Application Of Novel Sensing Technologies For Plantar Pressure Monitoring

Analysis of plantar pressure distribution and exploring the body posture are important inthe field of biomedical and sports-related applications.Two different sensing system were developed and validated in this thesis:A smart insole was developed for the measurement of plantar pressure distribution using optical fiber Bragg grating（FBG）sensing technology.Four FBG sensors characterized by different wavelengths were encapsulated into a silica gel insole for pressure measurement.Plantar positions mounted with FBG sensors in silica gel insole include 1st metatarsus,3rd metatarsus,5th metatarsus,and heel position.All FBG sensors were multiplexed together with one optical fiber cable.Performance and functional properties of all FBG based pressure sensors were calibrated in the laboratory to evaluate plantar pressure distribution.Five male subjects were selected for performing four different tests including simple standing test and varying the body postures while standing straight on the smart insole.During standing tests,plantar pressure observed at the heel position was 50%higher than the 1st and 3rd metatarsus,while the pressure of the 5th metatarsus position presents very limited pressure,which is only 20%of the pressure of the heel position.In varying body posture tests,three tests were conducted,1.Body moves forward 2.Chair posture 3.Forward fold.Almost 90%same results were obtain by each subject,while performing above four tasks.The smart insole successfully recorded both plantar pressure change and body posture change in terms of the wavelength values collected by FBG sensors.A smart shoe was designed for determining different body postures using Flexi Force and Flex sensor.Four Flexi force sensors and one Flex sensor were gummed on the PVC based insole to form an intelligent shoe.The Flexi force sensors placed at 1st metatarsus,5th metatarsus,3^rd metatarsus and heel position whereas Flex sensor positioned at the center of the1^st and 3^rd metatarsus positions.The final insole composed of three layers,1.Shoe insole,2.PVC based insole with all sensors and 3.Fabric layer.All the layers were stitch and incorporate into the shoe.Five male subjects were nominated to perform four different body postures.In tree pose the force increase at each sensor position,and almost same results obtained for 2^nd and 3^rd-time test.When the subjects move from straight position to forward steadily,sensor at 1^stt metatarsus show continuous increase in force,sensors present at 3^rd and 5^th metatarsus decrease slowly while the hell position sensor reach at 0 level after 1^st step.The bend angle was also increase as subjects move forward.For the chair and sit posture,1^st and 3^rd metatarsus’s sensor show increase in force at each step while the 5^th metatarsus and heel position sensor exhibit decrease in force as compare to the previous step.The bend of the foot also increase as the subjects make chair and sit posture.Forward fold posture by the subject results increase in force at 1^st metatarsus,for 5^th and 3^rd metatarsus’s sensor,the force become stable after the 1^st step while the heel position sensor decrease continuously.