Convert FRR/TFR protocols into per-inlet pump settings, volumes, and residence times for lipid nanoparticle production. Free. Client-side.
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Load example LNP micromixer planner data to see the full workflow
| Inlet | Solution | Flow (mL/min) | Volume (mL) | Final conc. |
|---|---|---|---|---|
| Aqueous | PBS | 9.000 | 1.500 | — |
| Organic | Lipid 10 mg/mL in ethanol | 3.000 | 0.500 | 2.50 mg/mL |
When to use
Do not use for
Most published mRNA-LNP protocols use 3:1 — it balances ethanol dilution kinetics, final ethanol content, and compatibility with standard 8–12 mg/mL lipid stocks. Start here.
FRR 3:1 leaves 25% ethanol in the formulation — you MUST dialyze or buffer-exchange before delivery. The tool does not compute ethanol content but it is implied by the FRR.
If your syringe pump maxes out at 10 mL/min and you ask for TFR 15, it will silently limit to 10. Check the pump specs BEFORE running. Also check backpressure with the Pressure Drop Calculator.
Actual mixing efficiency depends on chip design (herringbone grooves, serpentine channels) and Reynolds number inside the mixer. The residence time here is a bulk average, not a mixing-time guarantee.
Aqueous fraction = FRR / (FRR + 1). Organic fraction = 1 / (FRR + 1). Per-inlet flow = TFR fraction. Per-inlet volume = finalVolume fraction. Final lipid concentration = lipidStock organicFraction. Residence time = mixerVolume / TFR (in consistent units, reported in ms). Run duration = finalVolume / TFR. Target mismatch is flagged when |final − target| / target > 1%.
Last validated 2026-04-07. Calculations are designed for planning and documentation support; verify procurement decisions against manufacturer specifications or institutional SOPs.
ConductScience LNP Micromixer Flow-Rate-Ratio Planner (v1.10.0). ConductScience, Inc. 2026. Available at: https://conductscience.com/tools/lnp-micromixer-planner
Final lipid concentration = lipid stock / (FRR + 1). That is the whole ballgame.
A 10 mg/mL lipid stock at FRR 3:1 gives a 2.5 mg/mL final formulation — the stock is diluted 4-fold (FRR + 1) by the aqueous phase. At FRR 5:1 the same stock gives 1.67 mg/mL, and at FRR 1:1 it gives 5 mg/mL.
This is why vendors publish FRRs of exactly 3:1 for most mRNA-LNP protocols: it is the default that translational labs converged on after years of optimization, and it pairs well with stock solutions in the 8–12 mg/mL range.
LNP self-assembly is a fast, kinetically controlled process. When the organic and aqueous phases mix, the ethanol concentration drops, and lipids precipitate into particles on a millisecond timescale.
If the mixer residence time is too short (< 5 ms), particles may not finish assembling before leaving the mixer. If too long (> 100 ms), particles can aggregate. The sweet spot for most mRNA-LNP systems is 10–50 ms, achieved at TFR 8–15 mL/min in standard herringbone chips.
Scaling up TFR to reduce residence time is the most common optimization knob in LNP production.
