Development of wearable and flexible ultrasonic sensor for skeletal muscle monitoring

Abstract

A wearable and flexible ultrasonic sensor was developed for monitoring of skeletal muscle contraction. The sensor was constructed using a PVDF piezoelectric polymer film without a matching layer or backing material. Due to its lightness (less than 1 gram), thinness (200 µm) and flexibility, this sensor was wearable and enabled non-invasive and continuous muscle monitoring without restricting muscle movement, which is not feasible using a conventional handheld ultrasonic probe. The developed sensor was used to monitor muscle contractions in the index finger by ultrasonic pulse-echo measurements and in the forearm by through-transmission measurements. It was successfully demonstrated that the tissue thickness variations were measured in accordance with the muscle contraction performed.

Classification of Individual Finger Flexions Using Ultrasound Radiofrequency Signals

“…The DWT-MAV method is at least 10 times faster than the ENV-LR method of 10 segments and 30 times faster than the ENV-LR ms between successive prediction time intervals [2]. Further research using wearable multiple single element UTs constructed out of PVDF material is the next step [67,68].…”

“…The results suggest that a multiple single element UTs could achieve similar accuracies of using a linear array probe. Implementation of multiple WUS [67] has a potential to perform individual finger flexions in a less costly and more practical manner than a conventional clinical ultrasound probe and imaging system.…”

Continuous Monitoring of Mechanical Properties of Plantar Soft Tissue Using Wearable Ultrasonic and Force Sensors for Diabetic Patients

“…In this study, plantar soft tissue mechanical properties are estimated using wearable sensors. A polyvinylidene fluoride (PVDF) piezoelectric polymer film ultrasonic sensor [8] along with a pressure sensor was used to estimate strain and stress, respectively.…”

“…In this study ultrasonic sensor was used for tissue displacement measurement. Since PVDF film is light and thin and has a good acoustic impedance matching to biological soft tissue and broadband ultrasonic performance [76][77][78], thus non-invasive continuous monitoring of plantar soft tissue thickness is possible, which is difficult using a conventional ultrasonic probe [8]. This sensor is constructed without any matching layer or backing material and can be cut into desired size and shape.…”

“…displacement sensor is supposed to be placed in the shoe, desirable sensor must be thin and flexible and should tolerate body weight. A polyvinylidene fluoride (PVDF) piezoelectric polymer film ultrasonic sensor[8] was used to estimate plantar tissue displacement due to an applied force by means of an ultrasonic pulse echo method as shown inFig. 3.14.…”