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Distributed acoustic sensors (DAS) are effective apparatus which are widely used in many application areas for recording signals of various events with very high spatial resolution along the optical fiber. To detect and recognize the recorded events properly, advanced signal processing algorithms with high computational demands are crucial. Convolutional neural networks are highly capable tools for extracting spatial information and very suitable for event recognition applications in DAS. Long-short term memory (LSTM) is an effective instrument for processing sequential data. In this study, we proposed a multi-input multi-output, two stage feature extraction methodology that combines the capabilities of these neural network architectures with transfer learning to classify vibrations applied to an optical fiber by a piezo transducer. First, we extracted the differential amplitude and phase information from the Phase-OTDR recordings and stored them in a temporal-spatial data matrix. Then, we used a state-of-the-art pre-trained CNN without dense layers as a feature extractor in the first stage. In the second stage, we used LSTMs to further analyze the features extracted by the CNN. Finally, we used a dense layer to classify the extracted features. To observe the effect of the utilized CNN architecture, we tested our model with five state-of-the art pre-trained models (VGG-16, ResNet-50, DenseNet-121, MobileNet and Inception-v3). The results show that using the VGG-16 architecture in our framework manages to obtain 100% classification accuracy in 50 trainings and got the best results on our Phase-OTDR dataset. Outcomes of this study indicate that the pre-trained CNNs combined with LSTM are very suitable for the analysis of differential amplitude and phase information, represented in a temporal spatial data matrix which is promising for event recognition operations in DAS applications., 15 pages, 9 figures. Title updated

There is an increasing demand in the synthesis of shape and size-controlled gold nanostructures (Au NSs) with greener methods. Therefore, we aimed to synthesize differently shaped and sized Au NSs using a greener technique under ambient conditions. In this study, we utilized pollen extracts of Corylus avellana, Juniperus oxycedrus and Pinus nigra species (collected from Kastamonu region of Turkey) for the synthesis. The extraction was performed in water in order to recover water soluble content from the pollen grains. The extracts were used to stabilize, and shape/size direct the HEPES (4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid) buffer synthesized Au NSs. UV-vis, powder X-ray diffraction (PXRD), scanning electron microscopy (SEM) characterizations proved synthesis of spherical, anisotropic and large Au NSs with this benign approach. The obtained Au NSs were possible to separate small and large Au NSs through centrifugation. Chemistry of pollen extracts played key role on morphology and stability of the Au NSs. The findings, for the first time, is revealing the synthesis of large Au nanorod bundles (>300 nm) along with hexagonal and spherical Au NSs under ambient conditions using pollen grain extracts, whose maturation took 24h.

This publication was based upon work supported by the King Abdullah University of Science and Technology (KAUST) Office of Sponsored Research (OSR) under Award No. REP/1/2880-01-01.

With the increased global population, it is more important than ever to expand accessibility to affordable personalized healthcare. In this context, a seamless integration of microfluidic technology for bioanalysis and drug delivery and complementary metal oxide semiconductor (CMOS) technology enabled data-management circuitry is critical. Therefore, here, the fundamentals, integration aspects, and applications of CMOS-enabled microfluidic systems for affordable personalized healthcare systems are presented. Critical components, like sensors, actuators, and their fabrication and packaging, are discussed and reviewed in detail. With the emergence of the Internet-of-Things and the upcoming Internet-of-Everything for a people–process–data–device connected world, now is the time to take CMOS-enabled microfluidics technology to as many people as possible. There is enormous potential for microfluidic technologies in affordable healthcare for everyone, and CMOS technology will play a major role in making that happen., King Abdullah University of Science and Technology (KAUST) Office of Sponsored Research (OSR) (OSR-2015-Sensors-2707 OSR-2016-KKI-2880) Technology Transfer Office (TTO) GEN-01-4014

Research on birds has long played an important role in ecological investigations, as birds are relatively easily observed, and their high metabolic rates and diurnal habits make them quite evidently responsive to changes in their environments. A mechanistic understanding of such avian responses requires a better understanding of how variation in physiological state conditions avian behavior and integrates the effects of recent environmental changes. There is a great need for sensor systems that will allow free-flying birds to interact with their environment and make unconstrained decisions about their spatial location at the same time that their physiological state is being monitored in real time. We have developed a miniature needle-based enzymatic sensor system suitable for continuous real-time amperometric monitoring of uric acid levels in unconstrained live birds. The sensor system was constructed with Pt/Ir wire and Ag/AgCl paste. Uricase enzyme was immobilized on a 0.7 mm sensing cavity of Nafion/cellulose inner membrane to minimize the influences of background interferents. The sensor response was linear from 0.05 to 0.6 mM uric acid, which spans the normal physiological range for most avian species. We developed a two-electrode potentiostat system that drives the biosensor, reads the output current, and wirelessly transmits the data. In addition to extensive characterization of the sensor and system, we also demonstrate autonomous operation of the system by collecting in vivo extracellular uric acid measurements on a domestic chicken. The results confirm our needle-type sensor system's potential for real-time monitoring of birds' physiological state. Successful application of the sensor in migratory birds could open up a new era of studying both the physiological preparation for migration and the consequences of sustained avian flight.

