Laser Induced Coffee‐Ring Structure through Solid‐Liquid Transition for Color Printing

Abstract

Metallic micro/nano structures with special physicochemical properties have undergone rapid development owing to their broad applications in micromachines and microdevices. Ultrafast laser processing is generally accepted as an effective technology for functional structures manufacture, however, the controllable fabrication of specific metallic micro/nano structures remains a challenge. Here, this work proposes a novel strategy of laser induced transient solid‐liquid transition to fabricate unique structures. Through modulating the transient state of metal from solid to liquid phase using the initial pulse excitation, the subsequent ultrafast pulse‐induced recoil pressure can suppress the plasma emission and removal of liquid phase metals, resulting in the controllable fabrication of coffee‐ring structures. The solid‐liquid transition dynamics, which related with the transient reflectivity and plasma intensity, are revealed by established two temperature model coupled with molecular dynamics model. The coffee‐ring structure exhibits tunable structure color owing to various optical response, which can be used for color printing with large scale and high resolution. This work provides a promising strategy for fabricating functional micro/nano structures, which can greatly broaden the potential applications.

Flexible Copper-Based Thermistors Fabricated by Laser Direct Writing for Low-Temperature Sensing

“…CuO plays the role of sensing temperature in the 1.0 W films, while Cu 2 O is the main medium for temperature sensing in the 1.3 W films. In the conduction process of CuO compared with that of Cu 2 O, the lattice distortion exists during the polaron hopping, which imparts additional drag on the motion of the charge-carrier and weakens the mobility of the carrier. − However, the holes as charge-carrier in the VB of Cu 2 O are more mobile . This contributes to the conductivity difference of the samples with 1.0 and 1.3 W. Furthermore, the sintered structure in the films with 1.3 W is denser.…”

Polarization‐Modulated Patterned Laser Sculpturing of Optical Functional Hierarchical Micro/Nanostructures

“…Hierarchical micro/nanostructures offer a way to regulate specific physical or chemical characteristics on a surface, such as high thermal conductivity [1,2] superhydrophobic/hydrophilic, [3,4] ice-phobic, [5,6] anti-reflection, [7][8][9] and structural color, [10,11] which have been widely studied and applied across various fields. Among them, the optical properties of micro-/nanostructured surfaces show more tunability due to the light response is intricately linked to the shape and size of the surface structures.…”

A Machine Learning-Combined Flexible Sensor for Tactile Detection and Voice Recognition

“…Due to the excellent elasticity and flexibility, polymers have been used as the substrate of a wearable sensor, such as polydimethylsiloxane (PDMS). , The active materials are the key components that convert the mechanical stimuli to an electrical signal. ,, A wide range of materials, including graphene, carbon nanotubes, SiC, MXene, metal nanoparticles, , and nanowires, have been used as the active materials. A series of processing methods have been developed to manufacture a flexible sensor, such as lithography, inject printing, , screen printing, infilling, and laser processing method. , Infilling active materials into the flexible substrate is a simple and efficient method for sensor fabrication, while the lithography and printing method is usually used to fabricate patterned sensors. , Laser processing has been recognized as a powerful method in various fields, such as micro/nanoprocessing, patterning, , and sensors . Laser processing has been demonstrated to be a high-throughput method, which realizes active materials synthesis and sensor patterning in one step. , In recent years, there has been growing interest in the flexible sensor fabrication through laser processing.…”

“…27,28 Infilling active materials into the flexible substrate is a simple and efficient method for sensor fabrication, while the lithography and printing method is usually used to fabricate patterned sensors. 29,30 Laser processing has been recognized as a powerful method in various fields, such as micro/nanoprocessing, 31 patterning, 32,33 and sensors. 3 Laser processing has been demonstrated to be a high-throughput method, which realizes active materials synthesis and sensor patterning in one step.…”