MEMS Comb-Drive Actuator — Electrostatic Resonance Simulator

Electrostatic Drive

DC bias V_DC 18 V

AC amplitude V_AC 8 V

Drive frequency ω/ω₀ 1.00×

Quality factor Q 18

Live Readouts

Shuttle displacement

0 nm

Electrostatic force

0.0 µN

Resonant frequency f₀

— kHz

Drive frequency

— kHz

Amplification (peak x / static x)

1.0×

How it works

A comb-drive is a set of N interleaved conductive fingers. Because the overlap length changes with displacement but the gap does not, the electrostatic force is constant with position (unlike a parallel-plate actuator, which has a pull-in instability):

F(V) = N · ε₀ · h · V² / g

N = finger pairs, h = device-layer thickness,
g = finger gap, ε₀ = 8.854×10⁻¹² F/m

The shuttle hangs on folded-flexure springs of stiffness k and moves as a driven, damped harmonic oscillator:

m·x″ + c·x′ + k·x = F(t)
ω₀ = √(k/m),  Q = m·ω₀ / c

Driving with V(t) = V_DC + V_AC·sin(ωt) makes F(t) ∝ V(t)², which mixes a DC offset, a term at ω, and a term at 2ω. When V_DC is the larger term the ω-component dominates and the usual resonance curve appears: displacement amplitude peaks near ω = ω₀ and scales roughly with Q, exactly as plotted live here as you sweep the frequency slider.

V_DC / V_AC — set the bias and drive-swing voltages across the comb.
ω/ω₀ — drive frequency relative to the mechanical resonance; sweep it through 1.0 to see the peak.
Q — quality factor (inverse damping); higher Q means a sharper, taller resonance peak.

Animation runs on a slowed, visually-scaled clock so the ~20 kHz mechanical resonance is visible to the eye; the frequency and force readouts are the real device values from the formulas above.

Moving shuttle comb Fixed frame comb

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