Ultrabroad Pressure Sensing and Highly Sensitive Gradient Ionogel-Based Fluorescent Flexible Wearable Bracelet

The growing interest in wearable devices for wireless real-time communication has underscored the challenges of practical implementation and the need for greater functional diversity. This work introduces a flexible, fluorescent wearable bracelet equipped with gradient ionogel (IG)-based pressure sensors, enabling instant wireless communication in various outdoor scenarios, both aerial and underwater, as well as passive rescue operations for individuals in distress. The device seamlessly connects to smartphones and personal computers through customized applications, allowing direct visualization of communication signals. The gradient multilayer ionogel (IG), regulated by multiarm ionic liquid cross-linkers, can achieve an ultrabroad pressure detection range from 1 Pa to 8.7 MPa with an extremely low detection limit of approximately 1 Pa, and an ultrahigh sensitivity (490.1 kPa^-1 at low pressure). The high measurement accuracy and sensitivity are attributed to the modular macroporous structure of the IGs. Given its direct contact with human skin, the device was subjected to skin irritation tests to ensure its biocompatibility and safety. Furthermore, the IG-derived wearable bracelet leverages its fluorescent properties to potentially reduce the rescue time for wearers in peril. Overall, we demonstrate a highly promising wearable electronics system that performs durably, reliably, accurately, and sensitively under challenging conditions, offering broad and versatile applications.