For the children who got the noisy reminders, that plunged to 9.5 per cent of the days.
Dr Doug Wilson, a former vice-president of an American pharmaceutical company who now chairs the company that makes the device, Nexus6, said: "If these results were from the use of a new medication, that would be the blockbuster medication of the decade."
Company founder Garth Sutherland, who was diagnosed with asthma six months after he was born in Hamilton 48 years ago and still suffers from it today, said: "For the first time we have shown some tremendous benefits with the smart inhaler."
"What we have is an audio-visual reminder on the smart inhaler that reminds the child, and often the parent too because the parent is often overseeing the medication for the child."
Amy Chan, a doctoral student who was the main organiser of the trial for Auckland University and also had asthma as a child, said the outcome was "hugely exciting".
"What we've been able to establish for the first time with this study is that the ringtone smart inhaler significantly improves adherence to preventative medication, which results in improved quality of life for children with asthma."
However the trial found the device had no significant effects on how often children missed school or had to go to hospital emergency departments.
The researchers, whose results will be published today in The Lancet Respiratory Medicine, said these effects were difficult to show because children missed school for many reasons and emergency department visits were rare.
The device clips on to standard asthma inhalers and also records when medication is taken so that patients, their parents and doctors can understand the reasons for any breathing problems.
At the time of the trial in 2010-2012 each device cost about US$220 ($285).
Nexus6 has raised $6.2 million in capital so far from private investors including Sir Stephen Tindall and Melbourne-based BioScience Managers, but Mr Sutherland said it would need to raise more capital this year to negotiate with inhaler manufacturers and funders such as Pharmac to market the device to asthma sufferers.
New Zealand has the world's second-highest rate of asthma, after Britain. A quarter of Kiwi children and a sixth of adults experience asthma symptoms during their lives.
Lilly Marchant can now jump on a trampoline without puffing, thanks to an asthma inhaler that reminded her when to take her medication.
Lilly, aged 10, used to have a coughing fit every time she went on the trampoline at her Te Atatu home.
"She would use the trampoline but she would just cough all the time," said her mother, Nicky Marchant.
"She couldn't really go for sleepovers because she would cough all the time.
She would just cough a lot, especially at night time. She pretty much had a constant cough for years.
"We were pretty much in and out of the doctor's and hospitals all the time. We went to heaps of different specialists."
But Lilly was one of a lucky 110 Auckland children who were given a "smart inhaler" in an Auckland University trial.
It was set to remind her to take her twice-daily puffs of preventive medication just before she cleaned her teeth at 8am and 7pm.
"It makes an animal noise, like a dog or something, and it does songs," she said.
And her coughing virtually stopped.
"It's pretty much all gone," Mrs Marchant said. "I think the puffer definitely made the difference - having the prevention, and remembering to have the prevention."
The device broke down three months after the trial ended, and Lilly does sometimes forget to take her puff again in the rush to get to school in the mornings.
On those days, "she'll start getting her cough back".
But she hasn't had a coughing attack bad enough to take her relief medication since last winter, and hasn't been to the hospital since the trial began.
More importantly, Mrs Marchant said: "She's done sleepovers and stuff now." And she can jump on the trampoline.
For more information see:
Smart Inhaler
The Lancet
