Flexible tactile sensors have been widely used in fields such as intelligent robots, human-computer interaction, and wearable technology. Tactile sensors with multi axis force perception are crucial for humans and robots to accurately identify and manipulate objects. Typically, multi axis force sensors (MAFS) based on flexible electronics have made progress by utilizing three-dimensional staggered structures, interlocking microstructures (such as pyramids, hemispheres), cross laminated structures, and planar sensing arrays. Although they have successfully detected normal and shear forces by monitoring different deformations in the contact area or relative movements between layers, issues such as signal crosstalk and structural complexity still hinder their widespread use. Alternatively, anisotropic materials (such as Janus thin films) and structures provide an effective solution for constructing electronic and optical tactile sensors with vector force detection capabilities.
In recent years, optical tactile sensors have attracted increasing attention due to their special advantages such as electrical safety, chemical inertness, high sensitivity, and flexibility. Optical microfibers/nanofibers (MNFs) with wavelength scale diameter exhibit minimal transmission loss (e.g.5 GPa), and compatibility with standard optical fibers. Especially, the strong evanescent field outside of MNF makes it a promising candidate for developing high-performance tactile sensors that can detect subtle pressures, material hardness, and surface textures.
Highlights of this article
This work reports a flexible multi axial force sensor implemented by U-shaped optical micro/nanofiber (MNF). MNF is embedded in an elastic thin film with a dome shaped protrusion at the top. When the protrusion is subjected to vector force, the embedded MNF undergoes anisotropic deformation, resulting in time-resolved changes in light transmission.
The detection sensitivity of normal force and shear force reached 50.7 dB N − 1 (14% kPa − 1) and 82.2 dB N − 1 (21% kPa − 2), respectively.
3. As a proof of concept application, tactile visualization of texture and relief pattern recognition is achieved at a spatial resolution of 160 µ m.
Source: Sensor Expert Network