Metal‐Organic Framework Reinforced Highly Stretchable and Durable Conductive Hydrogel‐Based Triboelectric Nanogenerator for Biomotion Sensing and Wearable Human‐Machine Interfaces

Abstract

Flexible triboelectric nanogenerators (TENGs) with multifunctional sensing capabilities offer an elegant solution to address the growing energy supply challenges for wearable smart electronics. Herein, a highly stretchable and durable electrode for wearable TENG is developed using ZIF‐8 as a reinforcing nanofiller in a hydrogel with LiCl electrolyte. ZIF‐8 nanocrystals improve the hydrogel's mechanical properties by forming hydrogen bonds with copolymer chains, resulting in 2.7 times greater stretchability than pure hydrogel. The hydrogel electrode is encapsulated by microstructured silicone layers that act as triboelectric materials and prevent water loss from the hydrogel. Optimized ZIF‐8‐based hydrogel electrodes enhance the output performance of TENG through the dynamic balance of electric double layers (EDLs) during contact electrification. Thus, the as‐fabricated TENG delivers an excellent power density of 3.47 Wm–2, which is 3.2 times higher than pure hydrogel‐based TENG. The developed TENG can scavenge biomechanical energy even at subzero temperatures to power small electronics and serve as excellent self‐powered pressure sensors for human‐machine interfaces (HMIs). The nanocomposite hydrogel‐based TENG can also function as a wearable biomotion sensor, detecting body movements with high sensitivity. This study demonstrates the significant potential of utilizing ZIF‐8 reinforced hydrogel as an electrode for wearable TENGs in energy harvesting and sensor technology.

High Strength and Toughness Polymeric Triboelectric Materials Enabled by Dense Crystal-Domain Cross-Linking

“…This ensures the same strain of the human body and the flexible wearable sensor, guaranteeing accurate signal acquisition. 19,52,53 As shown in Figure 5a, the polymeric triboelectric material-based TENG is used for self-powered wearable sensing. Fluorinated ethylene propylene (FEP) film is used as the negative triboelectric material, polymeric triboelectric material (2.0 M sodium citrate solution for 48 h, 2 × 2 cm 2 ) is used as the positive triboelectric material, polydimethylsiloxane (PDMS) is used as the spacer layer, and copper is used as the electrode to generate induced charges (Figure 5a).…”

Advancing healthcare applications: wearable sensors utilizing metal–organic frameworks

“…The prepared triboelectric nanogenerator is a wearable biomotion sensor that detects body movements with high sensitivity. 141 This real-time feedback can help individuals optimize their exercise routines and avoid overexertion.…”

Ionic hydrogels-based triboelectric nanogenerators for self-powered human–machine interfaces

“…In the pursuit of developing a highly stretchable and durable wearable ionic hydrogel-based TENG, Kim's group [52] successfully prepared a resilient, highly stretchable, and flexible ionic hydrogel based on PAAm-LiCl. This wearable hydrogel-based TENG sensor exhibits remarkable sensitivity in recognizing human body movements.…”

“…Image for 'VR Control': Reproduced with permission. [52] Copyright 2023, Wiley. Image for 'Non-Contact Gesture Recognition': Reproduced with permission.…”

“…Copyright 2022, Wiley. Image for 'VR Control': Reproduced with permission [52]. Copyright 2023, Wiley.…”