Research And Design Of Miniature Nuclear Magnetic Resonance System

Nuclear magnetic resonance(NMR),as a common measurement technique,has been widely known by everyone.At present,the most advanced nuclear magnetic resonance spectrometers using superconducting magnets have ultra-fine resolution,and the accompanying problems are huge volume,expensive cost,and complicated maintenance.In many applications,a portable,economical,and easy-to-maintain nuclear magnetic resonance spectrometer is urgently needed to support field and portable use.Therefore,it is of great practical significance to take the design of the miniature nuclear magnetic resonance system as the research content.In this paper,glucose solution is used as the test object,and the noninvasive portable integrated nuclear magnetic resonance technology is studied.The ultimate goal is to design a practical,portable,and rapid detection miniature nuclear magnetic resonance instrument.The thesis mainly focuses on the analysis and selection of the structure of the main magnet of the MRI instrument,the selection and matching of the main probe of the MRI instrument(the RF coil),and the design and construction of the RF transceiver system,providing test and experimental data.The thesis mainly completes the following work:First,introduce the related theory of nuclear magnetic resonance and the basic structure and performance index of the RF transceiver system.Through theoretical derivation and parameter calculation,the design index of each module of the system is formulated.Second,design the RF probe,that is,the RF coil.Through electromagnetic simulation of various coils,select the solenoid that meets the index as the RF probe;design two signal source pulse modulation optimization schemes to improve the flexibility of the transceiver system;The hardware circuit of the transceiver system is studied to solve the problems of system isolation and saturation during the design process.Third,build a miniature nuclear magnetic resonance test platform,test each module,including key parameters such as transmit power,gain,noise figure,sensitivity,etc.,verify the design plan,analyze the existing problems,propose improvement plans,and provide the next step for the integrated system Reliable support.