  This paper presents a non-contact vital signs (respiration and heartbeat)
monitoring system that utilizes visible light sensing (VLS) technology. We have
for the first time demonstrated the ability to wirelessly (non-contact) sense
vital signs using only reflected incoherent light signals from a human subject.
The VLS-based system is implemented by using simple visible light source,
photodetector and data acquisition/processing unit, and is used with the
developed signal processing algorithms to turn slight variations in reflected
light power into accurate measurements of respiration and heart rate. To assess
the accuracy of our method, the results were compared with reliable
measurements using a contact-based monitoring device (ground truth). More than
94% of accuracy was observed in test results including both breathing and
heartbeat rates in different scenarios as compared to the state-of-the-art
baseline methods such as contact-based vitals monitoring devices. These
competitive results have demonstrated that VLS-based vitals monitoring
innovation is indeed a viable, powerful, attractive, low-cost and safe method.
This study represents a substantive departure from the traditional ways of
doing non-contact vitals monitoring methods (e.g., radio-frequency-based radars
and imaging-based cameras) and is poised to make big contributions to this
area. Since vital signs monitoring is a ubiquitous element of medicine, this
work would also impact the entire health care community, from patients in their
homes, to doctor's offices, to large medical institutions and industries. This
technology has potential to address numerous conditions and situations in which
vital signs are critical indicators such as sleep apnea and
human-computer-interaction applications.
