This Small Business Innovation Research (SBIR) Phase I project aims to develop a high-volume and low-cost nanomanufacturing process of biologically inspired repeatable polymer fibrillar adhesives as new gripping materials for commercial applications. A manufacturing process for high-speed, continuous, and large-area manufacturing of high aspect ratio and three-dimensional polymer micro/nanofiber arrays with a compliant backing layer will be studied.
The broader/commercial impact of this project will be the potential to provide repeatable fibrillar adhesives with large volume and high uniformity for applications in sports, defense, space, robotics, and other industries. The processes and methods to be developed in this study would also improve the understanding in the nanomanufacturing of high aspect ratio polymer structures with three-dimensional features.
Micro/nano-fibrillar structures on the feet of geckos, spiders, beetles, flies, and other animals have been of great interest because they can repeatedly attach to a wide range of surfaces with high and controllable gripping strength while leaving no residue. Furthermore, such fibrillar gripping structures are self-cleaning, which allows for long lifetime and repeated use without significant performance degradation. The multi-level hierarchical structure enables fibers at each level of the hierarchy to deform individually to adapt to roughness at various length scales, which leads to strong adhesion to a wide range of smooth and rough surfaces. For example, densely packed gecko foot-hairs with saucer-shaped endings can create adhesion strong enough to carry the high body mass (up to a few kilograms) of geckos through a combination of intermolecular van der Waals and capillary forces. A wealth of academic research has been published toward the goal of understanding, modeling, and mimicking fibrillar adhesion with engineered materials. Many different techniques have been reported on small batch micro/nano fabrication protocols which make it possible to fabricate fibrillar material arrays on the order of several square centimeters. These techniques generally require expensive and time consuming lithographic microfabrication processes, and can take several days to produce a small material sample. In order to make the transition from a material that is academically interesting into one that is of high commercial value, scaled-up manufacturing processes must be developed to greatly accelerate the manufacturing time and reduce manufacturing costs. Demonstrating that large scale manufacturing of such materials is possible is a necessary step in developing cost-effective materials for a wide array of commercial applications ranging from ultra-gripping materials to skin adhesives for securing facemasks, prosthetics, or cosmetic materials to the body. The objective of this project was to demonstrate and characterize the feasibility of high volume micro/nano-manufacturing of engineered biologically-inspired polymer fibrillar adhesives. We developed several processes to duplicate expensive micro/nano fabrication processes in a very cost effective way. We built and tested a prototype automated manufacturing system which enabled continuous manufacturing at a fraction of the original production time and cost. This allows for scaled up and accelerated fabrication of complex three dimensional micro/nano structures using cheap materials such as plastics This technology is not limited to the fabrication of bio-inspired adhesives; it may be applied to the large scale fabrication of other functional micro/nano structures such as biosensors, medical devices and materials, and even small scale robots.
