As common pollutants, heavy metals (HMs) have received significant research interest. These metals can be found in the environment due to geological processes or human activities, such as mining, industrial production, and petrochemical plants.
Heavy metals are a concern due to their toxicity to humans and animals and are considered to be common pollutants in the environment. They can cause serious health problems, such as kidney damage, high blood pressure, nervous system damage, and fertility defects, among others.
Therefore, it is important to have precise and compact HM detection technologies to assess their concentrations in the environment and screen for health issues arising from their pollution.
In recent years, electrochemical sensing techniques have become increasingly popular for on-site screening of HM pollutants, owing to their high sensitivity, long-term stability, low cost, compact instrumentation, simple sample handling requirements, and high accuracy. Consequently, numerous miniaturized electrochemical devices modified with different nanomaterials have been developed, and miniaturized electrochemical sensing techniques have been applied in a wide variety of areas.
Now, a team of researchers from the Pusan National University (PNU), South Korea, comprehensively reviewed the recent developments in electrochemical sensors for heavy metal detection.
“Conventional analytical techniques for HM detection are difficult to use for on-field analysis. There is, therefore, an urgent need for portable electrochemical sensors that are easy to use, cost-effective, and suitable for rapid on-site detection,” explains Professor Seung-Cheol Chang, who led the research.
The team mainly focused on miniaturized electrochemical sensors that are suitable for on-site detection of HM pollutants. They explored different sensor variants such as screen-printed electrodes (SPEs), paper-based electrodes, and nanomaterial-coated sensors made from carbon nanocomposites, metal nanoparticles, and metal-compound nanocomposites.
According to their analysis, miniaturized electrochemical sensors based on SPEs and paper-based electrodes offer low-cost and time-efficient analysis while also reducing the required amount of sample and supporting electrolytes. They also effectively address the limitations of conventional laboratory-based methods.
Furthermore, nanomaterial-based sensors exhibit high specificity and sensitivity, enabling the detection of ultra-trace amounts of HMs with high accuracy in a wide variety of environmental conditions.
Despite the advances in electrochemical sensors, there are still some limitations that need to be addressed. The team acknowledges that the current electrochemical detection approaches suffer from poor selectivity, inadequate level of detail, and interference by foreign species that can have detrimental effects during on-site analysis.
Additionally, the sensors’ detection ability can decrease over time due to dissolved oxygen species. The researchers emphasized the need for portable lab-on-a-chip approaches and large-scale manufacturing of disposable, flexible, and wearable electrochemical sensors. They also stressed the importance of innovative electrochemical detection strategies for HM sensing in human biofluid samples, such as saliva, blood, and urine.
“One of the most difficult tasks is the commercialization of the advanced and systematic ideas put forward by academia, pharmaceutical industries, and government bodies in combination with proper validation techniques,” says Prof. Chang while talking about the future of research on electrochemical sensors for HMs.
Nonetheless, the team is confident that ongoing research in electronics, nanotechnology, and materials technology can help to overcome existing issues and enable more rapid and precise on-site detection of HMs. Such advancements can contribute to a safer and healthier environment. This study sheds light on the current advances in electrochemical detection technologies, which can serve as a valuable resource for the present and inspire future research.
