Stretchable Unsymmetrical Piezoelectric BaTiO₃ Composite Hydrogel for Triboelectric Nanogenerators and Multimodal Sensors

TLDR

Improving the output performance of triboelectric nanogenerators is essential for expanding their use in flexible and wearable bioelectronics. This study designs and fabricates a flexible, stretchable, and highly transparent TENG from an unsymmetrical PAM/BTO composite film, where the performance can be tuned by adjusting the amount and distribution of BaTiO₃ nanocubes. The enhanced output arises from the unsymmetrical integration of polyacrylamide hydrogel with BaTiO₃ nanocubes, allowing the triboelectric response to be tailored through BTO content and spatial distribution. The stretchable hydrogel electrode withstands over eightfold stretching, and by optimizing BTO content and distribution the TENG output improves, enabling high‑sensitivity pressure sensing from 0.25 to 6 N at low frequency, while the combined piezoresistive, piezoelectric, and triboelectric effects allow multimodal sensing of human motion, pressure, and curvature.

Abstract

Improving output performance of triboelectric nanogenerators (TENGs) is crucial for expanding their applications in smart devices, especially for flexible and wearable bioelectronics. In this study, we design and fabricate a flexible, stretchable, and highly transparent TENG based on an unsymmetrical PAM/BTO composite film, made of polyacrylamide (PAM) hydrogel and BaTiO3 nanocubes (BTO NCs, BTO), and the TENG performance can be tailored by adjusting the amount and distribution location of BTO. The stretchable hydrogel electrode could bear over 8 times stretching. By changing the content and distribution location of BTO in the unsymmetrical hydrogel film, the output of the fabricated TENGs could be improved, acting as pressure sensors with high sensitivity to distinguish a spectrum of forces (0.25-6 N) at the low frequency. The mechanism of the enhanced output performance of the PAM/BTO composite hydrogel-based TENG is discussed in detail. By integrating piezoresistive, piezoelectric, and triboelectric effects, the optimized TENG and piezoresistive sensors are used as multimodal biomechanical sensors for detecting the motions of human bodies, pressure, and curvature with high sensitivity.