Yifei Jin1
University of Nevada Reno1
Yifei Jin1
University of Nevada Reno1
Microfluidic devices made from polydimethylsiloxane (PDMS) have been widely used for diverse biomedical applications. However, due to poor printability of PDMS, current 3D printing techniques cannot be used to print microfluidic devices. As a result, it is necessary to investigate new PDMS-based materials for 3D printing purpose. In this study, we have investigated a fumed silica-PDMS suspension which can serve as a matrix bath material for embedded 3D printing (e-3DP) application. Thus, it is technically feasible to directly print a sacrificial ink, Pluronic F127, into complex 2D or 3D patterns in a fumed silica-PDMS matrix bath. After printing, PDMS in the matrix bath can be crosslinked and the sacrificial ink can be removed to form a microfluidic chip with embedded hollow channels. In the fabrication process, the inherent microstructures of fumed silica provide in-situ supports to hold the deposited patterns, while PDMS maintains the shape of the microfluidic chip for a long term after crosslinking. In this study, the rheological properties, mechanical properties, and transparency of the fumed silica-PDMS suspension have been systematically studied. It is found that the addition of fumed silica particles can effectively adjust the rheological properties, making PDMS change from viscous solution to yield-stress suspension suitable for e-3DP. Also, the mechanical properties of the crosslinked fumed silica-PDMS have been enhanced with the increase of the fumed silica concentration. Although the transparency of PDMS has been weakened by mixing with fumed silica particles, the visibility of the printed microfluidic chips is still acceptable. Also, the filament formation mechanism has been investigated by printing Pluronic F127 filaments in the suspension and the filament fidelity has been studied. Finally, two representative microfluidic chips for biomedical applications have been successfully printed to validate the effectiveness of the proposed fumed silica-PDMS suspension-enabled e-3DP method.