Measuring Vibrations in Vacuum

Problem

Micromechanical structures like MEMS cantilevers are sensitive to environmental conditions. In air, viscous damping lowers the resonance frequency and reduces the quality factor, limiting performance analysis. To characterize real dynamic behavior, measurements must be done under vacuum—but many conventional systems are not suitable for such environments.

Solution

The PICOSCALE Vibrometer, thanks to its compact and vacuum-compatible design, allows precise vibration measurements inside vacuum chambers. It also supports through-silicon measurements, enabling characterization even after MEMS packaging.

Implementation

• A standard AFM cantilever (MSCT chip) was measured inside a Tescan Vega3 SEM under both air (1.0×10³ mbar) and vacuum (3.6×10⁻³ mbar) conditions.

• Only thermal vibrations were analyzed—no active actuation was applied.

• Displacements were recorded at the free end of the cantilever and transformed to amplitude spectra using FFT averaging.

Results

• In vacuum, the resonance peak showed a much sharper profile with a higher quality factor.

• A ~0.3 kHz upward shift in resonance frequency was observed in vacuum, confirming reduced damping.

• The system’s performance remained stable across both pressure conditions.

Conclusion

SmarAct’s PICOSCALE Vibrometer allows high-fidelity vibration measurements in vacuum, making it ideal for evaluating MEMS dynamics under realistic conditions. It enables manufacturers and researchers to verify device behavior before packaging or in final-use environments.