[1] [1] ARIFIN A, AGUSTINA N, DEWANG S, et al. Polymer optical fiber-based respiratory sensors：various designs and implementations[J]. Journal of sensors, 2019, 2019：7-12.

[2] [2] HALEEM A, AL-OBAIDY A H, HALEEM S. Air quality assessment of some selected hospitals within baghdad city[J]. Engineering and technology journal, 2019, 37(1)： 59-63.

[3] [3] ZHANG X, AI J W, ZOU R P. Compressible and stretchable magnetoelectric sensors based on liquid metals for highly sensitive, self-powered respiratory monitoring[J]. ACS applied materials and interfaces, 2021, 13(13)：15727-15737.

[4] [4] HATAMIE A, ANGIZI A, KUMAR S, et al. Review- textile based chemical and physical sensors for healthcare monitoring[J]. Journal of the electrochemical society, 2020, 167(3)：1-15.

[5] [5] SU K, YANG Y, ZHAO T, et al. A wireless energy transmission enabled wearable active acetone biosensor for non-invasive prediabetes diagnosis[J]. Nano energy, 2020, 74：104941.

[6] [6] BENNETT A. Monitoring of vital bio-signs by multimode speckle based optical fiber sensor[J]. Optics express, 2020, 28(14)：20830-20844.

[7] [7] ROSSOL S L, YANG J K, TONEY-NOLAND C, et al. Non-contact video-based neonatal respiratory monitoring[J]. Children, 2020, 7(10)：171.

[8] [8] DINH J B T, NGUYEN T, PHAN H P, et al. Stretchable respiration sensors：advanced designs and multifunctional platforms for wearable physiological monitoring[J]. Biosensor and bioelectronics, 2021, 166：112460.

[9] [9] HILL S H, ANNESLEY B. Monitoring respiratory rate in adults[J]. British journal of nursing, 2020, 29(1)：1-12.

[10] [10] HASSAN O, AL-AZAWI R, MAHDI B. Image processing technique for zinc ion sensing using a crystalline fiber sensor[J]. Engineering and technology journal, 2021, 39(10)：1539-1543.

[11] [11] HEMALATHA R, REVATHI S. Photonic crystal fiber for sensing application[J]. International journal of engineering advanced technology, 2020, 9(5)：598178.

[12] [12] MONFARED Y E, AHMADIAN A, DHASARATHAN V. Liquid-filled highly asymmetric photonic crystal fiber Sagnac interferometer temperature sensor[J]. Photonics, 2020, 7(2)：33.

[13] [13] SHAO M, SUN H, LIANG J, et al. In-fiber Michelson interferometer in photonic crystal fiber for humidity measurement[J]. IEEE sensors journal, 2021, 21(2)： 1561-1567.

[14] [14] MA J, YU H H, JIANG X, et al. High-performance temperature sensing using a selectively filled solid-core photonic crystal fiber with a central air-bore[J]. Optics express, 2017, 25(8)：9406.

[15] [15] SUHAILIN F H, ALWAHIB A A, KAMIL Y M, et al. Fiber-based surface plasmon resonance sensor for lead ion detection in aqueous solution[J]. Plasmonics, 2020, 15：1369-1376.

[16] [16] FAKHRI M A, ABDULRAZZAQ M J, ALWAHIB A A, et al. Theoretical study of a pure LiNbO3/quartz waveguide coated gold nanorods using supercontinuum laser source[J]. Optical materials, 2020, 109：110363.