The new study was published in the journal Aging-US.
The sensor is connected to a small electronic backpack.
The study involved 1.2 million people in 76 low and middle-income countries.
It is controlled by magnets - carrying payloads directly to a tumour, blood clot or infection.
"If we restore whale populations to pre-whaling levels seen at the beginning of the 20th century, we'll restore a huge amount of lost function to ocean...