Detecting human-robot distances at the micrometer-scale is essential for advanced human–robot interaction, yet existing flexible sensors are typically limited to millimeter-scale resolution. Here, we develops a flexible sensor using quasi-1D TaSe₃ nanowires to measure micrometer-scale distances via the photothermoelectric (PTE) effect. The sensor has self-powered operation (zero bias), ultrabroadband photoresponse (405 nm to 10.6 µm), good bending stability (no degradation after 500 bends), and strain-insensitive photocurrent. Importantly, it achieves 1 µm spatial resolution for distance detection within 100 µm, suggesting micrometer-scale sensitivity. These results highlight the potential of TaSe₃-based PTE sensors for advancing human-robot systems.