Aerosol-Jet Printed Fine-Featured Triboelectric Sensors for Motion Sensing

Triboelectric motion sensors, based on the generation of a voltage across two dissimilar materials sliding across each other as a result of the triboelectric effect, have generated interest due to the relative simplicity of the typical grated device structures and materials required. However, these sensors are often limited by poor spatial and/or temporal resolution of motion due to limitations in achieving the required device feature sizes through conventional lithography or printing techniques. Furthermore, the reliance on metallic components that are relatively straightforward to pattern into fine features limits the possibility to develop transparent sensors. Polymers would allow for transparent devices, but these materials are significantly more difficult to pattern into fine features when compared to metals. Here, we use an aerosol-jet printing (AJP) technique to develop triboelectric sensors using a wide variety of materials, including polymers, which can be directly printed into finely featured grated structures for enhanced sensitivity to displacement and speed of motion. We present a detailed investigation highlighting the role of material selection and feature size in determining the overall resolution of the resulting motion sensor. A 3-channel rotary sensor is also presented, demonstrating the versatility of the AJP technique in developing more complex triboelectric motion sensors.European Research Council (ERC-2014-STG-639526, NANOGEN) Marie Sklodowska Curie Fellowship (H2020-MSCA-IF-2015-702868

Investigation of Ion Release from Ni-Cr Alloy in Various Acidity Conditions

Cytotoxicity is in direct correlation to the level of ion release, with non-precious alloys having higher ion release than that of precious alloys. The most often used non-precious dental alloy is Ni-Cr alloy. The aim of the investigation was to determine the type and quantity of ions released from Ni-Cr alloy (Wiron 99(r), Bego, Germany), in acid solutions with different pH values, and to determine the influence of the type of acid solution, its pH value, and duration of interaction on ion release. The overall sample consisted of 180 pieces of Ni-Cr alloy, 60 samples submerged in each of three different solutions (buffered phosphate solutions pH 3.5 and pH6, and lactic acid solution pH 3.5). Quantity of ion release was measured on solution samples taken at 10 different time intervals by means of the ICP-AES method. Average release of Ni ions in lactic acid solution was 432.42 μg/L, while the highest average Ni+ ions release of 541.67μg/L was measured in buffered phosphate solution pH 6.0. MANOVA demonstrated significant influence of the type of solution on Ni ion release (p<0.01), while the time of exposure was not a significant factor (p=0.23). Zn ions demonstrated the lowest average ion release (88.95 μg/L, phosphate solution pH 3.5). Statistically significant influence of the type of solution and pH value on ion release was determined, except for chromium ions (p<0.05). Dentobacterial plaque acidity is sufficient to start corrosion of Ni-Cr dental alloys

Trace Element (TE) Release from Two Different Base Alloys Unde Conditions Imitating Oral Saliva

Electrochemical conditions in the oral cavity lead to a release of metal ions into the patient\u27s saliva. The aim of this study was to examine and compare the types andquantities of metal ions released from two base alloys: Co-Cr-Mo alloy (WironitR, Bego, Germany) and Ni-Cr alloy (Wiron 99, Bego, Germany) under in vitro conditions imitating artificial saliva. We soaked ten sets of each alloy having 497 mm2 exposure surface for 1, 2, 3, 4, 5, 6, 7, 14, 21 and 30 days (six pieces each set) in phosphate buffered saline (pH 6.0). TE in the phosphate buffered saline (saliva) were assessed by ICP-AES (JY 50P, Jobin-Ywon, France) with the detection limit of 10 mg/L. We found detectable amounts (mg/L) of TE (Mean SD) released from Co-Cr-Mo alloy (Mean SD): Co 337 (170), Fe 21 (15) Zn 87 (56), Ni 41 (68), and Cr 49 (42) and detectable amounts of TE released from Ni-Cr alloy (Mean SD): Co 265 (300), Fe 247 (256) Zn 92 (46), Ni 542 (668), and Cr 396 (410). The manufacturer did not indicate the presence of Fe, Zn, and Ni in the Co-Cr-Mo alloy and the presence of Fe, Co and Zn, in the Ni-Cr alloy. A significantly higher amount of Fe, Ni and Cr was released from Ni-Cr alloy (p<0.05), and a considerably higher amount of Co was released from Co-Cr-Mo alloy, although it did not reach a statistically significant level (p>0.05), while there was no significant difference between the two alloys for Fe ion release (p>0.05). We must keep in mind that the amount of the released TE may be much higher than the reported values in this study, after the laboratory procedures (casting, polishing, etc.) and allergenic essential TE Cr, Co, and Ni may be present locally in a considerably higher amount

An Automated Environment for Hardware Testing Using PXI Instrumentation and LabVIEW Software

Reliable and fast testing was a requirement in the serial production of the advanced wireless microphone MIKME. Hence, a system for automatic testing, fully adapted for the product, was developed. The system comprises: 1) a specially designed test fixture – bed-of-nails, on which the device under test is placed, 2) the PXI platform and 3) an application developed in LabVIEW environment. Throughout the design of this system the goal was to achieve maximal automation of the entire test procedure in order to minimize the influence of human factor, and therefore save time and significantly reduce the possibility of error

Ratings of usability of didactic models: a comparative case study in Croatia and Germany

The study refers to the unfavourable reputation and status of general didactics as well as its decreasing importance in teacher education. This is a result of poor performance achieved in international tests by students. They score low on knowledge and arguments, and empirical studies indicate that didactic models are useless. In view of the above problem, the aim of this article is to examine the validity of the argument that didactic models are useless. It is necessary to examine if general didactics are being in an unfavourable position along with its possible successors in the international context. In order to achieve that, we conducted an empirical study into the usability of didactic models for lesson planning in Croatia and compared it with the results obtained in previous research in Germany. The term usability means the advantages of theory in practice. On the basis of the results of the empirical study, we concluded that didactic models are not generally unusable. Additionally, they are different according to their usability. These results open a path for further research on this topic in the international context