A precise diagnosis has been taken as one of the initial conditions for efficiently treating cancer, for which a technique called biopsy that used to remove a piece of solid tissue or a sample of cells for laboratory testing. Though traditional tumor biopsies can informatively identify diseases when patients are experiencing certain signs and symptoms in an area of concern, they are not satisfying enough due to their invasive nature, which could pose the risk of bleeding and infection to patients . Alternatively, the recent fluid biopsy technique combined with microfluidics can detect disease through blood or other body fluids rather than solid tissue, which increasingly receives attention in terms of its non-invasiveness and simplicity. DNA Fragments for Cancer Diagnosis The primary target of a liquid biopsy in cancer diagnosis is molecular markers known as cell-free DNA (cfDNA). cfDNA includes all non-encapsulated DNA, and these nucleic acid fragments...