Applications And Researches Of Superconducting Quantum Interference Devices

Superconducting Quantum Interference Device(SQUID) can change the weak magnetic signal into measurable voltage, i.e. it is magnetic flux sensor. SQUID is the most sensitive instrument for measuring magnetic field, it can detect a change of one billionth of geomagnetism(0.5×10-4T) . On the basis of SQUID, we can have many kinds of sensors and instruments. As a sensitive magnetic sensor, it is widely applicable in biomagnetism, geophysics and nondestructive evaluations etc.. Therefore, it is a worthwhile project about the application and study of SQUID. This paper launches an exploration and analyse about the way of the study, which is based on the comprehensive and systematic illustration of the applications and perspectives on SQUID, meanwhile, it puts emphasis on the research of characteristic analyse of SQUID magnetocardiography and design of practical digital filter, In addition, this paper proposes a noise cancellation techniques in MCG based on wavelet packet analyse, it proves that an extreme effect can be achieved with this method. Finally, it researches the general design of system, design and finish a amplified circuit of weak signal. It mainly consists of the following parts:The first part illustrates the application and perspectives of SQUID. It detailed introduces the basic principles, fabrication techniques and application of SQUIDS, in addition, it sums up the current application highlights and research developments at home and abroad. Moreover, it also proposes related measures and suggestions for China's SQUIDS application and development based on its actual development conditions.The second part analyses the characteristics of MCG and main resource of interface noise. Based on the fourier transform , it also designs practical digital filter and suggests a method via wavelet packet analyse, Moreover, through traditional fourier transform and wavelet packet separately it compares their different noise cancellation effect on MCG, the results of experiments have proved that noise cancellation techniques in MCG based on the wavelet packet analyse can obtain a good filter effect under the precondition of small distortion.MCG is a method to non-invasively record and analyse the magnetic signal generated by the heart's function, which is also one of the most important applications of SQUID. As magnetocardiography is widely applicable in medical treatment, noise cancellation technique in MCG has been a hot problem to solve as soon as possible which is extremely significant for SQUIDS' application on biomedicine.In the third part, this paper comprehensively designs and analyses SQUID system, in addition, it puts emphasis on a further research of the key technique, i.e. hardware design of weak signal amplified circuit. Moreover, it has realized the voltage amplification under mV class.