Hydrogen sensors are of increasing importance in connection with the development and expanded use of hydrogen gas as an energy carrier and as a chemical reactant. There are an immense number of sensors reported in the literature for hydrogen detection and in this work these sensors are classified into eight different operating principles. Characteristic performance parameters of these sensor types, such as measuring range, sensitivity, selectivity and response time are reviewed and the latest technology developments are reported. Testing and validation of sensor performance are described in relation to standardisation and use in potentially explosive atmospheres so as to identify the requirements on hydrogen sensors for practical applications.

Hydrogen Sensors - A review

Metal oxide semiconductor gas sensors are utilised in a variety of different roles and industries. They are relatively inexpensive compared to other sensing technologies, robust, lightweight, long lasting and benefit from high material sensitivity and quick response times. They have been used extensively to measure and monitor trace amounts of environmentally important gases such as carbon monoxide and nitrogen dioxide. In this review the nature of the gas response and how it is fundamentally linked to surface structure is explored. Synthetic routes to metal oxide semiconductor gas sensors are also discussed and related to their affect on surface structure. An overview of important contributions and recent advances are discussed for the use of metal oxide semiconductor sensors for the detection of a variety of gases—CO, NOx, NH3 and the particularly challenging case of CO2. Finally a description of recent advances in work completed at University College London is presented including the use of selective zeolites layers, new perovskite type materials and an innovative chemical vapour deposition approach to film deposition.

https://www.mdpi.com/1424-8220/10/6/5469/pdf

Metal Oxide Semi-Conductor Gas Sensors in Environmental Monitoring

The theoretical and experimental issues relevant to neutrinoless double beta decay are reviewed. The impact that a direct observation of this exotic process would have on elementary particle physics, nuclear physics, astrophysics, and cosmology is profound. Now that neutrinos are known to have mass and experiments are becoming more sensitive, even the nonobservation of neutrinoless double beta decay will be useful. If the process is actually observed, we will immediately learn much about the neutrino. The status and discovery potential of proposed experiments are reviewed in this context, with significant emphasis on proposals favored by recent panel reviews. The importance of and challenges in the calculation of nuclear matrix elements that govern the decay are considered in detail. The increasing sensitivity of experiments and improvements in nuclear theory make the future exciting for this field at the interface of nuclear and particle physics.

/pdf/double-beta-decay-majorana-neutrinos-and-neutrino-mass-2tfhqvhys8.pdf

Double Beta Decay, Majorana Neutrinos, and Neutrino Mass

An apparatus may include a semiconductor chip and a fluidics assembly. The semiconductor chip has an array of wells and an array of sensors and each sensor of the array of sensors is in fluid communication with a well of the array of wells. The fluidics assembly is located on top of the semiconductor chip and is configured to deliver fluids to the semiconductor chip. The fluidics assembly includes a flow expansion chamber configured to introduce the fluids, an outlet portion configured to pipe out the fluids, and a flow chamber portion. The flow chamber portion is configured to allow the fluids to flow from the flow expansion chamber to the outlet portion and to allow the fluids to interact along the way with material in the array of wells. The flow expansion chamber has a curved wall at the top or bottom so that the height of the flow expansion chamber at the center is less than at the walls that restrict the fluids to the left and right.

Methods and apparatus for measuring analytes using large scale fet arrays

Methods and apparatus relating to FET arrays including large FET arrays for monitoring chemical and/or biological reactions such as nucleic acid sequencing-by-synthesis reactions. Some methods provided herein relate to improving signal (and also signal to noise ratio) from released hydrogen ions during nucleic acid sequencing reactions.

Methods and apparatus for measuring analytes

Compact, U-shaped microwave resonators have been designed and implemented with RF MEMS switches to obtain frequency tunable narrow-band devices. The U-shape has been used to develop a resonator optimizing its size. In addition, RF MEMS ohmic switches have been introduced to implement the frequency tunability in a small range and to provide a high signal rejection ratio in the ON-OFF states. Device configurations working at frequencies between 20 GHz ca. and 26 GHz ca. have been studied.

U-shaped MEMS tunable microwave resonators

Stiction occurring in the release phase is a severe problem in many MEMS devices. This phenomenon is due to capillary forces and solid-solid adhesion, which develops during drying after a wet etching process. The possibilities and the limits of the use of a solvent with low surface tension is investigated in the case of MEMS resonators fabricated on silicon-on-insulator substrate. It is shown as in this case it is possible to obtain stiction-free structures without the necessity of more expensive and complicated techniques such as supercritical drying or hydrofluoric acid (HF) vapor etching. The fabrication and design limit of this solution are also investigated. © 2013 Society of Photo-Optical Instrumentation Engineers (SPIE) (DOI: 10

Wet release technology for bulk-silicon resonators fabrication on silicon-on-insulator substrate

Large millimetric and submillimetric telescopes can play a crucial
 role in our understanding of the Universe, allowing the direct
 measurement of early galaxies or the investigation of the earliest
 stages of star formation. The B modes of CMB polarization are a
 direct probe of the Inflationary epoch and their measurement
 promises to provide information on the scale of energies at which
 the process took place. For these investigations (and many
 others), large detectors arrays with thousands of pixels are
 needed, to achieve high mapping speeds. This is especially true in
 the case of mm and sub/mm observations from extremely cold and dry
 locations like Dome-C, where ultra-low temperature detectors,
 reaching photon noise limited performance, are needed to fully
 exploit the excellent quality of the site. In this paper we
 present the working principle of the Microwave Kinetic Inductance
 Detectors and their status of development in Italy, focusing on
 the key aspects that make them ideal for large arrays of sensors.

Development of KIDs detectors for large submillimetric telescopes

Nowadays MEMS device fabrication requires an accurate knowledge of silicon etching parameters. We studied the relation between thin film masking layers residual stress and the orientation dependence of the silicon etching rate using TMAH solutions. In particular we focused on widely used masking films such as SiO/sub 2/ and Si/sub 3/N/sub 4/. Dedicated test structures were designed, fabricated and tested. We found an influence of the masking layer residual stress on the silicon etching rate anisotropy and a lower value of anisotropy for higher stressed structures.

http://ieeexplore.ieee.org/iel5/8531/26945/01197364.pdf

Influence of masking layer stress on anisotropic silicon etching in TMAH solutions

This paper presents the performance of a MEMS zero-level chip cap package implemented with through-the-cap vertical interconnects. The interconnect as well as the hermetic bond and sealing are established using flip-chip thermo-compression bonding by creating a copper-tin to gold metallic (solder) joint. The hermeticity of the packages is assessed via electrical measurements of encapsulated MEMS resonators and the RF performance of 3D interconnects is evaluated via microwave measurements of integrated coplanar waveguides. Design guidelines imposed by concurrent requirements of the flip-chip assembly process and the RF performance are discussed. The developed technology for the MEMS cap uses CMOS-compatible materials and the CMOS fabrication process.

Benno Margesin

Papers

U-shaped MEMS tunable microwave resonators

Wet release technology for bulk-silicon resonators fabrication on silicon-on-insulator substrate

Development of KIDs detectors for large submillimetric telescopes

Influence of masking layer stress on anisotropic silicon etching in TMAH solutions

Performance and Perspectives of Zero-Level MEMS Chip Packages with Vertical Interconnects