Low-cost 3D-printed mask system for versatile selective sample deposition on in situ TEM chips

In situ liquid electron microscopy has emerged as a powerful technique for studying dynamic processes at the nanoscale. However, selective deposition of samples on in situ biasing MEMS chips is far from straightforward due to the relatively small area of the electron-transparent window and the compact design of the three electrodes. This is particularly challenging for samples dispersed in solvents or those fabricated through physical vapor deposition. Here, we address these challenges by proposing a simple, low-cost, 3D-printed loading stage with an integrated mask system. Our design enables controlled deposition, as demonstrated by the successful deposition of AuPdPt nanoparticles from liquid suspension, sputtered Au clusters, and a cluster-based Au thin film onto the working electrode. The design can be easily fabricated in any electron microscopy lab, making it accessible and adaptable to various MEMS in situ chips and sample types.