A. Franklin
Duke University,
United States
Summary:
Semiconducting carbon nanotubes (CNTs) have been pursued for use in electronic biosensors for decades. Their all-surface molecular structure, sizeable semiconducting bandgap, and solution-phase compatibility make them highly sensitive and versatile options for transducing biomarker-related electrical signals. However, amid the thousands of reports on CNT-based electronic biosensors, very little attention has been given to identifying (let alone addressing) the impact of leakage current, signal drift, and device-to-device variation, particularly under operation in biologically relevant ionic media. This talk will present recent results focused on tackling these issues in a CNT transistor-based biosensor platform (i.e., bioFETs or ion-sensitive FETs). For instance, a variety of passivation strategies were studied to determine the role of leakage current compared to the detection signal, revealing that a bilayer epoxy/high-k dielectric stack was most effective at minimizing deleterious leakage. The influence of signal drift, particularly in strong ionic solutions (e.g., 1X PBS), was also found to play a significant role in many previous reports of CNT-based biosensors that were characterized by sequential biomarker concentration spikes. Finally, strategies for addressing device-to-device variation in these biosensors will be discussed, including the motivation for a printed thin-film device rather than a single-CNT configuration. Two things seem certain about this field: 1) the promise of CNT-based biosensors continues to suggest they are worth ongoing pursuit, and 2) there is much work remaining towards achieving a reproducible, reliable electronic biosensing technology from CNTs.