Laser-induced direct graphene patterning: from formation mechanism to flexible applications

Abstract

Laser-induced graphene (LIG), which is directly fabricated by laser carbonization of polymers, has gained much attention in recent years since its first discovery in 2014. Specifically, featuring native porosity, good mechanical properties, and excellent electrical/electrochemical properties, it is considered a promising material for flexible electronic devices. Meantime, LIG can be processed in the atmosphere within a few seconds, thereby significantly reducing the fabrication cost of graphene. Facilitated by these features, this methodology has received great development with worldwide efforts in the following years, including the formation mechanism of LIG, the diversity of laser sources (from infrared laser to ultraviolet laser), the diversity of carbon sources (thermoset polymers, thermoplastic polymers, and natural polymers), and property modulation of LIG (porosity, electrical property, hydrophilic/hydrophobic property, electrochemical property), along with the broad applications of LIG in various flexible electronic devices. Here, the recent advances in the mechanism studies and preparation methods of LIG are comprehensively summarized. The various technologies for the modification of LIG are reviewed. A thorough overview of typical LIG-based flexible electronic devices is presented. Finally, the current challenges and future directions are discussed.

Laser-Guided, Self-Confined Graphitization for High-Conductivity Embedded Electronics

“…For graphene oxide modification, the massive chemical agents and poor electrical conductivity limit its further application [ 16 ]. The laser-induced carbonization technique has been recently developed to convert the polymer into laser-induced graphene (LIG) in a high-precision, high-efficient, and pollution-free manner [ 17 ], which has been widely used in the actuators [ 18 ], electromagnetic devices [ 19 ], sensors for life sciences [ 20 ], and energy storage devices [ 21 ]. Various carbon-containing polymers, such as paper, nanocellulose, textile [ 22 ], wood, food [ 23 ], and phenolic resin [ 24 ], have been proven to be effective in the fabrication of LIG.…”

“…Various carbon-containing polymers, such as paper, nanocellulose, textile [ 22 ], wood, food [ 23 ], and phenolic resin [ 24 ], have been proven to be effective in the fabrication of LIG. Especially, the LIG property (e.g., electrical property) can be easily adjusted by altering the laser power or scanning speed, i.e, high laser power or low scanning speed is helpful to the sufficient carbonization, thus improving the electrical property of LIG (~ 2,500 S/m) [ 17 ]. Existing LIG processing techniques primarily focus on surface irradiation, thereby requiring additional encapsulation procedures after LIG fabrication.…”

Laser-Induced Graphene Strain Sensor for Conformable Lip-Reading Recognition and Human–Machine Interaction

“…These sensors can monitor various physiological strain signals, including pulse, respiratory rate, and heartbeat, and can be integrated with hands, feet, and other human organs to capture electrophysiological information for HMI. − Flexible sensors attached to the face can realize effective sensing of facial expressions or lip-reading information. − However, the movement of human facial muscles are complex, for example, masseter and temporal muscles control occlusion, smile muscles control expression, and so on . Hence, it is crucial to design a lip-reading strain sensor that primarily senses the lip area while remaining unaffected by the deformation of other facial muscles.…”