Fabrication of Meander and Spiral Type Micro Inductors

TO obtain microstructure of magnetic devices, the thin film inductors were fabricated by the process such as thin film manufacturing, photolithography and wet etching. The frequency characteristics of these devices are measured at high frequency range. When the inductor sizes of the spiral and the meander type are same, the inductance and the quality factor of the spiral type inductor are larger than those of the meander type inductor, but the driving frequency of the spiral type inductor is lower than that of the meander typejinductor.

Bioinspired Multiscale Wrinkling Patterns on Curved Substrates:An Overview

The surface wrinkling of biological tissues is ubiquitous in nature.Accumulating evidence suggests that the mechanical force plays a significant role in shaping the biological morphologies.Controlled wrinkling has been demonstrated to be able to spontaneously form rich multiscale patterns,on either planar or curved surfaces.The surface wrinkling on planar substrates has been investigated thoroughly during the past decades.However,most wrinkling morphologies in nature are based on the curved biological surfaces and the research of controllable patterning on curved substrates still remains weak.The study of wrinkling on curved substrates is critical for understanding the biological growth,developing threedimensional(3D)or four-dimensional(4D)fabrication techniques,and creating novel topographic patterns.In this review,fundamental wrinkling mechanics and recent advances in both fabrications and applications of the wrinkling patterns on curved substrates are summarized.The mechanics behind the wrinkles is compared between the planar and the curved cases.Beyond the film thickness,modulus ratio,and mismatch strain,the substrate curvature is one more significant parameter controlling the surface wrinkling.Curved substrates can be both solid and hollow with various 3D geometries across multiple length scales.Up to date,the wrinkling morphologies on solid/hollow core-shell spheres and cylinders have been simulated and selectively produced.Emerging applications of the curved topographic patterns have been found in smart wetting surfaces,cell culture interfaces,healthcare materials,and actuators,which may accelerate the development of artificial organs,stimuli-responsive devices,and micro/nano fabrications with higher dimensions.

Electrons dynamics control by shaping femtosecond laser pulses in micro/nanofabrication: modeling, method, measurement and application

During femtosecond laser fabrication,photons are mainly absorbed by electrons,and the subsequent energy transfer from electrons to ions is of picosecond order.Hence,lattice motion is negligible within the femtosecond pulse duration,whereas femtosecond photon-electron interactions dominate the entire fabrication process.Therefore,femtosecond laser fabrication must be improved by controlling localized transient electron dynamics,which poses a challenge for measuring and controlling at the electron level during fabrication processes.Pump-probe spectroscopy presents a viable solution,which can be used to observe electron dynamics during a chemical reaction.In fact,femtosecond pulse durations are shorter than many physical/chemical characteristic times,which permits manipulating,adjusting,or interfering with electron dynamics.Hence,we proposed to control localized transient electron dynamics by temporally or spatially shaping femtosecond pulses,and further to modify localized transient materials properties,and then to adjust material phase change,and eventually to implement a novel fabrication method.This review covers our progresses over the past decade regarding electrons dynamics control(EDC)by shaping femtosecond laser pulses in micro/nanomanufacturing:(1)Theoretical models were developed to prove EDC feasibility and reveal its mechanisms;(2)on the basis of the theoretical predictions,many experiments are conducted to validate our EDC-based femtosecond laser fabrication method.Seven examples are reported,which proves that the proposed method can significantly improve fabrication precision,quality,throughput and repeatability and effectively control micro/nanoscale structures;(3)a multiscale measurement system was proposed and developed to study the fundamentals of EDC from the femtosecond scale to the nanosecond scale and to the millisecond scale;and(4)As an example of practical applications,our method was employed to fabricate some key structures in one of the 16 Chinese National S&T Major Projects,for which electron dynamics were measured using our multiscale measurement system.

