The proliferation of private, corporate and community Wi-Fi hotspots in city centers and residential areas opens up new opportunities for the collection of biomedical data produced by sensors carried by mobile non-hospitalized subjects. In this paper we investigate the possibility of using these many hotspots as gateways for biomedical data transmission. A disruption-tolerant application is presented, that can record biomedical data while the subject is not in the range of a Wi-Fi hotspot, and upload recorded data to a remote monitoring center whenever a hotspot is located nearby. Results of a field trial are presented, with a scenario involving a subject wearing an ECG-enabled sensor, walking in the streets of a residential area.