Pressure-Sensitive Adhesive Materials Under Human-Centric Extreme Environments

Maintaining the adhesion strength of flexible pressure-sensitive adhesives (PSAs) is crucial for advanced applications such as health monitoring with mounting wearable sensor devices especially under challenging surroundings. However, these polymer adhesives must also perform in harsh conditions. Herein, we consider adhesive, mechanical, and optical properties of common medical-grade double-sided PSAs by simulating extreme human-centric environments. Diverse temperature conditions, water and humidity exposure, and cyclical loads were selected and tested such as very low and high temperatures (e.g., polar regions or deserts), underwater and sweat environments (intense physical activity), and cyclical shear complex stresses. Additionally, we demonstrated that variable adhesive performance and optical transparency of pressure-sensitive materials can be directly related to changes in their morphologies, surface roughness, swelling state, and alternation of the mechanical contact area helping to establish the broader rules of design for wearable human health monitoring sensors for long-term mounting and protection of wearable devices, sensors, and electrodes.