© 2016, National Academy of Sciences. All rights reserved. Emerging classes ofconcentrator photovoltaic (CPV) modules reach efficiencies that are far greater than those of even the highest performance flat-plate PV technologies, with architectures that have the potential to provide the lowest cost of energy in locations with high direct normal irradiance (DNI). A disadvantage is their inability to effectively use diffuse sunlight, thereby constraining widespread geographic deployment and limiting performance even under the most favorable DNI conditions. This study introduces a module design that integrates capabilities in flat-plate PV directly with the most sophisticated CPV technologies, for capture of both direct and diffuse sunlight, thereby achieving efficiency in PV conversion of the global solar radiation. Specific examples of this scheme exploit commodity silicon (Si) cells integrated with two different CPV module designs, where they capture light that is not efficiently directed by the concentrator optics onto large-scale arrays of miniature multijunction (MJ) solar cells that use advanced III-V semiconductor technologies. In this CPV+scheme ("+" denotes the addition of diffuse collector), the Si and MJ cells operate independently on indirect and direct solar radiation, respectively. On-sun experimental studies of CPV+modules at latitudes of 35.9886° N (Durham, NC), 40.1125° N (Bondville, IL), and 38.9072° N (Washington, DC) show improvements in absolute module efficiencies of between 1.02% and 8.45% over values obtained using otherwise similar CPV modules, depending on weather conditions. These concepts have the potential to expand the geographic reach and improve the cost-effectiveness of the highest efficiency forms of PV power generation.

Freeform (physically flexible, stretchable and reconfigurable) electronics can be critical enabler for advanced personalized healthcare. With increased global population and extended average lifetime of mankind, it is more important than ever to integrate advanced electronics into our daily life for advanced personalized healthcare. In this paper, we discuss some critical criteria to design such electronics with enabling applications.

We report short circuit current (Jsc) enhancement in crystalline silicon (C-Si) photovoltaic (PV) using low-cost Ohmic contact engineering by integration of Nickel mono-silicide (NiSi) for back contact metallization as an alternative to the status quo of using expensive screen printed silver (Ag). We show 2.6 mA/cm2 enhancement in the short circuit current (J sc ) and 1.2 % increment in the efficiency by improving the current collection due to the low specific contact resistance of the NiSi on the heavily Boron (B) doped Silicon (Si) interface.

Compact algal reactors are presented with: (1) closely stacked layers of waveguides to decrease light-path to enable larger optimal light-zones; (2) waveguides containing scatterers to uniformly distribute light; and (3) hollow fiber membranes to reduce energy required for gas transfer. The reactors are optimized by characterizing the aeration of different gases through hollow fiber membranes and characterizing light intensities at different culture densities. Close to 65% improvement in plateau peak productivities was achieved under low light-intensity growth experiments while maintaining 90% average/peak productivity output during 7-h light cycles. With associated mixing costs of ∼1 mW/L, several magnitudes smaller than closed photobioreactors, a twofold increase is realized in growth ramp rates with carbonated gas streams under high light intensities, and close to 20% output improvement across light intensities in reactors loaded with high density cultures.

In today's digital age, the increasing dependence on information also makes us vulnerable to potential invasion of privacy and cyber security. Consider a scenario in which a hard drive is stolen, lost, or misplaced, which contains secured and valuable information. In such a case, it is important to have the ability to remotely destroy the sensitive part of the device (e.g., memory or processor) if it is not possible to regain it. Many emerging materials and even some traditional materials like silicon, aluminum, zinc oxide, tungsten, and magnesium, which are often used for logic processor and memory, show promise to be gradually dissolved upon exposure of various liquid medium. However, often these wet processes are too slow, fully destructive, and require assistance from the liquid materials and their suitable availability at the time of need. This study shows Joule heating effect induced thermal expansion and stress gradient between thermally expandable advanced polymeric material and flexible bulk monocrystalline silicon (100) to destroy high-performance solid state electronics as needed and under 10 s. This study also shows different stimuli-assisted smartphone-operated remote destructions of such complementary metal oxide semiconductor electronics.

The rapid expansion of mobile technology is transforming the biomedical landscape. By 2016 there will be 260 M active smartphones in the US and millions of health accessories and software “apps” running off them. In parallel with this have come major technical achievements in lab-on-a-chip technology leading to incredible new biochemical sensors and molecular diagnostic devices. Despite these advancements, the uptake of lab-on-a-chip technologies at the consumer level has been somewhat limited. We believe that the widespread availability of smartphone technology and the capabilities they offer in terms of computation, communication, social networking, and imaging will be transformative to the deployment of lab-on-a-chip type technology both in the developed and developing world. In this paper we outline why we believe this is the case, the new business models that may emerge, and detail some specific application areas in which this synergy will have long term impact, namely: nutrition monitoring and disease diagnostics in limited resource settings.

