Ultrasonic sensors and techniques for motion tracking and characterization of biological soft tissues

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Various chronic ailments such as arthrosclerosis affecting blood circulation and rheumatoid arthritis affecting the musculoskeletal system in elderly people impair their physical ability. Upon onset of a physical disorder elderly people are often placed on bed rest and require assistance from caregivers to maintain their daily activities. Early diagnosis of such ailments is crucial for devising appropriate treatment strategies aimed to impeding further progression of the disease. Mechanical properties of biological tissues contain significant and vital information for medical diagnosis. Ultrasound has been a powerful tool for diagnosis and is widely used since it is noninvasive, risk-free (no ionizing radiation exposure), and capable of capturing images in real-time at a high frame rate and at low-cost. Ultrasonic diagnostic techniques can provide not only static images of anatomical structures but also real-time dynamic information of internal tissue motion associated with physical activities and physiological condition. Real-time and continuous ultrasonic monitoring is beneficial for carrying out diagnosis outside clinical facilities and laboratories, without interfering with daily life activities. However, the current portable ultrasound imaging system and ultrasound probe may not be suitable for a long-time and continuous monitoring at home. Therefore, film-type flexible and dedicated ultrasonic sensors are beneficial for providing stable contact with chosen locations of a human body, such as a neck, arm and leg, which is curved, deformable and movable. It is also desirable that such sensors be wearable and compact. This research program will develop a low-cost, lightweight, reliable, mass-producible and disposable non-invasive ultrasonic wearable sensor (WUS) technology for automatic and continuous assessment of arterial functions for cardiac health monitoring. Using the developed WUS technology, a clinical application for continuous monitoring of cardiovascular functions such as blood pressure waveforms and artery stiffness will be established. Disposability of the sensor is desirable for a medical device that contacts a human body since it does not require disinfection or sterilization after its usage. The developed WUS technology will include advanced signal processing algorithms that can automatically detect arterial regions and estimate arterial diameter changes in real-time. The developed WUS technology will allow monitoring of cardiovascular health conditions of patients outside hospitals, clinics, and laboratories. Furthermore, people will be able to wear cost-effective ultrasonic sensors that will continuously monitor their health conditions.