Shaaista Hasan received her M.Sc. in Physics and Applied Physics from Shimane University, Japan in September 2025. Currently she is a D1 student from University of Tsukuba, working at NIMS as a Junior Researcher. Her research theme on the formation and transport properties of CNT-based intramolecular junction transistors, mainly focusing on the in-situ TEM manipulation to fabricate CNT-intramolecular junctions, and on the junction chemistry for molecular-level sensing mechanism.

Carbon nanotube (CNT)-based sensors have shown promising results, owing to the ballistic transport of charge carriers, and the high surface-to-volume ratio provide more surface areas for functionalization and sensing.1,2 Up to now, most CNT-based sensors use the metal/semiconducting properties of CNTs, while the role of the most fascinating feature of chirality, is unknown. The sensing mechanism at the molecular level is not clear, such as the active sites and bonding nature with functional groups and influence on CNT transport. The current work is aimed at elucidating the sensing mechanisms at molecular level by using CNT-junction transistors as a model device.3,4 The device compatibility with observation and in-situ manipulation under a transmission electron microscope (TEM) makes it possible to observe well-defined atomic structures along with the chirality-dependent electronic structure of CNTs. Currently, on-grid fabrication of junctions with locally modified chiralities has been demonstrated, with progress towards on-chip fabrication of CNT-junction devices (Figure 1).

1. S. Ishihara, J. Labuta, T. Nakanishi, T. Tanaka & H. Kataura. Amperometric Detection of Sub-ppm Formaldehyde Using Single-Walled Carbon Nanotubes and Hydroxylamines: A Referenced Chemiresistive System. ACS Sensors 2, 1405-1409, doi:10.1021/acssensors.7b00591 (2017).
2. S. Ishihara et al. Actuator-Driven, Purge-Free Formaldehyde Gas Sensor Based on Single-Walled Carbon Nanotubes. Nanomaterials 15, 962 (2025).
3. D.-M. Tang et al. Semiconductor nanochannels in metallic carbon nanotubes by thermomechanical chirality alteration. Science 374, 1616-1620, doi:10.1126/science.abi8884 (2021).
4. D.-M. Tang et al. Chirality engineering for carbon nanotube electronics. Nat Rev Electr Eng 1, 149-162, doi:10.1038/s44287-023-00011-8 (2024).