Abstract
Laser-induced graphene (LIG) is a multifunctional graphene foam that is commonly direct-written with an infrared laser into a carbon-based precursor material. Here, a visible 405 nm laser is used to directly convert polyimide into LIG. This enabled the formation of LIG with a spatial resolution of ∼12 μm and a thickness of <5 μm. The spatial resolution enabled by the relatively smaller focused spot size of the 405 nm laser represents a >60% reduction in LIG feature sizes reported in prior publications. This process occurs in situ in an SEM chamber, thus allowing direct observation of LIG formation. The reduced size of the LIG features enables the direct-write formation of flexible electronics that are not visible to the unaided eye. A humidity sensor is demonstrated which could detect human breath with a response time of 250 ms. With the growing interest in LIG for flexible electronics and sensors, finer features can greatly expand its utility.
Original language | English |
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Pages (from-to) | 10902-10907 |
Number of pages | 6 |
Journal | ACS Applied Materials and Interfaces |
Volume | 12 |
Issue number | 9 |
DOIs | |
State | Published - Mar 4 2020 |
Funding
C.Z., A.H., and P.D.R. acknowledge support from the U.S. Department of Energy (DOE) under Grant DE-SC0002136. The authors acknowledge that the graphene synthesis and some of the Raman measurements were performed in the Nanofabrication Research Laboratory at the Center for Nanophase Materials Sciences, which is a DOE Office of Science User Facility. M.G.S. and J.M.T. acknowledge the Air Force Office of Scientific Research (FA9550-19-1-0296) for providing funding. The use of the LIG sensor to detect humidity from human breath in this work did not meet the definition of human subject research at Rice University; therefore, no IRB protocol approval was needed.
Keywords
- flexible sensor
- high resolution
- laser-induced graphene
- visible laser