Stretchable and Self-Powered Mechanoluminescent Triboelectric Nanogenerator Fibers toward Wearable Amphibious Electro-Optical Sensor Textiles

Abstract

Flexible electro-optical dual-mode sensor fibers with capability of the perceiving and converting mechanical stimuli into digital-visual signals show good prospects in smart human-machine interaction interfaces. However, heavy mass, low stretchability, and lack of non-contact sensing function seriously impede their practical application in wearable electronics. To address these challenges, a stretchable and self-powered mechanoluminescent triboelectric nanogenerator fiber (MLTENGF) based on lightweight carbon nanotube fiber is successfully constructed. Taking advantage of their mechanoluminescent-triboelectric synergistic effect, the well-designed MLTENGF delivers an excellent enhancement electrical signal of 200% and an evident optical signal whether on land or underwater. More encouragingly, the MLTENGF device possesses outstanding stability with almost unchanged sensitivity after stretching for 200%. Furthermore, an extraordinary non-contact sensing capability with a detection distance of up to 35 cm is achieved for the MLTENGF. As application demonstrations, MLTENGFs can be used for home security monitoring, intelligent zither, traffic vehicle collision avoidance, and underwater communication. Thus, this work accelerates the development of wearable electro-optical textile electronics for smart human-machine interaction interfaces.

Keywords: amphibious sensor textile; electro‐optical synergy; mechanoluminescent; noncontact; triboelectric nanogenerator fiber.

Figure 1

a) Schematic representation of the MLTENGF principle. b) Cross‐sectional SEM image of the MLTENGF. c) SEM image showing the surface morphology of ZnS:Cu particles doped in Ecoflex. d) Energy dispersive spectrum of zinc, sulfur, and copper elements. e) Photo of a stretchable MLTENGF, maintaining good performance when stretched to 200% strain level, alongside its corresponding optical image. f) SEM image of MLTENGF wound into a butterfly‐shaped structure (scale: 500 µm). g) Tensile stress–strain behavior at different doping concentrations (0–50%) with an initial length of 300 mm. h) Photo of a flexible MLTENGF, capable of wrapping around a finger and lifting a 100 g weight.

Figure 2

a) Dynamic loading structure schematic for MLTENGF frictional electrical performance. b) Schematic representation of the working principle of the MLTENGF. c) Numerical calculation of the corresponding electric potential distribution using COMSOL software. d) Atomic‐scale electron cloud potential well model describing the charge transfer at the copper foil and Ecoflex/ZnS:Cu contact interface. e) Variation in V _OC and f) I _SC at different doping concentrations (0–50%). The output voltage of the MLTENGF under g) different applied loads and i) different stretch levels. i) Stability test of the MLTENGF under a specific stretch level of 200%.

Figure 3

Response of voltage signals to different ranges of motion: a) walking, b) running, and c) jumping. d) Schematic representation of the principle for spatial pressure distribution sensing in TENG under the influence of photoelectric synergy. e) Photo of electronic fabric with a 3 × 3‐pixel MLTENGF sensor. f,g) Output voltage (V _OC) and luminosity of each pixel MLTENGF sensor array's pressure distribution when pressing Z₃₁, Z₂₂, and Z₁₃ with fingers. h) Schematic and equivalent circuit of an “intelligent zither” based on MLTENGF sensors. i) Output signals for five notes (DO, RE, MI, SOL, and LA) and arbitrary note combinations of the “intelligent zither”.

Figure 4

a) Schematic representation of an anti‐theft alarm carpet. b) Equivalent circuit diagram of the anti‐theft alarm carpet. c) Output signals of the anti‐theft alarm carpet in “On–Off” states. d) Schematic energy level diagram for green luminescence in ZnS:Cu under stress. e) Photoelectrically coordinated communication of MLTENGF pressure sensors in an aquatic environment using Morse code. f) Schematic diagram of Morse code principles. g) Transmission of corresponding information underwater by MLTENGF pressure sensors using Morse code.

Figure 5

a) Schematic representation of a non‐contact sensing system with Ecoflex/ZnS:Cu as the charge generation layer and CNTF as the charge capture layer. b) Mechanism of non‐contact induction in MLTENGF. c) Variations in output voltage and sensitivity with separation distance. d) Output voltages correspond to different distances. e) Non‐contact sensing performance of the reported proximity sensor. f) Illustration of MLTENGF applications in pedestrian and vehicle collision avoidance. g,h) Application scenarios of obstacle MLTENGF sensors for avoiding vehicles (rear) and robots (front). i) Schematic representation of non‐contact MLTENGF sensors detecting proximity to unknown marine life forms. j) Real‐time output signals of non‐contact MLTENGF sensors based on the approach and retreat of fish in aquatic environments.