A self-powered porous ZnS/PVDF-HFP mechanoluminescent composite film that converts human movement into eye-readable light

Abstract

This study reports on a self-powered mechanoluminescent flexible film that converts human movement into green, yellow, and white light that are visible to the naked eye. The film is simply a highly porous composite material that was prepared using a piezoelectric polymer and ZnS luminescent powders. The highly effective mechanoluminescence capabilities stem from both the film's porous structure and the strong interactions between poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) and ZnS particles. The porous film's sensitivity helps the conversion of mechanical disturbances into electrical energies and induces the electroluminescence of ZnS particles. The particle-film interactions induced a high β-phase, which is the most effective piezoelectric phase, in the PVDF-HFP film. Similar to polymeric materials, the composite film is highly processable and can be written into arbitrary shapes or patterns using a pipette or stamping techniques. Finger rubbing or ultrasonication makes the mechanoluminescence patterns readable. This composite mechanoluminescent film provides high potential for future applications in electronic skins, smart electronics, and information encryption techniques.

Construction of Infrared‐Light‐Responsive Photoinduced Carriers Driver for Enhanced Photocatalytic Hydrogen Evolution

“…The peak at about 25.9° assigns to the (002) plane of CNT (JCPDS 08‐0415) 31. The distinct XRD patterns of PVDF‐HFP and poly(vinylidene fluoride‐ co ‐chlorotrifluoroethylene) (PVDF‐CTFE) microfibers prepared by microfluidic technology (Figure S1, Supporting Information), respectively centered at 19.9° (Figure 2a) and 20.2° (Figure 2b), are in good agreement with the previous reports 32–34. The results suggest that the β‐phase (piezoelectric phase) and α‐phase (without piezoelectric effect) crystal polymorphs are respectively the domain phases in PVDF‐HFP and PVDF‐CTFE, which are further substantiated by the Fourier transform infrared (FT‐IR) measurements (Figure S2, Supporting Information).…”

Near infrared mechanoluminescence from Sr3Sn2O7: Nd3+for in situ biomechanical sensor and dynamic pressure mapping

“…Nevertheless, as Figure D shows, ML emission is recoverable after being recharged by an irradiation process, and this recoverable performance keeps stable even after eight cycles of loading and UV‐charging. These results indicate that ML could be ascribed to a trap‐dominant luminescence process . As the loaded force increases, the ML intensity increases sharply to a maximal value and attenuates due to the consumption of trapped carriers after the removal of force.…”

“…These results indicate that ML could be ascribed to a trap-dominant luminescence process. 27,28 As the loaded force increases, the ML intensity increases sharply to a maximal value and attenuates due to the consumption of trapped carriers after the removal of force. However, when the samples are irradiated by highenergy photons of 254 nm light, the traps will be refilled, and ML is recovered then.…”

Trap-controlled mechanoluminescent materials

“…However, strain gauges and piezoelectric sensors are not suitable in situations where one requires rapid and high-resolution analysis of stress distributions in the target structures [316][317][318][319]. In our view, the ideal sensor for these dynamic studies would use a 2D-optical probe that provides high-spatial and temporal resolution maps of stress distributions in the target structure [320][321][322][323][324][325][326]. ML coatings are promising candidates for this type of stress-sensing application.…”

“…67) [124,125,368,369]. The ability to generate NIR light from ML materials using ultrasound excitation [23,102,174,326], coupled with the greater transmission of NIR photons through living tissue could lead to exciting developments in medicine, including high-contrast in vivo imaging of tumors and other diseased states. Moreover, by coating NIRemitting materials to anatomical structures or prosthetic devices in animal models of human bone disease, one can envisage using ML-based biomechanical imaging in the NIR2 window to study the effect of load on stress distributions in implanted joints and bones, and to identify defects or failing structures within the living system.…”