In this article, we introduce a rapid and simple fabrication method to realize a 3-dimensional (3-D) microfluidic channel with a near-perfect circular cross section. This new concept of fabrication method is defined by metal wire removal process, where the metal wire such as a thin soldering wire for the 3-D circular shape is commercially available. For the microfluidic channel mold, PDMS (polydimethylsiloxane) was poured on several shapes such as 3-D circular, helix, and double helix shapes, of soldering wire and solidified. The soldering wire was then melted out by heating. With the two-step process, rapidly and simply fabricated 3-D circular microfluidic channels can be obtained. CPAE (endothelial cell line) cells were cultured inside the channel to evaluate the biocompatibility of the fabricated microfluidic channel. Our method will be very useful in making various circular shapes of 3-D microfluidic devices that need multi-depth and round corners inside the channel.

Purpose -The purpose of this paper is to investigate the thermal behaviors of high power LED packages to enhance the thermal performances of low temperature co-fired ceramic chip on board (LTCC-COB) package. Thermal analysis demonstrated an improved LTCC-COB package design that is comparable to a metal lead frame package with low thermal resistance. Design/methodology/approach -The LED device developed in this study is a LTCC package mounted directly on the metal PCB. A numerical simulation was performed to investigate the thermal characteristics of the LED module using the finite volume method, which is embedded in commercial software (Fluent V.6.3). Thermal resistance and temperature measurement validate the simulated results.Findings -The effect of the thickness of the die attach material on the thermal resistance was dominant due to low thermal conductivity, and the junction temperature decreased significantly with slight increases in thermal conductivity, especially when the value was less than 5 W/mK. The results reveal that the thermal resistance of MCPCB is about 49 per cent-58 per cent of the junction to board thermal resistance. The thermal model results showed good agreement with experimental results. Originality/value -The developed model overcomes the large thermal resistance of a conventional LTCC package for high power LED module. The extensive results have demonstrated an improved thermal design, optimal dimensions of each component and boundary conditions for high power LTCC-COB type package.