Hemorrhagic shock (HS) is the leading cause of death for people with traumatic injuries. The onset of HS is correlated with marked changes in the plasma vasopressin levels and some studies indicate that administrating vasopressin in the bloodstream can help stabilize the situation. This situation calls naturally for the use of implantable devices for both the monitoring and treatment of HS. In this work, we present a self-powered hemorrhagic-shock autonomous integrated device (hemoAID) that continuously monitors vasopressin levels and releases vasopressin automatically when levels drop below a certain threshold. We demonstrate that the device can operate at physiological concentrations of vasopressin, in sheep serum, thus paving the way towards the development of an autonomous implantable device for HS prevention.

The use of point-of-care (POC) devices in limited resource settings where access to commonly used infrastructure, such as water and electricity, can be restricted represents simultaneously one of the best application fits for POC systems as well as one of the most challenging places to deploy them. Of the many challenges involved in these systems, the preparation and processing of complex samples like stool, vomit, and biopsies are particularly difficult due to the high number and varied nature of mechanical and chemical interferents present in the sample. Previously we have demonstrated the ability to use solar-thermal energy to perform PCR based nucleic acid amplifications. In this work demonstrate how the technique, using similar infrastructure, can also be used to perform solar-thermal based sample processing system for extracting and isolating Vibrio Cholerae nucleic acids from fecal samples. The use of opto-thermal energy enables the use of sunlight to drive thermal lysing reactions in large volumes without the need for external electrical power. Using the system demonstrate the ability to reach a 95°C threshold in less than 5 minutes and maintain a stable sample temperature of +/- 2°C following the ramp up. The system is demonstrated to provide linear results between 10(4) and 10(8) CFU/mL when the released nucleic acids were quantified via traditional means. Additionally, we couple the sample processing unit with our previously demonstrated solar-thermal PCR and tablet based detection system to demonstrate very low power sample-in-answer-out detection.

While photocatalytic water-splitting is a promising alternative energy source, low photocatalytic efficiencies in the visible spectrum hinders its widespread deployment and commercialization. Although screening combinations of new materials and characterizing their reaction kinetics offers possible improvements to efficiency, current experiments are challenged by expensive bulky setups and slow recovery of particles downstream. Optofluidics is a good platform for screening Z-scheme catalysts cheaply and rapidly. By alleviating the problems of mass transport it can also potentially increase reaction rates and efficiencies. Here, we demonstrate a novel optofluidic device based on applying catalyst sol-gels on planar channels while measuring the reaction output by monitoring the depletion of the redox mediators. We use our setup to study the kinetics of the TiO(2)-Pt water-splitting reaction mediated by I(-)/IO(3)(-) redox pairs under different flow rates. In particular, for TiO(2)-Pt, we show ~2-fold improvements in reaction rates and efficiencies.

We describe a conducting polymer device that can induce electrically controlled density gradients of normal and cancerous cell lines, and hence can be used as a tool for the study of cell-cell interactions.

Thinned silicon based complementary metal oxide semiconductor (CMOS) electronics can be physically flexible. To overcome challenges of limited thinning and damaging of devices originated from back grinding process, we show sequential reactive ion etching of silicon with the assistance from soft polymeric materials to efficiently achieve thinned (40 μm) and flexible (1.5 cm bending radius) silicon based functional CMOS inverters with high-κ/metal gate transistors. Notable advances through this study shows large area of silicon thinning with pre-fabricated high performance elements with ultra-large-scale-integration density (using 90 nm node technology) and then dicing of such large and thinned (seemingly fragile) pieces into smaller pieces using excimer laser. The impact of various mechanical bending and bending cycles show undeterred high performance of flexible silicon CMOS inverters. Future work will include transfer of diced silicon chips to destination site, interconnects, and packaging to obtain full...

We present a compact water-cleaning reactor with stacked layers of waveguides containing gradient patterns of optical scatterers that enable uniform light distribution and augmented water-cleaning rates. Previous photocatalytic reactors using immersion, external, or distributive lamps suffer from poor light distribution that impedes scalability. Here, we use an external UV-source to direct photons into stacked waveguide reactors where we scatter the photons uniformly over the length of the waveguide to thin films of TiO2-catalysts. We also show 4.5 times improvement in activity over uniform scatterer designs, demonstrate a degradation of 67% of the organic dye, and characterize the degradation rate constant.

Control of cell migration is receiving a great deal of attention due to its relevance to the engineering of tissues. Here we report a device that contains a conducting polymer stripe and achieves a continuum of microenvironments for cell growth under the influence of an applied bias. Marked differences are observed in the migration behaviour of bovine aortic endothelial cells (ECs) as a function of location along the polymer stripe, and a 3-fold variation is achieved in EC migration speed and directional persistence time. Moreover, the device induces directional cell migration along the conducting polymer stripe. A gradient in adsorbed fibronectin indicates that a spatial variation in cell adhesion is at play. The ability to control cell migration behaviour using external electrical stimuli highlights the potential of using conducting polymers as “active” substrates for the non-invasive control of cell behaviour.