Flexible copper sensor can detect  heavy metals in sweat

An international team of researchers led by the University of São Paulo in Brazil has developed a portable copper sensor that is able to detect heavy metals such as lead and cadmium in sweat. 

In a paper published in the journal Chemosensors, the scientists explain that heavy metals are present in batteries, cosmetics, food and other things that are part of everyday life. When they accumulate in the human body, however, they can become toxic and cause health problems. 

“High levels of cadmium can lead to fatal problems in the airways, liver and kidneys. Lead poisoning damages the central nervous system and causes irritability, cognitive impairment, fatigue, infertility, high blood pressure in adults and delayed growth and development in children,” Paulo Augusto Raymundo Pereira, last author of the article, said in a media statement.

According to Raymundo Pereira, humans eliminate heavy metals mainly in sweat and urine, and analyses of these biofluids are a vital part of toxicological tests as well as treatment.

So far, devices to detect heavy metals in biofluids have been made with expensive materials. The new solution, on the other hand, has been produced using polyethylene terephthalate [PET], on top of which there is a conductive flexible copper adhesive tape, a label of the kind that can be bought from a stationer’s with the sensor printed on it, and a protective layer of nail polish or spray.

“The exposed copper is removed by immersion in ferric chloride solution for 20 minutes, followed by washing in distilled water to promote the necessary corrosion,” study co-author Robson R. da Silva said. “All of this ensures speed, scalability, low power and low cost.”

The device is connected to a potentiostat, a portable instrument that determines the concentration of each metal by measuring differences in potential and current between electrodes. The results are displayed on a computer or smartphone using appropriate software.

In the researchers’ view, the system is simple enough to be used by non-specialists without training, as well as by technicians in hospitals, clinics and doctor’s offices. 

The device can also be used in several types of environmental management situations, such as artesian wells that are regulated and require constant monitoring to analyze water quality.

The sensor’s performance in detecting lead and cadmium was assessed in trials using artificial sweat enriched under ideal experimental conditions. Adaptations are required before the device can be patented.