Multimodal magnetic sponge-based triboelectric nanogenerator for energy harvesting, force sensing, and controlled drug delivery

Abstract

In recent years, triboelectric nanogenerators (TENGs) have been driving sustainable energy solutions and precision applications in smart devices and the medical field, thanks to their multifunctionality and self-powered capabilities. A multifunctional magnetic sponge based on a magnetic sponge triboelectric nanogenerator (MS-TENG) is introduced in this study, integrating mechanical and magnetic energy harvesting with intelligent controlled drug delivery capabilities. The magnetic sponge is fabricated by incorporating hard magnetic NdFeB particles and liquid metal into an Ecoflex sponge. Excellent energy harvesting performance is demonstrated by the MS-TENG, as the incorporation of liquid metal allows output generation with only a single wire inserted into the sponge. At an external load of 240 MΩ, a maximum power density of 267.67 mW/m² is achieved. Additionally, a strong linear correlation between the output voltage and current of the MS-TENG with applied force is exhibited, establishing it as a reliable self-powered force sensor. Simultaneously, the anisotropic deformation of the NdFeB elastomer enables it to function as a self-powered magnetic field sensor, capable of detecting the magnitude and direction of external magnetic fields. More importantly, this anisotropic deformation allows MS-TENG to operate as a magnetic soft robot, facilitating precise drug delivery in response to external magnetic fields. Furthermore, by utilizing the non-contact mode of TENG, the position and movement of the MS-TENG within the body can be monitored using a simple aluminum electrode plate. This work introduces a novel strategy for the development of TENG-based devices in multi-energy harvesting and drug delivery applications for soft robotics.