Electrochemical sensors play a significant role in detecting chemical ions, molecules, and pathogens in water and other applications. These sensors are sensitive, portable, fast, inexpensive, and suitable for online and in-situ measurements compared to other methods. They can provide the detection for any compound that can undergo certain transformations within a potential window. It enables applications in multiple ion detection, mainly since these sensors are primarily non-specific. In this paper, we provide a survey of electrochemical sensors for the detection of water contaminants, i.e., pesticides, nitrate, nitrite, phosphorus, water hardeners, disinfectant, and other emergent contaminants (phenol, estrogen, gallic acid etc.). We focus on the influence of surface modification of the working electrodes by carbon nanomaterials, metallic nanostructures, imprinted polymers and evaluate the corresponding sensing performance. Especially for pesticides, which are challenging and need special care, we highlight biosensors, such as enzymatic sensors, immunobiosensor, aptasensors, and biomimetic sensors. We discuss the sensors' overall performance, especially concerning real-sample performance and the capability for actual field application.

https://www.mdpi.com/1424-8220/21/12/4131/pdf

A Review of Nanocomposite-Modified Electrochemical Sensors for Water Quality Monitoring.

Boosting Electric Double Layer Capacitance in Laser-Induced Graphene-Based Supercapacitors

Au@Carbon quantum Dots-MXene nanocomposite as an electrochemical sensor for sensitive detection of nitrite.

The successful exfoliation of few-layer graphene from monolith graphite in 2004 has stimulated an exponential growth in graphene research. Ten years later, a facile and cost-effective method was discovered to synthesize high-quality graphene by directly scribing commercially available polymer using a CO2 laser under ambient conditions. The product, denoted as laser-induced graphene (LIG), featured high porosity, excellent electron conductivity, intrinsic photothermal effects and tunable surface properties. Since the discovery, LIG has attracted intense attention from both academia and industry and found broad applications in areas such as energy conversion and storage, sensors, antibacterials and desalination. In this review, we focus on the recent advances of LIG in environmental applications. We start with the development of synthetic techniques, including the precise engineering of LIG properties and the transfer strategies towards functional LIG composites. The achievement in synthesis enables the environmental applications of LIG in a broad context. Finally, the challenges and opportunities in solving different environmental issues using LIG are discussed.

Laser-induced graphene for environmental applications: progress and opportunities

Laser-enabled flexible electrochemical sensor on finger for fast food security detection.

Electrochemical sensor for nitrite detection in water samples using flexible laser-induced graphene electrodes functionalized by CNT decorated by Au nanoparticles

In this paper, a novel low cost electrode material for electrochemical sensing is presented which demonstrates excellent electrochemical response to nitrite while being amenable to implementation in disposable point of care nitrite sensors. Laser induced grapheneous carbon (LIG) is based on a simple laser engraving method to fabricate electrodes by inducing conductive paths onto Kapton polymer substrate. The working electrode was modified by Gold Nanoparticles (AuNPs), multiwalled carbon nanotubes (MWCNT) and AuNPs/MWCNT. The modified electrodes were characterized by electron microscopy coupled with energy x-ray dispersive spectroscopy (SEM-EDX), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Surface morphology and electrochemical methods confirms confirm the successful implementation of LIG electrodes whose electrocatalytic performance is highly improved after modification. This suggests the synergetic effect between AuNPs and MWCNTs with the excellent conductivity and large specific surface area. By means of square wave voltammetry (SWV), the limit of detection of the proposed sensor is $6.75\ \mu\mathrm{M}$ , which is low enough for practical applications. In conclusion, AuNPs/MWCNT modified LIG electrodes demonstrated good electrochemical behavior and promising future use in disposable nitrite electrochemical sensors.

Investigation of Laser Induced Graphene Electrodes Modified by MWNT/AuNPs for Detection of Nitrite

In this work, 405 nm wavelength laser is used to transform orange plastic Kpton to carbonaceous material graphene induced by laser. This thermal process enable the design of three like screen-printed electrodes for the electrochemical application. The effect of the pulse width variation of the laser during the patterning on the electrochemical behavior of the induced material was studied. Then the selected electrode 20 ms as pulse width was used to test the aptitude to detect 4-Aminophenol.

Graphene Induced Using 405 nm Laser as Electrode Material for the Electrochemical Sensing Application

The aim of the research is to find the most suitable electrode that can be used to estimate the electrical behavior of cells and biological tissue by measuring the aging of the fish and obtaining results according to physical analysis. For this purpose, the measurements were performed in the frequency range of 1 Hz to 7 MHz, where two areas of dispersion are indicated, $\alpha$ dispersion at low frequency and $\beta$ dispersion at high frequency. The result shows that the cylindrical electrode is more suitable for measurement because it solves the problem of fiber anisotropy. In addition, the needle electrode has higher resistance values compared to the other electrode.

Sami Ameur

Papers

Electrochemical sensor for nitrite detection in water samples using flexible laser-induced graphene electrodes functionalized by CNT decorated by Au nanoparticles

Investigation of Laser Induced Graphene Electrodes Modified by MWNT/AuNPs for Detection of Nitrite

Graphene Induced Using 405 nm Laser as Electrode Material for the Electrochemical Sensing Application

The impact of electrodes on the reduction of anisotropy in biological tissue