"I've always been immersed in the rugby culture and played quite a bit of rugby growing up, actually suffering concussions," Buchanan said.
"Rugby and concussion is a topical issue that is constantly under the spotlight.
"With wearable technology becoming an emerging trend in contact sport, I thought it was a perfect opportunity to combine my industrial design knowledge and look to find a solution to the problem."
Existing head gear only protected players against cuts and abrasions and not concussion, Buchanan said.
Mouthguards could help absorb the shock of a big knock, but it was debated whether they could prevent a concussion.
The design in the mouthguard, called NERVE, uses motion sensors which detect knocks to the head that are missed by the human eye.
If an athlete wearing the mouthguard is hit hard enough, the sensors communicate wirelessly to the team doctor's iPad or tablet.
Using an algorithm the risk is calculated by measuring the impact and where it was located and the player's previous concussion history to determine whether the player should return to play.
A Herald investigation into the links between rugby and dementia in March found a disproportionate number of former Taranaki rugby legends were suffering from the heartbreaking condition.
The common thread: concussion after concussion in their younger days playing professional rugby.
Head judge Mike Jensen said Buchanan's design addressed a topical issue for New Zealand sport and culture.
"We must be coming close to a culture change with an older generation of All Blacks linked with dementia.
"What is exciting about Spencer's design is that it is not one product, he's developed an entire system encompassing sensors in a fully sealed, non-corrosive mouthguard, a charger unit and an app."
Five New Zealand entries will progress to the international James Dyson Award competition with the chance to win the grand prize of $60,000 to put towards commercialising their idea.
