This Small Business Innovation Research (SBIR) Phase I project will demonstrate the commercial feasibility of producing high-toughness spider silk fibers for use in personal ballistic armor. Spider silk is one of nature's most remarkable materials, possessing high tensile strength and high extensibility, giving it an unrivaled toughness as compared with common synthetic fibers. In addition, it is lightweight, breathable, and flexible making it an ideal material for use in protective clothing such as body armor. Previous approaches to produce synthetic spider silk proteins have been based on incomplete silk sequences and previous efforts to create a silk spinneret have not sufficiently replicated the conditions inside the silk gland. In this project, the latest advances in genetic engineering and synthetic biology will be used to redesign a natural silk gene to enable expression of silk protein in a recombinant host. This methodology is similar to recent work which enabled the production of chemicals and fuels from renewable sources. Advanced microfluidics manufacturing will be used to create a spinneret that replicates a natural spider's silk gland. Combined, these technologies will result in a reproducible, scalable, and "green" method of manufacturing the next generation of high performance fibers for personal protective armor. The broader impact/commercial potential of this project is the creation of high-performance and lightweight body armor utilizing a better material at a lower price than current ballistic fibers. The market for body armor in the US is in the hundreds of millions of dollars annually; the proposed product will be able to achieve a significant profit margin due to its low initial costs and straightforward scale-up. Tougher, more comfortable, and cheaper bulletproof vests will benefit police, soldiers, guards, and anyone else who faces harm from projectiles. Lightweight and tough fibers have applications in numerous other markets, ranging from textiles to sporting goods. In addition, the ability to precisely control silk fiber properties will enable better understanding the assembly mechanisms of protein-based fibers and enable the creation of novel materials with mechanical properties tailored to application requirements. Finally, the research proposed herein will enable the inexpensive production of protein materials (specifically, silk materials) for use in a wide variety of non-fibrous systems including tissue engineering scaffolds, medical devices, and optical sensors