▎ 摘　　要

Motion tracking has attracted great attention in the fields of real-time tracking, nanorobotics, and targeted therapy. For achieving more accurate motion tracking, the highly sensitive position-sensitive detector (PSD) is desirable. Here, we demonstrate a meliorated PSD based on graphene-Si heterojunction for motion tracking. The position sensitivity of PSD was improved by employing surface engineering of graphene. Through modulating the transport property of graphene, nearly 20-fold increase of sensitivity was achieved under weak light, and at the same time, the detection limit power was reduced to similar to 2 nW. A motion tracking system was developed based on the improved PSD, and human arm swing was tracked, which demonstrated high sensitivity and real-time tracking capabilities of the PSD. In addition, the PSD can support up to similar to 10 kHz high-frequency tracking. This work provides a new strategy for improving the performance of PSD, and promotes the development of two-dimensional materials in novel opto-electronic devices.