1,569 research outputs found

    Room-Temperature Compressive Transfer Printing of Nanowires for Nanoelectronic Devices

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    Recently, there has been a growing interest in the controlled alignment and robust bonding process of nanowires (NWs) on nanoelectronic devices. In this paper, we developed an innovative process for the fabrication of NW-based devices by room-temperature and low-pressure compressive transfer printing of NWs, in which NWs could be simultaneously aligned and bonded onto the metal electrodes. In this process, chemically synthesized NWs were first transferred and aligned on an intermediate substrate by contact printing and then finally printed onto a target substrate with mechanically soft Au electrodes, which enables the embedding of aligned NWs under low-pressure (5 bar) and room-temperature condition. The resulting contact between NW and Au electrodes exhibits Schottky behavior and high mechanical bonding strength (>567 MPa). The electrical characteristics could be converted from Schottky to Ohmic contact through thermal annealing treatment at 250 degrees C for 5 min due to Cr diffusion and direct Cr-ZnO contact formation. The applications of the fabricated devices as ultraviolet (UV) and gas sensors were successfully demonstrated. Furthermore, NW-based electronic devices were fabricated on a flexible substrate by using this process and showed mechanical and electrical robustness under mechanical bending conditions

    SliceNStitch: Continuous CP Decomposition of Sparse Tensor Streams

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    Consider traffic data (i.e., triplets in the form of source-destination-timestamp) that grow over time. Tensors (i.e., multi-dimensional arrays) with a time mode are widely used for modeling and analyzing such multi-aspect data streams. In such tensors, however, new entries are added only once per period, which is often an hour, a day, or even a year. This discreteness of tensors has limited their usage for real-time applications, where new data should be analyzed instantly as it arrives.How can we analyze time-evolving multi-aspect sparse data 'continuously' using tensors where time is 'discrete'? We propose SLICENSTITCH for continuous CANDECOMP/PARAFAC (CP) decomposition, which has numerous time-critical applications, including anomaly detection, recommender systems, and stock market prediction. SLICENSTITCH changes the starting point of each period adaptively, based on the current time, and updates factor matrices (i.e., outputs of CP decomposition) instantly as new data arrives. We show, theoretically and experimentally, that SLICENSTITCH is (1) 'Any time': updating factor matrices immediately without having to wait until the current time period ends, (2) Fast: with constant-time updates up to 464× faster than online methods, and (3) Accurate: with fitness comparable (specifically, 72 - 100%) to offline methods

    Breath Gas Sensors for Diabetes and Lung Cancer Diagnosis

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    Recently, the digital healthcare technologies including non-invasive diagnostics based on Internet of Things (IOT) are getting attention. Human exhaled breath contains a variety of volatile organic compounds (VOCs), which can provide information of malfunctions of the body and presence of a specific disease. Detection of VOCs in exhaled breath using gas sensors are easy to use, safe, and cost-effective. However, accurate diagnosis of diseases is challenging because changes in concentration of VOCs are extremely small and lots of body factors directly or indirectly influence to the conditions. To overcome the limitations, highly selective nanosensors and artificial intelligent electronic nose (E-nose) systems have been mainly researched in recent decades. This review provides brief reviews of the recent studies for diabetes and lung cancer diagnosis using nanosensors and E-nose systems.
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