Strain-insensitive flexible anomalous Hall-effect sensors for interactive wearables

Anomalous Hall effect (AHE) sensors present a compelling platform for emerging interactive electronics. Practical integration in flexible electronics, however, has been limited by the large Hall signal drift occurring under mechanical deformation. In this work, we micropatterned Hall crosses with 1.5-nm-Co/1-nm-Pt bilayers on 2.5-μm-thick ultrathin foils, achieving a high sensitivity of 100 Ω T⁻¹ and stable sensing performance down to a bending radius of 200 μm. To ensure stable performance under continuous bending, we employed a zero-offset Hall (ZOH) measurement strategy to decouple mechanical deformation effects from the magnetic response. In this scheme, the current direction through the Hall cross is alternated and the corresponding signals are averaged, effectively canceling out deformation-induced artifacts in the magnetic measurements. Owing to their mechanical conformability and strain-insensitive operation, the ZOH-enabled AHE sensors demonstrate strong potential for interactive wearables, as exemplified in on-skin human-machine interfaces for Morse code communication and on-skin presenter control, as well as in magnetic soft robots with on-board sensing.