Biomedical Engineering Reference
In-Depth Information
Fig. 8.2
0.1-kg palm NMR system (From Ref. [
3
])
(this magnet and the magnet of the commercial system both produce the static field
of approximately 0.5 T). To receive the NMR signal weakened by the small magnet,
we developed a partially integrated, high-performance RF transceiver and a separate
high-quality planar coil.
After the design of the 2-kg portable system, we developed two new miniature
NMR systems, which we call
the palm NMR system
and the
1-chip NMR system
[
3
]. They represent yet another orders-of-magnitude size reduction and lab-on-a-
chip capability. The palm NMR system, shown in Fig.
8.2
, is the smallest complete
NMR system to our best knowledge. It is 1,200 times lighter, 1,200 times smaller,
yet 150 times more spin-mass sensitive than the 120-kg commercial system of [
1
].
As compared to the 2-kg portable NMR system, the palm system is 20 times lighter,
30 times smaller, and yet 2.5 times more spin-mass sensitive. To attain this further
substantial size and cost reduction, we use a tiny magnet only the size of a ping-pong
ball. This considerably lowers the NMR signal, which we overcome by designing a
new, high-performance RF transceiver. As the signal is already lowered by the ping-
pong-ball-sized magnet, the palm system uses a high-quality solenoidal coil, not to
further weaken the signal.
The 1-chip NMR system is shown in Fig.
8.3
. In this system, even the NMR
coil is integrated as a planar spiral in the silicon IC chip along with the transceiver
developed for the palm system. The transceiver's performance allows the use of
the lossy on-chip coil that lowers the signal-to-noise ratio. Not to further weaken
the signal-to-noise ratio, the 1-chip system operates with the same hamburger-sized
magnet of the 2-kg portable system. Due to this magnet, the weight reduction from
the portable system is by 25 %, but the point of the 1-chip system is lab-on-a-chip
