What is a nanopore and how does it work?

A nanopore is a tiny protein channel — approximately 1.4 nanometers in diameter — embedded in an electrically insulating membrane. The MinION/Yenos platform uses a flow cell containing 2,048 such nanopores, with salt solution on both sides of the membrane. When a voltage is applied across the membrane, ions flow through the nanopores, generating a stable electrical current of approximately 180 picoamperes (pA) per pore. When a molecule (in this case, an osmium-tagged miRNA) is driven through the nanopore by the electrical field, it temporarily blocks the ionic current, causing a characteristic dip in the current signal. By recording these current blockage events, the system can count individual miRNA molecules with single-molecule precision.