Graphene forms under microscopeâ€™s eye

WhiteBrightLight
Published on Feb 19, 2022
You donâ€™t need a big laser to make laser-induced graphene (LIG). Scientists at Rice University, the University of Tennessee, Knoxville and Oak Ridge National Laboratory (ORNL) are using a very small visible beam to burn the foamy form of carbon into microscopic patterns.
The labs of Rice chemist James Tour, which discovered the original method to turn a common polymer into graphene in 2014, and Tennessee/ORNL materials scientist Philip Rack revealed they can now watch the conductive material form as it makes small traces of LIG in a scanning electron microscope.
The altered process, detailed in the American Chemical Societyâ€™s ACS Applied Materials & Interfaces, creates LIG with features more than 60% smaller than the macro version and almost 10 times smaller than typically achieved with the former infrared laser.
Lower-powered lasers also make the process less expensive, Tour said. That could lead to wider commercial production of flexible electronics and sensors.
â€œA key for electronics applications is to make smaller structures so that one could have a higher density, or more devices per unit area,â€ Tour said. â€œThis method allows us to make structures that are 10 times denser than we formerly made.â€
To prove the concept, the lab made flexible humidity sensors that are invisible to the naked eye and directly fabricated on polyimide, a commercial polymer. The devices were able to sense human breath with a response time of 250 milliseconds.

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