Key points from article :
Liquid biopsies look for cancer cells circulating in blood.
But they do not always show up in a single blood sample.
Cancer cells that end up in the bloodstream do not survive for long.
University of Michigan designed a wearable device to monitor blood continuously.
Collected 3.5 times more cancer cells than testing in vitro every 20 minutes.
Could replace some surgical biopsies.
Device tested in dogs - study published in Nature Communications.
