Direct laser-reduction of graphene oxide (GO), as a lithography-free approach, has been proven effective in manufacturing in-plane micro-supercapacitors (MSCs) with fast ion diffusion.

A novel all-femtosecond-laser-processing technique is proposed for the fabrication of 2D periodic metal nanostructures inside 3D glass microfluidic channels, which have applications to real-time surface-enhanced Raman spectroscopy (SERS). In the present study, 3D glass microfluidic channels are fabricated by femtosecond-laser-assisted wet etching. This is followed by the space-selective formation of Cu-Ag layered thin films inside the microfluidic structure via femtosecond laser direct writing ablation and electroless metal plating. The Cu-Ag films are subsequently nanostructured by irradiation with linearly polarized beams to form periodic surface structures. This work demonstrates that a double exposure to laser beams having orthogonal polarization directions can generate arrays of layered Cu-Ag nanodots with dimensions as small as 25% of the laser wavelength. The resulting SERS microchip is able to detect Rhodamine 6G, exhibiting an enhancement factor of 7.3 × 10 8 in conjunction with a relative standard deviation of 8.88%. This 3D microfluidic chip is also found to be capable of the real-time SERS detection of Cd 2+ ions at concentrations as low as 10 ppb in the presence of crystal violet. This technique shows significant promise for the fabrication of high performance microfluidic SERS platforms for the real-time sensing of toxic substances with ultrahigh sensitivity.

We demonstrate a novel approach to rapidly fabricate conductive silver electrodes on transparent flexible substrates with high-bonding strength by laser-direct writing. A new type of silver ink composed of silver nitrate, sodium citrate, and polyvinylpyrrolidone (PVP) was prepared in this work. The role of PVP was elucidated for improving the quality of silver electrodes. Silver nanoparticles and sintered microstructures were simultaneously synthesized and patterned on a substrate using a focused 405 nm continuous wave laser. The writing was completed through the transparent flexible substrate with a programmed 2D scanning sample stage. Silver electrodes fabricated by this approach exhibit a remarkable bonding strength, which can withstand an adhesive tape test at least 50 times. After a 1500 time bending test, the resistance only increased 5.2%. With laser-induced in-situ synthesis, sintering, and simultaneous patterning of silver nanoparticles, this technology is promising for the facile fabrication of conducting electronic devices on flexible substrates.

Stretchable electronic sensing devices are defining the path toward wearable electronics. High-performance flexible strain sensors attached on clothing or human skin are required for potential applications in the entertainment, health monitoring, and medical care sectors. In this work, conducting copper electrodes were fabricated on polydimethylsiloxane as sensitive stretchable microsensors by integrating laser direct writing and transfer printing approaches. The copper electrode was reduced from copper salt using laser writing rather than the general approach of printing with pre-synthesized copper or copper oxide nanoparticles. An electrical resistivity of 96 μΩ cm was achieved on 40-μm-thick Cu electrodes on flexible substrates. The motion sensing functionality successfully demonstrated a high sensitivity and mechanical robustness. This in situ fabrication method leads to a path toward electronic devices on flexible substrates. Electronic supplementary materialThe online version of this article (doi:10.1007/s40820-017-0139-3) contains supplementary material, which is available to authorized users.

Microlenses (MLs) and microlens arrays (MLAs) are assuming an increasingly important role in optical devices. In response to this rapid evolution in technology, emphasis is being placed on research into new manufacturing methods for these devices as well as the characterization of their performance. This paper provides an overview of the fabrication of MLs and MLAs by electrical, mechanical, chemical, and optical methods. As each processing method has distinct advantages and limitations, the most significant characteristic parameters and the measurement of these parameters are discussed for each method. These parameters are then used as indices to evaluate and improve each of the processing methods. Some examples of practical applications of MLAs, especially for micromechanical optoelectronic devices, are also given. This paper aims to summarize the present development and the state of the art in processing technology of MLs and MLAs.