Various segments of the wireless industry continue to make for attractive investments. The latest: Nitronex raises $21.8 million; Vocel increases its purse from an existing investor; and The MicroOptical Corporation attracts funds for its video eyewear product.

Nitronex closed $21.8 million in venture funding led by Alloy Ventures. Nitronex develops and manufactures RF power transistors for the commercial and broadband wireless infrastructure markets. The company plans to use the funds to complete the development and expand manufacturing of several new products; accelerate hiring; expand into new global markets; and take advantage of emerging opportunities in cellular, WiMAX and broadband.

Mobile content delivery company Vocel closed additional funding from Torstar Corporation. Although terms of the funding agreement were not disclosed, Vocel says it intends to use the funds to help fuel future growth if its Interactive Commerce Accelerator (INCA) mobile marketing and promotion engine, which launched last week with Qualcomm and Midwest Wireless.  INCA technology is designed to enable mobile phone users to purchase content, including ringtones, wallpaper and games, with just one click.

The MicroOptical Corporation closed $11.5 million in financing, led by Atlas Venture. The funding will be used to accelerate manufacturing operations for the myvu video eyewear product, which is designed to transform the user's portable video experience by creating a large-screen effect integrated into eyeglasses. The technology works with a range of portable devices, including video-enabled wireless handsets. The larger screen in the myvu video eyewear makes it easier to watch any video, the company explains. The Hillman Company, Intel Capital and Turner Broadcasting also participated in the round.