Mri coil design and receiver system for ultra low field magnetic resonance imaging / Projeto e construção de um equipamento de imagens por ressonância magnética para uso em rotina clínica e em pesquisa

AUTOR(ES)
DATA DE PUBLICAÇÃO

2001

RESUMO

In this work current vs. voltage (I vs. V) and alternating conductivity (ac) measurements were carried out in poly[(2-methoxy- 5-hexyloxy)-pphenylenevinilene] ? MEH-PPV light-emitting diodes having zinc oxide (ZnO) as transparent anode and Al as metallic cathode. MEH-PPV is a PPV derivative, which emits in the red spectral region; ZnO has a work function similar to that of ITO, but it is less aggressive to the polymer, less expensive and easily processed. The retificated I vs. V curves shows that the direct current depends on the temperature. Moreover, the real and imaginary components of alternating conductivity (ac) present typical behavior of somewhat disordered material: the imaginary component grows as a function of the frequency and the real component was observed to be frequency independent for lower frequencies, and follows a power-law above a certain frequency. The Random Energy Free Barrier model approaches and a resistance in series for the interface phenomenon were developed and adjusted for the ac results. From this experimental-theoretical fitting we obtained important parameters of the devices as well as, quantitative informations about the MEH-PPV transport phenomenon.

ASSUNTO(S)

nuclear magnetic resonance instrumentação transdutores para imagem mri coil magnetic resonance imaging ressonância magnética imagem

ACESSO AO ARTIGO

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