Improved Stability of Carbon Nanotube Electrolyte-Gated Field-Effect Transistors through Lipophilic Membrane Encapsulation

Electrolyte-gated carbon nanotube field-effect transistors (EG-CNTFETs) are a promising bio-sensing platform, but the instability of carbon nanotubes (CNTs), e.g., high leakage current and hysteresis, remains a major limitation. In this paper, we demonstrate that incorporating a lipophilic membrane on the semiconducting channel reduces the EG-CNTFET stabilization time to 34 minutes compared to an hour for state-of-the-art devices. Moreover, the on-off ratio of the devices improves over time (9.76 ± 4.16 to 24.55 ± 20.99), whereas the on-off ratio of devices without the membrane decreases (88.7 ± 29.9 to 61.1 ± 23.9). As proof-of-concept, the encapsulated devices were functionalized with an ion-selective membrane for detecting ammonium ion. The calibration curve showed a linear detection range from 0.01 mM to 100 mM with a coefficient of determination of 94.71%, and a sensitivity of 0.143 μA/decade.