CAREER: Optofluidic Solar Indoor Lighting Towards Sustainable Buildings

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According to the U.S. Energy Information Administration, the building sector accounts for more than 70% of all U.S. electricity use and 40% of total U.S. energy consumption. Buildings are also responsible for over one-third of U.S. greenhouse gas emissions, which is more than any other sector of the economy. This project addresses an important national and societal need for green and sustainable buildings. The research explores a novel optofluidic approach that can make full use of rooftop solar energy not only for interior illumination of buildings with active control of lighting power, but also for other indoor solar activities such as indoor farming and photovoltaic generation using excess sunlight. The research outcomes will truly offer a new paradigm in solar energy solutions in the pursuit of buildings that are energy-efficient and environmentally friendly. The innovations of the proposed technology include compact and lightweight solar lighting systems, constant illumination at a comfortable level, electricity reduction in buildings, a high-quality indoor environment, and excess solar energy for other solar indoor activities. The project requires interdisciplinary research and training on issues ranging from electrical engineering and surface science, all the way to optics and energy applications. Graduate students will gain first-hand experience from this interdisciplinary research and be well prepared to be future leaders. Through the collaborations with SDSU’s educational programs, outreach activities will be also conducted with the goal of promoting participation of K-12 and community college students from underrepresented groups and women in higher education in STEM disciplines. The objective of this project is to develop an optofluidic solar indoor lighting (OFSIL) system that can make full use of rooftop solar energy not only for interior illumination of buildings with active control of lighting power, but for other indoor solar activities such as indoor farming and photovoltaic generation. The PI recently developed electrowetting-driven liquid prisms that enabled high-performance beam steering without any mechanical moving parts. In this project, the concept of the tunable liquid prism is used as a low-cost, lightweight, and precise beam steering mean to realize smart solar indoor lighting. The project firstly focuses on fundamental studies of nanomaterials and optofluidic phenomena to achieve high-performance solar beam steering. Secondly, three-dimensional (3D) numerical simulation studies are implemented for the concept demonstration of active lighting control and design optimization of the large-scale lighting system. Lastly, an arrayed form of optofluidic solar lighting systems is developed to demonstrate the feasibility to capture sunlight outside and guide it to interiors through optical fibers for building’s illumination. The developed research outputs utilize natural sunlight for indoor lighting to significantly reduce electricity use in buildings as well as provide healthy and productive indoor environment under comfortable sunlight illumination as a move towards green and sustainable buildings. The technology developed in this research can be further used for other underground structures (e.g. subways, tunnels, basements, shelters, etc.) where natural sunlight can be enjoyed for indoor lighting and even make possible the cultivation of plants in deep underground structures.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.