Multilayered optofluidics for sustainable buildings

Abstract

Indoor climate control is among the most energy-intensive activities conducted by humans. A building facade that can achieve versatile climate control directly, through independent and multifunctional optical reconfigurations, could significantly reduce this energy footprint, and its development represents a pertinent unmet challenge toward global sustainability. Drawing from optically adaptive multilayer skins within biological organisms, we report a multilayered millifluidic interface for achieving a comprehensive suite of independent optical responses in buildings. We digitally control the flow of aqueous solutions within confined milliscale channels, demonstrating independent command over total transmitted light intensity (95% modulation between 250 and 2,500 nm), near-infrared-selective absorption (70% modulation between 740 and 2,500 nm), and dispersion (scattering). This combinatorial optical tunability enables configurable optimization of the amount, wavelength, and position of transmitted solar radiation within buildings over time, resulting in annual modeled energy reductions of more than 43% over existing technologies. Our scalable “optofluidic” platform, leveraging a versatile range of aqueous chemistries, may represent a general solution for the climate control of buildings.

Recent advances in solar infrared light regulating smart windows based on organic materials

“…This work used confined fluid flows switching between visibly transparent fluids, which absorb in the NIR, such as glycerol, or between air and aqueous solutions containing carbon black as a broadband NIR absorber. [78] This latter system demonstrated only 16% transmission loss in the visible spectrum but reduced NIR transmission 77%. The temperature within a scaled-room model reduced 7°C.…”

“…Adapted with permission. [78] NIR, near infrared; PMMA, poly(methyl methacrylate). a transparent to a scattering state within tenths of a degree Celsius.…”

“…An optofluidic system was suggested wherein aqueous solutions are flowed through multilayer‐channeled structures under digital control (Figure 8). This work used confined fluid flows switching between visibly transparent fluids, which absorb in the NIR, such as glycerol, or between air and aqueous solutions containing carbon black as a broadband NIR absorber [78] . This latter system demonstrated only 16% transmission loss in the visible spectrum but reduced NIR transmission 77%.…”

“…(c) Measured temperature of a PMMA plate behind a fluid layer across an injection sequence of each fluid from (b). Adapted with permission [78] . NIR, near infrared; PMMA, poly(methyl methacrylate).…”

Bio‐Inspired, Scalable, and Tri‐Mode Stimuli‐Chromic Composite for Smart Window Multifunctionality

“…The hydro-/solvato-chromic mode is promising for smart window applications by integrating with fluid/air devices as reported in recent reports. [44][45][46] With similar optical performance to the mechanochromic mode, the hydro-/solvato-chromic mode can serve as an alternative method for on-demand privacy control in daily life. More importantly, this mode shows an advantage to tuning films into clear (high ballistic transmittance) under both stretched and released states, which can serve as a predominated control in extreme circumstances.…”