This paper presents a hydrogen sensor based on palladium-yttrium (Pd-Y) alloy nanosheet. Zigzag-shaped Pd-Y nanosheet with a thickness of 19.3 nm was deposited on a quartz substrate by using an ultrahigh-vacuum magnetron sputtering system and shadow mask. The atomic ratio of palladium to yttrium in the nanosheet was 0.92/0.08. The fabrication process was simple and low-cost, and the sensor can be mass-produced. The experimental results show the sensor has a superior sensitivity, reversibility, and reproducibility. The resistive-based hydrogen detection mechanism in this research is much simpler and more compact compared to the optical-based detection method.Griffith Sciences, Griffith School of EngineeringFull Tex

A miniature FBG vibration sensor with high performance and low angle dependence has been proposed and applied in the two-dimensional vibration measurement of a vibration isolation platform in this paper. Considering the bonding points with maxim replacement, the sensitivity and resonant frequency theoretical model of the elastomer and packaged small-diameter FBG were established. The genetic algorithm was utilized to achieve the globally optimized structure sizes under multiple constraints, while the modal simulation analysis was carried out to verify the result. A novel ‘figure of merit’ defined as the product of the resonant frequency, the sensitivity, and the inverse of package volume was proposed for the performance evaluation of the sensor in the unit space of its package. The first-order and second-order frequencies of its X/Y direction of 1105.4 Hz/1266.1 Hz, while the sensitivity is 127.861 pm/g and 116.668 pm/g, correspondingly. The cross-interference in the X/Y directions of the sensor is less than 2%. Moreover, the test results of the angle dependence of the sensitivity show that the sensor possesses consistent sensitivity in all directions of the 2-d plane, while the fitted sin functions in the X/Y direction have a high R ² of 0.99851 and 0.99831, respectively. Finally, the 2-D vector vibration measurement capacity of this sensor was demonstrated on a rubber spring vibration isolation platform. The results show that this miniature 2-D vibration sensor is suitable for medium-high frequencies vibration vector measurement and has a bright application prospect for the monitoring of machines.

In the present work, centrifugal deposited Au-Pd core-shell nanoparticle (NP) film was proposed for the room-temperature optical detection of hydrogen gas. The size dimension of 44, 48, 54, and 62 nm Au-Pd core-shell nanocubes with 40 nm Au core were synthesized following a solution-based seed-mediated growth method. Compared to a pure Pd NP, this core-shell structure with an inert Au core could decrease the H diffusion length in the Pd shell. Through a modified centrifugal deposition process, continues film samples with different core-shell NPs were deposited on 10 mm diameter quartz substrates. Under various hydrogen concentration conditions, the optical response properties of these samples were characterized by an intensity-based optical fiber bundle sensor. Experimental results show that the continues film that was composed of 62 nm Au-Pd core-shell NPs has achieved a stable and repeatable reflectance response with low zero drift in the range of 4 to 0.1% hydrogen after a stress relaxation mechanism at first few loading/unloading cycles. Because of the short H diffusion length due to the thinner Pd shell, the film sample composed of 44 nm Au-Pd NPs has achieved a dramatically decreased response/recovery time to 4 s/30 s. The experiments present the promising prospect of this simple method to fabricate optical hydrogen sensors with controllable high sensitivity and response rate at low cost.

Touch serves as an important medium for human–environment interaction. The piezoresistive tactile sensor has attracted much attention due to its convenient technology, simple principle, and convenient signal acquisition and analysis. In this paper, conductive beads-on-string polyvinyl alcohol (PVA)/polyaniline doped with dodecyl benzene sulfonic acid (PANI-DBSA) nanofibers were fabricated via the electrospinning technique. Due to the special nanostructure of PVA-coated PANI-DBSA, the tactile sensor presented a wide measuring range of 12 Pa–121 kPa and appreciable sensitivity of 8.576 kPa⁻¹ at 12 Pa~484 Pa. In addition, the response time and recovery time of the sensor were approximately 500 ms, demonstrating promising prospects in the field of tactile sensing for active upper limb prostheses.