Hydrophobically associated ionic conductive hydrogels as strain, pressure, and an electronic sensor for human motions detection

The potential uses of strain-sensitive and conductive hydrogels in a variety of sectors, including soft robotics, interfaces between humans and machines, along with tracking health, have been generating a great deal of scientific interest. Utilization is still restricted by poor tensile characteristics, poor electrical signal transmission, high hysteresis energy, low conductivity, low stretching, and slow shape recovery with large response times. In the present work, a simple and effective approach is employed to create stretchable and conductive hydrogels using acrylamide (AAm) and butyl acrylate (BA). By physically crosslinking hydrophobic BA into hydrophobically coupled with AAm monomer. Amphiphilic sodium dodecyl sulfate was utilized as a cross-linker and micelle-forming agent, while NaCl creates the hydrogel as an ionic conductive material, and interactions among hydrophobic regions within the hydrogel framework considerably enhance the hydrogels mechanical characteristics. With a 553 kPa of fracture stress, 696% tensile strain was observed. It is a good option to sense strain due to remarkable sensitivity (Gauge factor = 9.95 at 500% strain) allowing for precise and reliable detection of a wide range of human movements such as (wrist and neck movement, elbow rotation, speaking and finger bending,) and handwriting due to its low hysteresis energy of 13.5 kJm−3 and considerable conductivity (6.809 mS/cm). Due to the excellent shape-recovery properties, the hydrogels can withstand hydrostatic pressure and return to their initial form after undergoing compression. The hydrogel strain sensor also demonstrated a quick response-recovery time of 130 and 150 ms respectively, a wide variety of strains (25–400%), and outstanding cyclic durability exceeding 400 cycles. This hydrogel can be applied as a metallic touch pen for various electronic devices.