An inventor who vanished after saying he was under attack over a groundbreaking technology is fine but keeping a low profile for his safety, according to his mother.

Julian Brown, 21, gained online notoriety thanks to his work in the energy field, particular the 'Plastoline' - a product he claims recycles plastic by turning it into gasoline.

The inventor, who lives in the Atlanta area and has 1.7million followers on Instagram, has not been heard from since July 9, when he posted a disturbing video claiming he was 'under attack.'

'Something is happening, keep me in your prayers please. SCREEN RECORD THIS. I don’t know,' Brown wrote on the post.

'I’m certainly under attack... I can’t go into so much detail,,' Brown said to the camera as he told his followers to 'keep your eyes open.'