Search Results (5)

This article focuses on the properties of the BaCeO₃ thin films formed by electron-beam vapor deposition and investigates the formation of barium cerates on supports with different thermal expansion coefficients (Stainless Steel, Invar, Glass Sealing, and Inconel substrates) and the influence of the technological parameters on the properties of the formed thin films with an emphasis on the stability of the films. Morphology and phase composition and mechanical and electrical properties were investigated. It was found that the main factors influencing the phase composition and morphology of the films are the temperature of the support and the deposition rate. However, the mechanical properties of the films are mostly influenced by strains introduced to thin films by using different supports. Two interesting features of the electrical properties of the studied strained films were noticed: the film with the highest in-plane tensile strain showed the lowest activation energy of total conductivity, whereas the film with the lowest strain showed the highest value of total conductivity. Full article

The objective of this study was to determine the characteristics of brush-painted Ag nanowires (NW) network electrode on a SiO₂ coated invar substrate for high performance curved thin film heaters (TFHs). To avoid influence of a conductive invar metal foil substrate, thin SiO₂ film was deposited on an invar substrate as an insulating layer. We measured sheet resistance, optical reflectance, and surface morphology of Ag NWs/SiO₂/invar as a function of the number of brush painting from one to four times. Optimized brush-painted Ag NWs network on a SiO₂/invar substrate showed a low sheet resistance 38.52 Ω/square, which was acceptable for fabrication of curved TFHs. Based on a lab-made bending and fatigue tester, critical radius of the optimized Ag NWs/SiO₂/invar electrode was found to be 6 mm. It demonstrated superior repeated flexibility of an Ag NW/SiO₂/invar substrate. Furthermore, we demonstrated the feasibility of using a brush-painted Ag NW/SiO₂/invar substrate as an electrode for curved TFHs. These curved TFHs fabricated on an Ag NW/SiO₂/invar substrate showed rapid heating properties and high saturation temperature even at low applied voltage due to low resistivity of Ag NW network. This indicates that a brush-painted Ag NW/SiO₂/invar substrate is a promising flexible electrode and substrate for high performance curved TFHs. Full article

We have studied characteristics of tin-doped indium oxide (ITO) films sputtered on flexible invar metal foil covered with an insulating SiO₂ layer at room temperature to use as transparent electrodes coated substrates for curved perovskite solar cells. Sheet resistance, optical transmittance, surface morphology, and microstructure of the ITO films on SiO₂/invar substrate are investigated as a function of the thickness from 50 to 200 nm. The optimized ITO film exhibits a low sheet resistance of 50.21 Ohm/square and high optical transmittance of up to 94.31% even though it is prepared at room temperature. In particular, high reflectance of invar metal substrate could enhance the power conversion efficiency of curved perovskite solar cell fabricated on the ITO/SiO₂/invar substrate. In addition, critical bending radius of the 150 nm-thick ITO film is determined by lab-designed outer and inner bending tests to show feasibility as flexible electrode. Furthermore, dynamic fatigue test is carried out to show flexibility of the ITO film on invar metal substrate. This suggests that the ITO/SiO₂/invar substrate can be applied as flexible electrodes and substrates for curved perovskite solar cells. Full article

Ultra-precision products which contain a micro-hole array have recently shown remarkable demand growth in many fields, especially in the semiconductor and display industries. Photoresist etching and electrochemical machining are widely known as precision methods for machining micro-holes with no residual stress and lower surface roughness on the fabricated products. The Invar shadow masks used for organic light-emitting diodes (OLEDs) contain numerous micro-holes and are currently machined by a photoresist etching method. However, this method has several problems, such as uncontrollable hole machining accuracy, non-etched areas, and overcutting. To solve these problems, a machining method that combines photoresist etching and electrochemical machining can be applied. In this study, negative photoresist with a quadrilateral hole array pattern was dry coated onto 30-µm-thick Invar thin film, and then exposure and development were carried out. After that, photoresist single-side wet etching and a fusion method of wet etching-electrochemical machining were used to machine micro-holes on the Invar. The hole machining geometry, surface quality, and overcutting characteristics of the methods were studied. Wet etching and electrochemical fusion machining can improve the accuracy and surface quality. The overcutting phenomenon can also be controlled by the fusion machining. Experimental results show that the proposed method is promising for the fabrication of Invar film shadow masks. Full article

A range of complex percutaneous procedures, such as biopsy or regional anesthesia, rely heavily on accurate needle insertion. Small variations in the mechanical properties of the pierced tissue can however cause deviations from the projected needle path and can thus result in inaccurate placement of the needle. Navigation of a rigid needle towards the target tissue is traditionally based on the surgeons capacity to interpret small variations in the needle insertion force. A more accurate measurement of these small force variations enables improvement in needle targeting, can potentially aid in enhancing force feedback in robotic needle placement and can provide valuable information on tissue-tool interaction. In this study we investigated several concepts for the design of a force sensor based on a fiber-optic Fabry-Pérot interferometer to measure needle-tissue interaction forces on the tip of a 18 G needle, where special attention was given to concepts for a sensor with (1), an intrinsic low cross-sensitivity to temperature and (2), elementary design and fabrication. Three concepts, using either a quartz capillary, an Invar capillary or a thin polyimide film as the force sensitive element were prototyped and subjected to both static and dynamic testing. The force transducer based on a quartz capillary presented the lowest cross-sensitivity to temperature ( $12\mathrm{m}\mathrm{N}{/}^{\circ }$ C) and good accuracy (maximum measurement error of 65 $\mathrm{m}\mathrm{N}$ /10 $\mathrm{N}$ ) in a measurement of static forces. However, limited strength of the sensor is expected to prevent usage of the quartz capillary in small diameter needles. The concepts for a sensor based on an Invar capillary or a thin polyimide film proved a higher cross-sensitivity to temperature ( $50\mathrm{m}\mathrm{N}{/}^{\circ }$ C and $220\mathrm{m}\mathrm{N}{/}^{\circ }$ C, respectively) and higher maximum measurement error (350 $\mathrm{m}\mathrm{N}$ /10 $\mathrm{N}$ , 800 $\mathrm{m}\mathrm{N}$ /10 $\mathrm{N}$ ), comparable to those of FBG-based sensors reported in literature, but are likely to be more suitable for integration in very small biopsy needles. Full article