Direct Nanocrystal Patterning on Suspended MEMS Microheaters for Dual‐Temperature Gas Sensing

Efficient integration of metal oxide nanocrystals with microelectromechanical systems (MEMS) microheaters is essential for developing compact gas‐sensing platforms, yet conventional deposition and patterning approaches often suffer from limited pattern fidelity and poor compatibility with suspended microheater structures. Here, we demonstrate a photoresist‐free strategy for the direct patterning and integration of In 2 O 3 nanocrystals onto suspended MEMS microheater membranes. This process is compatible with fragile suspended MEMS structures and produces sensing patterns with a linewidth of 200 µm confined to the suspended heating region. This approach enables sensor arrays comprising individually addressable microheater‐based gas sensors and facilitates their integration into compact gas‐sensing systems. By operating the sensors at distinct temperatures, dual‐temperature sensing responses are obtained from the same sensing material. When combined with machine‐learning‐based analysis, these responses enable reliable gas classification with an accuracy of up to 100%. Together, these results establish a directly patterned MEMS microheater platform that combines spatially defined nanocrystal integration with dual‐temperature sensing and data‐driven gas classification.