Tunneling based ten attomolar DNA biosensor

Early-stage detection prevents disease progression and complications in treatment procedures, especially for infectious diseases. This requires rapid and accurate sensing technologies and techniques that remove the need for expensive and time-consuming sample preparation and transfer to the labs and the running of multiple experiments. To that end, point-of-care (POC) testing has been introduced for quick disease diagnostics that enables caregivers to start early treatment, leading to improved health outcomes. Here, we introduce a tunneling current bio-sensing technology based on a metal–insulator–electrolyte junction, which is highly sensitive to charge variations at the insulator–electrolyte interface. The charge variations occur as a response of hybridization of complementary DNA sequences to DNA primers immobilized on the insulator surface. This leads to the label-free detection of as little as tens of DNA molecules or, equivalently, samples with 0.01 fM concentrations. Since the sensing is based on a single terminal measurement of current with respect to a reference electrode, our technology can enable the creation of novel compact medical and portable POC devices for real-time disease detection.