Abstract
This paper describes an innovative yet straightforward fabrication technique to create three-dimensional microstructures with controllable tapered geometries by combining conventional photolithography and thermal reflow of photoresist. Positive photoresist-based microchannel structures with varying width-to-length ratios were reflowed after their fabrication to generate three-dimensional funnel structures with varying curvatures. A polydimethylsiloxane hourglass-shaped microchannel array was next cast on these photoresist structures, and primary human lung microvascular endothelial cells were cultured in the device to engineer an artificial capillary network. Our work demonstrates that this cost-effective and straightforward fabrication technique has great potential in engineering three-dimensional microstructures for biomedical and biotechnological applications such as blood vessel regeneration strategies, drug screening for vascular diseases, microcolumns for bioseparation, and other fluid dynamic studies at microscale.
Highlights
Microstructures with well-defined three-dimensional (3D) profiles are of great interest in a variety of scientific and engineering fields, including optics [1,2,3,4,5,6,7], fluid dynamics [8], and biomedical technology [9,10]
Channels with a circular cross-section geometry were proposed for constructing physiological-like microvessels for the investigation of the structure and function of blood vessels [17,18,19] and for highthroughput pharmacological screens towards personalized treatment of vascular diseases [20]
Photoresist structures were patterned on a silicon wafer by photolithography, followed by an additional heating step to obtain 3D tapered structures
Summary
Microstructures with well-defined three-dimensional (3D) profiles are of great interest in a variety of scientific and engineering fields, including optics [1,2,3,4,5,6,7], fluid dynamics [8], and biomedical technology [9,10]. One of the most well-known traditional techniques to fabricate round(ed) microchannels is by molding polymers or hydrogels following insertion of tubular components into the matrix [21,22] This method allows facile fabrication and is applicable to a variety of casting materials, the dimensions and surface properties of channels are limited by the size and material properties of the inserts. For the fabrication of complex channel designs, previous studies employed adapted chemicaland gas dry etching [9,23] and laser writing techniques [24] to achieve precise circular cross-section of microchannels These microfabrication techniques required the use of non-biocompatible chemicals, and the fabrication of complex channel networks remained challenging. The limited resolution of the sugar printing did not allow the fabrication of structures smaller than 100 μm
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