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Mechanoluminescence (ML) materials can convert mechanical stimuli into visible signals for real-time visualization of stress sensing. Since stress sensing solely based on ML absolute strength is susceptible to the external environment, ratiometric ML detection approach is expected to provide stress description with improved accuracy and stability. In this study, a stress-dependent ratiometric ML is achieved using the Eu2+ and Mn2+ co-doped SrMg2(PO4)2 (SMP) phosphors, enabling color-resolved visualization of uploaded stress stimulus. Moreover, the linear relationship between the ML intensity ratio (MLIR) and the applied stress leads to an obvious variation in ML color upon different applied stress. Herein, the as-explored ML composites films as an artificial skin could provide a visualization and quantification tool for monitoring human knee motion with great accuracy and precision. [ABSTRACT FROM AUTHOR]

Eu3+‐doped calcium niobate CaNbxO6 phosphors were successfully prepared by a solid‐state reaction, and the crystal structure, morphology, energy transfer process, and temperature‐dependent behaviors were systematically investigated. The CaNbxO6 host matrix presents the self‐activated characteristic emission at 470 nm due to the charge transfer transition of Nb5+–O2+, and the corresponding photoluminescence intensity reaches the maximum intensity when the nonstoichiometric ratio of Ca2+/Nb5+ ions is 1:1.9. Moreover, the energy transfer process from the host (470 nm) to Eu3+ (612 nm) ions in the CaNb1.9O6:Eu3+ phosphor is demonstrated, and the corresponding energy transfer efficiency is significantly enhanced compared with that of stoichiometric sample. Furthermore, it is observed that nonstoichiometric ratio of Nb5+ ions deteriorates the thermal quenching of the matrix while guaranteeing the thermal stability of the activators, resulting in the relative sensitivity (Sr) of CaNb1.9O6:Eu3+ being greatly improved from 2.235% to 3.673% K−1. Herein, these results provide an effective strategy for manipulating the sensitivity of optical thermometers of phosphors based on the induced modulation of the temperature‐response performance via nonstoichiometric control. [ABSTRACT FROM AUTHOR]

Due to the efficient and flexible flight ability of bats, bat-like robots have become the focus of research in the field of bionic robots. Aerodynamic calculation is an important part of the research field of bat-like robot, which is the basis of the structure design and flight controller design of bat-like robot. However, due to the complex flight mechanism of bats, there is no mature theoretical method to calculate the flight aerodynamic force of bat-like robots. To solve this problem, this paper takes the membrane of a bat-like robot as the research object and analyzes in detail the effects of wing folding and unfolding and flexible deformation of the membrane on the chord length, passive torsion angle and relative velocity. Based on quasi-steady state model and blade element method, a set of aerodynamic calculation method for flexible deformed wing is established. In order to verify the effectiveness of the proposed method, the theoretical calculation results and the results of the fluid-structure interaction simulation are compared and analyzed under various working conditions. The two results are in good agreement under each working condition, and the errors are all within reasonable range, which proves the effectiveness of the method. This study can provide a theoretical basis for rational structure design and precise flight control of bat-like robot. [ABSTRACT FROM AUTHOR]

Mechanoluminescence (ML) materials can convert mechanical stimuli into visible signals for real-time visualization of stress sensing. Since stress sensing solely based on ML absolute strength is susceptible to the external environment, ratiometric ML detection approach is expected to provide stress description with improved accuracy and stability. In this study, a stress-dependent ratiometric ML is achieved using the Eu2+ and Mn2+ co-doped SrMg2(PO4)2 (SMP) phosphors, enabling color-resolved visualization of uploaded stress stimulus. Moreover, the linear relationship between the ML intensity ratio (MLIR) and the applied stress leads to an obvious variation in ML color upon different applied stress. Herein, the as-explored ML composites films as an artificial skin could provide a visualization and quantification tool for monitoring human knee motion with great accuracy and precision. [ABSTRACT FROM AUTHOR]