Fabrication of shape controllable alginate microparticles based on drop-on-demand jetting

Drop-on-demand jetting was combined with a gelation technique to fabricate alginate microparticles into varied shapes. First, uniform alginate microdroplets were generated by adjusting the parameters of the voltage waveform which is applied to a piezoelectric print-head. Next, the alginate microdroplets were solidified by calcium ions, resulting in the formation of alginate microparticles. The collision of alginate microdroplets with the surface of CaCl₂ solution and a cross-linking reaction caused formation of microparticles of spherical, elliptical, tail-shaped, and other shapes. The effect of printing parameters including microdroplet velocity and concentration of CaCl₂ solution on microparticle shape was systematically studied. We found that tail-shaped microparticles were better to form lines compared to spherical microparticles. Our findings can guide efforts for more precise fabrication of differently shaped alginate microparticles using drop-on-demand jetting for application in bioprinting, drug delivery, and cell encapsulation.