Development of skin-patchable capacitive micromachined ultrasonic transducer (CMUT) with bending modulation

Abstract

This thesis reports the development and implementation of a flexible micro-sized ultrasonic transducer that enables it to attach to the skin. A previous ultrasonic transducer is hard to adhere to the skin because of too bulky and rigid, so it is not able to be utilized continuously. In this work, the developments of patch-type ultrasound coupling medium, flexible micro-sized ultrasonic transducer, and flexible device with bending modulation were conducted for the implementation and utilization of the patchable ultrasonic transducer. For the development of a patch-type ultrasound coupling medium, biocompatible silk material was used and characteristics of adhesiveness, ultrasound transmission, and conformal contact were analyzed. The patch-type ultrasound coupling medium was verified through ultrasound imaging, heating, and stimulation. To fabricate a flexible micro-sized ultrasonic transducer, micro-electromechanical systems (MEMS) and flex-to-rigid (FTR) process were conducted. The electrical, mechanical, and acoustic properties of the flexible ultrasonic transducer were analyzed and durability and uniformity of the FTR CMUT were verified. To maintain a specific bending angle, low melting temperature metal alloy (LMPA) was inserted among ultrasonic elements. Through inserting LMPA, an ultrasonic transducer with bending modulation was implemented. Based on the flexible ultrasonic transducer with bending modulation, organ-specific ultrasound stimulation was conducted to treat rheumatoid arthritis