Fabrication of Circular Cross-section Microchannels with Stenosis via DLP 3D Printing and PDMS Membrane Inflation for...

Microfluidic models mimicking the complex architecture of biological vessels require circular cross-sectional channels to accurately simulate hemodynamic conditions, shear stress, and cell behavior in native vasculature. Traditional soft lithography techniques typically yield rectangular channels, leading to non-physiological flow patterns and poor mimicry of the human circulatory system. Herein, we present an accessible hybrid fabrication method that integrates Digital Light Processing (DLP) 3D-printed master molds with a polydimethylsiloxane (PDMS) membrane inflation technique to produce high-fidelity circular microchannels. The primary goal of this protocol is to provide a cleanroom-free strategy for creating biomimetic vascular models with tunable stenosis geometries. The proposed protocol comprises four essential stages: (1) Computer-Aided Design (CAD) of master molds incorporating a 10% height compensation to account for material shrinkage, (2) DLP 3D printing and post-processing of resin molds, (3) PDMS casting and oxygen plasma-assisted bonding to a thin elastic membrane, and (4) controlled pneumatic membrane inflation followed by a second PDMS casting to seal the circular structure. We demonstrated that this approach enables the precise tuning of channel diameters, which range from 300 µm to 1000 µm, by carefully modulating the internal inflation pressure. The performance of the resulting microchannels was evaluated through structural characterization, including cross-sectional circularity analysis, surface roughness measurement via scanning electron microscopy (SEM), and pneumatic burst testing to ensure bonding stability. Our findings indicate that this method supports the accessible and reproducible fabrication of circular microchannels, offering a robust platform for future research in vascular physiology, thrombosis modeling, and drug screening applications.