586 research outputs found
Bridging the gap: rewritable electronics using real-time light-induced dielectrophoresis on lithium niobate
In the context of micro-electronics, the real-time manipulation and placement of components using optics alone promises a route towards increasingly dynamic systems, where the geometry and function of the device is not fixed at the point of fabrication. Here, we demonstrate physically reconfigurable circuitry through light-induced dielectrophoresis on lithium niobate. Using virtual electrodes, patterned by light, to trap, move, and chain individual micro-solder-beads in real-time via dielectrophoresis, we demonstrate rewritable electrical contacts which can make electrical connections between surface-bound components. The completed micro-solder-bead bridges were found to have relatively low resistances that were not solely dominated by the number of interfaces, or the number of discrete beads, in the connection. Significantly, these connections are formed without any melting/fusing of the beads, a key feature of this technique that enables reconfigurability. Requiring only a low-power (~3.5 mW) laser source to activate, and without the need for external power supply or signal generation, the all-optical simplicity of virtual-electrodes may prove significant for the future development of reconfigurable electronic systems
Ingersoll, infidels, and Indianapolis: freethought and religion in the Central Midwest
Indiana University-Purdue University Indianapolis (IUPUI)During the “Golden Age of Freethought” in the United States from the 1870s to the 1910s, Robert Ingersoll (1833-1899) acted as one of its most popular and influential figures within the movement, whose supporters advocated for skepticism, science, and the separation of church and state. However, his role as a “public intellectual” has been challenged by scholars of the period, who argue that he was merely a popularizer of ideas. This conclusion does not adequately describe Ingersoll’s role within the period. Rather, Ingersoll was a synthesizer of ideas, making complex concepts of philosophy, theology, science, and history into palatable lectures and books for an eager and understanding public. As a complementary counterpoint to his role as synthesizer, he also spurred a multiplicity of responses from believers and nonbelievers alike who imbibed his ideas. As such, his role in the central Midwest, Illinois and Indiana in particular, supports his place as a public intellectual. From his public discourses with the evangelist Dwight Moody and other believers, his influence on the Freethinker Society of Indianapolis, to his answers to Indianapolis clergy, Ingersoll’s experiences in the Midwest solidified his place within American history as a compelling and thoughtful public intellectual
Multilayered nanoplasmonic arrays for self-referenced biosensing
Nanostructured sensors based on localized surface plasmon resonance (LSPR) offer a number of advantages over other optical sensing technologies, making them excellent candidates for miniaturized, label-free chemical and biological detection. Highly sensitive to local refractive index changes, the resonance peaks of the nanosensors shift by different amounts when subject to different biological and chemical environments. Modifications to the nanostructure surface allow for the detection of specific molecules and chemicals with shifts so sensitive that the presence of single molecules can be detected. However, this extreme sensitivity has its drawbacks. Resonance shifts also occur because of temperature shifts, light-intensity fluctuations, and other environmental factors. To distinguish detection from drift, a secondary sensor region is often required. This often doubles the size of the device, requires two light sources and detectors (or complex optics), doubles the sample volume required (which may be expensive, or may not be possible if the sample quantity is limited), and subjects the reference to potential biofouling. Here, we present a new proof-of-concept multilayered LSPR sensor design that incorporates both a sensing layer and an encapsulated reference layer within the same region. By doing so, we are able to monitor and correct for sensor drift without the need for a secondary reference channel. We demonstrate the suitability of this sensor for sucrose concentration measurements and for the detection of biotin–avidin interactions, while also showing that the sensor can self-correct for drift. We believe that this multilayer sensor design holds promise for point-of-care diagnostics
Reversible DNA micro-patterning using the fluorous effect
We describe a new method for the immobilisation of DNA into defined patterns with sub-micron resolution, using the fluorous effect. The method is fully reversible via a simple solvent wash, allowing the patterning, regeneration and re-patterning of surfaces with no degradation in binding efficiency following multiple removal/attachment cycles of different DNA sequences
Whisky tasting using a bimetallic nanoplasmonic tongue
Metallic nanostructures are ideal candidates for optical tongue devices thanks to their chemical stability, the sensitivity of their plasmonic resonance to environmental changes, and their ease of chemical-functionalization. Here, we describe a reusable optical tongue comprised of multiplexed gold and aluminum nano-arrays; a bimetallic device which produces two distinct resonance peaks for each sensing region. Through specific modification of these plasmonic arrays with orthogonal surface chemistries, we demonstrate that a dual-resonance device allows us to halve sensor sizes and data-acquisition times when compared to single-resonance, monometallic devices. We applied our bimetallic tongue to differentiate off-the-shelf whiskies with > 99.7% accuracy by means of linear discriminant analysis (LDA). This advance in device miniaturization, functionalization, and multiplexed readout indicates nanoplasmonic tongues will have future applications in chemical mixture identification in applications where portability, reusability, and measurement speed are key
Nanoplasmonic discrimination of organic solvents using a bimetallic optical tongue
