In recent times, the utilization of three-dimensional (3D) printing technology, particularly a variant using digital light processing (DLP), has gained increasing fascination in the realm of microfluidic research because it has proven advantageous and expedient for constructing microscale 3D structures. The surface wetting characteristics (e.g., contact angle and contact angle hysteresis) of 3D-printed microstructures are crucial factors influencing the operational effectiveness of 3D-printed microfluidic devices. Therefore, this study systematically examines the surface wetting characteristics of DLP-based 3D printing objects, focusing on various printing conditions such as lamination (or layer) thickness and direction. We preferentially examine the impact of lamination thickness on the surface roughness of 3D-printed structures through a quantitative assessment using a confocal laser scanning microscope. The influence of lamination thicknesses and lamination direction on the contact angle and contact angle hysteresis of both aqueous and oil droplets on the surfaces of 3D-printed outputs is then quantified. Finally, the performance of a DLP 3D-printed microfluidic device under various printing conditions is assessed. Current research indicates a connection between printing parameters, surface roughness, wetting properties, and capillary movement in 3D-printed microchannels. This correlation will greatly aid in the progress of microfluidic devices produced using DLP-based 3D printing technology.

In recent times, the utilization of three-dimensional (3D) printing technology, particularly a variant using digital light processing (DLP), has gained increasing fascination in the realm of microfluidic research because it has proven advantageous and expedient for constructing microscale 3D structures. The surface wetting characteristics (e.g., contact angle and contact angle hysteresis) of 3D-printed microstructures are crucial factors influencing the operational effectiveness of 3D-printed microfluidic devices. Therefore, this study systematically examines the surface wetting characteristics of DLP-based 3D printing objects, focusing on various printing conditions such as lamination (or layer) thickness and direction. We preferentially examine the impact of lamination thickness on the surface roughness of 3D-printed structures through a quantitative assessment using a confocal laser scanning microscope. The influence of lamination thicknesses and lamination direction on the contact angle and contact angle hysteresis of both aqueous and oil droplets on the surfaces of 3D-printed outputs is then quantified. Finally, the performance of a DLP 3D-printed microfluidic device under various printing conditions is assessed. Current research indicates a connection between printing parameters, surface roughness, wetting properties, and capillary movement in 3D-printed microchannels. This correlation will greatly aid in the progress of microfluidic devices produced using DLP-based 3D printing technology.

This article presents the feasibility of a flyback charger for electric vehicles (EV) based on silicon-carbide (SiC) devices. The flyback topology is simplest, but its device voltage stresses are strongly affected by the transformer leakage inductance. To reduce the device voltage stresses by recovering the energy stored in the transformer leakage inductance, an active-clamp circuit and active snubber circuit are adopted in both sides of the transformer. Also, the active-clamp circuit helps to reduce the switching losses by making zero-voltage-switching (ZVS) condition. By deriving the loss equations of switching devices and transformer as a function of the switching frequency and magnetic flux swing, design optimization considering loss and volume is attempted. The snubber capacity and diode voltage stress are quantitatively suggested through the analysis of the power absorbed by the active snubber. Based on the analysis, a 3.3 kW/100 kHz prototype is designed and experimented to show the feasibility. Test results demonstrate 96.7% peak efficiency and 96.4% full load efficiency at 330V output voltage.

The paper proposes a new synchronous rectification (SR) for a two-transformer active-clamp forward-flyback converter (ACFF). The proposed method synchronizes the overlapped turn-on interval of SR field effect transistors (FETs) to the falling edge of the primary-side gate signals. The proposed method eliminates the voltage spike of SR FETs in discontinuous conduction mode. The interval of the overlap is fixed regardless of the input voltage or output power of the converter. This requires no additional voltage or current sensing and saves the computational resources of microcontroller unit. The performance of the proposed SR is verified by an 800 V-14 V 100-W prototype two-transformer ACFF.