This mint sized capsule contains magnetic nanoparticles, able to bind to specific compounds of interest. In the case of cancer, the compound of interest would be hormones that certain cancers produce. Since the membrane of the sensor is semi-permeable, these hormones can flow into the capsule but the nanoparticles remain inside. The more a cancer grows, the more of these hormones are produced. Therefore the rate of cancer growth can be detected by clusters of nanoparticles bound to hormones in the capsule, using MRI scan instead of performing biopsies.
A similar technique is supposed to be used in identifying silent heartattacks. In this instance, the capsule monitors proteins released by heart muscles when they burst open during a heart attack. Researches are going even further to cut the use of MRI scans as a whole as these are very expensive and time consuming to say the least. A magnetic "wand" or hand held scanner that can be used to scan the area where the capsule has been implanted is in the wood works.
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