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The frictional properties of a uniaxial tensile strained graphene interface are studied using molecular dynamics simulations. A misfit interval statistical method (MISM) is applied to characterize the atomistic misfits at the interface and strain soliton pattern. During sliding along both armchair and zigzag directions, the lateral force depends on the ratio of graphene flake length (L) to strain soliton spacing (L s ) and becomes nearly zero when L is an integer multiple of 3L s . Furthermore, the strain solitons propagate along the armchair sliding direction dynamically, while fission and fusion are repeatedly evidenced along the zigzag sliding direction. The underlying superlubric mechanism is revealed by a single-atom quasi-static model. The cancellation of lateral force for the contacting atoms exhibits a dynamic balance when sliding along the armchair direction but a quasi-static balance along the zigzag direction. A diagram of flake length with respect to tensile strain (L−ε) is proposed to predict the critical condition for the transition from nonsuperlubricity to superlubricity. Our results provide insights on the design of superlubric devices.

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The miniaturization of spectrometers have attracted much attention owning to the demand for portable or in situ spectral analysis in a wide variety of fields, but it is a great challenge to push them into practical applications due to high cost, complicated configuration, and sensitivity to external disturbance. We report on a miniature Fourier transform (FT) spectrometer based on fiber-tip Fizeau interferometer. Hand pulling or any other types of force can be used to drive optical path difference (OPD) scan. Interferences are monitored as a function of time by two photodetectors, one is used to detect the whole interferogram while the other to measure single-wavelength interferogram. In this design, the instantaneous interference intensity as well as OPD can be obtained in an accurate way so that the exact spatial interferogram of the incident spectrum can be worked out. Consequently, the incident spectrum can be retrieved by FT method. A resolution of 7.69 cm−1 in the wavelength range of 1400 nm ∼ 1700 nm is achieved. Experimental results show that the performance of our device is comparable to the commercial benchtop spectrometer. Our device is independent of the complicated fabrication procedures, easy of usage, and cost effective. We envision that the proposed design will inspire a new concept for constructing simple and cheap spectrometers that is well suited for practical applications.