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We demonstrate ‘through-substrate’ sensing of fluids for application in the terahertz spectroscopy of biological materials. This technique employs planar Goubau lines with integrated photoconductive material, formed on a flexible, thin polyimide substrate, and bonded to a microfluidic channel. Few-picosecond pulses are used to probe liquid samples confined within the channel, over a total interaction...
We demonstrate how a transfer function model based parameter extraction method, combined with total variance analysis, allows the extraction of both the complex refractive index and the thickness of a sample over a bandwidth of >6 THz from THz time-domain spectroscopy measurements. We discuss how the techniques developed have been applied to absorbent powders measured at variable low temperatures.
We present an on-chip time domain terahertz (TD-THz) system in which picosecond pulses are generated in low-temperature-grown gallium arsenide (LT-GaAs) and detected in graphene. The detected pulses were found to vary in amplitude, full width at half maximum (FWHM), and DC offset when sampled optically at different locations along a 50-μm-long graphene photoconductive (PC) detector. The results demonstrate...
We demonstrate the excitation and electrostatic modulation of a planar, resonant plasmonic circuit, comprised of a two-dimensional electron system (2DES) integrated into three different on-chip, terahertz-frequency coplanar waveguides. We utilise a Schottky gate formed across the 2DES in one device to create a resonant cavity in which the carrier concentration, and therefore the cavity resonant frequency,...
This work reports on the extraordinary THz transmission properties of shape optimized metallic subwavelength aperture arrays, and its dependence upon incident beam angle. The resonant frequency of the aperture array has been shown to vary between 0.82 – 0.97 THz due to incident angle alone, while maintaining excellent (>85%) peak transmission.
Since its origins in the sociology of the mid‐twentieth century, scholarship on police and policing has broken interdisciplinary ground and played a substantial role in shaping policy. This chapter is designed to tell two stories about the trajectory of police and policing research over the last part of the twentieth century and the first decade of the twenty‐first. It puts the public police center...
We demonstrate the integration of planar Goubau lines with microfluidic systems for the measurement of liquid samples including water and isopropanol. Picosecond pulses are generated and detected by the inclusion of low-temperaturegrown GaAs based photoconductive switches which transmit picosecond pulses along the transmission line. A change in the propagation velocity of pulses is detected and is...
Design for Manufacture and Assembly (DFMA) principles form an established framework used to design products in the modern developed world. These principles are assumed to be universal in the design process; however, they are not universally applicable when designing for the developing world for several reasons. First, because the physical conditions in which a product is manufactured are very different,...
Measuring currents and waves from a subsurface mooring using ADCPs is a useful technique in regions of the world where the use of surface buoys is problematic — either because of ship traffic or theft. This paper evaluates the utility of inexpensive MEMS-based inertial sensors for measuring the platform motion. We find that these sensors are capable of providing the necessary measurements of attitude...
It is well known that devices based on chemical vapor deposited (CVD) graphene exhibit substantial variability of their electrical properties [1]. However, the sources of such variability and how they might be controlled remain poorly understood. Here, we methodically investigate variability of CVD graphene field-effect transistors (GFETs) transferred with three polymer scaffolds: PMMA, polycarbonate...
Broadband time-domain spectroscopy was used to measure the terahertz frequency absorption of protein single crystals in order to study global protein dynamics. Temperature dependent dynamics were measured for lysozyme, and the terahertz frequency spectrum of mouse urinary protein was compared to calculated spectra.
We demonstrate optimization of planar terahertz (THz) frequency Goubau lines to achieve a ∼ 2 THz bandwidth. This has allowed high resolution, on-chip THz spectra of polycrystalline materials to be recorded over temperatures ranging from 4–292 K.
Facebook has rapidly become for many the dominant means for sharing images, and the number of shared images accessible to any given Facebook user is easily in the tens of thousands. The sheer volume of pictures relegates most to obscurity, yet some of those pictures would be of great interest -- if a person could only find them. This research explores ways to harness latent semantic information associated...
We present a new measurement technique for the sub-Kelvin excitation and detection of on-chip terahertz frequency radiation in high magnetic fields. We present a monolithically integrated heterostructure, which allows a mesoscopic electronic system to be combined with an on-chip terahertz device, and show dynamic imaging of a THz photoconductive switch at 200 mK in a 12 T field, together with THz...
We review the use of Raman spectroscopy and ultrahigh-vacuum scanning tunneling microscopy (UHV-STM) to characterize water trapped between a chemical vapor deposition grown monolayer graphene sheet and a mica substrate at room temperature. The few-layered water observed displays properties different than that of bulk or crystalline water, and it can be manipulated using a STM tip. This work gives...
Chemical vapor deposition growth of graphene on polycrystalline copper foil is a demonstrated technique for obtaining large-area, predominantly monolayer graphene. However, such growth results in grain boundaries between rotationally misoriented graphene grains. We employ scanning tunneling microscopy and spectroscopy to examine the electronic properties of grain boundaries (GBs) and scattering off...
Wafer-scale, high-quality graphene growth, functionalization, and transfer to arbitrary surfaces are required to make the next generation of novel carbon-based nanoelectronics. To that end, we perform chemical vapor deposition of graphene on Cu and find that the Cu surface crystallography affects the graphene growth. Hexagonal, low-index Cu(111) gives high-quality, monolayer graphene at the fastest...
We demonstrate an increase in bandwidth, from 600 GHz to 1.5 THz, of planar Goubau-line on-chip devices with integrated low-temperature-grown (LT) GaAs photoconductive (PC) switches, using a substrate-thinning technique. The effect of substrate thinning was investigated both experimentally and theoretically, and the increase in bandwidth then used for spectroscopy of overlaid polycrystalline materials.
Tracking a user's hand for 3D rendering and visualization creates a sense of presence in virtual reality environments. At present, tracking devices built for both research and consumer use are increasingly accessible, with ever improving spatiotemporal accuracy. This work seeks to contribute a new design which offers an ability to track the fingers and palm. The hand tracking method described herein...
The authors examine information management and tracking of drugs in supply chains within the pharmaceutical industry. The focal concern in this setting is counterfeit drugs, a dilemma of paramount importance for public health and the well-being and safety of patients. The authors advocate RFID and related technologies, including EPCglobal's Electronic Product Code Information Services (EPCIS) and...
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