Thin Sensors Research Articles

Biomechanics of Proximal Hamate Autograft in Scaphoid Nonunion.

Purpose Treatment of proximal scaphoid fractures remains a challenge with a risk of nonunions and avascular necrosis due to its retrograde blood supply. The ipsilateral proximal hamate has been described as a viable autograft option for osteochondral reconstruction of the proximal scaphoid. Our study evaluated the changes in the contact area and pressure of the radioscaphoid joint after proximal hamate autograft reconstruction. Methods Thin sensors (Tekscan Inc., Boston, MA) were placed in the radiocarpal joints of six fresh-frozen cadaveric forearms. Each specimen's tendons were loaded to 150 N in neutral, 45-degree flexion/extension positions through five cycles. Through a dorsal wrist approach, the proximal 10 mm of the scaphoid and hamate was excised. The proximal hamate autograft was affixed to the scaphoid with K-wires. Peak contact pressures and areas at the scaphoid facet were determined and averaged across loading cycles. Results At the radioscaphoid facet, peak contact pressures were equivalent, although an increasing trend in the neutral and extended wrist position was seen. At the radiolunate facet, contact pressure had an increasing trend in the hamate reconstructed wrists in all wrist positions. Contact areas had a decreasing trend and were nonequivalent at the radioscaphoid facet in the hamate reconstructed wrist. Conclusion After hamate autograft, the contact areas were not equivalent between the native and reconstructed wrists but contact pressures were equivalent in the facets. The proximal hamate has a more pointed morphology compared with the proximal scaphoid, which would explain the change in contact area in the hamate autografted wrist. Our study suggests hamate autograft may present a viable reconstruction for the proximal pole of the scaphoid without significantly altering peak contact pressures at the radioscaphoid facet.

A thin film force sensor on AISI 5140 steel surface with multilayer SI3N4/AL2O3 film as insulation structure

To develop a thin film force sensor on AISI 5140 steel surface, alternating stack thin films of silicon nitride and alumina were sputtered on the 5140 steel surface as the insulating structure before NiCr thin film electrodes were deposited. The insulation was investigated by measuring the resistance between different electrodes. The sample cross-section was examined and a nano-scratch test was carried out. Finally, a Ni80Cr20 thin film strain gauge was formed on the surface of a well-insulated sample with a hard masque, and its force (0 ∼ 250 kN and 0 ∼ 500 N) and temperature (25 °C ∼ 200 °C) responses were investigated. The results show that the alternating four-layer Si3N4/Al2O3 thin film structure can provide insulation close to 1.2 GΩ with a thickness of 2360 nm. The insulation layers have fine adhesion to 5140 steel, and there is no significant inter-layer diffusion which indicates the integrity of the multi-layer structure. The resistance strain coefficient of the sensor is 1.57 ∼ 1.67, and the resistance temperature coefficient is 190.3 ppm/ °C.

Capacitive response of nanoporous HMDSO film coated interdigited electrodes towards VOCs molecules

In this paper, nano-porous thin films capacitive-type sensors have been fabricated for the detection of volatile organic compounds (VOCs) using the micro sized interdigitated electrodes (IDEs). The sensitive layers were elaborated from hexamethyldisiloxane (HMDSO) using plasma enhanced chemical vapor deposition (PECVD) technique. The choice of HMDSO polymer as sensitive layer is based on its low dielectric constant compared to analytes ones. The sensing performances of plasma polymers were strongly correlated to their chemical and physical properties, which depend directly on the plasma polymerization conditions including monomer pressure. The sensor sensitivity was at its highest value of 0.32, 0.24 and 0.20 pF/ppm towards methanol, ethanol and acetone, respectively, for the device fabricated with the smallest gap (36 µm) and higher monomer pressure (50 Pa). Chemical and morphological structures of the elaborated thin sensitive layers have been investigated by Fourier transform infrared spectroscopy (FTIR) and atomic force microscopy (AFM) and scanning electron microscope (SEM), respectively.

The Performance of V2O5:Ag Nanoparticles as Thin Film and Bulk Pellet Sensor for NO2 and NH3 Detection

A comparison of gas sensing performance of V2O5:Ag nanoparticles as thin film and as bulk pellet toward NO2 and NH3 is presented. V2O5:Ag nanoparticles thin films were deposited by vacuum thermal evaporation method on glass substrates while the pellets were prepared by powder technology. XRD patterns of thin film and pellet were polycrystalline with an orthorhombic structure. The value of average grain size is about 60 nm. The morphological properties of the samples have been distinguished by atomic force microscopy (AFM) and field effect scanning electron microscopy (FESEM) which indicated that the films showed homogeneous surfaces morphology and contained pores between the grains. Sensing results showed a various response to NO2 and NH3 gases. It was found that the sensitivity of thin films sensor is superior to that of the pellets sensor.

