SBIR Phase I: Scalable Manufacturing Technology for Mobile Signal Penetrating Energy-Efficient Low-Emissivity Windows

The broader impact/commercial potential of this Small Business Innovation Research (SBIR) Phase I project will be low-emissivity windows capable of allowing wireless signals to pass through. Presently, almost all commercial low-emissivity windows severely block mobile signals from entering buildings - a serious problem in today's world that demands fast and uninterrupted mobile connectivity.

The proposed low-emissivity windows can be manufactured cost-competitively and significantly reduce the costs of installing indoor cellular aids such as routers and antennas. This technology will accelerate the further adoption of low-emissivity windows to reduce greenhouse gas emissions as well as support the further deployment of 5G technologies.

This SBIR Phase I project proposes to investigate scalable manufacturing of mobile, signal transmissive, low-emissivity windows by using lithographic deposition of photoresist structures on the glass substrate prior to low-emissivity vacuum coating. The project proposes to deposit photoresist structures with non-conductive spacers on glass substrate, reducing the low-emissivity coating’s electric conductivity that prevents wireless signal passthrough.

Dielectric layers will be deposited over the sidewalls to form protective layers over the low-emissivity coatings to protect against oxidative corrosion. The width of the photoresist structures will range between 2 to 5 micrometers to minimize the degradation of low-emissivity coatings to less than 2%, to maintain thermal performance. After low-emissivity coating deposition, the non-planar spacers will subsequently collapse into the photoresist layer restoring low-emissivity coatings to their original planar position thereby rendering the photoresist structure invisible to the eye.

Furthermore, the team will explore additional photoresist designs to address potential lighting diffractions that may form on the finished window.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.