A skin patch that may end up replacing needle sticks is being tested at U.C. San Diego.
Researchers from the University of California, San Diego, are working on a non-invasive glucose-monitoring device that can be placed on the skin of patients with diabetes to measure their glucose levels.
In a proof-of-concept study published in Analytical Chemistry, Amay Bandodkar, a graduate student, and colleagues describe a flexible device with patterned electrodes that are placed on temporary tattoo paper. After the patient applies the tattoo device to the skin, an electrical current, delivered for 10 minutes, forces sodium ions in the fluid between skin cells to gravitate to the electrodes. The sodium ions carry glucose molecules that are measured by a sensor in the tattoo.
“The concentration of glucose extracted by the noninvasive tattoo device is almost [a] hundred times lower than the corresponding level in the human blood,” Bandodkar said in an online report issued by the U.C. San Diego New Center. “Thus we had to develop a highly sensitive glucose sensor that could detect such low levels of glucose with high selectivity.”
An earlier device with a similar purpose was produced by Cygnus Inc. The GlucoWatch, an electrochemical glucose sensor for noninvasive glucose monitoring, also relied on the reverse iontophoresis technique to extract fluid from the skin to measure glucose levels. However, this device was discontinued because patients experienced skin irritation, Bandodkar said.
To sidestep the problem of skin irritation, the researchers covered the tattoo’s electrodes with a biocompatible agarose gel, offering enhanced electrical contact between the sensor and the skin, he wrote.
Bandodkar and colleagues tested the device on several volunteers and monitored glycemic levels following food consumption. The tattoo device performed as well as the commercial glucose meter, they reported.
“This preliminary investigation indicates that the tattoo-based iontophoresis-sensor platform holds considerable promise for efficient diabetes management,” Bandodkar and colleagues said.
“Efforts are presently underway to build on this preliminary work to develop a tattoo-based biosensor for continuous noninvasive glucose monitoring,” they noted.