[Preparation and methodological analysis of chitosan-based ultrasound-coupled hydrogel pads]

This study aims to optimize the process for preparing chitosan-based ultrasound-coupled hydrogel pads and investigate their application potential in ultrasonography. Chitosan, 2-acrylamido-2-methylpropanesulfonic acid, and N-isopropylacrylamide were used as the main materials to prepare chitosan-based ultrasound-coupled hydrogel pads. The free-radical polymerization conditions were optimized by a three-factor, three-level orthogonal test with the tensile strength and ultrasound image quality of the hydrogel pads as evaluation indicators. The optimal prescription was selected by optimizing three factors of raw material ratio, polymerization temperature, and freeze-drying time. The structure and performance of the hydrogel pads were characterized by a scanning electron microscope, a universal testing machine, and an ultrasonic diagnostic instrument. The results showed that the optimal prescription was as follows: the chitosan: 2-acrylamide-2-methylpropanesulfonic acid: N-isopropylacrylamide ratio of 2:0.55:17.27, the polymerization temperature of 25 ℃, and the freeze-drying time of 48 h. The ultrasonically-coupled hydrogel pads prepared under these conditions were transparent, with a porous structure, good adhesion, and high tensile strength. The hydrogel pads had good swelling properties and the swelling degree decreased slowly on day 10. The quality of the ultrasound images obtained via chitosan-based hydrogel pads was not significantly different from that obtained via medical ultrasound coupling agent. In this study, we analyzed the effects of different preparation processes on the gel formation of chitosan-based ultrasound-coupled hydrogel pads. The hydrogel pads were transparent and mild and non-irritating to the human body, serving as an ultrasound transmission material for ultrasonography.