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Excess heat capacity in a bolometric detector has the consequence of increasing or leading to multiple device time constants.  The Mo/Au bilayer transition edge sensor (TES) bolometric detectors initially fabricated for the high resolution mid-infrared spectrometer (HIRMES) exhibited two response thermalization scales, one of which is a few times longer than estimates based upon the properties of the bulk materials employed in the design. The relative contribution of this settling time to the overall time response of the detectors is roughly proportional to the pixel area, which ranges between ∼0.3 and 2.6 mm2.  Use of laser ablation to remove sections of the silicon membranes comprising the pixels results in a detector response with a smaller contribution from the secondary time constant.  Additional information about the nature of this excess heat capacity is gleaned from glancing incidence X-ray diffraction, which reveals the presence of molybdenum silicides near the silicon surface which is a consequence of the bi-layer deposition.  Quantitative analysis of the concentration of excess molybdenum, estimated with secondary ion mass spectroscopy, is commensurate to the additional heat capacity needed to explain the anomalous time response of the detectors. [ABSTRACT FROM AUTHOR]

This article describes a simple though extremely effective sensor for acetone monitoring in the breath. The sensor is capable of monitoring the presence of acetone at parts per million (ppm) concentrations, thus being suitable for a diabetes diagnosis. It has a dimension of $3 {\,\,\mathrm {mm}} \times 6 {\,\,\mathrm {mm}}$ and a cost of less than one dollar. The small dimensions allow one to greatly limit the power required to increase its temperature, and its high selectivity with respect to other gases present in the breath reduces the risk of false-positive responses. The sensor is based on a thin alumina substrate on which platinum strips are deposited on both faces. A thin Nb2O5 layer with a nanometric thickness provides the required sensitivity and selectivity. Sensor prototypes have been characterized by field emission scanning electron microscopy (FESEM) and X-ray photoelectron spectroscopy (XPS) and proved an inherent linear response up to a few ppm of acetone. [ABSTRACT FROM AUTHOR]

This paper discloses two high-sensitivity probes for Eddy Current Nondestructive Test (NDT) of buried and surface defects. These probes incorporate eight and 32 magnetoresistive sensors, respectively, which are optimized for high sensitivity and spatial resolution. The signal processing and interfacing are carried out by a full-custom application-specific integrated circuit (ASIC). The ASIC signal chain performs with a thermal input-referred noise of 30 nV/ $\sqrt{\text{Hz}}$ at 1 kHz, with 66 mW of power consumption, in a die with 3.7×3.4 mm $^2$. NDT results are presented, showing that there is an increase in spatial resolution of surface defects when contrasted to prior art, enabling the probes to resolve defects with diameters of 0.44 mm, pitches of 0.6 mm, and minimum edge distance as low as 0.16 mm. The results also show that the probe for buried defects is a good all-round tool for detection of defects under cladding and multiple-plate flat junctions. [ABSTRACT FROM AUTHOR]

A kirigami-based strategy was investigated for strain transduction, using serpentine gold traces embedded in thin-film Parylene C. Multiple kirigami slit designs were evaluated via COMSOL simulation and mechanical force testing; sensors having tightly packed slits stretched up to 17.5 mm (350% strain) before mechanical failure and 9 mm (180% strain) before electrical failure. Strain transduction was achieved by monitoring DC resistance changes during stretching. DC resistance linearly increased with strain, with sensitivities up to 0.16 $\Omega$ /mm (gauge factor = 0.007) and minimal hysteresis. High-frequency trace impedance and inter-trace capacitance were also investigated during strain cycling. Capacitance increased with strain and high-frequency impedance show a nonlinear strain relationship. The biocompatible construction and extremely low profiles (20 $\mu \text{m}$ thick) of these sensors are attractive for minimally invasivein vivostrain sensing applications. [2018-0130] [ABSTRACT FROM AUTHOR]

Superconducting titanium thin films are good candidates for transition edge sensors. In this paper, we deposit titanium thin films on cooled silicon-on-insulator substrates by using electron-beam evaporation. The deposition rate dependence of the film stress, resistivity, and superconducting transition temperature are presented and analyzed. The relationship between film electrical properties and thickness is discussed. For investigating the heating influence on thin Ti films, a depth profile of oxygen diffusion in the films is also analyzed by X-ray photoelectron spectroscopy. [ABSTRACT FROM AUTHOR]

We report on investigation of the mechanical properties of paper electronics (printed and made out of paper). One key objective of such paper electronics is to achieve ultraflexibility. Therefore, it is important to understand electrical functionality and reliability of paper electronics under various physical (mechanical) deformations. Here, we show the general mechanical properties of the cellulose paper used and its electrical behavior under applied strain, tackling the main effects that need to be identified when building paper-based systems, from product performance and stability perspective. An overview of the stress–strain behavior of silver ink on paper is discussed, and then, we tackle a more specific analysis of the performance variations of paper sensors made with recyclable household materials when exposed to various mechanical conditions of tensile and compressive bending. This paper is important for developing stable wearable sensors for incorporation into Internet of Everything applications. [ABSTRACT FROM PUBLISHER]

This paper deals with the development of an accurate and precise humidity sensor, which is based on the extension of Thompson and Lampard theorem and a sol–gel-based thermally and chemically stable metal oxide thin film. In light of the extension of the theorem, most appropriate conductors are shaped around the material and the resulting sensor has cross conductance, which is the function of thickness only. It is fabricated and tested for different ranges of humidity. It is found that the fabricated sensor has outstanding static and dynamic characteristics. [ABSTRACT FROM PUBLISHER]

In this paper, we are proposing a novel rapid sol–gel thin-film porous metal–oxide-based surface acoustic wave (SAW) humidity sensor. For the SAW sensor, the center frequency of 433.92 MHz has been selected, and the device has been configured in a high-frequency oscillator circuit to explore the frequency response in the presence of water vapor. The sensitive thin film of sol–gel $\gamma $ -Al2O3 coated with a drop dry method offers very high surface-to-volume ratio with the distribution of micropores making the sensor highly sensitive for moisture detection. Pore morphologies of the film have been studied by field emission scanning electron microscope and atomic force microscopy. The \gamma $ phase of alumina of the film has been characterized with X-ray diffraction. The sensor has been tested from 3% relative humidity (RH) to 85% RH. The proposed sensor has very fast ( T_{r}= 1 s) response time and excellent yield ratio in comparison with the conventional commercial capacitive aluminum oxide sensor. The sensitivity (3%–20% RH) and the hysteresis (3%–85% RH) are found to be 120-Hz/% RH and 0.3%, respectively. The sensor can be useful for different applications, including moisture dispersion inside electronic gadgets, dryers, ovens, textile production, semiconductor device processing, food processing, medicine, and sealed packages. [ABSTRACT FROM PUBLISHER]

A very sensitive thin-film sensor was developed using a meandering coplanar line fabricated from Sr33Ti16O51 film (3 \mu \textm thick), amorphous Co85Nb12Zr3 film ( 1~\mathrm mm \times 2.45 mm, 0.3–2 \mu \textm thick), and Cu/Cr film (2/0.1 \mu \textm ). The deposited SrTiO film enhanced the sensitivity of a magnetic field sensor, a phase change of more than 30°/Oe and a gain of over −40 dB being achieved simultaneously. The maximum phase change (sensitivity) was observed for a CoNbZr film thickness of $\sim 0.5$ –1 \mu \textm . The sensitive bias field and carrier frequency increased as the CoNbZr film thickness increased. The optimum CoNbZr film thickness was realized by the tradeoff between the sensitive bias field and the volume of the CoNbZr film. [ABSTRACT FROM AUTHOR]