A controllable liquid mold for fabrication of 3D spherical structures and arrays

This study presents a fabrication method for spherical or ellipsoidal structures, achieved by using a liquid mold in a controlled manner. In order to verify this method, the physical relationship between liquid drops and pre-cured PDMS mixture was investigated during fabrication by altering properties such as density, viscosity, and surface tension. The results show that the lateral capillary force plays a critical role in fabricating hollow dome-like structures in a well-arranged array format. The degree of sphere of the fabricated structures was theoretically examined and was consistent with experimental data. This method is useful for fabricating hollow spherical structures with easy-to-fabricate protocols, and is affordable for general laboratories not equipped with conventional clean room facilities. Standard molding techniques for spherical structures are commonly cumbersome and difficult, since the removal process of the spherical rigid mold from the structure is almost impossible, or destructive to the fabrication. The current fabrication method uses a liquid fabrication mold, therefore providing a noninvasive means of forming spherical structures in pre-cured polymeric mixtures for micro- and meso-scale level applications. This method is also potentially beneficial for producing dynamic culture arrays with a sufficient supply of cell media to maintain controlled cellular environments that can directly induce stem cell differentiation and proliferation.