Fast fabrication of large area concave microlens arrays

A single-step process for rapid fabrication of large-area concave microlens arrays using a diode-pumped solid state (DPSS) laser operating at 473 nm is developed. Using tartrazine sensitized gelatin layer treated with tot’hema - mixture of iron (II)-, manganese (II)- and copper(II)gluconate- (denoted short as tSTG) and a direct laser writing device developed in our laboratory, we could produce 10 000 uniform microlens arrays within 30 min. Uniform microlenses with different diameters and depth can be produced by varying the laser power, exposure time and dye concentration

THE TASK OF THE NEW SCIENCE

Industrial developments, primarily followed by quantitative growth without influence of a qualitative component of creation, raise the question of the survival of the community itself. New science should find the solution of environmental development of modern society, i.e. to contribute to the development of qualitatively different formula of life

Three dimensional mathematical model of tooth for finite element analysis

Introduction. The mathematical model of the abutment tooth is the starting point of the finite element analysis of stress and deformation of dental structures. The simplest and easiest way is to form a model according to the literature data of dimensions and morphological characteristics of teeth. Our method is based on forming 3D models using standard geometrical forms (objects) in programmes for solid modeling. Objective. Forming the mathematical model of abutment of the second upper premolar for finite element analysis of stress and deformation of dental structures. Methods. The abutment tooth has a form of a complex geometric object. It is suitable for modeling in programs for solid modeling SolidWorks. After analyzing the literature data about the morphological characteristics of teeth, we started the modeling dividing the tooth (complex geometric body) into simple geometric bodies (cylinder, cone, pyramid,...). Connecting simple geometric bodies together or substricting bodies from the basic body, we formed complex geometric body, tooth. The model is then transferred into Abaqus, a computational programme for finite element analysis. Transferring the data was done by standard file format for transferring 3D models ACIS SAT. Results. Using the programme for solid modeling SolidWorks, we developed three models of abutment of the second maxillary premolar: the model of the intact abutment, the model of the endodontically treated tooth with two remaining cavity walls and the model of the endodontically treated tooth with two remaining walls and inserted post. Conclusion Mathematical models of the abutment made according to the literature data are very similar with the real abutment and the simplifications are minimal. These models enable calculations of stress and deformation of the dental structures. The finite element analysis provides useful information in understanding biomechanical problems and gives guidance for clinical research

Application of tot’hema eosin sensitized gelatin film for adaptive microlenses

In this paper we showed that tot’hema eosin sensitized gelatin (TESG) film can be used for adaptive microlenses fabriacation. The mechanical properties of a pure gelatin film were improved by adding tot’hema solution. We found that the elasticity of TESG film depend on the tot’hema concentration. By stretching the film, the microlenses were deformed uniaxially, and microlenses focal length can be tuned. The achieved microlenses focal lengths range from 0.05 to 0.2 mm

Characterization and Optimization of Real-Time Photoresponsive Gelatin for Direct Laser Writing

There is an abundance of plastic materials used in the widest range of applications, such as packaging, machine parts, biomedical devices and components, etc. However, most materials used today are non-decomposable in the environment, producing a huge burden on ecosystems. The search for better, safer alternatives is still on. Here we present a detailed analysis of a simple, cheap, non-toxic, even edible, eco-friendly material, which can be easily manufactured, laser patterned and used for the fabrication of complex structures. The base substance is gelatin which is made photoresponsive by adding plasticizers and sensitizers. The resulting films were analyzed with respect to their optical, thermal and mechanical properties, which can be modified by a slight variation of chemical composition. The material is optimized for rapid laser-manufacturing of elastic microstructures (lenses, gratings, cantilevers, etc.) without any waste or residues. Overall, the material properties were tailored to increase photothermal responsivity, improve the surface quality and achieve material homogeneity, transparency and long-term stability (as verified using electron microscopy, infrared spectroscopy and differential scanning calorimetry)

Detection of high pressure phase transitions in RE3+ doped Y2O3 and Y2MoO6 through luminescence measurements

Rare earth ions (RE3+) are highly sensitive to local symmetry so changing the symmetry is reflected in their luminescence spectra. In this work we investigated the high pressure photoluminescence properties of cubic and monoclinic Y2O3, as well as, monoclinic Y2MoO6, doped either with Eu3+ or Sm3+ ions. Photoluminescence emission of cubic Y2O3 :Sm3+ and Y2O3 :Eu3+ phases were recorded up to the pressure of 20 GPa and 15 GPa, respectively. With varying pressure, the intensity ratio of 4G5/2 → 6H7/2 and 4F3/2 → 6H7/2 Sm3+ emission shows three distinct regions. Furthermore, the intensity ratio of 5D0 → 7F1 and 5D0 → 7F2 Eu3+ emission of the cubic matrix has similar pressure dependence as Sm3+ doped phase. A steep pressure dependence evident in the range of 9.2-13.1 GPa could be used for detecting a pressure induced cubic to monoclinic phase transition of Y2O3 matrix. It matches well the behavior of the pressure sensitive Sm3+ spectra in the range of 9.1-11.6 GPa, which is proven to appear due to a phase transition at ~ 11 GPa. The monoclinic Y2O3 :Eu3+ also has a pressure-sensitive intensity ratio of 5D0→7F1 and 5D0→7F2 emission lines. Measurements for the monoclinic Y2O3 :Eu3+ matrix were recorded up to 8 GPa. The dependence is unambiguous, without any phase transitions in the measured region. The nature and high sensitivity suggests that this dependence can be used as an efficient high pressure sensor. Photoluminescence emission measurements of Y2MoO6:Sm3+ and Y2MoO6:Eu3+ phases were recorded up to 12 and 11.5 GPa, respectivelly. Intensity ratio variation of 4G5/2→6H5/2 and 4G5/2→6H7/2 Sm3+ emission lines, as well as of 5D0 → 7F1 and 5D0 → 7F2 Eu3+ emission lines as a function of pressure can be also used for detection of the Y2MoO6 phase transition. The accomplished results demonstrate the properties of Y2MoO6:Sm3+ and Y2MoO6:Eu3+ inorganic phosphors, with emmision linear dependance of the intensity ratio on the pressure up to 8 GPa, could be used as an efficient high pressure sensor.VII Serbian Ceramic Society Conference - Advanced Ceramics and Application : new frontiers in multifunctional material science and processing : program and the book of abstracts; September 17-19, 2018; Belgrad