Design And Implementation Of Ultrasonic Generator For Cartilage Rehabilitation

With the rapid development of technology, the electronic technologies related with the medical standards are increasingly being used. Medical electronic equipments are also widely used at home and in the hospital. Millions of cases of fractures and cartilage damage occur every year. The demand for the medical equipments that can repair fractures or cartilage is growing, while the requirements for stability and power are very high. Therefore, the development of special electronic ultrasound equipments for cartilage rehabilitation has a very important value.Cartilage plays an important role in bearing load, reducing friction between the bones in human body. Based on the relevant domestic and overseas document, it is found that the low-intensity pulsed ultrasound (LIPUS) can promoting the healing of fracture or cartilage damage. It is generally considered that the best parameter of LIPUS for healing is as follows. Strength:30mW/cm2, frequency:1.5MHz, pulse width:200μs and repetition frequency:1KHz, and 20min/d.This thesis firstly describes the study about LIPUS promoting cartilage damage healing, then a detailed analysis of characteristics and matching circuit of ultrasonic transducer is introduced. By comparing the advantages and disadvantage of working in the series resonant frequency and parallel resonant frequency, the matching circuit is designed.The main circuit is divided into four modules. They are signal generator module, controllable gain amplifier module, power amplifier module and analog switch module. The control core is the F2812 minimum system board.Firstly, based on the direct digital frequency synthesis (DDS) principle, ultrasonic signal generator module is designed with AD9833 chip by F2812 controlling. Based on the characteristics of software controlling of AD603, the controllable gain amplifier module is designed by two chips of AD603. With the characteristics of low noise, low distortion and wide bandwidth, AD811 chip is used to achieve the power amplifier module. The signal is controlled by the analog switch with PWM programmed by F2812. The design of cartilage rehabilitation ultrasonic generator is completed.The design does the experiments on the circuit board, programming in the Code Composer Studio 3.3 with F2812. According to the proposed scheme in Altium Designer 09, a PCB board is made out and finished welding and debugging. The result proves that the design can output a sine wave with 5.06V peak-to-peak value. The results prove that the design is executable and can be a foundation for the further development of the future.