Erik J. Brandon

California Institute of Technology, Pasadena, California, United States

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Publications (17)31.5 Total impact

  • 224th ECS Meeting; 10/2013
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    ABSTRACT: The ability to quickly store and deliver a significant amount of electrical energy at ultralow temperatures is critical for the energy-efficient operation of high altitude aircraft and spacecraft, exploration of natural resources in polar regions and extreme altitudes, and astronomical observatories exposed to ultralow temperatures. Commercial high-power electrochemical capacitors fail to operate at temperatures below –40 °C. According to conventional wisdom, mesoporous electrochemical capacitor electrodes with pores large enough to accommodate fully solvated ions are needed for sufficiently rapid ion transport at lower temperatures. It is demonstrated that strictly microporous carbon electrodes with much higher volumetric capacitance can be efficiently used at temperatures as low as –70 °C. The critical parameters, with respect to electrolyte properties and electrode porosity and microstructure, needed for achieving both rapid ion transport and efficient ion electroadsorption in porous carbons are discussed. As an example, the fabrication of an electrochemical capacitor with an outstanding performance at temperatures as low as –60 and –70 °C is demonstrated. At such low temperatures the capacitance of the synthesized electrodes is up to 123 F g−1 (≈76 F cm−3), which is 50–100% higher than that of the most common commercial electrochemical capacitor electrode at room temperature. At –60 °C selected cells based on ≈0.2 mm electrodes exhibited characteristic charge–discharge time constants of less than 9 s, which is faster than the majority of commercial devices at room temperature. The achieved combination of high energy and power densities at such ultralow temperatures is unprecedented and extremely promising for the advancement of energy storage systems.
    Advanced Functional Materials 04/2012; 22(8). DOI:10.1002/adfm.201102573 · 11.81 Impact Factor
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    ABSTRACT: Inflatable/deployable structures are under consideration as habitats for future Lunar surface science operations. The use of non-traditional structural materials combined with the need to maintain a safe working environment for extended periods in a harsh environment has led to the consideration of an integrated structural health management system for future habitats, to ensure their integrity. This article describes recent efforts to develop prototype sensing technologies and new self-healing materials that address the unique requirements of habitats comprised mainly of soft goods. A new approach to detecting impact damage is discussed, using addressable flexible capacitive sensing elements and thin film electronics in a matrixed array. Also, the use of passive wireless sensor tags for distributed sensing is discussed, wherein the need for on-board power through batteries or hardwired interconnects is eliminated. Finally, the development of a novel, microencapuslated self-healing elastomer with applications for inflatable/deployable habitats is reviewed.
    Acta Astronautica 04/2011; 68(7-8-68):883-903. DOI:10.1016/j.actaastro.2010.08.016 · 1.12 Impact Factor
  • MRS Online Proceeding Library 01/2011; 814. DOI:10.1557/PROC-814-I9.7
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    ABSTRACT: Double-layer capacitor electrolytes employing 1,3-dioxolane as a cosolvent with acetonitrile have been evaluated in coin cells using electrochemical impedance spectroscopy and dc charging and discharging tests. Addition of the lower-melting-point 1,3-dioxolane to the standard acetonitrile solvent was found to extend the low-temperature operational range of test cells beyond that of commercially available cells. By adjusting the concentration of the tetraethylammonium tetrafluoroborate salt used, the equivalent series resistance can be minimized to enable optimal power delivery at a given temperature. (C) 2008 The Electrochemical Society.
    Journal of The Electrochemical Society 01/2008; 155(10). DOI:10.1149/1.2961044 · 3.27 Impact Factor
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    ABSTRACT: This work describes the design and testing of organic electrolyte systems that extend the low temperature operational limit of double-layer capacitors (also known as supercapacitors) beyond that of typical commercially available components. Electrolytes were based on a tetraethylammonium tetrafluoroborate/acetonitrile system, modified with low melting co-solvents (such as formates, esters and cyclic ethers) to enable charging and discharging of test cells to as low as −75°C. Cell capacitance exhibited little dependence on the electrolyte salt concentration or the nature of the co-solvent used, however, both variables strongly influenced the cell equivalent series resistance (ESR). Minimizing the increase in ESR posed the greatest design challenge, which limited realistic operation of these test cells to −55°C (still improved relative to the typical rated limit of −40°C for commercially available non-aqueous cells).