Effect of Fractal Topology on the Resistivity Response of Thin Film Sensors.

We discuss the effect of topological inhomogeneity of very thin metallic conductometric sensors on their response to external stimuli, such as pressure, intercalation, or gas absorption, that modify the material's bulk conductivity. The classical percolation model was extended to the case in which several independent scattering mechanisms contribute to resistivity. The magnitude of each scattering term was predicted to grow with the total resistivity and diverge at the percolation threshold. We tested the model experimentally using thin films of hydrogenated palladium and CoPd alloys where absorbed hydrogen atoms occupying the interstitial lattice sites enhance the electron scattering. The hydrogen scattering resistivity was found to grow linearly with the total resistivity in the fractal topology range in agreement with the model. Enhancement of the absolute magnitude of the resistivity response in the fractal range thin film sensors can be particularly useful when the respective bulk material response is too small for reliable detection.

A thin acoustic touchless sensor using flexural vibration

This paper investigates a thin sensor used to detect the position of an object in front of an ultrasonic transducer using changes in the radiation impedance. The sensor consists of a rectangular plate and a piezoelectric transducer, and the configuration is determined based on the results of a finite element analysis simulation. Stripe flexural vibration modes are generated on the plate, radiating sound waves into the air between the plate and the object. The radiation angle of these sound waves is dependent on the driving frequency, resulting in a change in the sound field and the electrical admittance characteristics. The sensing performance is examined using two resonant vibration modes. The sensor can determine the position of an object uniquely within a two-dimensional area, and the lower resonant mode gave a wider measurable range. The sensitivity is improved six-fold over that of our conventional sensor using the same sensing mechanism.

Evaluation of coplanar line type thin film magnetic field sensor with narrow slits

We have proposed coplanar line type thin-film magnetic field sensor with narrow slits. The slit is employed to flow more carrier current on the signal line by improving the impedance matching. Several sensors having 6, 10, 26, 36, and 50 μm slit widths were fabricated and evaluated from the phase and the amplitude of the transmission coefficient (S21) and reflection coefficient (S11) measured by the network analyzer. The amplitude of S21 with slit was improved about five times larger than the sensor without one at around 2 GHz. The appropriate slit width was evaluated as around 10 μm for the coplanar line type thin film magnetic field sensor and the sensitivity will enhance more than 10 times higher than the sensor without slits.

Effect of Rapid Thermal Annealing on Material, Electrical, and Sensing Characteristics of Ag-Doped CaTiO3-CuO Thin Film Carbon-Dioxide Gas Sensors

The effect of rapid thermal annealing (RTA) on CO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> sensing characteristics of RF-sputtered and Ag-doped CaTiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> -CuO thin films has been studied in this work. The surface morphology, grain size, surface chemical states, <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">I–V</i> characteristics, and sensing ability of the films, have been evaluated for postdeposition RTA at different temperatures (400 °C–600 °C) and time (0–60 s). As the annealing temperature was raised, crystallinity improved and the grain size increased. Indeed, XRD revealed that RTA resulted in strong crystallographic orientation in the films. XPS analysis revealed no changes in the oxidation states and chemical composition of the material. <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">I–V</i> measurements show that the resistance of the film decreases as RTA temperature increases. On the other hand, the sensing characteristics reveal an optimum grain size for the best sensitivity. The films annealed at 500 °C for 60 s, leading to a grain size of about 10 nm, display the highest sensor response of 54%, when exposed to 1000 ppm of CO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> .

Polymeric Nanofibriller Matrix on ITO Substrate for Flexible Chemical Sensing Applications

