研究目的
To develop and demonstrate an array of optical fibre long period grating sensors for simultaneous in situ temperature and relative humidity monitoring in mechanical ventilators.
研究成果
The LPG array successfully monitored temperature and RH changes in mechanical ventilation with high sensitivity (0.46 nm/°C for temperature and 0.53 nm/RH% for humidity) and fast response times, enabling breath-to-breath measurements. It demonstrated potential for in situ monitoring to improve patient care by providing real-time data close to the lungs, which could help prevent complications like ventilator-associated pneumonia. Future work should focus on optimizing sensor parameters and expanding to multi-parameter sensing, including biomarkers.
研究不足
The study was conducted in a laboratory setting with a bench model; clinical validation in human patients is needed. The temperature range achieved was lower than body temperature (up to 35°C), indicating potential issues with ventilator equipment. The coating thickness and grating period may require optimization for higher sensitivity. Biocompatibility of materials, while addressed, needs further in vivo testing.
1：Experimental Design and Method Selection:
The study used an array of two long period gratings (LPGs) inscribed in an optical fibre, with one LPG coated with silica nanoparticles for RH sensitivity and the other left bare for temperature sensitivity. The sensors were operated in reflection mode using a fibre coupler and spectrometer. The layer-by-layer deposition method was employed for coating.
2：Sample Selection and Data Sources:
The sensors were tested in a bench model with a mechanical ventilator (NIPPY3+, B&D Electromedical Ltd) and inside an endotracheal tube to simulate clinical conditions. Data were collected using a CCD spectrometer.
3：List of Experimental Equipment and Materials:
Optical fibres (Fibercore PS750), tungsten-halogen lamp (Ocean Optics HL-2000), CCD spectrometer (Ocean Optics HR4000), fusion splicer (Fujikura 70S), fibre coupler (Newport F-CPL-S12785), temperature and humidity data logger (Maxim Integrated DS1923), chemicals (PAH, SiO2 nanoparticles SNOWTEX 20L, KOH, ethanol).
4：Experimental Procedures and Operational Workflow:
LPGs were fabricated using point-by-point and amplitude mask techniques. One LPG was coated with 10 layers of PAH/SiO2 nanoparticles. The array was spliced together, a gold mirror was sputtered on the tip, and it was calibrated in a Petri dish and tested inside an endotracheal tube with the ventilator operating at different breathing rates (8 and 15 breaths per minute). Reflection spectra were recorded every 500 ms.
5：Data Analysis Methods:
Central wavelengths of attenuation bands were tracked from the spectra. Sensitivity was calculated from calibration curves, and temperature effects were subtracted for RH measurements using the difference between coated and bare LPG responses.
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