Biomarkers contained in human exhaled breath are closely related to certain diseases. As a noninvasive, portable, and efficient health diagnosis method, the breath sensor has received considerable attention in recent years for early disease screening and prevention due to its user-friendly and easy-accessible features. Although some key challenges have been addressed, its capability to precisely monitor specific biomarkers of interest and its physiological relevance to health metrics is still to be ascertained. In this context, we analyzed the rational design and recent advance of breath sensors for healthcare monitoring. This review begins with an introduction to exhaled breath biomarkers and their sensing technologies, such as chemoresistive, humidity-sensitive, electrochemical, and colorimetric principles. Then, a systematic overview of their emerging applications in early disease screening, drunk driving inspection, apnea monitoring, and exhaled breath condensate analysis are demonstrated. Finally, we discuss the challenges and opportunities of breath sensors for noninvasive healthcare monitoring. With the ongoing research efforts, the continuous breakthrough in breath sensors and their attractive applications is foreseeable in the future.
Keywords: breath sensors; disease diagnosis; exhaled biomarkers; healthcare monitoring; noninvasive method; portable electronics; sensing principles; sensor design.