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

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.