Abstract & Overview
This thesis presents the development of a wearable ultrasonic sensor to monitor muscle contractions.A flexible and lightweight ultrasonic sensor was constructed using a polyvinylidene fluoride piezoelectric polymer film, sandwiched by electrodes on the top and the bottom, and sealed by protection/insulation layer.A numerical simulation model of the sensor, based on Mason's electric equivalent circuit model of piezoelectric resonators, was developed.The internal losses of piezoelectric polymers were considered in the mathematical representation of the numerical simulation model for accurate prediction of its ultrasonic performance.The performance and frequency characteristics of the developed sensors were investigated by numerical simulations and experiments.The results of the numerical simulations and experiments show that the developed sensor operates in dual frequencies due to the effect of the non-piezoelectric layers, specifically of the silicone adhesive layers.The ultrasonic signal strength of the sensor with respect to the sensor size was investigated.Experiments were conducted to demonstrate the capability of the developed wearable sensor for monitoring static and dynamic muscle contractions.The muscle thickness changes measurement has been used to monitor muscle activities during contractions.The flexibility and lightweight of the sensor allows the sensor to be attached to the body area of interest without restricting the underlying tissue movements, which is not feasible using a conventional handheld ultrasonic probe.