The authors present here a facile electrochemical approach to synthesize Poly(Aniline) nanofibriller matrix on ITO coated PET substrate for development of wearable or embeddable sensors. Electrochemical parameters were optimized for even diametric synthesis and controlled length of Poly (Aniline)) nanofibers. A three – step chrono potentiometric deposition was found to be efficient for the synthesis of the matrix. Precise tuning of galvanic conditions during the synthesis process was highly effective and repetitive towards controlling the nucleation of Poly (Aniline) seeds on the substrate that serves as the basis of nanofibers with presumable diameter range. Charge conduction behaviour of the matrix was studied via Linear Sweep Voltammetry and a semiconducting nature was observed. The synthesized nanofibrillar sensor platforms were subjected to Scanning Electron Microscopy (SEM), UV-VIS Spectroscopy and FTIR spectroscopy for elucidation of morphological and structural aspects. The distribution of nanofibers network throughout the substrate was uniform and dendritic. Flexibility characteristics of the sensors were studied by bending the sensor to different radii and in-situ monitoring of resistance. The synthesized sensor platforms were subjected to NO2 sensing in chemiresistive mode under dynamic conditions to investigate the applicability of the same under real-time applications. Upon exposure to different concentrations of NO2, the devices exhibit a rapid response at concentrations as low as 1 ppm. The betterment in overall sensing behaviour in comparison to conventional thin film type sensors could be attributed to the one-dimensional structure of nanofibers leading to effective diffusion on analyte molecules and low scattering loss during charge transport. These flexible sensors can be interesting for novel mobile applications.

An experimental study on the frost formation over a flat plate: Effect of frosting on heat transfer

Frost accumulation on cooled surfaces generates thermal barrier between the surface and air. Apart from the frost layer thickness, the thermal properties of the frost also affect its heat transfer characteristics. In this experimental study, the effect of the frosting on heat transfer is investigated at different cold surface temperatures and at different air velocities in a closed loop wind tunnel. A large number of experiments is performed by altering the parameters of free stream air velocity, relative humidity, and cold plate temperature. Frost layer impact on heat transfer rate is measured through a high precision thin film heat flux sensor for 60 min. Accordingly, heat flow was significantly obstructed due to frosting. The rate of diminishment in the heat flux was not found to be constant over time but shows a decreasing trend. Furthermore, an enhancement on the heat transfer was reported during the early stage of frost formation under certain environmental conditions, majorly due to the increase in effective heat transfer area induced by ice crystals and corresponding increase in latent heat generation. The densification of the frost layer and its effect on the total thermal resistance was discussed. Based on the convective heat and mass transfer balance over the frost layer, frost surface temperature was predicted. Lastly, a correlation for estimating the heat transfer decrease during frosting is proposed via non dimensional numbers.

Effect of Mn doping on electrochemically synthesized Mn-La2O3 thin films non-enzymatic glucose sensor

Effect of Mn doping on electrochemically synthesized Mn-La2O3 thin films non-enzymatic glucose sensor

Results obtained with FBK pixel sensor prototypes for the HL-LHC tracker upgrade of the CMS experiment

The High Luminosity Phase of the CERN Large Hadron Collider (HL-LHC) will require an extensive upgrade of the CMS Inner Tracking system based on high radiation tolerant silicon pixel sensors capable of withstanding fluences up to 23 × 1015 neq/cm2 (1 MeV equivalent neutrons). Thin planar and 3D pixel sensors have been recently selected by CMS to be installed in the upgraded pixel tracker. Thanks to their structure, the 3D pixel sensors have some advantages with respect to planar ones, and are presently more suitable candidates for the innermost layer of the tracker. In this presentation results obtained with FBK planar and FBK 3D sensors readout by prototype read-out chip RD53A will be shown. Both sensor types have 25 × 100 μm2 pitch and 150 μm thickness, and they were manufactured in collaboration with INFN. The sensors readout by the chip were irradiated to several fluences up to the one foreseen for HL-LHC. The analysis of collected data shows very high hit detection efficiency and good spatial resolution as measured after irradiation.

METHODS FOR REMOTE QUALITY CONTROL OF COMPOSITES WITH ORGANIC AGGREGATES

The Chinese construction industry has been using the Internet of Things (IoT) to monitor building materials and structures for many years. The achievements of the Chinese construction industry in IoT applications can be used to study and monitor the performance of building materials, including green buildings (energy-efficient building materials).&#x0D; The aim of research: study and optimization methods for remote quality control of composites with organic aggregates.&#x0D; With the help of the developed methods, the following dependencies were obtained: dependences of stresses inside composites with organic aggregates on external influences obtained using a sensor Keyes brick thin film pressure sensor, dependences of deformations inside composites with organic aggregates on external influences obtained using a sensor ultrasonic ranging sensor, dependences of humidity inside composites with organic aggregates on external influences obtained using a sensor Soil moisture sensor, dependences of rheology (cement paste setting time) obtained using a sensor Ph-sensor module.

