BRIAN Bellhouse, who has died aged 80, was a pioneering medical engineer who founded one of the most successful Oxford University spin out companies.

Professor Bellhouse's invention of a needle-less drug-injection gun would eventually lead to a US firm buying his company for £542m.

He described his PowderJect invention as being of 'Star Trek' like technology, similar to that used by Leonard 'Bones' McCoy in the science fiction show.

He set up Oxford University's medical engineering unit and ran it until his retirement in 2004.

Brian John Bellhouse was born on October 1, 1936 in Winchelsea, East Sussex to parents May and Francis Bellhouse, who ran a garage but later worked in the medical engineering department Brian founded at Oxford University.

He grew up in the area and was educated at Westminster Abbey Choir School, in London.

He sang in the choir at the Queen's wedding before moving to Rye Grammar School.

In 1957, after completing National Service, he studied maths at Magdalen College, Oxford, where he met his future wife Elisabeth Goldie when asked to give her and two friends a lift to a party.

The couple married the following year and would have six daughters, Elspeth, Cathy, Mary, Anna, Emily and Maggie, and a son, Tom, while living in the city.

He obtained his DPhil in the department of Engineering Science at Oxford in 1964 and was later appointed as a university lecturer in the same department.

In 1966 he was elected as a tutorial fellow at Magdalen College and became a professor of engineering science in 1998.

He set up the Department’s highly successful medical engineering unit, which he ran until he retired in 2004.

But it was his invention of a needle-less drug-injection gun that would make Mr Bellhouse famous and also make him his fortune.

He was working on a powdered injector to deliver genetic materials into plant cells during research in 1992 when he thought to apply it to humans.

When he was approached by young businessman Paul Drayson, the pair unlocked its commercial potential and the company PowderJect was born.

It would become the most successful Oxford University spin out company when it was sold to US company Chiron in 2003 for £542 million.

Through his financial success he supported the causes he cared about, including Oxford Children's Hospital – where there is now a Bellhouse-Drayson ward.

After the company's success he returned to the world of academia as head of the medical engineering unit he founded.

Mr Bellhouse played football and cricket for local and college teams into his 50s and also completed a double Atlantic sailing crossing with his sister and brother-in-law in 2004.

In his retirement he became a director of Woodruff Farm, which manufactures oils and fats, and bought several farms and pieces of land in Oxfordshire and Sussex on account of his passion for agriculture.

He died on June 12 after being trampled by cows trying to save his black Labrador Baldrick, while on a walk on his farm in Sussex.

He is survived by his wife Elisabeth, his seven children and 21 grandchildren.