Innovative procedure for precise deposition of wrinkled hydrogel films using direct inkjet printing

This manuscript presents an inkjet-based strategy to fabricate wrinkled hydrogel surfaces with controlled characteristics (period and amplitude). For this purpose, a monomer mixture containing a crosslinking agent, a hydrophilic monomer, and a photoinitiator were deposited onto polycarbonate substrates. Upon UV irradiation and controlled drying under a vacuum atmosphere, either one-generation or hierarchical two-generation wrinkles were formed. More interestingly, the wrinkle characteristics depend on the crosslinking agent and monomer concentration in the solution so that larger wrinkles were observed in diluted solutions. Equally, the wrinkle period and amplitude also gradually grow by increasing the number of deposited layers. Atomic force microscopy was carried out to finely characterize the wrinkle dimensions as well as their eventual preferential orientation and distribution. Besides, hydrogel surfaces have been evaluated in terms of cytocompatibility, given their potential interest for biomedical applications.The authors acknowledge the financial support given by FONDECYT Grant No. 1170209 and FONDEQUIP No. EQM150101 for the use of FESEM facilities. M.A. Sarabia acknowledges the financial support provided by CONICYT through the doctoral program Scholarship Grant. J. Rodriguez-Hernandez acknowledges financial support from Ministerio de Ciencia, Innovación y Universidades (Project MAT2016-78437-R, FONDOS FEDER, and RTI2018-096328-B-I00