Effect of MWNT concentration on hydrogen gas sensing property of MWNT-ployaniline composite

In this present work, we have synthesized conducting MWNT/PANI nanocomposite using in-situ oxidative polymerization at low temperatures. The MWNT content has been varied in the PANI matrix within the range of 2 wt%, 5 wt%, 7.5 wt%, and 10 wt% and characterized the physicochemical properties using XRD, SEM, TEM, and I–V plots. The MWNT loading effect on the gas sensing properties of MWNT-PANI composite for hydrogen (H2) was analyzed by preparing chemiresistor type gas sensors. The XRD, SEM, TEM, and electrical measurements clearly show that the properties like crystallite, conductivity, stability, and morphology of composite material have been affected and improved after MWNT addition to the PANI matrix. The sensor performance at different temperatures was tested by monitoring the variation in resistance of the chemiresistor after hydrogen gas exposure. We found that the more sensitivity and fast response of Hydrogen gas (500 ppm) for 10% MWNT/PANI is 2.1 with response time 150 s. It has been observed that the sensing behavior of MWNT/PANI thin film suitable sensor for the detection of Hydrogen gas at low temperatures.

Human–Machine Interaction through Advanced Haptic Sensors: A Piezoelectric Sensory Glove with Edge Machine Learning for Gesture and Object Recognition

Human–machine interaction (HMI) refers to systems enabling communication between machines and humans. Systems for human–machine interfaces have advanced significantly in terms of materials, device design, and production methods. Energy supply units, logic circuits, sensors, and data storage units must be flexible, stretchable, undetectable, biocompatible, and self-healing to act as human–machine interfaces. This paper discusses the technologies for providing different haptic feedback of different natures. Notably, the physiological mechanisms behind touch perception are reported, along with a classification of the main haptic interfaces. Afterward, a comprehensive overview of wearable haptic interfaces is presented, comparing them in terms of cost, the number of integrated actuators and sensors, their main haptic feedback typology, and their future application. Additionally, a review of sensing systems that use haptic feedback technologies—specifically, smart gloves—is given by going through their fundamental technological specifications and key design requirements. Furthermore, useful insights related to the design of the next-generation HMI devices are reported. Lastly, a novel smart glove based on thin and conformable AlN (aluminum nitride) piezoelectric sensors is demonstrated. Specifically, the device acquires and processes the signal from the piezo sensors to classify performed gestures through an onboard machine learning (ML) algorithm. Then, the design and testing of the electronic conditioning section of AlN-based sensors integrated into the smart glove are shown. Finally, the architecture of a wearable visual-tactile recognition system is presented, combining visual data acquired by a micro-camera mounted on the user’s glass with the haptic ones provided by the piezoelectric sensors.

Effect of annealing treatment on response characteristics of Pd-Ni alloy based hydrogen sensor

The response rate and anti-interference performance are crucial to the detect performance for Pd-based hydrogen sensors. In this study, a resistance- type palladium-nickel (Pd90Ni10) thin film hydrogen sensors were prepared by the ion beam sputtering method. Sensors with an optimized Pd90Ni10 thickness (90 nm) which showed the fastest response for hydrogen were selected to study the effect of annealing treatment to the response rate and anti-interference performance. Four groups of samples were annealed at 250°C, 300°C, 350°C, and 400°C in air atmosphere for 4 hours, respectively. The impact of annealing treatment on base resistance stability and hydrogen response characteristics were studied. SEM, EDS and XRD analysis were carried out to reveal the relationship between response characteristics and microstructures. Results show that annealing treatment was beneficial to the base resistance stability and response rate. Samples annealed at 350°C showed the best base resistance stability and response rate. Furthermore, the difference of response rate ∆ was improved for the annealing treatment, indicating the improvement of the hydrogen sensor regarding the anti-interference effect to other gases. Meanwhile, a new mechanism including mutli-factors of Pd-Ni alloy about the anti-interference of oxygen was proposed based on our study. Besides, the sensors with the optimized fabrication process were tested in mixed standard gas with various hydrogen concentrations. This work provides an outstanding guidance to fabricate of hydrogen sensors of high response rate and anti-interference performance.

