4D Direct Laser Writing of Submerged Structural Colors at the Microscale

Abstract

Biomimetic stimuli‐responsive structure colors (SCs) can improve the visualization and identification in the micro functional structure field such as information encryption/decryption and smart actuators. However, it is still challenging to develop the ability to 4D print arbitrary submerged colorful patterns with stimuli‐responsive materials at the microscale. Herein, a hydrogel photoresist with feature resolution (98 nm) for the fabrication of 4D microscopic SCs by the femtosecond direct laser writing method is developed. The 4D printed woodpile SCs are grouped as pixel palettes with various laser parameters and they spanned almost the entire color space. The coloring mechanism of diffraction gratings is not only investigated by optics microscopy and spectroscopy but also supported by simulation. Moreover, the 4D printed hydrogel‐integrated amphichromatic fish constructions and pixelated painting can visually discolor reversibly by regulating the solution pH. This finding promises an ideal coloring method for sensors, anti‐counterfeiting labels, and transformable photonic devices.

Single‐Step 3D Printing of Micro‐Optics with Adjustable Refractive Index by Ultrafast Laser Nanolithography

“…Next to it, we study the distinct behavior of ray and wave optics for elements < 100 µm in dimensions. Such additional control of refractive index enrich the toolbox of 3D printing approaches for refractive and diffractive optics forward programmable 4D printing of materials, [ 26 ] specifically for designable devices dedicated to optical applications.…”

Temperature Tunable 4D Polymeric Photonic Crystals

“…[ 28 ] Very recently, 4D microscopic photonic crystals with 100 nm resolution have been patterned for the visible range, and their structural colors have been controlled by regulating the solution pH. [ 29 ] These examples demonstrate how different responsive materials can be photopolymerized into photonic structures whose properties can be controlled by their isotropic shape change in a liquid environment. Despite the large deformation offered by hydrogel‐based materials, their operation and integration are limited to a few applications because of the need of a swelling solvent.…”

“…However, the tuning of laser‐printed 3D photonic crystals in liquid environments has only recently been reported, [ 29 ] and to the best of our knowledge, the unique example reporting a TP‐DLW‐fabricated tunable woodpiles working in dry environment exhibits a slight refractive index tuning without reporting the relative change in the stopband. [ 43 ] Here, we report on the fabrication of a polymeric woodpile with a well‐defined stop band in the near infrared range that can be reversibly tuned in response to temperature variation.…”

“…However, the tuning of laser-printed 3D photonic crystals in liquid environments has only recently been reported, [29] and Adv. Funct.…”

Femtosecond laser regulatory focus ablation patterning of a fluorescent film up to 1/10 of the scale of the diffraction limit

“…Furthermore, they can manipulate the amplitude, phase, and polarization of the transmitted or reflected light, enabling the function of logic and memory, which is of significance to advanced photonic integrated circuits. [6][7][8][9][10] Although numerous patterning technologies of fluorescent materials have been developed and reported, an ideal strategy is still lacking and desired. In consideration of the weak stability of QDs and perovskites due to their sensitivity to solvents, heat and light, the frequently used traditional photolithography process is not suitable.…”