Evaluation and Optimization of a Cross-Rib Micro-Channel Heat Sink

This article presents a novel cross-rib micro-channel (MC-CR) heat sink to make fluid self-rotate. For a thermal test chip (TTC) with 100 w/cm2, the cross-ribs micro-channel were compared with the rectangular (MC-R) and horizontal rib micro-channel (MC-HR) heat sinks. The results show that, with the cross-rib micro-channel, the junction temperature of the thermal test chip was 336.49 K, and the pressure drop was 22 kPa. Compared with the rectangular and horizontal ribs heat sink, the cross-rib micro-channel had improvements of 28.6% and 14.3% in cooling capability, but the pressure drop increased by 10.7-fold and 5.5-fold, respectively. Then, the effects of the aspect ratio (λ) of micro-channel in different flow rates were studied. It was found that the aspect ratio and cooling performance were non-linear. To reduce the pressure drop, the inclination (α) and spacing (S) of the cross-ribs were optimized. When α = 30°, S = 0.1 mm, and λ = 4, the pressure drop was reduced from 22 kPa to 4.5 kPa. In addition, the heat dissipation performance of the rectangular, staggered fin (MC-SF), staggered rib (MC-SR) and cross-rib micro-channels were analyzed in the condition of the same pressure drop, MC-CR still has superior heat dissipation performance.

Continuous Encapsulation of Vitamin E Using Polycaprolactone and Tween 20 in a Micro-Channel

Encapsulation of vitamin E is the preservation of the biological activities of vitamin E for various applications. In the first part of this research, factors affecting the batch encapsulation of vitamin E, including PCL concentration, the concentration of Tween 20, and the volumetric ratio of aqueous phase to organic phase were experimentally investigated. The Box-Behnken experimental design and response surface methodology were implemented to determine the optimal operating conditions of the batch encapsulation. At the optimal conditions, the percentage of vitamin E encapsulation (%EC) was 98.69%, using the PCL concentration, the Tween 20 concentration, and the volumetric ratio of aqueous phase to organic phase of 3.6 g/L, 0.6 g/L, and 0.9 mL: 1 mL, respectively. The second part is to enhance the productivity by applying the optimized formulation of vitamin E encapsulation in a continuous process using a micro-channel encapsulator. The effect of residence time was investigated. At the residence time of 1 s, the percentage of vitamin E encapsulation of 97.28% and the productivity of 153.61 mg/(mL∙min) were achieved.

Design of MIRA, a low-noise pixelated ASIC for the readout of micro-channel plates

We present the design of the first prototype of MIRA (MIcro-channel plate Readout ASIC) that has been designed to read out Micro-Channel Plates (MCP), in particular for UV spectroscopy. MIRA will be able to detect the cloud of electrons generated by each photon interacting with the MCP, sustaining high local and global count rates to fully exploit the MCP intrinsic dynamic range with low dead time. The main rationale that guided the electronics design is the reduction of the input Equivalent Noise Charge (ENC) in order to allow operations with lower MCP gain, thus improving its lifetime, crucial aspect for long missions in space. MIRA features two selectable analog processing times, 133 ns or 280 ns (i.e. fast mode or slow mode), granting a count rate per pixel of 100 kcps. Moreover, it shows an Equivalent Noise Charge ENC = 17 e r m s − . A spatial resolution of 35 μm and an operation with zero dead time, due to the readout, are targeted. The low noise, high count rate and high spatial resolution requirements are expected by keeping a compact pixel size (35 μm × 35 μm) for a total of 32 × 32 pixels in a 2 mm × 2 mm ASIC area. In this work, the ASIC design is described.