Optical gas sensors play an increasingly important role in many applications. Sensing techniques based on mid-infrared absorption spectroscopy offer excellent stability, selectivity and sensitivity, for numerous possibilities expected for sensors integrated into mobile and wearable devices. Here we review recent progress towards the miniaturization and integration of optical gas sensors, with a focus on low-cost and low-power consumption devices.

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We describe a solid state implementation of a quantum computer using ballistic single electrons as flying qubits in 1D nanowires. We show how to implement all the steps required for universal quantum computation: preparation of the initial state, measurement of the final state and a universal set of quantum gates. An important advantage of this model is the fact that we do not need ultrafast optoelectronics for gate operations. We use cold programming (or pre-programming), i.e., the gates are set before launching the electrons; all programming can be done using static electric fields only.PACS numbers: 03.67. Lx, 85.30.S, 85.30.V In recent years quantum information processing emerged as an important field for theoretical and experimental investigation [1]. Using quantum mechanical phenomena for storing and manipulating information it is possible to outperform classical algorithms [2,3]. This motivated the present "gold rush" for actual physical implementations. There are different proposals for building a quantum computer (quputer, for short). These include ion traps, NMR quantum computation, cavity QED and single photonics. Among these a solid state implementation of a quputer [4]-[12] has some advantages, including scalability, miniaturization and flexibility in design. A recent experimental result is the control of a qubit using a superconducting Cooper-pair box [13].In this article we extend and analyze our model for quantum computation with ballistic electrons proposed in [14]. The main idea is to use ballistic electrons as flying qubits in 1D quantum wires used as electron waveguides. Several requirements have to be met by any implementation of a quputer (DiVincenzo's checklist [15]): (i) well defined qubits; (ii) low decoherence; (iii) initial state preparation; (iv) final state measurement; (v) universal set of quantum gates. We show how to implement all these steps with ballistic electrons. (i) The qubit Our physical qubit consists of two adjacent 1D quantum wires, called the 0-and the 1-rail, respectively (dual rail representation [16]). We define the logical state |0 by the presence of a single electron of energy E k in the 0-rail and the logical state |1 by the presence of a single electron (with same energy) in the 1-rail. How realistic is this situation? For a semiconductor at low temperatures, the electron density in the conduction band is due to impurities ionization. For a donor concentration of 10 13 cm −3 , the density of electrons in the conduction band for intrinsic GaAs is ∼ 10 −5 cm −3 even at 1 K; therefore a single electron injected in the conduction band is clearly distinguishable from the no electron state. A correspondence between single and dual rail representations is shown in Fig. 1. (ii) Coherence An essential requirement for any implementation of a quputer is to maintain the coherence of the qubits during the entire pe- riod of computation. Since we use ballistic single electrons in 1D nanowires, their phase coherence is preserved. The parameter which characterizes the coheren...

We report on the integration of inkjet-printed graphene with a CMOS micro-electro-mechanical-system (MEMS) microhotplate for humidity sensing. The graphene ink is produced via ultrasonic assisted liquid phase exfoliation in isopropyl alcohol (IPA) using polyvinyl pyrrolidone (PVP) polymer as the stabilizer. We formulate inks with different graphene concentrations, which are then deposited through inkjet printing over predefined interdigitated gold electrodes on a CMOS microhotplate. The graphene flakes form a percolating network to render the resultant graphene-PVP thin film conductive, which varies in presence of humidity due to swelling of the hygroscopic PVP host. When the sensors are exposed to relative humidity ranging from 10–80%, we observe significant changes in resistance with increasing sensitivity from the amount of graphene in the inks. Our sensors show excellent repeatability and stability, over a period of several weeks. The location specific deposition of functional graphene ink onto a low cost CMOS platform has the potential for high volume, economic manufacturing and application as a new generation of miniature, low power humidity sensors for the internet of things.

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With its remarkable electro-thermal properties such as the highest known thermal conductivity (~22 W cm−1∙K−1 at RT of any material, high hole mobility (>2000 cm2 V−1 s−1), high critical electric field (>10 MV cm−1), and large band gap (5.47 eV), diamond has overwhelming advantages over silicon and other wide bandgap semiconductors (WBGs) for ultra-high-voltage and high-temperature (HT) applications (>3 kV and  >450 K, respectively). However, despite their tremendous potential, fabricated devices based on this material have not yet delivered the expected high performance. The main reason behind this is the absence of shallow donor and acceptor species. The second reason is the lack of consistent physical models and design approaches specific to diamond-based devices that could significantly accelerate their development. The third reason is that the best performances of diamond devices are expected only when the highest electric field in reverse bias can be achieved, something that has not been widely obtained yet. In this context, HT operation and unique device structures based on the two-dimensional hole gas (2DHG) formation represent two alternatives that could alleviate the issue of the incomplete ionization of dopant species. Nevertheless, ultra-HT operations and device parallelization could result in severe thermal management issues and affect the overall stability and long-term reliability. In addition, problems connected to the reproducibility and long-term stability of 2DHG-based devices still need to be resolved. This review paper aims at addressing these issues by providing the power device research community with a detailed set of physical models, device designs and challenges associated with all the aspects of the diamond power device value chain, from the definition of figures of merit, the material growth and processing conditions, to packaging solutions and targeted applications. Finally, the paper will conclude with suggestions on how to design power converters with diamond devices and will provide the roadmap of diamond device development for power electronics.

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