A Highly Sensitive Self‐Assembled‐Nanoparticles e‐Skin Sensor for Controlling Avatar Facial Micro‐Expressions

With their unique electrical, mechanical, and surface properties, gold nanoparticles (AuNPs) open up new possibilities for sensor technology. In particular, conductive thin films constructed from ligand‐stabilized AuNPs are considered an ideal sensing platform due to their high surface area, excellent conductivity, and biocompatibility. However, most methods for making conductive AuNPs thin‐film sensors with excellent sensitivity require expensive equipment. In this work, an innovative resistive strain sensor consisting of AuNPs and poly (allylamine hydrochloride) (PAH) based on the mutual adsorption of positive and negative charges using a low‐cost layer‐by‐layer self‐assembly (LBL‐SA) approach on a flexible polyester substrate is developed. The conductance changes at low temperatures of the AuNPs/PAH agree with the Arrhenius‐type activation of charge transport. Additionally, the maximum gauge factor of the sensor is shown experimentally to be ≈656 when 1% strain is applied to the sensor film. This work demonstrates that the sensor detects body motions, eyeball movements, and facial micro‐expressions. For detecting eyeball movements and facial micro‐expressions, the macro‐recall can reach 91.5% and 98.8%. Simultaneously, the sensor can control the virtual avatar's eye movements and human facial micro‐expressions in VR. Therefore, nanoparticle‐based sensors can be extensively used in future applications related to healthcare and human‐computer interaction. A polyelectrolyte‐based solution is developed as a molecular linker connecting individual gold nanoparticles, guiding them to self‐assemble layer‐by‐layer to form a thin layer of mechanical strain‐sensing gold nanoparticles. The device can be used to control the micro‐expressions and activities of avatars through the physical movements of the human eye and facial micro‐expressions.