2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/102803We propose a method to modulate the bandgaps in quasi-metallic carbon nanotubes using a transverse electric field. Unlike previous investigations, we include curvature effects of the nanotubes by incorporating both $π$- and $σ$-orbitals in our tight-binding calculations. The calculations show that the small curvature-induced bandgaps decrease quadratically with electric field amplitude to zero. As the electric field amplitude continues to increase, the bandgap then expands in a similar manner to that presented in earlier studies. The bandgap dependence is verified by analytical calculations, which also agree with preceding analyses for the limit of no curvature.6 pages, 2 figures, accepted to Europhysics LettersMesoscale and Nanoscale PhysicsMaterials Sciencetext