Experimental and theoretical investigation of sensing parameters in carbon nanotube-based DNA sensor.

Nowadays, sensitive biosensors with high selectivity, lower costs and short response time are required for detection of DNA. The most preferred materials in DNA sensor designing are nanomaterials such as carbon and Au nanoparticles, because of their very high surface area and biocompatibility which lead to performance and sensitivity improvements in DNA sensors. Carbon nanomaterials such as carbon nanotubes (CNTs) can be considered as a suitable DNA sensor platform due to their high surface-to-volume ratio, favourable electronic properties and fast electron transfer rate.

Generation of annular beam by a novel class of Fresnel zone plate.

We introduce a type of Fresnel zone plate (FZP) in which its phase is shifted radially outward. This FZP can easily and precisely turn an incident plane wave into an annular beam at its focal plane. High efficiency and flexibility are the advantages of generating doughnut beams by this method.