Fabrication of Micro -Optical Devices by a Femtosecond Laser

Femtosecond laser is a perfect laser source for materials processing when high accuracy and small structure size are required. Due to the ultra short interaction time and the high peak power, the process is generally characterized by the absence of heat diffusion and, consequently molten layers. Various induced structures have been observed in materials after the femtosecond laser irradiation. Here, we report on fabrication of micro-optical devices by the femtosecond laser. 1) formation of optical waveg...

Ultrashort pulsed laser induced complex surface structures generated by tailoring the melt hydrodynamics

We present a novel approach for tailoring the laser induced surface topography upon femtosecond(fs)pulsed laser irradiation.The method employs spatially controlled double fs laser pulses to actively regulate the hydrodynamic microfluidic motion of the melted layer that gives rise to the structures formation.The pulse train used,in particular,consists of a previously unexplored spatiotemporal intensity combination including one pulse with Gaussian and another with periodically modulated intensity distribution created by Direct Laser Interference Patterning(DLIP).The interpulse delay is appropriately chosen to reveal the contribution of the microfluidic melt flow,while it is found that the sequence of the Gaussian and DLIP pulses remarkably influences the surface profile attained.Results also demonstrate that both the spatial intensity of the double pulse and the effective number of pulses per irradiation spot can further be modulated to control the formation of complex surface morphologies.The underlying physical processes behind the complex patterns’generation were interpreted in terms of a multiscale model combining electron excitation with melt hydrodynamics.We believe that this work can constitute a significant step forward towards producing laser induced surface structures on demand by tailoring the melt microfluidic phenomena.

Two-photon polymerization-based 4D printing and its applications

Two-photon polymerization(TPP)is a cutting-edge micro/nanoscale three-dimensional(3D)printing technology based on the principle of two-photon absorption.TPP surpasses the diffraction limit in achieving feature sizes and excels in fabricating intricate 3D micro/nanostructures with exceptional resolution.The concept of 4D entails the fabrication of structures utilizing smart materials capable of undergoing shape,property,or functional changes in response to external stimuli over time.The integration of TPP and 4D printing introduces the possibility of producing responsive structures with micro/nanoscale accuracy,thereby enhancing the capabilities and potential applications of both technologies.This paper comprehensively reviews TPP-based 4D printing technology and its diverse applications.First,the working principles of TPP and its recent advancements are introduced.Second,the optional4D printing materials suitable for fabrication with TPP are discussed.Finally,this review paper highlights several noteworthy applications of TPP-based 4D printing,including domains such as biomedical microrobots,bioinspired microactuators,autonomous mobile microrobots,transformable devices and robots,as well as anti-counterfeiting microdevices.In conclusion,this paper provides valuable insights into the current status and future prospects of TPP-based4D printing technology,thereby serving as a guide for researchers and practitioners.

Flexible Evanescent Wave Interference Lithography System for Sub-half-Wavelength Complex Relief Structures Fabrication

Surface microstructures impart various useful properties to objects,for example,improving optical characteristics,wettability,and sliding properties.It is well known that biomimicking relief structures are effective in making such properties arise and have been studied to be applied to various devices.Furthermore,they are expected to be utilized not only for improving a particular property but also for adding more complex functions on a device's urface by fabricating different multi-functional structures on a single surface in the future.However,to begin with,artificially fabricating such biomimicking special functional relief is difficult.One typical feature of biomimicking surfaces is the dual-scale structure,the smaller one of which is less than 200 nm.Moreover,in the case of realizing the more complex devices,it is necessary to fabricate various forms as changing process conditions dynamically.In this study,we proposed and developed a flexible evanescent wave interference lithography system as a novel fabrication method,which allows us to realize the fabrication of sub-half-wavelength complex relief structures.Firstly,we theoretically analyzed the fundamental behavior of the fabricated structure and found that the proposed concept has the potential to realize one of the target complex structures.Secondly,we developed the proposed system with high process flexibility,in which the number of beams,the azimuth angles,and the polarization can be simply manipulated.Finally,we validated the concept of the designed system by some experiments,where we fabricated dual-scale structures with 840-nm and 190-nm fringe patterns simultaneously.