Spinneret based Tunable Engineered Parameters

Nanofibers are one of the most intriguing 1D building blocks with unique properties. Nanofibers are being increasingly used in a variety of applications including biomedical, materials, electronics, etc. Numerous techniques exist to-date that are able to fabricate these high aspect ratio (length/diameter) fibers. 

Our Non-electrospinning Approach

We have pioneered Spinneret based Tunable Engineered Parameters (STEP, US Patents 990293, 9029149 and 9,753,023), which does not require an electrical source during fiber fabrication. Elimination of the electrical source overcomes notable shortcomings of electrospinning method and provides control on fiber diameter, spacing, orientation and architecture. Using customizable fiber architectures, we study mechanobiology, develop advanced materials and methods to characterize individual, multiple and bundles of fibers. In collaboration with Behkam lab, we have pioneered Spun-wrapped Aligned Nanofiber (SWAN) lithography process for permanent features on 3D objects of different shapes and sizes. 

Spun-wrapped aligned nanofiber (SWAN) lithography for fabrication of micro/nano-structures on 3D objects

Fabrication of micro/nano-structures on irregularly shaped substrates and three-dimensional (3D) objects is of significant interest in diverse technological fields. However, it remains a formidable challenge thwarted by limited adaptability of the state-of-the-art nanolithography techniques for nanofabrication on non-planar surfaces. In this work, we introduce Spun-Wrapped Aligned Nanofiber (SWAN) lithography, a versatile, scalable, and cost-effective technique for fabrication of multiscale (nano to microscale) structures on 3D objects without restriction on substrate material and geometry. SWAN lithography combines precise deposition of polymeric nanofiber masks, in aligned single or multilayer configurations, with well-controlled solvent vapor treatment and etching processes to enable high throughput (>10−7 m2 s−1) and large-area fabrication of sub-50 nm to several micron features with high pattern fidelity. Using this technique, we demonstrate whole-surface nanopatterning of bulk and thin film surfaces of cubes, cylinders, and hyperbola-shaped objects that would be difficult, if not impossible to achieve with existing methods. We demonstrate that the fabricated feature size (b) scales with the fiber mask diameter (D) as b1.5 ∝ D. This scaling law is in excellent agreement with theoretical predictions using the Johnson, Kendall, and Roberts (JKR) contact theory, thus providing a rational design framework for fabrication of systems and devices that require precisely designed multiscale features.

Study led by Behkam Lab, Virginia Tech

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