Liquid Class Bench

Delivered

Bias

CV

shot to shot, estimated

Time

per transfer

Channel pressure and tip contents

Air-gap pressureLiquid in tipPiston stroke

Below zero is suction. The gap between stroke and liquid is lag. Drag to scrub.

Where the error comes from

µL vs target

Gray bars lose volume, blue bars add it.

Fastest setting within

Speed vs accuracy

Sampled settingPareto frontCurrent

Each dot is one setting. Left is faster, lower is more accurate.

Total error = |bias| + 2·CV. Click a point to load it.

Aspirate rate × dispense rate

other settings from the sidebar

Lighter is more accurate. Box: best. Ring: current. Click to use.

What the simulator computes

One transfer through an air-displacement channel with a conical 200 µL tip. The liquid is a lumped plug pushed by an air spring. A run takes a few milliseconds.

Column dynamics

ρ·I(h)·dQ/dt = P_out − P_air − ρ·g·h + 2σ·cosθ / r(h) − [ R(h) + ½ρ|Q| / A₀² ]·Q P_air = n / V_air isothermal air gap (150 µL channel + tip) R(h) = 8μ/(3πk)·(r₀⁻³ − r(h)⁻³) + 3μ/r₀³ Poiseuille in the cone + Sampson orifice term I(h) = (1/πk)·(1/r₀ − 1/r(h)) + 2/(πr₀) inertance of the column

The stroke is pre-corrected for the column weight, so the remaining error is dynamic: what rates, delays and blowout control.

Loss mechanisms

Mechanism	Model	Main controls
Not drawn in yet	Flow lags the piston with time constant R·V_air/P; the tip leaves before the column catches up	Aspirate rate, aspirate delay
Degassing bubbles	Heuristic loss once air-gap suction passes 20 kPa	Aspirate rate
Dripped in transit	Column re-equilibrates when the hydrostatic support of the reservoir disappears	Fixed geometry
Wall film	Film forms only above the dewetting speed (Cox–Voinov), with Aussillous–Quéré thickness, then drains under gravity (Jeffreys profile)	Dispense rate, dispense delay
Left in tip	Column still in the tip when it lifts	Dispense delay, blowout volume
Hanging drop	Tate-limited drop stays on the orifice unless the liquid tail leaves as a jet (Weber number above 4)	Dispense and blowout rate
Splash / spray	Jet splash above Mundo K ≈ 57; blowout spray above about 2.5 m/s air speed	Dispense rate, blowout rate
Outside cling	Landau–Levich film on the outer wall during withdrawal; half of it reaches the well	Viscosity (2 mm immersion)

Limits

Demo in development. Coefficients come from textbook scaling laws, not a calibrated instrument: use the trends, not the numbers. Volatile, foaming and non-Newtonian liquids are out of scope.