In-situ Growth of ZnO Nanostructures on the Pores and Surface of Soft 3D Structures for Energy Storing, Conversion and Bioinspired Sensing

Abstract

Conventional approaches struggle to produce the next generation of bio-inspired sensing systems because of their rigid structure, lack of deformation, and poor electron conduction. Multifunctional, flexible, and soft electronic components based on bio-inspired systems are vital for health monitoring, robotics, and human-machine interaction. Here, we developed a soft, highly porous 3D foam-structured electrode-based electrochemical capacitor that functions as a multifunctional device, serving as a pressure sensor, energy storage unit, and energy converter. For the device fabrication through an in-situ hydrothermal synthesis method, we grew a nanoflower (NF) structure of ZnO on the surface and internal walls of the conductive polydimethylsiloxane/multiwalled carbon nanotube (PDMS/MWCNT) 3D foam. The electrode showed high sensitivity (2.95 %/kPa) to applied pressure (9.8 kPa to 98 kPa), minimal hysteresis, and reliable current generation (~2 mA at 29 kPa), with an energy density of 28.7 mWh•g⁻¹ for the fabricated electrochemical capacitor at 2.1 mA•g⁻¹. Moreover, the capacitor can operate with both aqueous and gel electrolytes, demonstrating its versatility and suitability for practical applications. Overall, the proposed PDMS/MWCNT/ZnO-NF 3D foam electrode marks a significant advancement in bio-inspired ionotronic systems, paving the way for next-generation smart devices in wearables that seamlessly integrate sensing and energy functionalities.