Label‐Free Detection of Few Copies of DNA with Carbon Nanotube Impedance Biosensors

Finding that needle in the haystack: A label-free on-chip detection strategy based on carbon nanotubes (see picture) was used to detect an oligonucleotide target sequence of which less than 2000 copies were present in a 30 μL sample droplet, without the need for PCR. Instead, sensitive low-noise impedance measurement coupled to field-effect detection enabled attomolar DNA detection in a heterogeneous environment.