Fig. 2: Principle of IsT-VPP process.
From: In-situ transfer vat photopolymerization for transparent microfluidic device fabrication
a The detailed structure of the IsT-VPP apparatus. b Measured separation forces of different contact areas for different material interfaces during VPP printing. Given the same contact area, the separation force between the part and the aux platform corresponding to the polymer-PDMS interface is the smallest. The separation force between the part and the vat surface represented by the polymer-FEP film interface is larger than the polymer-PDMS interface. A glass sheet works as the main build platform because the polymer-glass interface has stronger bonding than the previous two interfaces and is weaker than the polymer-polymer interface. The bonding force between neighboring layers of the printed part is derived from the resin’s ultimate strength. c A simplified Y-junction fluidic mixer model is used to illustrate the IsT-VPP process and its three orthographic views. d, e Fabrication of the bottom portion and partial channel using only the main build platform and the corresponding projection images. f Fabrication of the channel roof using the aux platform and the corresponding grayscale mask image. g, h In-situ transfer of the channel roof to the previously built part with bonding connection in the Z-direction via the second exposure and the corresponding mask image. i Fabrication of the rest of the part using the main build platform.