    Journal of Power Sources 06/2007; 170(1):225-232. DOI:10.1016/j.jpowsour.2007.04.001 · 6.22 Impact Factor
  • Lisong Zhou · Soyoun Jung · Erik Brandon · Thomas N. Jackson
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    ABSTRACT: We present two different kinds of semiconductor strain sensors: ungated n+ micro-crystalline silicon (n+ μC-Si), and gated hydrogenated amorphous silicon (a-Si:H). Both sensor types are fabricated on flexible polyimide substrates. The sensors were characterized with bending perpendicular, parallel, and at 45° with respect to the sensor bias direction, and for several bending diameters. Sensor size and power consumption are significantly reduced compared to metallic foil strain sensors. Small sensor size and ease of integration with a-Si:H thin-film transistors also allows arrays of strain sensors or combinations of strain sensors with varying geometric orientation to allow strain direction as well as magnitude to be unambiguously determined.
    IEEE Transactions on Electron Devices 03/2006; 53(2-53):380 - 385. DOI:10.1109/TED.2005.861727 · 2.47 Impact Factor
  • Lisong Zhou · T. Jackson · E. Brandon · W. West
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    ABSTRACT: We have fabricated hydrogenated amorphous silicon (a-Si:H) TFTs on Kapton<sup>(R)</sup> polyimide flexible substrates and characterized their response to deployment-like mechanical stresses and to radiation exposure. To maintain substrate flatness and provide improved thermal transfer during fabrication, we used a pressure-sensitive silicone gel adhesive layer to mount Kapton<sup>(R)</sup> substrates onto glass carriers. The test results, presented in this paper, are encouraging for space use of a-Si:H TFTs on polymeric substrates. Device function was retained even after 1 Mrad fast electron irradiation, and irradiation-induced device changes were removed by low-temperature thermal annealing. Although some TFTs were destroyed by substrate stressing, the majority survived with only small changes, suggesting that care in device design and placement may reduce or eliminate this problem.
    Device Research Conference, 2004. 62nd DRC. Conference Digest [Includes 'Late News Papers' volume]; 07/2004
  • Erik J. Brandon · William West · Emily Wesseling
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    ABSTRACT: Organic thin-film transistors (OTFTs) employing a flexible, conductive carbon particle-polymer composite material for the drain-source ohmic contacts are reported herein. The contacts can be deposited using standard stencil printing techniques and are processed at low temperature, thereby facilitating their integration with heat sensitive substrates. The carbon contacts were stencil printed on a silicon dioxide gate dielectric layer, and the poly(3-hexylthiophene) semiconductor was deposited via solution casting from toluene. The OTFTs exhibited field-effect behavior over a range of drain-source and gate voltages, similar to devices employing deposited gold contacts. © 2003 American Institute of Physics.
    Applied Physics Letters 12/2003; 83(19-83):3945 - 3947. DOI:10.1063/1.1625794 · 3.30 Impact Factor
  • E.J. Brandon · E.E. Wesseling · Vincent Chang · W.B. Kuhn
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    ABSTRACT: A low-profile microinductor was fabricated on a copper-clad polyimide substrate where the current carrying coils were patterned from the existing metallization layer and the magnetic core was printed using a magnetic ceramic-polymer composite material. Highly loaded ferrite-polymer composite materials were formulated, yielding adherent films with 4πM<sub>s</sub>≈3900 G at +5000 Oe applied DC field. These composite magnetic films combine many of the superior properties of high temperature ceramic magnetic materials with the inherent processibility of polymer thick films. Processing temperatures for the printed films were between 100°C and 130°C, facilitating integration with a wide range of substrates and components. The quality factor of the microinductor was found to peak at Q=18.5 near 10 MHz, within the optimal frequency range for power applications. A flat, nearly frequency independent inductance of 1.33 μH was measured throughout this frequency range for a 5 mm×5 mm component, with a DC resistance of 2.6 Ω and a resonant frequency of 124 MHz. The combination of printed ceramic composites with organic/polymer substrates enables new methods for embedding passive components and ultimately the integration of high Q inductors with standard integrated circuits for low profile power electronics.
    IEEE Transactions on Components and Packaging Technologies 10/2003; 26(3-26):517 - 523. DOI:10.1109/TCAPT.2003.817641 · 0.96 Impact Factor
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    ABSTRACT: Inductors play a key role in DC-DC converters, but few options exist for implementing on-chip inductors for highly miniaturized, monolithic power converters. Microinductors constructed by standard microelectronic fabrication techniques with magnetic films as the core material have been investigated during the past 20 years with mixed results. A 13-mm<sup>2</sup> microinductor based on a spiral geometry and having L = 3.2 μH and Q = 1.3 at 1 MHz is reported here. Key issues regarding microinductor design and performance are discussed.
