Publications

@article{Ballaji2020-wp,

title = {A textile sleeve for monitoring oxygen saturation using 

 multichannel optical fibre photoplethysmography},

author = {Hattan K Ballaji and Ricardo Correia and Serhiy Korposh and Barrie R Hayes-Gill and Francisco U Hernandez and Byron Salisbury and Stephen P Morgan},

year  = {2020},

date = {2020-11-01},

journal = {Sensors (Basel)},

volume = {20},

number = {22},

pages = {6568},

publisher = {MDPI AG},

abstract = {Textile-based systems are an attractive prospect for wearable 

 technology as they can provide monitoring of key physiological 

 parameters in a comfortable and unobtrusive form. A novel system 

 based on multichannel optical fibre sensor probes integrated 

 into a textile sleeve is described. The system measures the 

 photoplethysmogram (PPG) at two wavelengths (660 and 830 nm), 

 which is then used to calculate oxygen saturation (SpO2). In 

 order to achieve reliable measurement without adjusting the 

 position of the garment, four plastic optical fibre (POF) probes 

 are utilised to increase the likelihood that a high-quality PPG 

 is obtained due to at least one of the probes being positioned 

 over a blood vessel. Each probe transmits and receives light 

 into the skin to measure the PPG and SpO2. All POFs are 

 integrated in a stretchable textile sleeve with a circumference 

 of 15 cm to keep the sensor in contact with the subject's wrist 

 and to minimise motion artefacts. Tests on healthy volunteers 

 show that the multichannel PPG sensor faithfully provides an 

 SpO2 reading in at least one of the four sensor channels in all 

 cases with no need for adjusting the position of the sleeve. 

 This could not be achieved using a single sensor alone. The 

 multichannel sensor is used to monitor the SpO2 of 10 

 participants with an average wrist circumference of 16.0 $±$ 

 0.6 cm. Comparing the developed sensor's SpO2 readings to a 

 reference commercial oximeter (reflectance Masimo Radical-7) 

 illustrates that the mean difference between the two sensors' 

 readings is -0.03%, the upper limit of agreement (LOA) is 

 0.52% and the lower LOA is -0.58%. This multichannel sensor 

 has the potential to achieve reliable, unobtrusive and 

 comfortable textile-based monitoring of both heart rate and SpO2 

 during everyday life.},

keywords = {multichannel, oxygen saturation, photoplethysmography, plastic   optical fibre, textile, wearable technology},

pubstate = {published},

tppubtype = {article}

}

@article{He2020-wu,

title = {Real-Time Humidity Measurement during Sports Activity using 

 Optical Fibre Sensing},

author = {Chenyang He and Serhiy Korposh and Francisco Ulises Hernandez and Liangliang Liu and Ricardo Correia and Barrie R Hayes-Gill and Stephen P Morgan},

year  = {2020},

date = {2020-03-01},

journal = {Sensors (Basel)},

volume = {20},

number = {7},

pages = {1904},

publisher = {MDPI AG},

abstract = {An optical fibre sensor for monitoring relative humidity (RH) 

 changes during exercise is demonstrated. The humidity sensor 

 comprises a tip coating of poly (allylamine hydrochloride) 

 (PAH)/silica nanoparticles (SiO2 NPs) deposited using the 

 layer-by-layer technique. An uncoated fibre is employed to 

 compensate for bending losses that are likely to occur during 

 movement. A linear fit to the response of the sensing system to RH demonstrates a sensitivity of 3.02 mV/% (R2 = 0.96), 

 hysteresis $±$ 1.17% RH when 11 bilayers of PAH/SiO2 NPs are 

 coated on the tip of the fibre. The performance of two different 

 textiles (100% cotton and 100% polyester) were tested in 

 real-time relative humidity measurement for 10 healthy 

 volunteers. The results demonstrate the moisture wicking 

 properties of polyester in that the relative humidity dropped 

 more rapidly after cessation of exercise compared to cotton. The 

 approach has the potential to be used to monitor sports 

 performance and by clothing developers for characterising 

 different garment designs.},

keywords = {humidity sensing, layer-by-layer, optical fibre sensor, real-time measurement, smart textiles, wearable technology},

pubstate = {published},

tppubtype = {article}

}