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Jeremy Junghans

Bio: Jeremy Junghans is an academic researcher from University of Arkansas. The author has contributed to research in topics: Laser diode & JFET. The author has an hindex of 8, co-authored 21 publications receiving 234 citations.

Papers
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Proceedings ArticleDOI
06 Mar 2018
TL;DR: In this article, a low-SWaP (Size, Weight and Power) diode array has been developed for a high-power fiber-coupled application, where custom ceramic micro-channel-coolers (MCCs) are used to dissipate the waste heat.
Abstract: A low-SWaP (Size, Weight and Power) diode array has been developed for a high-power fiber-coupled application. High efficiency (~65%) diodes enable high optical powers while minimizing thermal losses. A large amount of waste heat is still generated and must be extracted. Custom ceramic microchannel-coolers (MCCs) are used to dissipate the waste heat. The custom ceramic MCC was designed to accommodate long cavity length diodes and micro-lenses. The coolers provide similar thermal performance as copper MCCs however they are not susceptible to erosion and can be cooled with standard filtered water. The custom ceramic micro-channel cooled array was designed to be a form/fit replacement for an existing copperbased solution. Each array consisted of three-vertically stacked MCCs with 4 mm CL, 976 nm diodes and beamshaping micro-optics. The erosion and corrosion resistance of ceramic array is intended to mitigate the risk of copperbased MCC corrosion failures. Elimination of the water delivery requirements (pH, resistivity and dissolved oxygen control) further reduces the system SWaP while maintaining reliability. The arrays were fabricated and fully characterized. This work discusses the advantages of the ceramic MCC technology and describes the design parameters that were tailored for the fiber-coupled application. Additional configuration options (form/fit, micro-lensing, alternate coolants, etc.) and on-going design improvements are also discussed.

Cited by
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Journal ArticleDOI
TL;DR: It is shown that this solid oxide “skin” enables many new applications for liquid metals including soft electrodes and sensors, functional microcomponents for microfluidic devices, self-healing circuits, shape-reconfigurable conductors, and stretchable antennas, wires, and interconnects.
Abstract: Gallium and several of its alloys are liquid metals at or near room temperature. Gallium has low toxicity, essentially no vapor pressure, and a low viscosity. Despite these desirable properties, applications calling for liquid metal often use toxic mercury because gallium forms a thin oxide layer on its surface. The oxide interferes with electrochemical measurements, alters the physicochemical properties of the surface, and changes the fluid dynamic behavior of the metal in a way that has, until recently, been considered a nuisance. Here, we show that this solid oxide “skin” enables many new applications for liquid metals including soft electrodes and sensors, functional microcomponents for microfluidic devices, self-healing circuits, shape-reconfigurable conductors, and stretchable antennas, wires, and interconnects.

497 citations

Journal ArticleDOI
TL;DR: In this article, a power converter operating at temperatures above 200 °C has been demonstrated, but work is still ongoing to design and build a power system able to operate in harsh environment (high temperature and deep thermal cycling).
Abstract: High temperature power electronics has become possible with the recent availability of silicon carbide devices. This material, as other wide-bandgap semiconductors, can operate at temperatures above 500 °C, whereas silicon is limited to 150-200 °C. Applications such as transportation or a deep oil and gas wells drilling can benefit. A few converters operating above 200 °C have been demonstrated, but work is still ongoing to design and build a power system able to operate in harsh environment (high temperature and deep thermal cycling).

293 citations

Journal ArticleDOI
TL;DR: In this paper, the authors describe emerging methods to pattern metals that are liquid at room temperature, including injection, injection, subtractive, additive, and additive techniques, which can be divided into four categories: (i) patterning enabled by lithography, (ii) injection, (iii) subtractive and (iv) additive techniques.
Abstract: This highlight describes emerging methods to pattern metals that are liquid at room temperature. The ability to pattern liquid metals is important for fabricating metallic components that are soft, stretchable, conformal, and in some cases, shape-reconfigurable. Applications include electrodes, antennas, micro-mirrors, plasmonic structures, sensors, switches, and interconnects. Gallium (Ga) and its liquid metal alloys are attractive alternatives to toxic mercury. This family of alloys spontaneously forms a surface oxide that dominates the rheological and wetting properties of the metal. These properties pose challenges using conventional fabrication methods, but present new opportunities for patterning innovations. For example, Ga-based liquid metals may be injected, imprinted, or 3D printed on either soft or hard substrates. The use of a liquid metal also enables rapid and facile room temperature processing. The patterning techniques organize into four categories: (i) patterning enabled by lithography, (ii) injection, (iii) subtractive techniques, and (iv) additive techniques. Although many of these approaches take advantage of the surface oxide that forms on Ga and its alloys, some of the approaches may also be suitable for patterning other soft-conductors (e.g., conductive inks, pastes, elastomeric composites).

269 citations

Journal ArticleDOI
04 Jun 2014-Langmuir
TL;DR: It is demonstrated that, dependent on dynamics of formation and resulting morphology of the liquid metal-substrate interface, GaInSn adhesion can occur in two modes, and it is demonstrated how these two adhesion modes limit microcontact printing of GaIn Sn patterns but can be exploited to repeatedly print individual sub-200 nm liquid metal drops.
Abstract: Gallium-based liquid metals are of interest for a variety of applications including flexible electronics, soft robotics, and biomedical devices. Still, nano- to microscale device fabrication with these materials is challenging because, despite having surface tension 10 times higher than water, they strongly adhere to a majority of substrates. This unusually high adhesion is attributed to the formation of a thin oxide shell; however, its role in the adhesion process has not yet been established. In this work, we demonstrate that, dependent on dynamics of formation and resulting morphology of the liquid metal–substrate interface, GaInSn adhesion can occur in two modes. The first mode occurs when the oxide shell is not ruptured as it makes contact with the substrate. Because of the nanoscale topology of the oxide surface, this mode results in minimal adhesion between the liquid metal and most solids, regardless of substrate’s surface energy or texture. In the second mode, the formation of the GaInSn–substrat...

198 citations

Journal ArticleDOI
TL;DR: The current state of wide bandgap device technology is reviewed and its impact on power electronic system miniaturization for a wide variety of voltage levels is described in this article, followed by an outline of the applications that stand to be impacted.
Abstract: The current state of wide bandgap device technology is reviewed and its impact on power electronic system miniaturization for a wide variety of voltage levels is described. A synopsis of recent complementary technological developments in passives, integrated driver, and protection circuitry and electronic packaging are described, followed by an outline of the applications that stand to be impacted. A glimpse into the future based on the current technological trends is offered.

192 citations