Ya Wei Lee

Applications of magnetic nanoparticles in engineering and biomedical science

This study mainly employs magnetic nanoparticles (MNPs) for an amazing variety of engineering and biomedical applications. Herein MNPs are fabricated from fine ferromagnetic particles of iron ferrite by chemical co-precipitation technique, and their average size is about 27 nm via HR-TEM micrograph and XRD analysis to investigate. In this study, MNPs have been demonstrated their excellent properties of heat transfer, electric conductivity, magnetism within the applications for multi-loop pulsating heat pipe (MLPHP), switch-based nanodevice, microfluidic on-chip system and nanogap-based DNA sensor. Based on the effect of magnetic field for MNPs, MLPHP can enhance thermal performance itself at different heating power. In addition, the switch-based nanodevice with MNPs can efficiently add and remove an electrical function of electron charging with current shift. Furthermore, the microfluidic chip utilizing MNPs is demonstrated that can be suited for drug delivThis study mainly employs magnetic nanoparticles (MNPs) for an amazing variety of engineering and biomedical applications. Herein MNPs are fabricated from fine ferromagnetic particles of iron ferrite by chemical co-precipitation technique, and their average size is about 27 nm via HR-TEM micrograph and XRD analysis to investigate. In this study, MNPs have been demonstrated their excellent properties of heat transfer, electric conductivity, magnetism within the applications for multi-loop pulsating heat pipe (MLPHP), switch-based nanodevice, microfluidic on-chip system and nanogap-based DNA sensor. Based on the effect of magnetic field for MNPs, MLPHP can enhance thermal performance itself at different heating power. In addition, the switch-based nanodevice with MNPs can efficiently add and remove an electrical function of electron charging with current shift. Furthermore, the microfluidic chip utilizing MNPs is demonstrated that can be suited for drug delivery. Finally, we use MNPs to develop an electrical approach to detect femtomolar DNA that can amplify the low target DNA concentration for a clinical gene diagnostic system.ery. Finally, we use MNPs to develop an electrical approach to detect femtomolar DNA that can amplify the low target DNA concentration for a clinical gene diagnostic system.

Effect of Increasing Wick Evaporation Area on Heat Transfer Performance for Loop Heat Pipes

This study investigates the effects of increasing the evaporating area of wick in a loop heat pipe (LHP). This work attempts to improve the performance of the loop heat pipe by increasing the number of grooves and thereby the surface area of the wick. The number of grooves is increased from eight to twelve. Experimental results show that increasing the number of grooves not only increases the surface area of the wick but also enhances LHP performance. When the evaporating surface area increases by 50%, which corresponds to increasing the number of grooves from eight to twelve, the heat transfer capacity increases from 310W to 470W and the thermal resistance is reduced from 0.21°C/W to 0.17°C/W. According to preliminary measurements, increasing the number of grooves in the loop heat pipe is highly promising for improving the heat transfer performance.

Dynamic Modeling and Identification of an Electric-Hydraulic Controlled Fuel Injection System

Fuel consumption, related to engine operation and performance, has always been emphasized in the modern design of heavy vehicles. For identifying the operational mechanism of a novel hydraulically actuated electronic unit injection (HEUI) system from the viewpoint of energy conversion, this study presents the estimation of a nonlinear autoregressive moving average with exogenous inputs (NARMAX) models. By this modeling approach, the correlation between injection pressure and fuel rate under normal operations is detected. When mapping the NARMAX models into the frequency domain, the frequency response functions (FRFs) representing the energy transfer mechanisms in the system can then be precisely obtained. Due to the high-order FRFs responsible for the non-linear coupling between the various input spectral components, the HEUI dynamics can be demonstrated as an energy resonance of 22.5 Hz.

Design of self-alignment devices with fluidic self-assembly for flip chip packages in batch processing

An advanced LED multi-die-bonding integration using a fluidic self-assembly technique is proposed in the field of flip chip packages. Different form the conventional pick-and-place methods for a single LED die bonding, the fluidic approach is a relatively new design and a batch process, which can achieve not only die self-alignment but die self-assembly. Here, the size of LED die is 1-mm-square chip with the thickness of 0.3 mm. Due to the smaller size of LED die, the die-bonding process is still in need of finding a suitable approach and breakthrough. In this study, our design of fluidic self-assembly device is based on the experimental test and simulation results. The device design is the gas-flow channels with the magnetism. The width, height and length of each gas-flow channel are 1.1 mm, 0.5 mm, and 1 cm, respectively. With the restriction of the channel width, this structure design can control well to die self-alignment. In addition, the design of two circular structures in the channel can form a flat rim to achieve the die self-assemble. This mechanism of fluidic approach can be useful to the LED die self-alignment and self-assembly in the future batch processing.