Micro-electro-mechanical devices (MEMS) are everywhere in today’s technology. Based on the integration of mechanical and electrical components on a micrometer scale – to give just one example – at least a dozen of them are in our mobile phones to regulate different activities ranging from motion, position and inclination monitoring of the phone, active filters for the different transmission bands and the microphone itself.
The extreme miniaturization in NEMS resonators offers the possibility to reach an unprecedented resolution in high-performance mass sensing. These very low limits of detection are related to the combination of two factors – a small resonator mass and a high-quality factor. The main drawback of NEMS is represented by the highly complex, multi-steps, and expensive fabrication processes.
These devices can be created in extreme nanoscale with sensors that are so sensitive that they can interact with single molecules. But their manufacturing costs are very high, so new technologies such as 3D printing have shown that similar structures can be created at low cost and with interesting intrinsic functionalities. However, so far, their performance as mass sensors is poor.
Researchers at the Hebrew University of Jerusalem (HUJI) with colleagues in Italy have published their findings on MEMS in the prestigious journal Nature Communications under the title “Reaching silicon-based NEMS performances with 3D printer nanomechanical resonators.” They investigated how it is possible to obtain mechanical nanoresonators from 3D printing with higher quality, stability, mass sensitivity and strength comparable to those of silicon resonators.
The research is the result of the collaboration doctoral student Ido Cooperstein and Prof. Shlomo Magdassi at HUJI and Stefano Stassi, Carlo Ricciardi, Mauro Tortello and Fabrizio Pirri at the Politecnico di Torino in Italy.
The different nanodevices (membranes, cantilever and bridges) were obtained by two-photon polymerization on new liquid compositions, followed by a thermal process that removes the organic content, leaving a ceramic structure with high rigidity and low internal dissipation. The samples thus obtained are then characterized by Laser Doppler vibrometry.
“The ability to fabricate complex and miniature devices that have performance similar to silicon ones,” said Magdassi, “by a quick and simple 3D printing process brings new horizons to the field of additive manufacturing and rapid manufacturing.”
“The NEMS that we have fabricated and characterized,” wrote the researchers, “have mechanical performances in line with current silicon devices, but they are obtained through a simpler, faster and more versatile process, thanks to which it is also possible to add new chemical-physical functionalities. For example, the material used in the article is Nd: YAG, normally used as a solid-state laser source in the infrared range.”