A preferred carbon nanotube-based device (1) includes a substrate (10), a catalyst layer (30) disposed on the substrate, and a plurality carbon nanotube arrays (50, 51) extending from the catalyst layer. The catalyst layer includes a plurality of catalyst blocks (33, 34), a thickness of the catalyst block is varied gradually from a first end thereof to an opposite second end thereof, and the catalyst block having a region with a thickness approximate to an optimum thickness for growing carbon nanotubes. The carbon nanotube arrays are arc-shaped, and bend in respective directions deviating from the region of optimum thickness. A preferred method for making the carbon nanotube-based device is also provided.