Diabetics have traditionally used test strip monitors, insulin shots and insulin pumps to control their blood glucose levels. Now, they have a simpler, non-invasive method.  

UT scientists have created a device that uses transparent graphene material and microneedles to monitor and control diabetic symptoms. By incorporating gold sensors to analyze sweat from the body, the device measures blood glucose, and its microneedles can supply medicine if necessary. 

Associate engineering professor Nanshu Lu and postdoctoral student Hyunjae Lee worked as part of the research team on the device. 

“We wanted a soft, flexible patch that would work with the patient’s body,” Lu said.

The team’s secret weapon is an algorithm they developed to compensate for problems in inaccurate readings of glucose concentration from sweat and differing environmental conditions.

Scientists at Google invented a smart contact lens that allows patients to monitor their blood glucose from tears. Although glucose is 50 times less concentrated in sweat than in tears, the device’s algorithm allows it to adjust for the discrepancies in results.

Graphene is the ideal material for this project — transparent, highly flexible and conductive. The device is highly conductive to electrochemical signals from sweat, which it can then efficiently transfer to the heating element. 

When the blood glucose levels reach above a threshold, the algorithm controls the patch’s heating element. The heat triggers the microneedles to release medicine, according to Lu. 

This device does not go under the patient’s skin while it measures blood glucose. Only the patch’s microneedles puncture the skin and supply medicine to the patient, according to Lu. However, the needles do not penetrate deeply enough to cause pain. 

The team used the microneedles to deliver metformin, a medication that controls blood glucose levels in diabetics. Patients usually take it in pill form, but the patch provides more consistent control, said Lu. 

The device is handy enough that patients can see the results with a smartphone app. It may soon even deliver drugs for diseases other than diabetes, according to Lee.

However, it’s is not yet ready for public use — it’s currently only functional for one or two days, as the microneedles degrade due to heat in the device. The team is working on improving the long-term application of the needles, according to Lu. 

The team has tested only the blood glucose monitor on humans so far. They tested the microneedle drug delivery system on animals and plan to test it on humans soon. 

“This [device] closes the whole loop of sensing, treatment and validation,” Lu said.