Toronto, Dec 4 (IANS): Canadian researchers have developed a sensor shaped like a smiley face which could help doctors detect metabolic problems in patients by attaching it to their skins.

"We wanted a design that could conceal the electrodes," says Vinci Hung, doctoral candidate in physical & environmental Sciences at University of Toronto Scarborough, who helped create the new sensor.

"We also wanted to showcase the variety of designs that can be accomplished with this fabrication technique," adds Hung.

The new tattoo-based solid-contact ion-selective electrode (ISE) is made using standard screen printing techniques and commercially available transfer tattoo paper, the same kind of paper that usually carries tattoos of Spiderman or Disney princesses.

In the case of the sensor, the "eyes" function as the working and reference electrodes, and the "ears" are contacts for a measurement device to connect to, according to a Toronto statement.

Hung contributed to the work while in the lab of Joseph Wang, professor at the University of California - San Diego. "It was a wonderful opportunity," Hung said. She worked directly with Wang, who is well-known for his innovations in the field of nanoengineering and is a pioneer in biosensor technology.

By using different sensing materials, the tattoos can also be modified to detect other components of sweat, such as sodium, potassium or magnesium, all of which are of potential interest to researchers in medicine and cosmetology.