Enhancement of limit of detection by inducing coffee-ring effect in water quality monitoring microfluidic paper-based devices

2019 ◽  
Vol 156 ◽  
pp. 316-322 ◽  
Author(s):  
Rajesh Ghosh ◽  
Vijay Vaishampayan ◽  
Arpita Mahapatra ◽  
Richa Malhotra ◽  
Sivasamy Balasubramanian ◽  
...  
Sensors ◽  
2020 ◽  
Vol 20 (12) ◽  
pp. 3432 ◽  
Author(s):  
Irina Yaroshenko ◽  
Dmitry Kirsanov ◽  
Monika Marjanovic ◽  
Peter A. Lieberzeit ◽  
Olga Korostynska ◽  
...  

Water quality is one of the most critical indicators of environmental pollution and it affects all of us. Water contamination can be accidental or intentional and the consequences are drastic unless the appropriate measures are adopted on the spot. This review provides a critical assessment of the applicability of various technologies for real-time water quality monitoring, focusing on those that have been reportedly tested in real-life scenarios. Specifically, the performance of sensors based on molecularly imprinted polymers is evaluated in detail, also giving insights into their principle of operation, stability in real on-site applications and mass production options. Such characteristics as sensing range and limit of detection are given for the most promising systems, that were verified outside of laboratory conditions. Then, novel trends of using microwave spectroscopy and chemical materials integration for achieving a higher sensitivity to and selectivity of pollutants in water are described.


Sensors ◽  
2021 ◽  
Vol 21 (11) ◽  
pp. 3775
Author(s):  
Arif Ul Alam ◽  
Dennis Clyne ◽  
M. Jamal Deen

Multi-parameter water quality monitoring is crucial in resource-limited areas to provide persistent water safety. Conventional water monitoring techniques are time-consuming, require skilled personnel, are not user-friendly and are incompatible with operating on-site. Here, we develop a multi-parameter water quality monitoring system (MWQMS) that includes an array of low-cost, easy-to-use, high-sensitivity electrochemical sensors, as well as custom-designed sensor readout circuitry and smartphone application with wireless connectivity. The system overcomes the need of costly laboratory-based testing methods and the requirement of skilled workers. The proposed MWQMS system can simultaneously monitor pH, free chlorine, and temperature with sensitivities of 57.5 mV/pH, 186 nA/ppm and 16.9 mV/°C, respectively, as well as sensing of BPA with <10 nM limit of detection. The system also provides seamless interconnection between transduction of the sensors’ signal, signal processing, wireless data transfer and smartphone app-based operation. This interconnection was accomplished by fabricating nanomaterial and carbon nanotube-based sensors on a common substrate, integrating these sensors to a readout circuit and transmitting the sensor data to an Android application. The MWQMS system provides a general platform technology where an array of other water monitoring sensors can also be easily integrated and programmed. Such a system can offer tremendous opportunity for a broad range of environmental monitoring applications.


Sensors ◽  
2021 ◽  
Vol 22 (1) ◽  
pp. 218
Author(s):  
Gookbin Cho ◽  
Sawsen Azzouzi ◽  
Gaël Zucchi ◽  
Bérengère Lebental

Carbon nanotubes (CNTs) combine high electrical conductivity with high surface area and chemical stability, which makes them very promising for chemical sensing. While water quality monitoring has particularly strong societal and environmental impacts, a lot of critical sensing needs remain unmet by commercial technologies. In the present review, we show across 20 water monitoring analytes and 90 references that carbon nanotube-based electrochemical sensors, chemistors and field-effect transistors (chemFET) can meet these needs. A set of 126 additional references provide context and supporting information. After introducing water quality monitoring challenges, the general operation and fabrication principles of CNT water quality sensors are summarized. They are sorted by target analytes (pH, micronutrients and metal ions, nitrogen, hardness, dissolved oxygen, disinfectants, sulfur and miscellaneous) and compared in terms of performances (limit of detection, sensitivity and detection range) and functionalization strategies. For each analyte, the references with best performances are discussed. Overall, the most frequently investigated analytes are H+ (pH) and lead (with 18% of references each), then cadmium (14%) and nitrite (11%). Micronutrients and toxic metals cover 40% of all references. Electrochemical sensors (73%) have been more investigated than chemistors (14%) or FETs (12%). Limits of detection in the ppt range have been reached, for instance Cu(II) detection with a liquid-gated chemFET using SWCNT functionalized with peptide-enhanced polyaniline or Pb(II) detection with stripping voltammetry using MWCNT functionalized with ionic liquid-dithizone based bucky-gel. The large majority of reports address functionalized CNTs (82%) instead of pristine or carboxyl-functionalized CNTs. For analytes where comparison is possible, FET-based and electrochemical transduction yield better performances than chemistors (Cu(II), Hg(II), Ca(II), H2O2); non-functionalized CNTs may yield better performances than functionalized ones (Zn(II), pH and chlorine).


2013 ◽  
Vol 133 (8) ◽  
pp. 1616-1624
Author(s):  
Zu Soh ◽  
Kentaro Miyamoto ◽  
Akira Hirano ◽  
Toshio Tsuji

2016 ◽  
Vol 15 (5) ◽  
pp. 1069-1074 ◽  
Author(s):  
Violeta-Monica Radu ◽  
Alexandru Anton Ivanov ◽  
Petra Ionescu ◽  
Gyorgy Deak ◽  
Marian Tudor

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