a-Si:H p-i-n Photodiode as a Biosensor

The p-i-n a-Si:H photodiode is a promising device as a transducer in biosensors. The native and light-induced localized state density and energy distribution in the energy gap of a-Si:H have a large effect on the photoconductivity of thin-film photodiodes. Depending on their nature, they play a crucial role in trapping and recombination processes and consequently influence the photodiode capacitance. The optical bias dependence of modulated photocurrent, OBMPC, method using the blue LED light is applied to clarify the nature and energy distribution of the energy gap density of states and their influence on the photodiode capacitance, from photodiodes transient response. It is observed that the deep defect states of the i-layer contribute to the capacitance at various bias voltages. Also, the capacitance achieves the upper limit around the built-in potential. Based on this method and obtained results, the a-Si:H p-i-n photodiode is used as a biosensor transducer in the detection of mammalian cell chemiluminescence

E-COMMERCE IN ECOTOURISM

U radu je opisana e-trgovina zasnovana na promociji i prodaji turističkih usluga u ekoturizmu. Kontinentalni dio Hrvatske ima dobre predispozicije za razvoj ruralnog turizma i ekoturizma. Kao destinacija ekoturizma odabran je Park prirode Kopački rit, Općina Bilje i njezini stanovnici. Na stranicama Internet informacijskog servisa World Wide Web (WWW) predstavljeni su turistički proizvodi i usluge destinacije poput gastronomije, kulture, spomenika, običaja i prirodnih ljepota s posebnim naglaskom na promatranju ptica, kao i knjiga gostiju i smještaj. Na temelju izvršenih rezervacija gostiju zaključujemo da ekoturizam poprima sve veću važnost. Dobiveni rezultati ukazuju na Web kao dobro sredstvo promocije ekoturističke destinacije i na potrebu uvođenja e-trgovine u ekoturizam i turizam općenito.The e-commerce based on the promotion and sale of services in ecotourism, is presented. The whole of continental Croatia has a potential for development of rural tourism and ecotourism. As ecotourism destinations, the Natural park Kopacki rit and the town Bilje, with their inhabitants, have been chosen. The Internet service WWW site presents destination tourism products and services, for example, gastronomy, culture, monuments, customs and natural beauties, with a special emphasis on bird-watching, showing also a guest book and a booking page. The results confirm the Web as a good means of ecodestination promotion. Based on a number of bookings, we conclude ecotourism to gain increasing importance

Detection of photoresponse of cell culture medium by a:Si:H photodiode under blue light exposure

This work investigates the influence of blue light on cell culture medium that is crucial for developing a biosensor for tumor cells. To this aim, the cell culture medium, DMEM and Trypsin, and 50% solution of DMEM and Trypsin were posted on the surface of amorphous silicon photodiodes and the variation of their photocurrent as a function of time was recorded. Results show, dependently on DMEM and Trypsin concentration, a photocurrent degradation and its unexpected increase after the expected influence of the Steabler-Wronski effect. Based on this, it is possible to separate the responses of the part belonging to the photodiode from that belonging to the medium. This indicates that the blue light is effective in modifying the cell culture medium behavior. Therefore, we infer that the developed sensor will be a good choice for monitoring mammalian cells living in DMEM medium and their response to different treatments

Indium-zinc-oxide thin films produced by low-cost chemical solution deposition: Tuning the microstructure, optical and electrical properties with the processing conditions

Indium-zinc-oxide (IZO) films were prepared by spin coating an ethanol-ethylene-glycol precursor solution with a Zn/(In + Zn) ratio of 0.36 on glass. The effects of temperature on the structure, microstructure, electrical, and optical properties of the IZO thin films were investigated by thermal analysis, Fourier-transform infrared spectroscopy, X-ray diffraction, electron and atomic-force microscopy, X-ray photoelectron spectroscopy and variable-angle spectroscopic ellipsometry. The prepared IZO thin films heated at 500, 600, and 700 °C in air were transparent, without long-range ordering, and with an RMS surface roughness of less than 1 nm. The lowest electrical resistivity at room temperature, 0.0069 Ωcm, was observed for the 115-nm-thick IZO thin film heated at 600 °C in air and subsequently post-annealed in Ar/H2. The thin film exhibited a microstructure characterized by grains typically 20 nm in size and had no organic residues. This film exhibits uniaxial optical anisotropy due to its ultra-thin lamellae with a high electron density. The ordinary refractive index was fitted as a Tauc-Lorentz-Urbach function, which is typical of an indirect absorption edge occurring in amorphous semiconductor materials. The principal absorption peak with an onset at about 2.8 eV and a Tauc gap energy of ∼2.6 eV is similar to those observed for In2O3. The described process of chemical solution deposition and subsequent curing is promising for the low-cost fabrication of IZO thin films for transparent electronics, and can be used to tune the structure and microstructure of IZO thin films, as well as their electrical and optical properties