Vital Signs Monitoring Using a New Flexible Polymer Integrated PPG Sensor

For remote registration of vital signs, non-invasiveness is attractive. The possibility of acute loss of consciousness threatens the lives of employees such as soldiers, fire fighters, police officers, and law enforcement personnel, who perform duties at hazardous or remote conditions. The brain cells die within three minutes after occurrence of hypoxia in cerebrospinal fluid. Consequently, acute occurrence of cardiac or pulmonary system failure reduces an employee’s likelihood of surviving due to the lack of ability for communication and the lack of ability for emergency calls. In the case of severe injury, a medic’s response time becomes a crucial parameter for increasing a person’s likelihood of survival. Continuous monitoring of vital signs therefore assists medics and employees by reducing response time to severe accidents. For detection of vital signs; electrocardiography, capnometry and pulse oximetry are being widely used as the golden standard for extraction of vital signs such as heart rate, respiration rate and blood oxygenation. But, these sensors require motionless attachment to specific areas of the body. The fact that employees are constantly in motion and sometimes covered by protection shields introduces difficulty concerning the continuous obtaining of vital signs. In this dissertation, we studied feasibility of replacing Electrocardiography by Photoplethysmography on mechanically flexible sensors. Three major studies were performed. First, we developed an algorithm for the detection of respiration rate from Photoplethysmography. During this study, a fast respond CO2 sensor was also modulated to detect respiration rate, and both methods were compared to respiration effort transducer. Second, we assessed the feasibility of fabricating PPG sensors on plastic polymers. During this study, we designed and integrated a novel PPG device, using inkjet-printing technology. At last, we developed a computationally inexpensive algorithm for the extraction of heart rate variability (HRV) from the morphology of PPG. Results were compared to HRV from commercial ECG and the performance of the device was evaluated respectively.