Every day hundreds of people die when they accidentally overdose on opiate drugs, like heroin or morphine. These agents depress breathing, causing respiratory failure. But, if an opioid antidote is administered sufficiently quickly, then the situation can be reversed. And a team at the University of Washington have developed a system that turns a mobile phone into a sonar device that can monitor a person's breathing and then sound the alarm if something goes wrong. Chris Smith spoke with Jacob Sunshine, an anaesthesiologist and assistant professor at the University of Washington, to discuss... Like this podcast? Please help us by supporting the Naked Scientists