Review of current ECG consumer electronics (pros and cons)

BackgroundSeveral wearable, medical-grade consumer ECG devices are now available and integrated into consumer electronics like multi sensor fitness watches and scales. Specific consumer ECGs can also come in the form of patches or thin sensor plates in credit card or other shapes. Watches with ECG capabilities are often multi vital sign sensor devices. The majority of these devices are usually connected to a mobile smartphone. However, there are pros and cons to their use. MethodsWe review here an exemplary selection of modern consumer ECG devices based on device type, recording method and the number of standard ECG channels derived. ResultsSingle-channel consumer ECG devices such as Smart Watches can be useful for detecting and monitoring atrial fibrillation and flutter and other arrhythmias, as well as ectopic complexes. However, they are currently limited with respect to recording duration and information content (a single-channel or limb‑lead ECG having less diagnostic information than a 12‑lead ECG). While some non watch-based consumer ECG devices can now record all 6 limb leads to yield increased information, no consumer ECG devices can currently reliably detect ST-segment deviations, potentially indicating myocardial infarction or ischemic episodes. Moreover, barriers to use still exist for at-risk elderly people. Finally, there currently is no universal data exchange format. ConclusionConsumer ECG devices, whether in fitness or fashionable design, allow for reliable detection of atrial fibrillation. Timely detection of atrial fibrillation and subsequent treatment might protect against stroke, especially in high-risk groups, yet prospective evidence is still lacking. Six-channel consumer ECG and longer data collection capabilities extend potential functionality, including for the monitoring of ST-segments and QT intervals. However, no currently available devices are sufficiently suitable for the detection of myocardial infarction or ischemia, which is why portable 12-channel technologies are desirable. For the reliable detection of a myocardial infarction, the determination of specific myocardial infarction blood markers and evaluation of patient medical history still is indispensable in addition to the 12 lead ECG.

Knock sensing and imaging from structural bending waves

This paper presents a novel knock imaging technique for human-to-things interfaces. It allows any object to use its own surface as an imaging sensor. The methodology is to sense the structural bending waves caused by the knock and reconstruct the intensity image through the beamforming of the wave signals. To verify this, we prepare a thin piezoelectric sensor array on a square plate. The performances are evaluated by measuring the beam peak, beamwidth, and sidelobe level in the reconstructed image. Finally, a real finger knock test is demonstrated, showing an image reconstruction that the position error is only 3 mm.

Grating-Based Surface Plasmon Resonance Sensor for Visible Light Employing a Metal/Semiconductor Junction for Electrical Readout

In this study, we proposed an electrical readout surface plasmon resonance (SPR) chemical sensor coupled with visible light to avoid significant light absorption of water. A gold (Au) diffraction grating with a submicrometer pitch, designed using the rigorous coupled-wave analysis (RCWA) method to have a submicrometer pitch and 30-nm-tall Au grating, was fabricated on an n-type silicon (n-Si) substrate by nanofabrication/microfabrication. The hot electrons generated by SPR on the grating are converted to photocurrent at the Schottky barrier at the Au/n-Si interface. The Schottky barrier height was estimated based on the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$I-V$ </tex-math></inline-formula> characteristics of the device to be <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$q{\Phi}_{\mathrm{B}} = 0.72$ </tex-math></inline-formula> eV. The peak shift of photocurrent was observed to be consistentwith the SPR theory when the concentration of glucose aqueous solution changed the refractive index on the Au grating. Assuming that the incident wavelength and angle were fixed, a noise analysis revealed a refractive index resolution of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$3.4-4.0 \times 10^{-5}$ </tex-math></inline-formula> refractive index unit (RIU). Since this structure eliminated bulky optics in SPR experiments, it would contribute to the realization of a thin single-chip label-free chemical sensor.

Characterization of 150 μm thick silicon microstrip prototype for the FOOT experiment

The goals of the FOOT (FragmentatiOn Of Target) experiment are to measure the proton double differential fragmentation cross-section on H, C, O targets at beam energies of interest for hadrontherapy (50–250 MeV for protons and 50–400 MeV/u for carbon ions), and also at higher energy, up to 1 GeV/u for radioprotection in space. Given the short range of the fragments, an inverse kinematic approach has been chosen, requiring precise tracking capabilities for charged particles. One of the subsystems designed for the experiment will be the MSD (Microstrip Silicon Detector), consisting of three x-y measurement planes, each one made by two single sided silicon microstrip sensors. In this document, we will present a detailed description of the first MSD prototype assembly, developed by INFN Perugia group and the subsequent characterization of the detector performance. The prototype is a wide area(∼ 100 cm2) single sensor, 150 μm thick to reduce material budget and fragmentation probability along the beam path, with 50 μm strip pitch and 2 floating strip readout approach. The pitch adapter to connect strips with the readout channels of the ASIC has been implemented directly on the silicon surface. Beside the interest for the FOOT experiment, the results in terms of cluster signal, signal-to-noise ratio, dynamic range of the readout chips, as well as long-term stability studies in terms of noise, are relevant also for other experiments where the use of thin sensors is crucial.