Cost-Effective Microfluidic-Based Transparency Switching Glass Visibility Control: Toward a Zero-Energy Smart Window Design

Smart window technologies are key to enhancing energy efficiency and user comfort in modern architecture. Traditional solutions like blinds and curtains face limitations in cost, maintenance, and space. This work introduces a microfluidic-based transparency-switching glass (MTSG), featuring microfluidic cavities filled with a liquid optically matched to the glass substrate. When filled, the cavities enable specular light transmission; in the absence of the liquid, internal wall roughening scatters light, rendering the cavities translucent. The MTSG achieves >85% transmittance modulation, ∼20 s switching time, with virtually no electrical power; if used, minimal power (<12 W/m2) is required, and only during switching. A unique curtain-rolling-like mechanism with the top portion maintained opaque and the bottom portion maintained transparent adds versatility and user-friendliness. This technology offers advantages over existing smart windows, including cost-effectiveness, use of readily available materials, and scalability for industrial production. Additionally, it addresses serious concerns related to power consumption, recyclability, and ease of operation. This design holds promise for smart visibility control in zero-energy buildings and sustainable architectural applications.