Carbon nanotubes are grown on a first substrate. The CNTs grown on the first substrate are immersed in a biological solution at a predetermined depth to functionalize ends of the CNTs with a biological molecule. The functionalized CNTs are harvested from the first substrate. A second substrate is functionalized with a complementary biological modification, which is a complementary binding partner to the biological molecule functionalized to the ends of the CNTs. The functionalized CNTs are attached to the second substrate by way of the complementary binding partner.