Optical Humidity Sensor Using Fluorescent Plastic Fiber and Its Application to Breathing-Condition Monitor

Abstract

The plastic fiber humidity sensor, the mechanism of which is based on an ionization reaction between water vapor and the fluorescent dye-doped polymer cladding, was studied. The conditions under which to obtain the maximum sensitivity were derived from the theory and experimental data. Under these conditions, the fluorescent plastic fiber could be used as an excellent optical humidity sensor head with good linearity over the wide humidity range. Due to its reproducibility and fast response property, its application to a breathing-condition monitor became possible.

Compact and Low-Cost Optical Fiber Respiratory Monitoring Sensor Based on Intensity Interrogation

“…x=Moving Average (10)-Moving Average (60) X'=x/x max (2) Moving Average (10) represents a 10 point moving average signal. Time for 10 points = 1 s Moving Average (60) represents a 60 point moving average signal.…”

“…Respiratory rate is the frequency of breaths and it provides important indications related to the health or physiological state of a patient. Techniques used to detect respiration activity include humidity [1,2], temperature [3], and movement of the human torso [4] during breathing. Generally, respiration monitoring sensors can be classified into contact (wearable) and non-contact types.…”

Fiber-optic sensors for monitoring patient physiological parameters: a review of applicable technologies and relevance to use during magnetic resonance imaging procedures

“…13. 112,113 Under the dry-state conditions in Fig. 13(a), the refractive index of cladding layer, n 2 , is slightly larger than that of the PMMA fiber core (n 1 ¼ 1.489), and the sensor head is a leaky-type head.…”

Optical fiber sensor for humidity monitoring based on thermal lens detection technique

“…In contrast, an optical fiber humidity sensor has not been developed in spite of being much in demand for real-time humidity remote monitoring in several fields, such as industry, farming and medicine. To our knowledge, 1) an optical absorption-based optical fiber humidity sensor that uses the fluorescence from a laser-diode-pumped Tm 3+ :YAG [1] and 2) a humidity sensor using a plastic polymer-coated optical fiber [2,3], which causes change in the refractive index due to attachment of water molecules, have been proposed. Several optical fiber water droplet sensors have also been proposed and developed with the exception of these sensors [4,5].…”

“…To overcome this problem, sensor 2) was proposed [2,3] and it has an extremely simple configuration, thereby enabling low cost preparation. The feature of this sensor is that the response time of this sensor is fairly high compared with that of conventional electrical sensors, such as resistance changing types [3].…”