Grand Challenges in Nanomaterial-Based Electrochemical Sensors

Abstract

Electrochemical sensors have an enormous potential in a wide variety of environmental, industrial, and medicinal applications. Apart from the immense success of glucose sensors, much more work is still needed in order to make electrochemical sensors have a widespread impact and application. For example, the current circumstances of the COVID-19 pandemic demonstrated the importance and urgency of having accurate and rapid diagnostic devices (Jiang et al., 2020). The advancement of sensors could truly help stop the spread of many infectious diseases (Vermisoglou et al., 2020) and detect the early onset of various illnesses such as neurodegenerative diseases (Kim et al., 2020). Compared to other diagnostic tools currently available, electrochemical sensors have many advantages such as low-cost, rapid and real-time detection with simple operation (Idili et al., 2019; Ligler and Gooding, 2019). They can also be mass-produced and miniaturized into portable devices (Li et al., 2017; Idili et al., 2019; Ligler and Gooding, 2019). The number of research groups reporting the development of novel electrochemical sensors is growing exponentially. Most of the reported sensors have carbon-and gold-based surfaces. These surfaces are popular amongst researchers because they are stable, biocompatible, and provide good electron transfer kinetics. Unfortunately, the unmodified surfaces often lack the sensitivity and selectivity required for the electrochemical detection of trace analytes. To overcome this challenge, nanomaterials have been incorporated within the electrode surfaces (Quesada-González and Merkoçi, 2018; Muniandy et al., 2019). Nanomaterials range from 1-100 nm in size and are extremely beneficial due to the large surface-to-volume ratio and surface area (Quesada-González and Merkoçi, 2018; Muniandy et al., 2019). Modification of nanomaterials on sensor surfaces allows them to have enhanced interfacial adsorption with improved electrocatalytic activity, biocompatibility, and faster electron transfer kinetics. All these advantages give the sensor a better selectivity and sensitivity toward the detection of specific analytes as well as a superior overall performance (

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“…There are mainly three major hurdles encountered in the development of electrochemical sensors: the attainment of a low limit of detection (LOD); limiting the interaction of unwanted interfering species; maintaining sensor stability and achieving reproducibility in complex real matrices [27]. The LOD indicates the lowest concentration/quantity that could be detected for an analyte and is a major criterion for a sensor performance as many times we are dealing with analytes that are present at trace levels in real samples.…”

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“…However, they are not yet ready to be utilized as a regular analytical tool in food corporations because the technology is in its infancy. The major obstacles faced in the development of electrochemical sensors are as follows: (1) achieving a low limit of detection (LOD); (2) nullifying non-specific adsorption of interfering species; (3) on-site detection of samples, or conversion of a sensor into a point-of-care device; (4) preserving the sensor’s stability and repeatability in complicated actual matrices [ 114 ]. Furthermore, when the analyte is a biological sample, i.e., bacteria, differentiation between living and dead cells is a major challenge.…”

“…Because it is impossible to evaluate every sensor generated in mass-production facilities, sensor-to-sensor repeatability is critical during the manufacturing process. Instead, when the sensors are manufactured, statistical sampling of a portion of the sensors is carried out, and the testing and calibration findings should be relevant to the entire batch [ 114 ]. Hydrogels, rubber-like composites, new polymers and organo-gels are often used to create tiny sensors with high stability.…”

“…The issues stated above, however, are applicable not just to clinical applications, but also to other industries such as food safety, environmental monitoring, forensic investigation, defense, military applications, agriculture, and the electronics industry. Fortunately, the breakthrough, made possible by the use of nanomaterials, is a huge step forward that affects all of the sectors described above [ 114 ].…”

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“…Concerning the efficiency of electrochemical devices, the ionic conductivity of the materials and solvent media play an important role in enhancing the performance of these devices [ 52 ]. It can be observed that the electrolyte possesses high electron mobility and low viscosity, which could result in a high electrochemical stability frame.…”