Publications

@article{Ballaji2021-ti,

title = {Optical fibre sensor for capillary refill time and contact 

 pressure measurements under the foot},

author = {Hattan K Ballaji and Ricardo Correia and Chong Liu and Serhiy Korposh and Barrie R Hayes-Gill and Alison Musgrove and Stephen P Morgan},

year  = {2021},

date = {2021-09-01},

journal = {Sensors (Basel)},

volume = {21},

number = {18},

pages = {6072},

publisher = {MDPI AG},

abstract = {Capillary refill time (CRT) refers to the time taken for body 

 tissue to regain its colour after an applied blanching pressure 

 is released. Usually, pressure is manually applied and not 

 measured. Upon release of pressure, simple mental counting is 

 typically used to estimate how long it takes for the skin to 

 regain its colour. However, this method is subjective and can 

 provide inaccurate readings due to human error. CRT is often 

 used to assess shock and hydration but also has the potential to 

 assess peripheral arterial disease which can result in tissue 

 breakdown, foot ulcers and ultimately amputation, especially in 

 people with diabetes. The aim of this study was to design an 

 optical fibre sensor to simultaneously detect blood volume 

 changes and the contact pressure applied to the foot. The CRT 

 probe combines two sensors: a plastic optical fibre (POF) based 

 on photoplethysmography (PPG) to measure blood volume changes 

 and a fibre Bragg grating to measure skin contact pressure. The 

 results from 10 healthy volunteers demonstrate that the 

 blanching pressure on the subject's first metatarsal head of the 

 foot was 100.8 $±$ 4.8 kPa (mean and standard deviation), the 

 average CRT was 1.37 $±$ 0.46 s and the time to achieve a 

 stable blood volume was 4.77 $±$ 1.57 s. For individual 

 volunteers, the fastest CRT measured was 0.82 $±$ 0.11 and the 

 slowest 1.94 $±$ 0.49 s. The combined sensor and curve fitting 

 process has the potential to provide increased reliability and 

 accuracy for CRT measurement of the foot in diabetic foot ulcer 

 clinics and in the community.},

keywords = {blood volume changes, Capillary refill time, contact pressure, fibre Bragg grating (FBG), optical fibre, peripheral arterial   disease, photoplethysmography (PPG), plastic optical fibre},

pubstate = {published},

tppubtype = {article}

}