Fabrication and test of the planar microcoil for NMR spectroscopy of samples in nL level

We present the optimal planar microcoils with inner radius in several hundreds of microns. The microcoils are used in the RF transceiver probe in NMR experiment. At a certain condition of experiment the geometry of microcoil is optimized by analytic simulation about the signal-to-noise ratio while varying the number of turns. The fabrication of microcoils has been finished by photolithography technique and copper electroplating. The SU-8 photoresist which features to form high-aspect ratio structure was used for constructing the mold utilized in copper electroplating. It is simple in our process that there is only including one electroplating step. The RF performance of planar microcoils fabricated has been test by impedance analyzer Agilent 4294 in the Agilent Open Lab in Beijing. For the microcoil of No. 500_3 on Sub.2, the measured RF inductance is 76.5 nH, and Q-factor 12.9. The comparison with the reports of other scholars has been performed. And the electronics setup used for NMR respond signal measurement is introduced.