The bidirectional DC-DC converters are widely used in the energy storage system (ESS) and DC distribution system. The power capacity is limited when the converter is operated with smooth power transfer. In addition, the directions of the inductor current and the capacitor voltage cannot change instantaneously. In this study, a rapid energy conversion technique for smoothing and accelerating the energy transfer under the same specification of the main components in steady state is proposed. Moreover, a bidirectional DC-DC converter with a high conversion ratio is proposed to overcome the commonly low voltage input from renewable energy sources. The operating principles of the proposed converter’s step-down and step-up modes are discussed in this study. Furthermore, to achieve rapid energy conversion, digital control is a crucial component in the converter system. A digital signal processor is used as the control platform, and a control strategy is formulated to achieve rapid energy conversion. The bidirectional DC-DC prototype converter with a 24 V battery, a DC bus of 200 V, and an output power of 500 W is constructed to confirm the feasibility of rapid energy conversion. The proposed converter can be operated in CCM, BCM, and DCM conditions. The transfer period can be completed within one switching cycle when the proposed converter is operated in BCM or DCM. The energy is freewheeled before energy conversion when the proposed converter is operated in CCM condition. In the experiment, the minimum transfer period is 6.29 µs on the DCM stage.

Bidirectional DC–DC converters are key devices in the DC distribution system and the energy storage system (ESS). It is important to consider the safety of the elements in the converter for rapid conversion of the power direction. Damages may occur to the power-related components in the circuit if the direction of the inductor current or the capacitor voltage changes instantaneously. To make the power flow change smoothly and quickly, this research proposed a bidirectional DC–DC converter with rapid energy transition technology implemented in the circuit architecture. The rapid energy bidirectional transition technology added a resonance path based on the LC resonant circuit, allowing rapid energy conversion through the resonance path. Therefore, the energy in the energy storage element could be quickly converted without causing circuit surges. Analyses of the converter operating in the step-up mode, the step-down mode, and the transition operation mode are presented. The proposed circuit architecture had a high voltage-conversion ratio and a simple architecture. A prototype bidirectional DC–DC converter with a full load of 500 W, a low side voltage of 24 V, and a high side voltage of 200 V was developed to prove the concept. The feasibility of the rapid energy bidirectional transition technology was verified by the simulation results and experimental results using the prototype converter. The maximum efficiencies in the step-up mode and the step-down mode were 95.3% and 93.8% respectively. Under full-load conditions, the transient time of the energy transition from the step-up mode to the step-down mode was 17.7 μs, and the transient time of the energy transition from the step-down mode to the step-up mode was 19.3 μs.

Meniscus-guided printing (MGP) has emerged as a versatile additive manufacturing strategy for the high-resolution fabrication of three-dimensional (3D) microarchitectures. However, the widespread implementation of soft, high-aspect-ratio conducting polymer (CP) microelectrodes for advanced bioelectronics remains limited by the lack of predictive frameworks linking printing parameters to print fidelity, mechanical stability, and electrochemical performance. We previously reported the direct MGP of high-aspect-ratio poly(3,4‑ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) pillar microelectrode arrays with tunable structural and electrochemical properties. Herein, we build on these studies by systematically correlating fundamental printing parameters, including ink composition, rheological properties, printing dynamics, and post-print thermal annealing conditions, with the mechanical and electrochemical performance of the 3D PEDOT:PSS pillar microelectrodes. The 3D-printed pillar microelectrodes were fabricated with high aspect ratios (up to 17), excellent geometric uniformity, mechanical integrity, and reliable electrochemical properties. Electrochemical performance showed a strong dependence on microelectrode architecture, pillar height, and thermal processing conditions. Notably, the 50 µm-tall PEDOT:PSS pillar microelectrodes demonstrated an eightfold increase in electrochemically active surface area (ECSA) and a 46% reduction in interfacial impedance at 100 Hz compared with planar PEDOT:PSS microelectrodes. Further optimization of pillar height and thermal annealing at 180 °C for 10 min enabled the 200 µm-tall PEDOT:PSS pillar microelectrodes to achieve a 3.7-fold higher ECSA, three times larger double-layer capacitance, and 82% lower charge-transfer resistance than the 50 µm-tall PEDOT:PSS pillar microelectrodes. Overall, this work provides a customizable material-process-property optimization paradigm for the robust MGP of soft 3D PEDOT:PSS microelectrode arrays for next-generation bioelectronic interfaces, tissue engineering, and electrochemical biosensing technologies.