Wearable Biosensors and Remote Patient Monitoring: Sensing Technologies, Clinical Applications, and Challenges in Digital Health

Health care has long been organized around episodic encounters, a measurement taken in a clinic and then not repeated for weeks or months, yet most of what determines a patient's trajectory happens in the long intervals between visits. Wearable biosensors, worn continuously and non-invasively on the body, promise to close that gap by making physiological and biochemical measurement continuous, and remote patient monitoring (RPM) promises to carry those measurements to clinicians wherever the patient lives. This review surveys the field for an applied-medical-technology audience. We describe the sensing technologies, spanning physical signals such as heart rate, electrocardiography, oxygen saturation, and activity, and the newer biochemical sensing of glucose, lactate, and other markers in sweat and interstitial fluid, and the flexible, stretchable materials that make comfortable skin-worn devices possible. We map the RPM system architecture that connects sensor to clinician through the Internet of Medical Things, cloud computing, and increasingly AI-based analytics, and we review clinical applications across cardiovascular, respiratory, metabolic, renal, gastrointestinal, and wound care. We then take a deliberately balanced view of the evidence, which is genuinely promising in places yet, on the strongest reading, still thin: meta-analyses of randomized trials have often failed to show that monitoring alone changes hard clinical outcomes, and value appears to depend on how monitoring is embedded in care rather than on the device itself. Finally, we examine the barriers that stand between promise and routine practice, sensor accuracy and validation, data quality, privacy and security, interoperability with health records, equity and the digital divide, regulation, and sustained patient adherence, and we argue that these, more than any sensing limitation, now govern the field. The review is narrative and is weighted toward skin-worn devices for chronic-disease monitoring.