Gravity-mediated liquid metal redistribution in asymmetric sawtooth microchannels for tilt sensing.

Controlling liquid metal (LM) wetting in confined microstructures is essential for reliable liquid-state electronics. Here, well-defined sawtooth microchannels are fabricated by soft replication from a metallic master, enabling systematic investigation of the relationship between channel geometry and electrical response. During injection, pressure decay produces graded LM filling within the sawtooth valleys. Upon tilting, gravity induces localized and angle-dependent LM redistribution rather than uncontrolled bulk sliding, thereby modifying the effective conductive pathway and generating an approximately sinusoidal resistance response. The resulting sawtooth LM tilt sensor exhibits a periodic response over a complete 360° rotation, with a monotonic interval from -90° to +90° that enables unique angle determination. Repeated 0.1° angular-step inputs produce distinguishable resistance changes, and the apparent system-level response time remains below 0.4 s under the tested conditions. The device maintains stable responses over 2000 rotation cycles and during intermittent measurements over a 30 day period. Its versatility is demonstrated in engineering attitude monitoring, human-motion sensing, angle-encoded information transmission, and surface-height mapping. This work presents a rational microstructure-design strategy for converting gravity-mediated LM redistribution into stable electrical outputs, providing a route toward liquid-state sensing and soft electronic systems.