Nanoconfined Bi2Se3@Carbon-Tube Inbuilt Heterointerface for Highly Stable Flexible Multimodal Sensor

Abstract

Flexible sensors normally require highly stable structural interfaces to sense various signals continuously and steadily under repeated deformation. Especially, for carbon-tube-derived flexible devices, however, functional components are typically deposited on the exterior of conductive networks, where they disrupt tube–tube contacts and leave active interfaces vulnerable to aggregation, delamination, and signal drift. Here, we report an internally nanoconfined Bi2Se3@carbon-tube hybrid with an inbuilt heterostructure architecture, in which Bi2Se3 is grown inside bamboo-like carbon tubes (BCTs). The BCT shell serves as both a continuous carrier pathway and a mechanically protective sheath, while the built-in Bi2Se3–carbon interface enables stable thermoelectric and photoinduced carrier transport. Compared with the externally decorated BCT@Bi2Se3, the product forms a more stable ink dispersion (over 130 days) and uniform spray-coated films, and the derived flexible sensor displays superior bending-piezoresistive (over 3000 cycles), thermoelectric (7-fold higher), and photoelectric (3.4-fold higher) multimodal response behaviors in a single device. Furthermore, mounted on a robotic finger, the sensor provides complementary descriptors of material, geometry, and optical appearance, showing an identified accuracy of 100% for six similar cups by fusing these signals to a one-dimensional convolutional neural network model. This internal encapsulation strategy converts fragile hybrid interfaces into protected, transport-efficient heterointerfaces for durable robotic perception.