Thermal management is one of the main challenges for the future of electronics [1]-[5]. With the ever increasing rate of data generation and communication, as well as the constant push to reduce volume and costs of industrial converter systems, the power density of electronics rises [6]. Consequently, cooling has an increasingly large environmental impact [7], [8], and new technologies are needed to efficiently handle the heat in a sustainable and cost-effective way [9]. Embedding liquid cooling directly inside the chip is a promising approach for a more efficient thermal management [5], [10], [11]. However, even in state-of-the-art approaches, the electronics and cooling are treated separately, leaving the full energy-saving potential of embedded cooling untapped. Here we demonstrate that co-designing microfluidics and electronics into the same semiconductor substrate, to produce a monolithically-integrated manifold microchannel (mMMC) cooling structure, provides efficiency beyond the state-of-theart. Our results show that heat fluxes exceeding 1.7 kW/cm 2 can be cooled down using only 0.57 W/cm 2 of pumping power. We observed an unprecedented coefficient of performance (>10 4 ) for single-phase water-cooling of heat fluxes exceeding 1 kW/cm 2 , corresponding to a 50-fold increase compared to straight microchannels, as well as a remarkably high average Nusselt number of 16. The proposed cooling technology enables further miniaturization of electronics, potentially extending Moore's law and greatly reducing energy consumption worldwide. Furthermore, by removing the need for large external heat sinks, we demonstrate how this approach enables ultra-compact
Artificial "electronic skin" is of great interest for mimicking the functionality of human skin, such as tactile pressure sensing. Several important performance metrics include mechanical flexibility, operation voltage, sensitivity, and accuracy, as well as response speed. In this Letter, we demonstrate a large-area high-performance flexible pressure sensor built on an active matrix of 16 × 16 carbon nanotube thin-film transistors (CNT TFTs). Made from highly purified solution tubes, the active matrix exhibits superior flexible TFT performance with high mobility and large current density, along with a high device yield of nearly 99% over 4 inch sample area. The fully integrated flexible pressure sensor operates within a small voltage range of 3 V and shows superb performance featuring high spatial resolution of 4 mm, faster response than human skin (<30 ms), and excellent accuracy in sensing complex objects on both flat and curved surfaces. This work may pave the road for future integration of high-performance electronic skin in smart robotics and prosthetic solutions.
Over the last decade, gallium nitride has emerged as an excellent material for the fabrication of power devices. Among the semiconductors for which power devices are already available on the market, GaN has the widest energy gap, the largest critical field, the highest saturation velocity, thus representing an excellent material for the fabrication of high speed/high voltage components.The presence of spontaneous and piezoelectric polarization allows to create a 2-dimensional electron gas, with high mobility and large channel density, in absence of any doping, thanks to the use of AlGaN/GaN heterostructures. This contributes to minimize resistive losses; at the same time, for GaN transistors switching losses are very low, thanks to the small parasitic capacitances and switching charges. Device scaling and monolithic integration enable high frequency operation, with consequent advantages in terms of miniaturization.For high power/high voltage operation, vertical device architectures are being proposed and investigated, and 3-dimensional structuresfin-shaped, trench-structured, nanowire-basedare demonstrating a great potential. Contrary to silicon, GaN is a relatively young material: trapping and degradation processes must be understood and described in detail, with the aim of optimizing device stability and reliability. This tutorial paper describes the physics, technology and reliability of GaN-based power devices: in the first part of the article, starting from a discussion of the main properties of the material, the characteristics of lateral and vertical GaN transistors are discussed in detail, to provide guidance in this complex and interesting field. The second part of the paper focuses on trapping and reliability aspects: the physical origin of traps in GaN, and the main degradation mechanisms are discussed in detail. The wide set of referenced papers and the insight on the most relevant aspects gives the reader a comprehensive overview on present and next-generation GaN electronics. IntroductionOver the past decade, gallium nitride has emerged as an excellent material for the fabrication of power semiconductor devices. Thanks to the unique properties of GaN, diodes and transistors based on this material have excellent performance, compared to their silicon counterparts, and are expected to find wide application in the next-generation power converters. Owing to the flexibility and the energy efficiency of GaN-based power converters, the interest towards this technology is rapidly growing: the aim of this tutorial is to review the most relevant physical properties, the operating principles, the fabrication parameters, and the stability/reliability issues of GaN-based power transistors. For introductory purposes, we start summarizing the physical reasons why GaN transistors achieve a much better performance than the corresponding silicon devices, to help the reader understanding the unique advantages of this technology.The properties of GaN devices allow the fabrication of high-efficiency (near or above 99 %)...
Dopamine is a neurotransmitter that modulates arousal and motivation in humans and animals. It plays a central role in the brain "reward" system. Its dysregulation is involved in several debilitating disorders such as addiction, depression, Parkinson's disease, and schizophrenia. Dopamine neurotransmission and its reuptake in extracellular space takes place with millisecond temporal and nanometer spatial resolution. Novel nanoscale electrodes are needed with superior sensitivity and improved spatial resolution to gain an improved understanding of dopamine dysregulation. We report on a scalable fabrication of dopamine neurochemical probes of a nanostructured glassy carbon that is smaller than any existing dopamine sensor and arrays of more than 6000 nanorod probes. We also report on the electrochemical dopamine sensing of the glassy carbon nanorod electrode. Compared with a carbon fiber, the nanostructured glassy carbon nanorods provide about 2× higher sensitivity per unit area for dopamine sensing and more than 5× higher signal per unit area at low concentration of dopamine, with comparable LOD and time response. These glassy carbon nanorods were fabricated by pyrolysis of a lithographically defined polymeric nanostructure with an industry standard semiconductor fabrication infrastructure. The scalable fabrication strategy offers the potential to integrate these nanoscale carbon rods with an integrated circuit control system and with other complementary metal oxide semiconductor (CMOS) compatible sensors.
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