Researchers from the Federal University of São Carlos (UFSCar) and the University of São Paulo (USP) are working on the development of electrochemical sensors produced by 3D printing on fallen tree leaves.
Led by Bruno Janegitz, professor at UFSCar and head of the Sensors, Nanomedicines and Nanostructured Materials Laboratory, and Thiago Paixão, professor at USP and head of the Electronic Languages and Chemical Sensors Laboratory, the research was supported by FAPESP and published in an article in the journal ACS Sustainable Chemistry & Engineering in February 2024.
To emphasise the applicability of the sensors, the researchers used them to detect dopamine and paracetamol in biological and pharmaceutical samples.
‘We used a carbon dioxide laser to print the design of interest onto a sheet by means of pyrolysis and carbonisation. We thus obtained an electrochemical sensor for use in determining dopamine and paracetamol levels. It is very easy to operate. A drop of solution containing one of these compounds is placed on the sensor to show the concentration,’ explains Janegitz.
The proposed method uses a laser beam to burn the sheet and convert the cellulose into graphite in a format suitable to function as a sensor. During the process, the parameters of the carbon dioxide (CO2) laser, such as power, pyrolysis scan rate and scan interval, are systematically adjusted to achieve the desired results.
‘The sensors were characterised using morphological and physico-chemical methods to enable the new carbonised surface generated on the leaves to be exploited exhaustively,’ adds Janegitz.
According to the researchers, the applicability of the sensors was confirmed by tests involving the detection of dopamine and paracetamol in biological and pharmaceutical samples. In the case of dopamine, the system proved efficient in a range between 10 and 1,200 micromoles per litre, with a detection limit of 1.1 micromole per litre. For paracetamol, the system worked well in a range between 5 and 100 micromoles per litre, with a detection limit of 0.76.
In the tests carried out as proof of concept, the electrochemical sensors derived from fallen tree leaves had satisfactory analytical performance and remarkable reproducibility, highlighting the potential to serve as an alternative to conventional substrates with significant gains in terms of cost and environmental sustainability, according to the study.
‘The used leaves would have been incinerated or, at best, sent for composting. Instead, they have been used as a substrate for high value-added devices in a major breakthrough for the manufacture of electrochemical sensors,’ emphasises Janegitz.
Growing market
The global market for electrochemical sensors is expected to reach around US$29.1 billion by 2032, with a compound annual growth rate of 6.32 per cent between 2023 and 2032, according to data from Precedence Research.
According to the research, electrochemical sensors have proved to play an essential role in the detection of toxic gases, since they are simple to develop, inexpensive and can react to various classes of harmful gases. In general, electrochemical sensors have a lifespan of six months to a year, depending on the gases detected and the environment.
Due to their high sensitivity, specificity and ability to be analysed quickly, electrochemical biosensors are also being used in the health sector. For example, paper-based electrochemical sensors were recently used to detect COVID-19 in less than five minutes.
The factors driving the electrochemical sensor market are the growing demand for safety and real-time monitoring of chemical processes and the emergence of nanotechnology-based biosensors with better performance and sensitivity, according to Precedence Research.