Diaphragm thickness vs sensitivity

Thickness is the strongest lever in diaphragm design, and it pulls several results in different directions at once.

Scaling laws

edge stress, sensitivity  ∝ (a/h)²
deflection                ∝ a⁴ / h³
resonance                 ∝ h / a²
safety factor             ∝ (h/a)²

Halving the thickness gives four times the sensitivity, eight times the deflection, half the resonant frequency and a quarter of the burst margin. Deflection grows faster than stress, so a thin diaphragm reaches the nonlinear regime (w₀ above about 0.2·h) before it reaches its fracture limit.

Example

For a 1000 µm square silicon diaphragm at 1 bar:

The table shows the usual design space: sensitivity rises steeply as the diaphragm thins, while nonlinearity and burst margin set the lower limit on thickness. Low-pressure sensors often add a central boss or corrugations to break this trade-off, which needs FEA.

Results are analytical first-order estimates and should be independently validated before use in safety-critical or production designs.