Noninvasive measurement of the vital signs of cancer patients with a dual-path microbend fiber sensor

A novel dual-path microbend fiber optic sensor is designed for noninvasive measurement of respiratory rate (RR) and heart rate (HR) for cancer patients. The performance of the microbend fiber sensor is assessed in two groups of cancer patients, cancer patients with pain and without pain, ranging from eighteen to ninety-six years old in a daily observational measurement with the sensor mattress under the mattress of the clinical bed. All the patients received standard clinical monitoring for evaluating the accuracy of our measurement results. The results of our study showed good consistency in the experimental results of RR and HR between the dual-path fiber sensor we proposed and the hospital equipment with average errors of 3.60 beats per minute (bpm) and 1.02 respiration per minute (rpm) in HR and RR measurement in cancer patients with pain and 1.87bpm and 1.27rpm in HR and RR measurement in cancer patients without pain, respectively. In HR monitoring, the single path microbend fiber optic sensor has 8035 minutes of data with a false report rate of 19.09%, while the dual-path microbend fiber optic sensor has 6188 minutes of data with a false report rate of 12.87%. The dual-path sensor has a smaller false report rate compared with the single path sensor due to pre-judgments of data with path 1 and path 2. To our best knowledge, it is the first time to propose and demonstrate a dual-path sensor to reduce the false report rate for HR and RR measurements. The results of the Blend-Altman method showed great agreement between our sensor and hospital standard monitor in HR and RR measurements. The independent sample t-test indicates that the HR of cancer patients may be an effective way to judge whether or not they have cancer pain. Our noninvasive dual-path microbend fiber sensor also showed the advantages of an easy fabrication process, simple structure, and low false report rate.