Design of ultrasound beamforming system using MEMS transducer array

Abstract

Recently, the demand for healthcare has increased. Thus, research has been increased in the device for diagnosis and treatment. Especially, demand for wearable medical monitoring the real-time physiological data has increased. In case of a simple treatment, research indicated available handheld devices is increasing rather than depend on the doctor. Previous studies use the RF (Radio Frequency) for the wireless power transmission, in-body network communication and the implanted device. . The RF that is commonly used, rarely used in medical equipment. The RF signal is absorbed into the human tissue at a RF, cannot pass through the human tissue. The problems by disrupting the cells internal to damage to the human body are generated RF that is mainly used. To avoid this disadvantages, ultrasound is used for medical application. Ultrasound has good propagation characteristics in the human tissue. And ultrasound does not damage the human tissue. From these reasons, the leading manufacturers in the world are making ultrasound medical equipment. However, ultrasound device is made of ceramic. Because of the nature of the ceramic transducer is a conventional ultrasound diagnostic device. Thus, the system has large size and high operating voltage. These drawbacks cannot be applied to handheld device used for wearable medical device. The advantage that low operating voltage, high integration and MEMS transducer with the convenience of operating circuit implementation, has emerged as a new option that is used in handheld device.In this thesis, we designed the beamforming system using MEMS transducer. The target performance that the ultrasonic stimulation and a wireless power transmission is the intensity more than 10 W/cm2 and the focal depth more than 1.7 cm.The system is designed in two types. The first is phase shifter. The proposed phase shifter consists of the phase shifter, variable gain amplifier and 0°/180° phase shifter, and it drives MEMS transducer array. The p...