1. Controlled Fragmentation of Single-Atom-Thick Polycrystalline Graphene
Ming Chen, Zhixun Wang, Xin Ge, Zhe Wang, Kazunori Fujisawa, Juan Xia, Qingsheng Zeng, Kaiwei Li, Ting Zhang, Qichong Zhang, Mengxiao Chen, Nan Zhang, Tingting Wu, Shaoyang Ma, Guoqiang Gu, Zexiang Shen, Linbo Liu, Zheng Liu, Mauricio Terrones, Lei Wei 
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2. Figure 1
Fragmentation of Monolayer Polycrystalline Graphene Sheet on a Polydimethylsiloxane Substrate versus on a Polycarbonate Substrate
(A) Photograph of a PC/MPG/PMMA sample undergoing necking process under axial stress.
(B) An optical image of the initial MPG sheet on copper.
(C) Schematics of MPG sheet under necking processes.
(D) Schematics of MPG sheet under the traditional shear-lag fracture (PDMS/MPG/PMMA) and optical morphologies of MPG sheet under the traditional shear-lag fracture with an applied strain of 20% and 100%, respectively. Cracks are random, and the sizes of the fragment pieces decrease as the strain increases.
(E) Schematics of MPG sheet under the necking process (PC/MPG/PMMA) and optical morphology of MPG sheet under the necking process with an applied strain of 20% and 100%, respectively. MPG sheet is fragmented into well-ordered ribbons with similar sizes at different strains.
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3. Figure 2 Spectroscopic and Microscopic Characteristics of MPG Ribbons
(A) Representative Raman spectra of MPG in different process steps.
(B and C) Representative Raman mapping (B) and SEM (C) images of the resulting MPG ribbons.
(D) Stress-strain measurements of PC/MPG/PMMA at different drawing speeds.
(E) Width of the resulting MPG ribbons at different drawing speeds. The error bar is the SD.
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4. Figure 3
Low-Voltage Aberration-Corrected HRTEM Characterization of the Resulting MPG Ribbons
(A) Low-magnification TEM image of two neighboring MPG ribbons with the submicron edges.
(B) AC-HRTEM image of an MPG ribbon.
(C) AC-HRTEM image of the ribbon (middle), referring to the purple rectangle in (B). Inset: the corresponding FFT image.
(D) AC-HRTEM image of the resulting ribbon (edge), referring to the green rectangle in (B). The dashed red lines and blue lines show the zigzag and armchair edges, respectively. Inset: the corresponding FFT image.
(E) AC-HRTEM image of the resulting ribbon with the grain boundary. The dashed orange line shows the crack propagation path.
(F) The zoomed-in image of the white rectangle in (E). The dashed white lines show two connected grains with 13° angle, and the light-blue line shows the grain boundary. 5|7|5 represents the grain boundaries defect.
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5. Figure 4
Enhanced Nitrogen-Doping Effect and pH Response Performance Based on the Fabricated MPG Ribbons
(A) High-resolution XPS spectra of N1s region of nitrogen-doped MPG sheet and MPG ribbons.
(B) Spectrum of N1s region of nitrogen-doped MPG ribbons showing contributions from pyrrolic, pyridinic, and quaternary nitrogen species.
(C) Bonding configurations for nitrogen atom (N1, quaternary nitrogen; N2, pyridinic nitrogen; N3, pyrrolic nitrogen) and hydroxyl groups in nitrogen-doped MPG sheet and MPG ribbons.
(D) VDir position versus pH for MPG sheet (blue) and MPG ribbons (red), including linear fittings to the data points (solid lines).
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6. Figure 5
Optically Transparent, Ultra-Thin, and Highly Skin-Conformal Tactile Sensor with Good Repeatability Based on the Fabricated MPG Ribbons
(A) Photograph of the PMMA/MPG ribbons on a glass slide.
(B) Measured optical transmittance of PMMA/MPG ribbons showing the ultra-transparent feature. The measured thickness of PMMA/MPG ribbons is ∼70 ± 15 nm, showing the ultrathin property. Inset: the atomic force microscopy image of PMMA/MPG ribbons.
(C) Photograph of the fabricated tactile sensor on fingerprint based on PMMA/MPG ribbons (left) and the zoomed-in image of the PMMA/MPG ribbons on fingerprint (right). The electrodes and PMMA/MPG ribbons are labeled.
(D) Mechanism of the fabricated tactile sensor with applied pressure.
(E) Ten cycles of the tactile sensing based on the fabricated PMMA/MPG ribbons when the external force increases from 0 to 15 N. The error bar is the SD.
(F) μOCT images of real-time deformation of the fingerprint (PMMA/MPG ribbons) at 0, 5, 10, and 15 N (from top to bottom).
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