Laser printing on fallen leaves can produce sensors for medical and laboratory use

The manufacturing of sensors through 3D printing combines speed, design freedom, and the possibility of using waste as a substrate. In the circular economy model, various results have been achieved, and typically discarded residues are used as low-cost resources. A research team in Brazil has proposed a highly creative solution that involves printing electrochemical sensors on fallen leaves. The team is led by Bruno Janegitz, Professor and Head of Sensors, Nanopharmaceuticals and Nanostructured Materials Laboratory (LSNANO) at the Federal University of San Carlos (UFSCar), and Thiago Paix ã o, Professor and Head of Electronic Tongue and Chemical Sensor Laboratory (L2ESQ) at the University of S ã o Paulo (USP). This initiative has received support from FAPESP and was emphasized in an article published in the journal ACS Sustainable Chemistry and Engineering.

Janegitz said, "We used CO2 (carbon dioxide) lasers to print designs of interest on leaves through pyrolysis and carbonization. Therefore, we obtained an electrochemical sensor for measuring levels of dopamine and paracetamol. It is very easy to operate. A drop of solution containing one of the compounds is placed on the sensor, and a potentiostat connected to it displays the concentration."

Simply put, the laser beam burns the leaves during the pyrolysis process, converting their cellulose into graphite, which is printed on the leaves in a shape suitable for use as a sensor. During the manufacturing process, the parameters of the CO2 laser, including laser power, pyrolysis scanning rate, and scanning gap, are systematically adjusted to obtain the best results.

Janegitz said, "These sensors have been characterized through morphology and physicochemical methods, allowing for a detailed exploration of the new carbonized surfaces generated on the leaves."

"In addition, the applicability of the sensor was confirmed through testing dopamine and paracetamol in biological and drug samples. For dopamine, the system is effective in the linear range of 10-1200 micromoles per liter, with a detection limit of 1.1 micromoles per liter. For paracetamol, the system has a linear range of 5-100 micromoles per liter, with a detection limit of 0.76."

In tests involving dopamine and paracetamol, as a proof of concept, the electrochemical sensor extracted from fallen leaves achieved satisfactory analytical performance and noteworthy reproducibility, highlighting its potential as a substitute for traditional substrates.

Replacing traditional materials with fallen leaves has produced significant benefits in reducing costs and, most importantly, environmental sustainability. Janegitz said, "These leaves would have been incinerated or at best composted. Instead, they are being used as substrates for high-value devices, which is a significant advancement in the manufacturing of next-generation electrochemical sensors."

Source: Laser Net