Former Liverpool keeper Loris Karius sustained a concussion in the 2018 Champions League final

Premier League footballers are taking part in a "ground-breaking" new concussion study this season that could lead to pitch-side diagnosis.

The study includes saliva and urine samples being taken from players with head injuries and uninjured 'control' players by club doctors after matches.

The samples are then put through a new test by University of Birmingham medics who are running the study.

It is hoped this will in time be done pitch-side using a handheld device.

"Having a black and white test that gives you a clear answer that's understandable to everyone - medical staff, players, coaches - is the holy grail," Dr Patrick O'Halloran, sports concussion research fellow at the University of Birmingham and academy doctor at Wolves, told BBC Sport.

"An objective test like this would be a game-changer and would really help at all levels of sport."

The 'Birmingham Concussion Test', which has been developed after a decade of research led by academic neurosurgeon Professor Tony Belli, looks for molecules in the blood, saliva or urine - known as microRNAs - that can act as biomarkers to indicate brain injury.

The team are developing a handheld device to conduct the test during a match and which will assist in concussion diagnosis and work out when those affected can return to play across sport.

"There will be a drop of saliva going on a chip and the chip is then inserted into a device, with the results sent to a mobile phone or tablet and the doctor would be able to see and interpret the results, possibly within a minute or two," said Prof Belli.

This study builds on ongoing research carried out by the University of Birmingham for the past two years in collecting and testing the urine and saliva of concussed Premiership and Championship rugby union players.

In November, MPs called on the government to introduce better concussion protocols in sport.

A report by the New York Hospital for Special Surgery external-link that month found concussion protocols in football were "ineffective" in almost two thirds of matches at the 2018 World Cup.

The Professional Footballers' Association said it "is and always has been committed to a duty of care" for all players" and has lobbied football authorities to "join with us on all aspects of health and safety in the game".

It added: "Neurological problems in later life - which may be connected to concussion, head injuries and heading the ball - have been on our agenda for the last 20 years."