Stanford Advisors


All Publications


  • Bicontinuous Mesoporous Metal Foams with Enhanced Conductivity and Tunable Pore Size and Porosity via Electrodeposition for Electrochemical and Thermal Systems ACS APPLIED NANO MATERIALS Katz, J. S., Zhang, C., Barako, M. T., Kim, H. K., Asheghi, M., Kenny, T. W., Goodson, K. E. 2020; 3 (12): 12408–15
  • Enhanced Capillary-Fed Boiling in Copper Inverse Opals via Template Sintering ADVANCED FUNCTIONAL MATERIALS Zhang, C., Palko, J. W., Barako, M. T., Asheghi, M., Santiago, J. G., Goodson, K. E. 2018; 28 (41)
  • Tailoring Permeability of Microporous Copper Structures through Template Sintering. ACS applied materials & interfaces Zhang, C., Palko, J. W., Rong, G., Pringle, K. S., Barako, M. T., Dusseault, T. J., Asheghi, M., Santiago, J. G., Goodson, K. E. 2018

    Abstract

    Microporous metals are used extensively for applications that combine convective and conductive transport and benefit from low resistance to both modes of transport. Conventional fabrication methods, such as direct sintering of metallic particles, however, often produce structures with limited fluid transport properties due to the lack of control over pore morphologies such as the pore size and porosity. Here, we demonstrate control and improvement of hydraulic permeability of microporous copper structures fabricated using template-assisted electrodeposition. Template sintering is shown to modify the fluid transport network in a manner that increases permeability by nearly an order of magnitude with a less significant decrease (38%) in thermal conductivity. The measured permeabilities range from 4.8 * 10-14 to 1.3 * 10-12 m2 with 5 mum pores, with the peak value being roughly 5 times larger than the published values for sintered copper particles of comparable feature sizes. Analysis indicates that the enhancement of permeability is limited by constrictions, i.e., bottlenecks between connecting pores, whose dimensions are highly sensitive to the sintering conditions. We further show contrasting trends in permeability versus conductivity of the electrodeposited microporous copper and conventional sintered copper particles and suggest these differing trends to be the result of their inverse structural relationship.

    View details for PubMedID 30096232

  • Enhanced Heat Transfer Using Microporous Copper Inverse Opals Lee, H., Maitra, T., Palko, J., Kong, D., Zhang, C., Barako, M. T., Won, Y., Asheghi, M., Goodson, K. E. ASME. 2018

    View details for DOI 10.1115/1.4040088

    View details for Web of Science ID 000432367100007

  • A method for quantifying in plane permeability of porous thin films. Journal of colloid and interface science Rong, G., Palko, J. W., Oyarzun, D. I., Zhang, C., Hammerle, J., Asheghi, M., Goodson, K. E., Santiago, J. G. 2018; 530: 667–74

    Abstract

    The in-plane permeability of porous thin films is an important fluid mechanical property that determines wicking and pressure-driven flow behavior in such materials. This property has so far been challenging to measure directly due to the small sidewall cross-sectional area of thin films available for flow. In this work, we propose and experimentally demonstrate a novel technique for directly measuring in-plane permeability of porous thin films of arbitrary thicknesses, in situ, using a manifold pressed to the top surface of the film. We both measure and simulate the influence of the two dimensional flow field produced in a film by the manifold and extract the permeability from measurements of pressure drop at fixed flow rates. Permeability values measured using the technique for a periodic array of channels are comparable to theoretical predictions. We also determine in-plane permeability of arrays of pillars and electrodeposited porous copper films. This technique is a robust tool to characterize permeability of thin films of arbitrary thicknesses on a variety of substrates. In Supplementary material, we provide a solid model, which is useful in three-dimensional printer reproductions of our device.

    View details for PubMedID 30007196

  • Thermal Management Research - from Power Electronics to Portables Jung, K., Zhang, C., Liu, T., Asheghi, M., Goodson, K. E., IEEE IEEE. 2018: 17–18
  • Extreme Two-Phase Cooling from Laser-Etched Diamond and Conformal, Template-Fabricated Microporous Copper ADVANCED FUNCTIONAL MATERIALS Palko, J. W., Lee, H., Zhang, C., Dusseault, T. J., Maitra, T., Won, Y., Agonafer, D. D., Moss, J., Houshmand, F., Rong, G., Wilbur, J. D., Rockosi, D., Mykyta, I., Resler, D., Altman, D., Asheghi, M., Santiago, J. G., Goodson, K. E. 2017; 27 (45)
  • COPPER INVERSE OPAL SURFACES FOR ENHANCED BOILING HEAT TRANSFER Lee, H., Maitra, T., Palko, J., Zhang, C., Barako, M., Won, Y., Asheghi, M., Goodson, K. E., ASME AMER SOC MECHANICAL ENGINEERS. 2017
  • Quasi-ballistic Electronic Thermal Conduction in Metal Inverse Opals. Nano letters Barako, M. T., Sood, A., Zhang, C., Wang, J., Kodama, T., Asheghi, M., Zheng, X., Braun, P. V., Goodson, K. E. 2016; 16 (4): 2754-2761

    Abstract

    Porous metals are used in interfacial transport applications that leverage the combination of electrical and/or thermal conductivity and the large available surface area. As nanomaterials push toward smaller pore sizes to increase the total surface area and reduce diffusion length scales, electron conduction within the metal scaffold becomes suppressed due to increased surface scattering. Here we observe the transition from diffusive to quasi-ballistic thermal conduction using metal inverse opals (IOs), which are metal films that contain a periodic arrangement of interconnected spherical pores. As the material dimensions are reduced from ∼230 nm to ∼23 nm, the thermal conductivity of copper IOs is reduced by more than 57% due to the increase in surface scattering. In contrast, nickel IOs exhibit diffusive-like conduction and have a constant thermal conductivity over this size regime. The quasi-ballistic nature of electron transport at these length scales is modeled considering the inverse opal geometry, surface scattering, and grain boundaries. Understanding the characteristics of electron conduction at the nanoscale is essential to minimizing the total resistance of porous metals for interfacial transport applications, such as the total electrical resistance of battery electrodes and the total thermal resistance of microscale heat exchangers.

    View details for DOI 10.1021/acs.nanolett.6b00468

    View details for PubMedID 26986050