Abstract
Electron beam lithography (EBL) is renowned to provide fabrication resolution in the deep nanometer scale. One major limitation of current EBL techniques is their incapability of arbitrary 3d nanofabrication. Resolution, structure integrity and functionalization are among the most important factors. Here we report all-aqueous-based, high-fidelity manufacturing of functional, arbitrary 3d nanostructures at a resolution of sub-15 nm using our developed voltage-regulated 3d EBL. Creating arbitrary 3d structures of high resolution and high strength at nanoscale is enabled by genetically engineering recombinant spider silk proteins as the resist. The ability to quantitatively define structural transitions with energetic electrons at different depths within the 3d protein matrix enables polymorphic spider silk proteins to be shaped approaching the molecular level. Furthermore, genetic or mesoscopic modification of spider silk proteins provides the opportunity to embed and stabilize physiochemical and/or biological functions within as-fabricated 3d nanostructures. Our approach empowers the rapid and flexible fabrication of heterogeneously functionalized and hierarchically structured 3d nanocomponents and nanodevices, offering opportunities in biomimetics, therapeutic devices and nanoscale robotics.
Highlights
Human thrive to harness materials—including both natural and synthetic ones—with modern technologies to find new technological opportunities
Electron beam lithography (EBL) and ion beam lithography (IBL) are renowned to provide fabrication resolution in the nanometer range, but the major limitation of these techniques is their incapability of arbitrary 3d nanofabrication[34,35,36]
We reported that electron beam lithography (EBL) and IBL can be used in combination—a precise alignment between these two nanolithography processes at nanoscale is necessary and technically demanding—to generate simple 2d and 3d nanostructures in silk proteins but IBL inevitably etches the top layer and tends to induce ion contamination[37]
Summary
Human thrive to harness materials—including both natural and synthetic ones—with modern technologies to find new technological opportunities. Lithography-based methods (such as mask-less multi-photon lithography, MPL, and mask-projection stereolithography, SL) are capable of creating 3d structures using synthetic polymers (i.e., resins) and natural ones (e.g., keratin, silk fibroin, and sericin, where chemical modifications are usually needed for photosensitivity) as photoresists. These photolithographic methods fundamentally suffer from diffraction-limited resolution (~100 nm)[9,12,14,15,16,17,18,19,20,21,22,23,24]. Our approach can be employed and facilely adapted by our peer researchers with commercially available EBL tools with simple modifications for a broad range of applications
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