Fig. 1.

Array of nanomechanical resonators. SEM images of 5×4 NEMS array used for nanomechanical mass spectrometry. Typical horizontal and vertical pitches are 20 and 55 µm respectively. a General view of the array, b zoom on two resonators (silicon is false-colored in deep blue), and their metal interconnects (AlSi). c, d zoom-in on interconnects and via. The first metal level is colored in deep yellow, the second one in light yellow. e Typical doubly clamped in-plane resonator used in this study. The beams are designed to resonate around 30 MHz for mode 1 and 80 MHz for mode 2. Typical dimensions for the resonant beam are: 160 nm (thickness), 300 nm (width), and 5–10 µm (length). In-plane motion transduction is performed using piezoresistive nanogauges in a bridge configuration to allow background cancellation. Electrodes are specifically patterned for efficient mode 1 and mode 2 actuation. For a resonance frequency f₀, bias voltages at f₀+∆f are applied to both nanogauges (with 180° dephasing). Tension/compression in the gauges mix their resistance change to obtain a downmixed differential output voltage at ∆f, typically around a few 10’s of kHz. f Schematic of the interconnect layout. Each resonator has a unique beam length, hence a unique resonance frequency