Air-Permeable Hydrogels with High Water Content

Hydrogels have gained immense popularity as the interface between biological tissues and the environment due to their exceptional properties and unique features. For biomedical applications like long-term signal monitoring, drug release, or pathogen blocking that necessitate continuous epidermal or tissue adhesion, free water and air exchange between the body and its surroundings become crucial. However, despite their excellent water permeability, hydrogels have over an order of magnitude lower oxygen permeability compared to other 'dry' soft materials (e.g. silicone rubber). This poor oxygen permeability in hydrogels is an intrinsic problem caused by the dense polar hydrogen-bonded network, which has long been a challenge to overcome. Herein, we present a strategy that achieves high oxygen permeability without compromising water content. The key to this approach is the fabrication of interconnecting microchannels within the bulk hydrogel material. More importantly, we demonstrate that the designed materials exhibit high oxygen permeability, allowing for long-term wear without causing itchiness or other uncomfortable sensations.