ère Anthropocène(2021)
Source :
Sensors, Volume 23, Issue 4, Pages: 1897, Sensors, 2023, 23 (4), pp.1897. ⟨10.3390/s23041897⟩
Publication Year :
2023
Publisher :
Multidisciplinary Digital Publishing Institute, 2023.

Abstract

Turbidity is a commonly used indicator of water quality in continental and marine waters and is mostly caused by suspended and colloidal particles such as organic and inorganic particles. Many methods are available for the measurement of turbidity, ranging from the Secchi disk to infrared light-based benchtop or in situ turbidimeters as well as acoustic methods. The operational methodologies of the large majority of turbidity instruments involve the physics of light scattering and absorption by suspended particles when light is passed through a sample. As such, in the case of in situ monitoring in water bodies, the measurement of turbidity is highly influenced by external light and biofouling. Our motivation for this project is to propose an open-source, low-cost in situ turbidity sensor with a suitable sensitivity and operating range to operate in low-to-medium-turbidity natural waters. This prototype device combines two angular photodetectors and two infrared light sources with different positions, resulting in two different types of light detection, namely nephelometric (i.e., scattering) and attenuation light, according to the ISO 7027 method. The mechanical design involves 3D-printed parts by stereolithography, which are compatible with commercially available waterproof enclosures, thus ensuring easy integration for future users. An effort was made to rely on mostly off-the-shelf electronic components to encourage replication of the system, with the use of a highly integrated photometric front-end commonly used in portable photoplethysmography systems. The sensor was tested in laboratory conditions against a commercial benchtop turbidimeter with Formazin standards. The monitoring results were analyzed, obtaining a linear trendline from 0 to 50 Nephelometric Turbidity Unit (NTU) and an accuracy of +/−0.4 NTU in the 0 to 10 NTU range with a response time of less than 100 ms.

Details

Language :
English
ISSN :
14248220
Database :
OpenAIRE
Journal :
Sensors
Accession number :
edsair.doi.dedup.....182b5a194d6c04aada1591806e3cf305
Full Text :
https://doi.org/10.3390/s23041897