AUTHOR=Månflod Johan , Gumbel Tove , Winkvist Maria , Hämäläinen Markku D. , Andersson Karl TITLE=Smartphone-based drug testing in the hands of patients with substance-use disorder—a usability study JOURNAL=Frontiers in Digital Health VOLUME=6 YEAR=2024 URL=https://www.frontiersin.org/journals/digital-health/articles/10.3389/fdgth.2024.1394322 DOI=10.3389/fdgth.2024.1394322 ISSN=2673-253X