• Construct a permanent magnet with a C-shaped yoke

    yashiro • 09/01/2022 at 15:30 • 0 comments

    Create a model of the magnet in Fusion360.

    I submit CAD drawings and order the yoke. The material of the yoke is SS400.

    These magnets do not adhere, but are simply stuck on by magnetic force.

    The magnetic flux density of this magnet appears to be 137mT.

    The major components are now in place.

    I have tried to obtain NMR signals using the constructed magnets.

    Apparently the homogeneity of the magnetic field is still not good. It will be improved in the future.

    Stay tuned for further updates.

  • Build an excitation amplifier (1)

    yashiro • 08/24/2022 at 08:27 • 0 comments

    Make an excitation amplifier for miniature MRI.

    This is no problem if an RF linear amplifier circuit is used.
    Let's build it right away.

    The main passive components are shown below.

    Build an input transformer; use a PCB and copper pipe to construct the bobbin.

    The RF transformer is rewound and adjusted many times.

    The components are mounted on the board in order from the smallest to the largest.

    The RF transformer is rewound and adjusted many times.

    IRFP510 is used as the amplifying element.

    It has a heat sink on the back of the board.

    Attempt to acquire a spin echo signal as a test of amplifier operation.

    The spin-echo signal can be observed after the two pulses.👀

    It is not perfect, but it performs satisfactorily.

  • First spin echo signal

    yashiro • 08/14/2022 at 07:21 • 0 comments

    The designed yoke is not yet complete, but since the magnet is available, we attempted to acquire spin-echo signals.画像画像The system was wrapped in aluminum foil for noise reduction.画像Although a little noisy, we were able to obtain the NMR signal of water in a small bottle.

    画像In addition, a miniature MRI gradient coil was designed using the target field method in MATLAB.

    画像The contour lines are the wires of the coil.

    画像Edit the contour lines calculated in MATLAB and convert them to data for the Kicad pattern, and you are done.画像画像Gradient coils are installed this way.