What does 'femtomolar sensitivity' mean?

A femtomole is 10⁻¹⁵ moles — one quadrillionth of a mole. Femtomolar (fM) sensitivity means the Yenos nanopore platform can detect miRNA present at concentrations as low as femtomoles per liter in a sample. For reference, a femtomolar concentration is roughly 600 molecules per milliliter. This extraordinary sensitivity means the test can detect cancer-associated miRNA overexpression even when tumors are small and shed relatively few molecules into circulation — which is precisely the scenario in Stage I and Stage II cancer. Traditional PCR-based methods can also achieve femtomolar sensitivity but only after extensive amplification, which is the step that introduces the data spread that Yenos eliminates.