Donghun Park - Academia.edu (original) (raw)

Papers by Donghun Park

Nature Communications, 2024

Aerosol jet printing has the potential to fabricate fine features on various substrates due to it... more Aerosol jet printing has the potential to fabricate fine features on various substrates due to its large stand-off distance. However, the presence of overspray and instability, particularly at high printing resolutions, has limited its widespread application. In this study, we introduce an efficient approach called annular acoustic focusing for aerosol jet printing. By determining the optimal focusing frequency (5.8 MHz) for silver nanoparticles using a particle ejection model, we achieve precise and stable printing. We also propose a modified print nozzle geometry, resulting in ultrafine traces (line width < 6 μm, overspray < 0.1 μm). Compared to printing without acoustic focusing, the line width of the traces decreases to 60 ± 5% while their conductivity increases to 180 ± 5%. Additionally, several 8 h experiments demonstrate excellent printing stability. This research opens up possibilities for the fabrication of conformal electronics with high precision and improved conductivity using aerosol jet printing.

Advanced materials and technologies, Oct 21, 2018

Additive manufacturing, Aug 1, 2021

Abstract The current technologies of 3D printing have a huge potential in the domain of printed r... more Abstract The current technologies of 3D printing have a huge potential in the domain of printed radio frequency (RF) electronic components, such as resistors, capacitors, inductors, and transmission lines. In this paper, we present the design, fabrication, and characterization of fully 3-D printed conical inductors for broadband applications. The cores of these conical-shaped inductors were all printed by engineered magnetic/dielectric materials: the first one with a polymer core was printed by the aerosol-jet (AJ) printing technology as a reference, the second one with an iron-cobalt core fabricated by a paste-extrusion (PE) method using our developed iron-cobalt-based magnetic ink, and the third one with a core fabricated (by the PE method) using iron-based powder. The conical inductor was placed at a 45° angle by mounting it on a lattice support structure, and this configuration ensured a reduction of the parasitic capacitance between the inductor and the substrate. As a result, it was possible, to achieve a resonant-free broadband performance beyond the Ka-band (26.5–40 GHz), thereby outperforming the commercial off-the-shelf (COTS) products. Numerical simulations were also performed to explain the inductor performance and pinpoint the optimal model parameters. As suggested by the lumped circuit model, the operational frequency of the fully 3D printed iron-powder-based-core inductor could be as high as 67 GHz, which is nearly two times larger than the commercial iron core inductor.

For the first time, we report the RF photonic downconversion of a quadrature phase-shift keyed si... more For the first time, we report the RF photonic downconversion of a quadrature phase-shift keyed signal using a millimeter-wave coupled phase modulator based on SEO125 nonlinear polymer. Design, simulation, fabrication, and experimental results are discussed.

Journal of Manufacturing and Materials Processing

In this paper, we report the use of additive manufacturing methods to fabricate a high aspect rat... more In this paper, we report the use of additive manufacturing methods to fabricate a high aspect ratio, low noise amplifier (LNA) for a handheld active sensor device operating at up to 1 GHz. The new form factor LNA incorporates a modification of a square-shaped commercial off-the-shelf (COTS) LNA into a 5:1 aspect ratio device without a loss in RF performance. For rapid prototyping, we employ both subtractive and additive manufacturing technologies, such as milling, extrusion-based syringe printing, and aerosol jet printing techniques to fabricate both small form factor and high aspect ratio devices. The 5:1 aspect ratio LNA demonstrated a 20% smaller form factor, a gain of 25 dB, and an NF less than 3 dB over an operating frequency range up to 1 GHz, comparable to the COTS LNA. Design, simulation, and experimental results are given to highlight the advantages of 3D printed hybrid electronic technology over the conventional PCB fabrication method for rapid prototyping of RF electronic...

Nonlinear Optics, 2017

Additive Manufacturing, 2019

Advanced Materials Technologies, 2018

Additive manufacturing has the potential to fabricate passive components (e.g., capacitors, resis... more Additive manufacturing has the potential to fabricate passive components (e.g., capacitors, resistors, inductors, etc.) of a radio frequency (RF) circuit with minimized dimensions and controllable shapes in order to realize high‐density RF electronics for applications such as high resolution radars, healthcare monitors, and wearable sensors that involve high data‐rate transmissions. Here a novel procedure to direct‐write 3D, solid‐core solenoid‐inductors with polymer‐core, iron‐core, and ferrite‐core using aerosol‐jet 3D printing is reported. Solid‐core solenoid inductors that are of order 30 mm3 in size are achieved and most importantly, commercially relevant inductance values of microhenry (for polymer‐core) to tens and hundreds of millihenry (for ferrite and iron cores) are demonstrated, which has been beyond the scope of the previous attempts in fabricating additively manufactured inductors. Furthermore, the authors direct‐write printed inductors of various geometries and pinpoi...

Conference on Lasers and Electro-Optics 2012, 2012

Optics Express, 2017

We report the RF photonic reception and downconversion of vector modulated RF signals using a mil... more We report the RF photonic reception and downconversion of vector modulated RF signals using a millimeter-wave coupled electrooptic phase modulator with in-plane slotted patch antennas based on SEO125 nonlinear polymer. We demonstrate experimental results with QPSK, 8-PSK, 16-QAM, 32-QAM, and 64-QAM millimeter-wave signals centered at 36 GHz. After downconversion to intermediate frequencies between 0.5 GHz and 2 GHz, the vector encoded signals are demodulated using an electrical signal analyzer and found to have measured error vector magnitudes below 8%. Design, simulation, fabrication, and experimental results are presented and discussed.