Patch Clamp Seal Calculator

Patch clamp seal quality is often screened with a small voltage step and the resulting steady leak current. This calculator converts those pulse checks into resistance and conductance, then adds ideal thermal-noise estimates so you can compare recordings under consistent bandwidth and temperature settings. Use the numeric benchmarks below to interpret results across cells, days, and rigs.

Seal calculator

Test step, ΔV (mV)

Command pulse amplitude used for the seal estimate.

Current entry method

Choose how you want to supply the measured current.

Leak current change, ΔI (pA)

Use the steady component of the pulse response.

Temperature (°C)

Used for thermal noise estimates.

Bandwidth (kHz)

Approximate measurement bandwidth (filter cutoff).

Holding potential (mV) optional

Used to predict |I| from the seal alone.

Effective capacitance (pF) optional

Estimate τ = R·C (useful for settling intuition).

Reset

Example data

Sample test pulses and resulting seal estimates.

ΔV (mV)	ΔI (pA)	Rseal (GΩ)	Gleak (nS)	Quality
5	2.5	2.000	0.5000	Gigaseal (≥ 1 GΩ)
10	5	2.000	0.5000	Gigaseal (≥ 1 GΩ)
10	1	10.00	0.1000	Ultra (≥ 10 GΩ)
20	2	10.00	0.1000	Ultra (≥ 10 GΩ)
50	3	16.67	0.06000	Ultra (≥ 10 GΩ)

This calculator estimates seal resistance from a voltage step and the corresponding steady current change.

R_seal = |ΔV| / |ΔI|
G_leak = 1 / R_seal
i_rms = √(4 k_B T B / R_seal)
v_rms = √(4 k_B T R_seal B)

Here, T is absolute temperature (K) and B is bandwidth (Hz). Noise terms are ideal thermal estimates and exclude amplifier and electrode contributions.

Apply a small test step (commonly 5–20 mV) in voltage clamp.
Measure the steady current level during the step window.
Enter ΔV and either ΔI, or baseline and pulse currents.
Set temperature and approximate bandwidth for noise estimates.
Optionally enter holding potential and capacitance for extra outputs.
Press Compute seal to view results above the form.
Use the export buttons to archive CSV or PDF reports.

Patch clamp seal resistance is routinely estimated from a small test step (often 5–20 mV) and the steady leak current that follows. This guide summarizes practical numeric benchmarks, how to interpret conductance and noise, and how optional outputs like predicted holding current and RC time constant support day-to-day decision making.

1) Gigaseal thresholds you can benchmark

A tight seal reduces leak pathways between pipette glass and membrane. A common working definition is Gigaseal ≥ 1 GΩ, with many labs targeting 5–10 GΩ when feasible. Below 100 MΩ, leakage often dominates small channel currents and increases baseline drift.

2) Conductance is the intuitive leak scale

Because G = 1/R, conductance maps directly to “how leaky” the seal is. A 1 GΩ seal corresponds to about 1 nS, 10 GΩ to 0.1 nS, and 100 MΩ to 10 nS. Use this to compare seals across different test steps.

3) Predicting seal-only current at a holding potential

The optional holding potential output uses |I| = |V|/R. For example, at −70 mV: 10 GΩ predicts ~7 pA, 1 GΩ predicts ~70 pA, and 100 MΩ predicts ~700 pA. This helps sanity-check whether your baseline is seal-limited or biology-limited.

4) Bandwidth strongly shapes apparent noise

Thermal (Johnson) noise grows with the square root of bandwidth. At 22 °C, 5 kHz, and 1 GΩ, the ideal estimates are about 0.29 pA RMS (current) and 285 µV RMS (voltage). Doubling bandwidth increases RMS noise by about √2.

5) Temperature changes are smaller than bandwidth changes

Noise scales roughly with √T in kelvin. Moving from 22 °C (295 K) to 37 °C (310 K) increases ideal thermal noise by only ~2–3%. In practice, electrode properties, bath composition, and mechanical stability often matter more than this temperature factor.

6) Measuring ΔI: steady state beats transients

Use the steady portion of the pulse response, not the initial capacitive transient. In delta mode, supply baseline and pulse currents measured over the same window (e.g., averaging after the transient has settled). This reduces overestimation of leakage from capacitive charging artifacts.

7) RC time constant explains settling and clamp feel

If you enter effective capacitance, the calculator reports τ = R·C. A 1 GΩ seal with 5 pF gives ~5 ms; 10 GΩ with 5 pF gives ~50 ms. Large τ can make responses look sluggish and can bias measurements if windows are too short.

8) Using results to troubleshoot seal quality

Low resistance can reflect dirty glass, damaged tips, excessive positive pressure, or poor membrane contact. If your resistance improves during suction but later falls, consider mechanical drift, bath vibration, or cell health. Track seal values with exports to correlate with success rate and stability.

For routine logging, many electrophysiology protocols record seal checks at the start of the experiment and after any major manipulation (pressure change, solution exchange, or mechanical repositioning). Keeping the test step and analysis window fixed makes trends meaningful, and the CSV/PDF exports help keep your notebook entries consistent.

1) What current should I enter for a seal test?

Use the steady leak component during the voltage step. Avoid the first transient peak and average a short window after settling for a more reliable ΔI-based resistance estimate.

2) Why does the calculator use absolute values?

Seal resistance depends on magnitudes of ΔV and ΔI. Current polarity reflects clamp sign conventions, not seal tightness, so absolute values prevent sign from flipping resistance.

3) Is a higher seal resistance always better?

Higher is generally better for reducing leak and noise, but stability matters too. A stable 1–5 GΩ seal can outperform a fragile 10 GΩ seal that drifts during recordings.

4) How accurate are the noise numbers?

They are ideal Johnson-noise estimates based on temperature, bandwidth, and Rseal. Real recordings include amplifier, electrode, access resistance, and environmental noise, so treat the values as lower bounds.

5) What bandwidth should I use?

Use your effective measurement bandwidth, usually close to the low-pass filter cutoff. If uncertain, enter the acquisition filter setting; compare runs consistently rather than chasing a perfect number.

6) Why does my seal estimate change with pulse amplitude?

Nonlinear leak pathways, membrane deformation, or measurement window differences can change ΔI with ΔV. Keep pulse size modest (commonly 5–20 mV) and measure steady-state current consistently.

7) Can I use this for cell-attached and whole-cell?

Yes for seal quality checks. In whole-cell, access resistance and series compensation affect currents, so interpret seal-only estimates cautiously and separate them from series resistance metrics.