Researchers from the Daegu Gyeongbuk Institute of Science and Technology in South Korea have recently developed a low-cost energy storage device to power electronic devices like wearable skin sensors. The supercapacitor, made with graphene ink that is sprayed onto flexible substrates, can be used for remote medical monitoring and diagnosis on wearable devices.
Materials scientist Sungwon Lee shared that as the demand for wearable devices and remote diagnosis has increased, scientists have focused on developing electronic skin devices. The team focused on "extremely tiny and flexible energy devices as a power source."
In healthcare, some patients are monitored through wearable ECG (electrocardiogram) monitors and biosensors. Biosensors can be in the form of adhesive patches which can help prevent cardiac or respiratory arrest.
Energy is stored when the micro-supercapacitors are charged and electrical charges accumulate on the electrodes. The device has a shorter charging time compared to rechargeable batteries but stores less energy.
To improve energy storage, scientists used graphene. Graphene electrodes are highly porous, giving space for more electrostatic reactions to occur so that more energy can be stored efficiently.
The micro-supercapacitor also has electrodes with interlocking teeth that look like combs. However, fabricating such a device is expensive and cannot be done on flexible and temperature-sensitive substrates.
Instead, the team developed a way to spray the graphene on a flexible substrate. The interlocking electrodes on the paper-thin energy storage device had excellent performance, shared the team.
The graphene ink had to be specifically sprayed onto the flexible substrate at a 45-degree angle and at 176 degrees Fahrenheit. The micro-supercapacitor is only 23 micrometers thin and can store energy four times more than Li-ion batteries.
The device can be attached to wearable devices, according to the scientists. The micro-supercapacitor efficiently storing energy "shows that it's possible to reduce the thickness of micro-supercapacitors for use in flexible devices, without degrading their performance," says Lee. They are still working to improve the device's capacity to store energy so they can be used on electronic skin devices.