Electrically tunable directional light scattering from soft thin membranes

Abstract

The possibility of electrically tuning the scattering of light from surfaces by dynamically varying their properties is desirable for controllable transparency devices and diffusion filters. As a difference from state-of-the-art approaches where scattering is changed isotropically, this paper presents the first smart-material-based technology enabling electrical modulations in a single or multiple directions, which can be selected dynamically. The effect is achieved from thin soft membranes with transparent PEDOT:PSS coatings, which are electrically deformed along a single or multiple axes, using dielectric elastomer actuation. Anisotropic scattering is induced by electrically tuning the formation of directional surface wrinkles. As a proof of concept, a bi-directional device is obtained by overlapping two 90°-shifted mono-directional layers that can be controlled independently. According to the activation of the layers, light can be scattered along either direction, as well as both of them. Prototypes made of an acrylic elastomer were demonstrated with mono-and bi-directional operations. Devices with a window-to-total area ratio of 1:4 also showed a maximum electrical reduction of optical transmittance from 75% to 4%. This functionality and possible extensions to more than two controllable directions suggest applicability as electrically controllable anisotropic light diffusers for dynamic light shaping, as well as tunable transparency surfaces.

Development of a High‐Performance, Anti‐Fouling Optical Diffuser Inspired by Morpho Butterfly's Nanostructure

“…In addition to the conventional diffusers mentioned above, various types of novel diffusers have been proposed to date. These include fibrous structures of wood/cellulose-based materials, [6][7][8]24,25] specific crystal structures, [26] liquid crystals, [27][28][29] polymer composites, [9,10,30] surface microwrinkles, [31][32][33][34][35][36][37] and laser-ablated surfaces. [38][39][40] It is remarkable that certain of these novel diffusers show tunable light diffusion upon mechanical/thermal/electrical stimuli, acting as smart windows.…”

Stretchable Optical Diffuser Constructed by Alternate Procedure of Interfacial Complexation and Thermal Crosslinking

“…[ 9 ] Therefore, the need for multifunctional integrated stretchable optical diffuser is uprising. [ 10 ] The incorporation of the scattering particles like cellulose nanocrystals into the transparent PDMS substrate endows the film with flexibility and scattering capacity, demonstrating undisturbed optical properties under stretching, twisting, and bending. [ 11 ] Laser ablation or creating deformable wrinkle to produce surface pattern on PDMS is also a common approach to realize stretchable optical diffuser.…”

Electrohydrodynamic printing of a dielectric elastomer actuator and its application in tunable lenses

“…Since then, extensive efforts have been made in the development of dielectric elastomer actuators (DEA) driven tunable lenses possessing superior electromechanical properties. DEs [12,13] are electrostrictive polymers and can achieve large actuated strain (> 380%), quick response speeds and high electromechanical energy densities (~ 3.4 MJ/m 3 ) [14][15][16][17][18], together with light weight, low cost and absence of noise pollution [9,[19][20][21][22][23][24]. The working mechanism behind a tunable lens using a DE actuator (DEA), which is a DE ring film coated with a compliant electrode assembled into a tunable lens, is illustrated in Figure 1(c) and (d).…”