Deformable Solid-state Iontronics for Tactile Stimuli-sensing and Feedback Actuation Devices

Abstract

Recently, improvements in materials science and engineering have laid the foundation for extended reality technologies, progressing beyond virtual/augmented reality and thus significantly growing the market of the real metaverse industry, highlighting the importance of human-machine interface technology. In particular, feedback technologies that detect external tactile information and convey it directly to humans are crucial elements of artificial sense-feedback loop systems in human-machine interfaces. These systems' main components are the reception and transformation of external tactile stimulus information, transmission of the collected information, and delivery of the signal. They can be implemented as tactile sensors for detecting stimuli and converting them into electrical signals, circuits for signal transmission, and feedback devices for sensory reproduction. However, there have been several challenges in constructing artificial sense-feedback loop systems, such as detecting multiple stimuli, minimizing signal interference, and reproducing diverse sensations. To overcome these limitations, iontronics, mimicking nature's efficient functionalities, have gained attention. The ion transport characteristics based on material transfer and the high optical and physical properties have led to significant growth in the field of iontronic material-based sensors and feedback devices. Implementing iontronics involves developing various ionic materials and designing and interpreting mechanisms using ion behavior and transfer phenomena. Therefore, this research paper aims to understand the ion behavior modulated by external tactile stimuli and utilize it, covering everything from the design of solid-state iontronic materials to the development of iontronic devices with various functionalities. This dissertation is organized into four chapters. Chapter 1 introduces the basics and theoretical background of solid-state iontronics. Chapter 2 discusses the design of visco-poroelastic iontronic materials and the development of mechano-selective tactile sensors that selectively detect multiple tactile stimuli, applying the piezoionic effect observed in these materials. Chapter 3 describes the development of tactile-visualization sensors that provide real-time visual feedback to tactile stimuli, mimicking the bioluminescence of natural organisms in response to mechanical stimuli. Finally, Chapter 4 overcomes the conflicting characteristics of traditional actuators by designing organic-inorganic hybrid iontronic materials and iontronic actuators, enhancing the unique properties of iontronic materials such as the electric double layer and electrode polarization phenomena.