High Precision Micromolding of Freestanding Heterogeneous 3D Microstructures for Sensing and Detection Applications

The primary goal of this research initiation proposal is to demonstrate a novel method of creating 3D microscale structures composed of heterogeneous materials. The novel microfabrication capabilities proposed here have the potential to be highly transformative, as they can be applied in any field where small size, precise control of geometry, and tunable material properties are of vital importance. Applications for micromolding technology are wide and varied, but include probes for low-weight space exploration, microrobotics for minimally invasive surgery, unique microcarriers for tailored drug delivery, and biomimetic structures for tissue engineering. There are established macroscale fabrication methods to create parts of virtually any shape, size or material; but when components begin to approach the milliscale-to-microscale range (thousands to tens of microns) there is a dearth of options for making 3D parts at high enough throughput to make them practical. One of the most established microfabrication methods—lithography based processing originally developed for integrated circuit fabrication—excels in the area of precision but is fundamentally limited to creating 2D features. A variety of 3D microprototyping methods have recently been demonstrated, but these have severe limitations in throughput and material types that can be processed. Micromolding or microforming processes hold promise to fill this microfabrication niche: they are generally capable of submicron patterning fidelity, amenable to 3D structure fabrication, compatible with a wide variety of materials, and capable of very high throughput. However, there are a series of challenges that stand in the way of micromolding becoming a reliable, predictable, highly adopted fabrication method. Namely, uncontrolled mold cavity overfilling causes unwanted film or “flash” around components, and difficulty in including multiple material types in a single molded part. The proposed research activities would demonstrate selective exposure of UV-curable polymers to generate 3D molded structures—eliminating “flash” of micromolded components—and combine this concept with sequential use of high-precision complementary 3D micromolds in order to generate features with multiple material types in a single structure. The proposed methods can be used together to create virtually any 3D microscale structure with high throughput and regional control over material properties.