Automatic patch clamp¶
These are automatic patch clamp algorithms adapted from the literature.
Main patch clamp algorithm¶
Amplifier start-up (on Multiclamp 700B):
Voltage-clamp.
Disable resistance metering and pulses.
Compensate pipette (slow and fast).
Set pulse amplitude and frequency (default 1e-2 and 1e-2, units unclear).
Set zap duration at 1 ms.
Do pipette offset (V=0).
Set holding potential V = 0.
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:
Move the manipulator with a safe move to a distance
cell_distance
above the target position, if specified.Do pipette offset and wait for 2 s.
Check that resistance has not increased by
1+cell_R_increase
.Move down by 1 µm and wait for 1 s (maximum total movement
max_distance
).Measure R. Unless R has increased by
1+cell_R_increase
, repeat (7).
Sealing:
Release the pressure and wait for 10 s.
If R is smaller than
1+cell_R_increase
timesR
: go back to approach (7). Note that pressure is now released.Set pressure at
pressure_sealing
(<0).If
R>gigaseal_R
: success (next stage).Ramp V down to
Vramp_amplitude
(default -70 mV) over durationVramp_duration
.Wait for at least
seal_min_time
, and untilR>gigaseal_R
(success) or time is out (seal_deadline
) (failure).Success or failure: release pressure.
Break-in:
If
R<gigaseal_R
: failure (seal lost).Increase max pressure by
pressure_ramp_increment
; fail if greater thanpressure_ramp_max
.If
zap
is True, do an electric zap.Do a pressure ramp up to max pressure, of duration
pressure_ramp_duration
; wait for 1.3 s.If
R<max_cell_R
: success.
Ending (also if stopped in the middle):
Stop the amplifier: disable resistance metering and pulses; current-clamp.
Set the pressure at
pressure_near
(>0).