autopatch.rst

Automatic patch clamp

These are automatic patch clamp algorithms adapted from the literature.

Main patch clamp algorithm

Amplifier start-up (on Multiclamp 700B):

1. Voltage-clamp.
2. Disable resistance metering and pulses.
3. Compensate pipette (slow and fast).
4. Set pulse amplitude and frequency (default 1e-2 and 1e-2, units unclear).
5. Set zap duration at 1 ms.
6. Do pipette offset (V=0).
7. Set holding potential V = 0.
8. Enable resistance metering (triggers voltage pulses).

Resistance check: 1. Set pressure at pressure_near (>0). 2. Do pipette offset (V=0) and wait for 4 s. 3. Check that the resistance is within specified bounds.

Approach:

1. Move the manipulator with a safe move to a distance cell_distance above the target position, if specified.
2. Do pipette offset and wait for 2 s.
3. Check that resistance has not increased by 1+cell_R_increase.
4. Move down by 1 µm and wait for 1 s (maximum total movement max_distance).
5. Measure R. Unless R has increased by 1+cell_R_increase, repeat (7).

Sealing:

1. Release the pressure and wait for 10 s.
2. If R is smaller than 1+cell_R_increase times R: go back to approach (7). Note that pressure is now released.
3. Set pressure at pressure_sealing (<0).
4. If R>gigaseal_R: success (next stage).
5. Ramp V down to Vramp_amplitude (default -70 mV) over duration Vramp_duration.
6. Wait for at least seal_min_time, and until R>gigaseal_R (success) or time is out (seal_deadline) (failure).
7. Success or failure: release pressure.

Break-in:

1. If R<gigaseal_R: failure (seal lost).
2. Increase max pressure by pressure_ramp_increment; fail if greater than pressure_ramp_max.
3. If zap is True, do an electric zap.
4. Do a pressure ramp up to max pressure, of duration pressure_ramp_duration; wait for 1.3 s.
5. If R<max_cell_R: success.

Ending (also if stopped in the middle):

1. Stop the amplifier: disable resistance metering and pulses; current-clamp.
2. Set the pressure at pressure_near (>0).