CNT-NeRF: Carbon Nanotube Forest Depth Layer Decomposition in SEM Imagery using Generative Adversarial Networks

Carbon nanotube (CNT) forests are imaged using scanning electron microscopes (SEMs) that project their multilayered 3D structure into a single 2D image. Image analytics, particularly instance segmentation is needed to quantify structural characteristics and to predict correlations between structural morphology and physical properties. The inherent complexity of individual CNT structures is further increased in CNT forests due to density of CNTs, interactions between CNTs, occlusions, and lack of 3D information to resolve correspondences when multiple CNTs from different depths appear to cross in 2D. In this paper, we propose CNT-NeRF, a generative adversarial network (GAN) for simultaneous depth layer decomposition and segmentation of CNT forests in SEM images. The proposed network is trained using a multi-layer, photo-realistic synthetic dataset obtained by transferring the style of real CNT images to physics-based simulation data. Experiments show promising depth layer decomposition and accurate CNT segmentation results not only for the front layer but also for the partially occluded middle and back layers. This achievement is a significant step towards automated, image-based CNT forest structure characterization and physical property prediction.

1. Introduction

Carbon nanotubes (CNTs) [17] are tubular nanostructures with remarkable mechanical, thermal, electrical, and chemical properties [9], [18]. Single-walled CNTs (SWNTs) may exibit metallic or semiconducting traits. Multi-walled CNTs (MWNTs) can be transformed into yarns [41] that are not only electrically conductive and strong, but also retain their flexibility and can even be tied into a knot. The properties of CNTs make them an appealing material for a wide range of applications, including dry spinning conductive, high-strength fibers [19], [41], piezoresistive sensing [23], [24], [30], electrochemical energy storage [5], [8], and thermal interface materials [6], [7].