Technology 4403 Microfabrication 4403 Assembly and Interfacing 4404 Optical Integration 4405 Flow Control 4405 Standard Operations 4406 Sample Preparation 4406 Injection and Separation 4407 Fluidic Reactors 4407 Particle and Cell Sorting 4409 Cell Trapping and Culture 4409 Applications 4410 Clinical Diagnostics 4410 Nucleic Acids 4411 Proteins 4412 Cell and Tissue Studies 4413 Environmental Monitoring 4414 Literature Cited 4414

Micro total analysis systems: latest achievements.

Micro-electrochemical discharge machining (ECDM) was studied in order to improve the machining of 3D micro-structures of glass. To minimize structures and obtain good surface microstructures, the effects of the electrolyte, the pulse on/off-time ratio, the voltage, the feedrate, the rotational speed, and the electrolyte concentration in the drilling and milling processes were studied.In ECDM, voltage is applied to generate a gas film and sparks on a tool electrode; however, high voltage produces poor machining resolution. To obtain a stable gas film over the whole surface of the tool at a low voltage, a new mechanical contact detector, based on a loadcell, was used; the immersion depth of the tool electrode in the electrolyte was reduced as much as possible. In this study, various micro-structures less than 100 μm in size, such as O 60 μm micro-holes, a 10 μm-thin wall, and a 3D micro-structure were fabricated to demonstrate the potential for micro-machining of glass by ECDM.

Micro-structuring of glass with features less than 100 μm by electrochemical discharge machining

Electrochemical discharge machining (ECDM) is a hybrid non-conventional machining process, used to machine electrically conductive and non-conductive materials. It is a preferred process to fabricate micro scale features like micro holes, micro channels, microgrooves and 3-dimensional intricate shapes on variety of materials. In order to improve the efficacy of ECDM process, certain technical augmentations are provided with basic configuration of ECDM. These augmentations result in developments of ECDM process variants. Further, research community has developed ECDM based triplex hybrid methods for further process enrichment. This review article presents a comprehensive review of these recent developments in ECDM process, its variants and their triplex hybrid methods. The future research possibilities are identified and presented as research potentials.

Developments in electrochemical discharge machining: A review on electrochemical discharge machining, process variants and their hybrid methods

Micro-machining has attracted great attention as micro-components/products such as micro-displays, micro-sensors, micro-batteries, etc. are becoming established in all major areas of our daily life and can already been found across the broad spectrum of application areas especially in sectors such as automotive, aerospace, photonics, renewable energy and medical instruments. These micro-components/products are usually made of multi-materials (may include hard-to-machine materials) and possess complex shaped micro-structures but demand sub-micron machining accuracy. A number of micro-machining processes are therefore, needed to deliver such components/products. The paper reviews recent development of hybrid micro-machining processes which involve integration of various micro-machining processes with the purpose of improving machinability, geometrical accuracy, tool life, surface integrity, machining rate and reducing the process forces. Hybrid micro-machining processes are classified into two major categories namely, assisted and combined hybrid micro-machining techniques. The machining capability, advantages and disadvantages of the state-of-the-art hybrid micro-machining processes are characterized and assessed. Some case studies on integration of hybrid micro-machining with other micro-machining and assisted techniques are also introduced. Possible future efforts and developments in the field of hybrid micro-machining processes are also discussed.

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Hybrid micro-machining processes: a review

High aspect ratio micromachining of glass by electrochemical discharge machining (ECDM)

Electrochemical discharge machining (ECDM) is demonstrated to be a potential process for 3D microstructuring of Pyrex glass. However, the key to widening ECDM micromilling applications lies in how to improve the machining accuracy. To improve the machining quality of the ECDM micromilling process, microgroove machining experiments were conducted in this study. Three factors affecting ECDM micromilling performance—pulse voltage, tool rotational rate and travel rate of tool—were taken up as machining parameters to investigate their influences on machining performance. The results indicate that optimum combinations of both pulse voltage and tool rotational rate will realize better machining accuracy. The feasibility of three-dimensional microstructure machining was demonstrated by layer-by-layer ECDM micromilling machining. Complex structures were made to demonstrate the great potential for the 3D microstructuring of Pyrex glass of the ECDM micromilling process.

http://iopscience.iop.org/article/10.1088/0960-1317/17/5/016/pdf

3D microstructuring of Pyrex glass using the electrochemical discharge machining process

Upconversion nanoparticles (UCNPs) and polymerizable molecules of aggregation-induced emission (AIE) were combined to produce white light emission. Blue and ultraviolet light-emitting doped lanthanide UCNPs (LiYF4:Yb3+/Tm3+@LiYF4:Yb3+), polymerizable red light-emitting 1,4-bis(piperidinyl-1-propenyl bromide)anthracene (1,4-BPPA), and green light-emitting 9,10-BPPA AIE molecules were mixed with photopolymerizable acrylate oligomers for photopolymerization to form a luminescent film. The fluorescence spectrum, obtained by exciting the LiYF4:Yb3+/Tm3+@LiYF4:Yb3+ UCNPs with 980 nm near-infrared light, exhibited visible light emission, and high-energy emission included ultraviolet light at 365 nm and blue light at 450 and 475 nm. The high-energy light produced through the transfer of energy from the UCNPs excited 1,4-BPPA and 9,10-BPPA molecules to emit red and green light, thus producing a hybrid of red, blue, and green light emission that resulted in white light. X-ray diffractometry, scanning electron microscopy, ultraviolet–visible spectrometry, and fluorescence spectrometry were used to analyze the materials. The CIE coordinates of the white light-emitting film were (0.3358, 0.3536), corresponding to a correlated color temperature of 5370 K. The results demonstrate that upconversion particles and polymerizable AIE molecules can be combined to fabricate a white light-emitting diode film. 

NIR-Driven White Light Diode Formed with UCNP@AIEgen Nanocomposites

This study presents a straightforward strategy that embeds a graphene interlayer between InGaN-based light-emitting diodes (InGaN LEDs) and patterned sapphire substrate (PSS substrate) for substantial improving device performances of wavelength stability and heat dissipation. The InGaN LEDs on the graphene interlayer/PSS substrate (Gr-LED) have lower piezoelectric fields of 1.16 MV/cm than 1.60 MV/cm for InGaN LEDs on the PSS substrate (Ref-LED). The low piezoelectric field diminishes the screen of the polarization field resulting in a stable electroluminescence peak wavelength. At 100 mA driving current, the chip temperature of Gr-LED shows a decrease in around 24.4 °C relative to Ref-LED. The thermal resistances measured in a vacuum environment are 351 and 128 °C/W for Ref-LED and Gr-LED, respectively. The low thermal resistance of Gr-LED is believed to be due to a low misfit dislocation density of the aluminum nitride nucleation layer that increases the vertical direction of heat transport to PSS. This work demonstrates that the graphene/PSS substrate is a promising substrate for high-power InGaN LEDs.

Wei Hsin Cheng

Papers

3D microstructuring of Pyrex glass using the electrochemical discharge machining process

NIR-Driven White Light Diode Formed with UCNP@AIEgen Nanocomposites

Improved wavelength stability and heat dissipation of InGaN-based light-emitting diodes using a graphene interlayer on patterned sapphire substrate