Optical sensor arrays serve as excellent tools for the recognition and discrimination of a variety of liquid and gas mixtures. They achieve this via pattern-based recognition from signals across multiple sensing regions, where each region is modified to produce a different interaction, such as partial-selectivity, with desired analytes. As their use progresses towards rapid, highly personalized diagnosis and component identification devices, reduction in complexity and data-acquisition time is key. One way to achieve this is through reducing the number of elements in the array without compromising the differential capabilities of the device. Here, we present a device with elements consisting of plasmonic sensors of two superimposed plasmonic nanoarrays; one fabricated using gold and the other aluminum. Each material produces a distinct plasmonic response while also allowing us to selectively functionalize each pattern with a different â€sensing chemistry.' This allows for the development of different partially-selective elements, via modification with functional thiols and silanes, respectively. Since optical sensing arrays of this type require multiple sensing regions, each producing a different optical response, our bimetallic method results in twice as much data from one measurement, providing the same amount of data necessary to allow for successful differentiation with fewer elements in the sensing array. We demonstrate that by altering the surface chemistry of the nanostructures we can tune their partial selectivity to organic solvents. We believe this technology could be useful in areas that rely on assays for simultaneous determination of multiple analytes, such as the medical, food and drug, and security industries
Origin for the enhanced copper spin echo decay rate in the pseudogap regime of the multilayer high-T_c cuprates
We report measurements of the anisotropy of the spin echo decay for the inner
layer Cu site of the triple layer cuprate, Hg_0.8Re_0.2Ba_2Ca_2Cu_3O_8 (T_c=126
K) in the pseudogap T regime below T_pg ~ 170 K and the corresponding analysis
for their interpretation. As the field alignment is varied, the shape of the
decay curve changes from Gaussian (H_0 \parallel c) to single exponential (H_0
\perp c). The latter characterizes the decay caused by the fluctuations of
adjacent Cu nuclear spins caused by their interactions with electron spins. The
angular dependence of the second moment (T_{2M}^{-2} \equiv )
deduced from the decay curves indicates that T_{2M}^{-2} for H_0 \parallel c,
which is identical to T_{2G}^{-2} (T_{2G} is the Gaussian component), is
substantially enhanced, as seen in the pseudogap regime of the bilayer systems.
Comparison of T_{2M}^{-2} between H_0 \parallel c and H_0 \perp c indicates
that this enhancement is caused by electron spin correlations between the inner
and the outer CuO_2 layers. These results provide the answer to the
long-standing controversy regarding the opposite T dependences of (T_1T)^{-1}
and T_{2G}^{-2} in the pseudogap regime of bi- and trilayer systems.Comment: 4 pages, 4 figure
Optical Tastebuds for Water Quality Testing
To achieve the UN Sustainable Development Goal of universal access to clean water and sanitation, we need to rethink centralized water systems with global net-zero carbon and sustainability in mind. One approach is to develop scalable off-grid systems that are reliable and easy to use and maintain. A major challenge for such systems is translating the standard laboratory-based monitoring of centralized systems to a more sustainable and scalable model for regularly and routinely monitoring system outputs, which consist of complex mixtures with varying concentrations of molecules and ions in water. Here, we demonstrate a preliminary sensor that, once fully developed, could allow for point-of-use measurements with a single output to monitor. Rather than developing multiple sensors to monitor the levels of each individual component in the water, our label-free, array-based design mimics the biological system of taste. The sensor is comprised of an array of nano-tastebuds made of tailored plasmonic metasurfaces. The combination of different signals from each nano-tastebud to the same sample yields a unique fingerprint for that sample. Through training, these fingerprints build an identification model. By integrating a fully developed sensor into decentralized water systems, we seek to provide non-expert end-users with an easy-to-read output capable of warning of imminent system failures
Optical Tastebuds for Water Analysis
We demonstrate a preliminary nano-tastebud sensor comprised of tailored plasmonic metasurfaces that, once fully developed, could be integrated into water treatment facilities as an early warning system to warn of imminent system failures
Prospective evaluation of echocardiographic parameters and cardiac biomarkers in healthy dogs eating four custom-formulated diets
IntroductionDiet-associated dilated cardiomyopathy (DCM) has been suspected in breeds that have not been previously noted to have a predisposition to the DCM phenotype. This study hypothesized that over 210 days, dogs fed diets with varying amounts of animal-sourced protein and carbohydrate sources would not be negatively impacted in terms of their cardiac parameters and function.MethodsThirty-two purebred beagles and 33 mixed-breed hounds were randomized into four diet groups and studied for 210 days. The diet groups were as follows: the high-animal-protein grain-free (HAGF) group, the low-animal-protein grain-free (LAGF) group, the high-animal-protein grain-inclusive (HAGI), and the low-animal-protein grain-inclusive (LAGI) group. Cardiac-specific biomarkers, endomyocardial biopsies, and linear and volumetric echocardiographic parameters were evaluated.ResultsThere was a treatment-by-day-by-breed effect observed for the normalized left ventricular internal diameter at end-diastole (p = 0.0387) and for the normalized left ventricular internal diameter at end-systole (p = 0.0178). On day 210, mixed-breed hounds fed the LAGI diet had a smaller normalized left ventricular internal diameter at end-diastole than on day 90. On day 210, beagles fed the LAGF diet had a larger normalized left ventricular internal diameter at end-systole than those fed the LAGI diet. Fractional shortening for beagles in the LAGF group was significantly lower (p = 0.007) than for those in the HAGI and LAGI groups. Cardiac-specific biomarkers and endomyocardial biopsies were not significantly different between breeds, diets, and various time points.DiscussionThis study did not detect the development of cardiac dysfunction throughout the study period through the echocardiographic parameters measured, select cardiac biomarkers, or endomyocardial biopsies. There were noted interactions of treatment, breed, and time; therefore, isolating a diet association was not possible. Future research should further investigate the other factors that may help to identify the variable(s) and possible mechanisms underlying suspected diet-associated DCM in dogs
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