High performance breathable conductive hydrogel sensor based on sodium alginate and polyacrylamide with cross-linked dual network structures.

Conductive hydrogels have attracted immense interest in the field of flexible electronic devices and biosensors. However, issues such as poor breathability, insufficient adhesion and water retention properties still remain and limit their applications as wearable sensors. To address these issues, a porous conductive hydrogel (SA/PAM/CTAB-GO) with high breathability (5.97 mg.cm·h), favorable conductivity (2.85 S/m), desirable adhesion (1.39 KPa) and moisture retention properties was synthesized by polymerization and crosslinking using sodium alginate and polyacrylamide as gel substrates, cetyltrimethylammonium bromide modified graphene oxide as foam stabilizer and Ca as crosslinking agent. The hydrogel exhibited excellent mechanical properties, water retention characteristics, and high breathability comparable to cotton. Moreover, the SA/PAM/CTAB-GO hydrogel presented excellent sensing sensitivity, fast response ability (225 ms), and favorable endurance, which monitored human motions sensitively and realized the accurate, sensitive and reliable detection of human ECG and EMG signals. The hydrogel sensor was applied in human-computer interaction and sensitively controlled robot arms and virtual characters. The design of dual network mechanism of calcium crosslinking and foam porosity method improved the sensing properties, breathability, adhesion, and stability of the hydrogel making it possesses high performance as wearable sensor and has promising application prospect in flexible electronics.