    IEEE Transactions on Magnetics 08/2003; 39(4-39):2049 - 2056. DOI:10.1109/TMAG.2003.812705 · 1.39 Impact Factor
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    ABSTRACT: The highest capacity rf sputtered cathode layers created for use in thin-film solid-state batteries have been found to require an annealing step with temperatures in excess of 700°C. Since this high-temperature process step is incompatible with silicon device technology and flexible polymer substrates, the development of a low-process temperature (less than or equal to 300°C) cathode layer has been undertaken. Thin-film cathode layers consisting of were deposited using planar magnetron rf sputtering and subsequently incorporated into thin-film solid-state cells comprised of a LiPON electrolyte and lithium metal anode. Film composition was examined using Rutherford backscattering spectrometry and inductively coupled plasma mass spectroscopy, while phase content and crystal structure were studied through X-ray diffraction experiments conducted at the Stanford Synchrotron Radiation Laboratory. Microstructure and morphology were examined using transmission and scanning electron microscopy. It was found that could be deposited at room temperature in a nanocrystalline state with a defined (104) out of plane texture and a high degree of lattice distortion. By heating these layers to 300°C, the average grain size was increased while lattice distortion was minimized. Electrochemical cycling data revealed that the low temperature annealing step increases cell capacity to near theoretical values while significantly improving both the rate capability and discharge voltage. Impedance analysis on test cells showed that the electronic resistance of the cells is decreased after heating to 300°C. © 2001 The Electrochemical Society. All rights reserved.
    09/2001; 148(10):A1078-A1084. DOI:10.1149/1.1400119
  • W.C. West · J.F. Whitacre · E.J. Brandon · B.V. Ratnakumar
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    ABSTRACT: Recent successes in the effort to miniaturize spacecraft components using MEMS technology, integrated passive components, and low power electronics have driven the need for very low power, low profile, low mass micro-power sources for micro/nanospacecraft applications. Recent work at JPL has focused upon developing thin film/micro-batteries compatible with temperature sensitive substrates. A process to prepare crystalline LiCoO<sub>2</sub> films with RF sputtering and moderate (<700°C) annealing temperature has been developed. Thin film batteries with cathode films prepared with this process have specific capacities approaching the practical limit for LiCoO<sub>2</sub>, with acceptable rate capabilities and discharge voltage profiles. Solid-state micro-scale batteries have also been fabricated with feature sizes on the order of 50 microns
    IEEE Aerospace and Electronic Systems Magazine 09/2001; 16(8-16):31 - 33. DOI:10.1109/62.942217 · 0.96 Impact Factor
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    ABSTRACT: Robotic outpost based exploration represents a fundamental shift in mission design from conventional, single spacecraft missions towards a distributed risk approach with many miniaturized semi-autonomous robots and sensors. This approach can facilitate wide-area sampling and exploration, and may consist of a web of orbiters, landers, or penetrators. To meet the mass and volume constraints of deep space missions such as the Europa Ocean Science Station, the distributed units must be fully miniaturized to fully leverage the wide-area exploration approach. However, presently there is a dearth of available options for powering these miniaturized sensors and robots. This group is currently examining miniaturized, solid state batteries as candidates to meet the demand of applications requiring low power, mass, and volume micro-power sources. These applications may include powering microsensors, battery-backing rad-hard CMOS memory and providing momentary chip back-up power. Additional information is contained in the original extended abstract.
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    ABSTRACT: The NASA roadmap outlining future deep space missions to Europa and other outer planetary destinations calls for continued reductions in the mass and volume of the spacecraft avionics. Spacecraft power electronics, including the power switches and converters, remain difficult to miniaturize due to the need for large numbers of discrete passive components such as resistors, capacitors, inductors and transformers. As part of the System-on-a-chip program at the Center for Integrated Space Microsystems and at the University of Arkansas, we are working to develop integrated or embedded passive components geared specifically for use in power management and distribution (PMAD) in future avionics over the next five to ten years. This will not only enable a scaling down of the power subsystems, but will make possible new architectures such as "distributed" PMAD. Additional information is contained in the original extended abstract.
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    ABSTRACT: Passivation films for thin film batteries have been prepared and the conductivity and voltage stability window have been measured. Thin films of Li2CO3 have a large voltage stability window of 4.8V, which facilitates the use of this film as a passivation at both the lithium anode- electrolyte interface at high cathodic potentials The ionic conductivity of the Li~C03 films are rather low, 5 x lo-' Skm, which may be due to the nanocrystalline texture of the sputtered thin films. Sputtered films of Li2CO3 show evidence of Liz0 incorporation, which affects the air stability of the films. Sputtering at higher power levels attenuates the Li20, thus improving air stability of the as-deposited films.
  • Space Technology Conference and Exposition; 09/1999