Femtosecond microsupercapacitors produced from leaves could easily be applied to wearable electronics, smart houses and IoTs
Schematic illustration of the production of femtosecond laser-induced graphene. Image credit: KAIST
Innovations in microelectronics and flexible electronics, especially energy storage devices have led to improvements in wearable devices having higher power density, longer lifetime and shorter charging time. 
However, the challenge remains with respect to the safe collection, recycling and processing of waste batteries, increasing waste battery generation due to rising consumption and use of electronic equipment. Another challenge persists regarding the neglect of fallen leaves from huge forest covers around the world. This inefficient disposal can contribute to forest fires or water pollution, endangering the flora and fauna inhabiting the forest. 
To solve both problems at once, a research team from the Korea Advanced Institute of Science and Technology (KAIST) in collaboration with the Korea Institute of Energy Research has developed a technology that can create porous 3D graphene microelectrodes with high electrical conductivity by irradiating femtosecond laser pulses on the surface of the leaves without additional materials. The researchers found this strategy to be applicable for developing new electronic components and thus came up with flexible microsupercapacitors. 
The technique not only helps in the creation of environment-friendly graphene-based electronic devices but also in their quick low-cost mass production. Such graphene micro-supercapacitors can help power wearables, such as electronic watches that could function as thermometers, hygrometers and timers. 
“Leaves create forest biomass that comes in unmanageable quantities, so using them for next-generation energy storage devices makes it possible for us to reuse waste resources, thereby establishing a virtuous cycle,” said Young-Jin Kim, professor at the Department of Mechanical Engineering, KAIST. 
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