DiaphragmCalc
Piezoresistive pressure sensor · first-pass design

Size a silicon pressure-sensor diaphragm in seconds, before you open FEA.

Deflection, edge stress, Wheatstone bridge sensitivity in mV/V/bar, burst margin and resonance (dry and oil-loaded) for clamped square and circular diaphragms. Closed-form plate theory with every assumption written down.

Geometry
Material
GPa
–
kg/m³
MPa
Pressure
×
–
Piezoresistors & bridge
–
V
Fluid loading
kg/m³

Results

Design insights

    Parameter sweep

    Results are analytical first-order estimates from thin-plate theory and should be independently validated (FEA and test) before use in safety-critical or production designs. See model assumptions.

    Guides

    The equations behind each number, with worked examples you can reproduce in the calculator.

    Pricing

    Single-point calculations, insights and short sweeps stay free. Pro is for when you are iterating a real design and need to hand results to someone else.

    Free

    Calculator

    $0
    • All single-point results and warnings
    • Design insights
    • Sweeps of thickness and pressure, 15 points
    • Copy results as text
    Pro

    Design workbench

    $19 one-time
    • Sweep any variable (size, E, doping), up to 200 points
    • CSV export of every sweep
    • PDF design report with inputs, equations and warnings
    • Baseline comparison with % deltas
    • Saved projects in your browser
    Payment by Lemon Squeezy. License key arrives by email. 14-day refund, no questions.
    Service

    Expert design review

    from $249
    • Review of your diaphragm, resistor placement and packaging assumptions
    • Written report with recommended changes and FEA plan
    • Fixed quote before any work
    Request a quote

    Design review for MEMS pressure sensors

    For hardware teams and researchers with a diaphragm design heading to FEA or fab. Reviewed by a researcher working on oil-filled piezoresistive pressure sensors with corrugated diaphragms: diaphragm mechanics, transduction and packaging failure mechanisms.

    What you send

    Target range and overpressure, diaphragm geometry and material, resistor layout if you have one, package and media. Drawings or a DiaphragmCalc export are enough to start.

    What you get

    A written review: first-order sizing check, sensitivity and nonlinearity budget, burst margin, resonance with media loading, packaging stress risks, and a short list of FEA runs worth doing.

    Turnaround and price

    You get scope and a fixed quote within two working days. Typical reviews start at $249.

    FAQ

    How accurate is this?

    It uses closed-form clamped-plate solutions (Timoshenko), Smith's p-silicon piezoresistance coefficient with Kanda's doping factor, and Lamb's added-mass model for fluid loading. Expect agreement with linear FEA to within a few percent for thin, small-deflection diaphragms with ideal clamping. Anisotropy, residual stress, bossed or corrugated geometry, real resistor size and package stress need FEA.

    Is this FEA?

    No. It is a first-pass analytical tool for choosing a sensible starting geometry and understanding trade-offs before detailed simulation.

    Why is my sensitivity higher than my measured device?

    The model assumes resistors sit at the point of peak edge stress. Real resistors average stress over their length, and packaging, temperature and doping reduce the response. Lower the stress-averaging factor (0.5–0.8 is typical) to account for this.

    What happens to my data?

    Calculations run in your browser. We count anonymous events (for example "calculation run", "square vs circular") with no cookies and no personal identifiers. Lead form data is used only to reply to you.

    Refunds

    Pro has a 14-day refund through Lemon Squeezy. Reply to your receipt email.