Christopher E. Tabor

Reconfigurable liquid metal circuits by Laplace pressure shaping

We report reconfigurable circuits formed by liquid metal shaping with <10 pounds per square inch (psi) Laplace and vacuum pressures. Laplace pressure drives liquid metals into microreplicated trenches, and upon release of vacuum, the liquid metal dewets into droplets that are compacted to 10–100× less area than when in the channel. Experimental validation includes measurements of actuation speeds exceeding 30 cm/s, simple erasable resistive networks, and switchable 4.5 GHz antennas. Such capability may be of value for next generation of simple electronic switches, tunable antennas, adaptive reflectors, and switchable metamaterials.

Control of Gallium Oxide Growth on Liquid Metal Eutectic Gallium/Indium Nanoparticles via Thiolation

Eutectic gallium-indium alloy (EGaIn, a room-temperature liquid metal) nanoparticles are of interest for their unique potential uses in self-healing and flexible electronic devices. One reason for their interest is due to a passivating oxide skin that develops spontaneously on exposure to ambient atmosphere which resists deformation and rupture of the resultant liquid particles. It is then of interest to develop methods for control of this oxide growth process. It is hypothesized here that functionalization of EGaIn nanoparticles with thiolated molecules could moderate oxide growth based on insights from the Cabrera-Mott oxidation model. To test this, the oxidation dynamics of several thiolated nanoparticle systems were tracked over time with X-ray photoelectron spectroscopy. These results demonstrate the ability to suppress gallium oxide growth by up to 30%. The oxide progressively matures over a 28 day period, terminating in different final thicknesses as a function of thiol selection. These results indicate not only that thiols moderate gallium oxide growth via competition with oxygen for surface sites but also that different thiols alter the thermodynamics of oxide growth through modification of the EGaIn work function.

Robust Pressure-Actuated Liquid Metal Devices Showing Reconfigurable Electromagnetic Effects at GHz Frequencies

Pressure-actuated liquid metal devices are demonstrated for reconfigurable electromagnetic fundamentals at GHz frequencies, including tunable dipole antennas, switchable shielding with 35-dB attenuation, ~ 30-dB polarizer attenuation, and ~ 40° diffraction from a linear grating. In addition to a wide variety of electromagnetic effects, these devices are further advanced by: being highly physically flexible; in use of nontoxic GaInSn (68.5% Ga, 21.5% In, and 10.0% Sn) alloy as enabled by a sealed closed system with an acidic vapor background; and nonalloying/corrosion-resistant carbon inks for electrical connection. Collectively, this work addresses a wide variety of electromagnetic fundamentals, and the device construction advances required for real-world applications.

Robust pressure-actuated liquid metal devices showing reconfigurable electromagnetic effects at GHz frequencies

Pressure-actuated liquid metal devices are demonstrated for reconfigurable electromagnetic fundamentals at GHz frequencies, including tunable dipole antennas, switchable shielding with 35 dB attenuation, ~30 dB polarizer attenuation, and ~40 degree diffraction from a linear grating. In addition to a wide variety of electromagnetic effects, these devices are further advanced by: being highly physically flexible; in use of non-toxic GaInSn (68.5% Ga, 21.5% In, and 10.0% Sn ) alloy as enabled by a sealed closed system with an acidic vapor background; and non-alloying/corrosion-resistant carbon inks for electrical connection. Collectively, this work addresses a wide variety of electromagnetic fundamentals, and the device construction advances required for real-world applications.

Materials for liquid RF electronics: Long term operation of gallium liquid metal alloys in reconfigurable RF applciations

Room temperature liquid electronics offers the potential of rewiring and reconfiguring functionality in real-time. One of the most promising materials recently explored for these components is gallium liquid metal alloys (GaLMAs) because of their non-toxic and self-healing properties. Unfortunately the reactive nature of the surface, with both oxygen to form a thin viscoelastic skin and alloy formation with solid metal electrodes, results in the need for better control over these interfaces. This control needs to be achieved while maintaining appropriate RF properties and reliability of the fluidic electronic components. In this work, we provide a new material set to control the interface of GaLMAs and characterize the effects on RF performance.

Front Matter: Volume 8983

This PDF file contains the front matter associated with SPIE Proceedings Volume 8983 including the Title Page, Copyright information, Table of Contents, Introduction, and Conference Committee listing.

Investigation of the Use of Stereo-Pair Data Sets in Electron Tomography Characterization of Organic-Based Solar Cells

The processes that generate current in organic photovoltaics (OPVs) are highly dependent on the micro-and nano-structure of the devices, especially at the donor-acceptor (D-A) interface. Light trapping strategies have been proposed to tailor absorption of incident sunlight and generate more photocurrent at the D-A interface. Recent studies have reported the use of a range of plasmonic nanostructures, such as nanoparticles, slit arrays and nanohole arrays to improve the power conversion efficiency (PCE) in OPVs [1, 2]. While incorporation of plasmonic nanostructures for light trapping in thin-film PV cells is an attractive solution for enhancement of the optical absorption and current density in an OPV without increasing the thickness of its active layers, little is known about the detailed structure, chemistry and bonding between the active layer and the plasmonic nanostructures. The understanding of this interface is vital to understanding why these nanoparticles improve the efficiency of such devices. This knowledge will provide a foundation for the engineering of new OPV devices with improved PCE.

Front Matter Volume 8622

This PDF file contains the front matter associated with SPIE Proceedings Volume 8622, including the Title Page, Copyright Information, Table of Contents, Introduction and Conference Committee listing.

Plasmonic antennas as building blocks for spin optics and quantum optics applications

In this invited paper, we review some of our latest works on plasmonic antennas and their interactions with photonic angular momentum. As receiving antennas, both theoretical and experimental results reveal that spiral plasmonic antenna responds differently to photons with left-hand circular polarization and right-hand circular polarization. This spin degeneracy removal finds many potential applications including extremely small circular polarization analyzer for polarimetric imaging, parallel near field probes for optical imaging and sensing, nano-lithography and high density heat assisted magnetic recording. On the transmitter side, through coupling quantum dot nano-emitters to spiral plasmonic antenna, nano-scale spin photon sources with high directivity and circular polarization extinction ratio is demonstrated. Numerical modeling and experimental evidences also indicate that the emitted photons can be imprinted with the photonic spin angular momentum and orbital angular momentum information simultaneously via the interactions between photonic angular momentum and plasmonic antennas. These findings not only are useful for the fundamental understanding of the interaction between plasmonic antennas and photonic angular momentum but also illustrate the versatility of plasmonic antennas as building blocks for practical spin optics and quantum optics devices and systems.