Check out our work on opioid overdose detection using smartphones https://www.technologyreview.com/s/612733/opioid-overdoses-could-be-prevented-by-an-app-that-listens-to-breathing/ https://www.scientificamerican.com/article/new-app-uses-sonar-to-detect-opioid-overdoses/ https://www.cnbc.com/2019/01/07/this-cellphone-app-can-detect-an-opioid-overdose-and-save-your-life.html