The only optimized whole-cell patch clamp that fully compensates for series resistance and eliminates series resistance errors (US patent 6,700,427)
• Voltage Clamp the largest, fastest whole-cell currents under physiologic conditions.
• No more oscillations at high compensation settings. It's stable even when over compensated
• Familiar IV converter architecture means super ease-of-use. It tunes just like the amps you are used to!
Detailed Description
The VE-2 is an optimized whole-cell voltage clamp amplifier featuring the Rs compensatorTM, a unique circuit that brings complete (100%) series resistance compensation to a conventional patch clamp. In contrast, other patch clamp that use standard Rs compensation will oscillate when set above ~90%. Consequently, other amplifiers always leave some uncompensated series resistance with a voltage error.
With the Rs Compensator, you can:
1. Voltage clamp Large and Fast ionic current, while maintaining voltage clamp control;
2. Plot accurate IV curves without shifts or distortions due to uncompensated RS;
3. maintain stable Rs compensation even as the pipette resistance shifts during an experiment. Notably, other amplifiers will oscillate if the access resistance decreases during an experiment.
For details on how the Rs compensatorTM works, click here.
VE-2 Operating Modes
The VE-2 has three operating modes: Voltage clamp, I=0, and Current Clamp.
Voltage Clamp: The pipette voltage is clamped to a command signal. The command signal is derived by summing the following signals: the external command (scaled BNC input); the holding potential (+/- 200mV via calibrated ten turn dial); and the pipette offset control (+/- 200mV calibrated via ten turn dial).
I=0: The pipette current is clamped at zero, and the command inputs are disabled. This mode is useful for determining the cell resting potential and for presetting holding commands.
Current Clamp: The pipette current is clamped to a command signal. The command signal is derived by summing the following signals: the external command (scaled BNC input); and the holding current control (+/- 20 nA). This mode is useful for evoking and recording action potential in excitable cells.
The VE-2 features an optimized, patented headstage design for wideband current clamp mode (20kHz bandwidth in most whole-cell configurations), allowing the VE-2 to record undistorted action potentials in excitable cells.
Series resistance compensation
Fully compensate series resistance using a calibrated ten-turn dial in either low (0-20Meg) or high (0-100Meg) resistance ranges.
Unmatched Capacitance Compensation
The VE-2 features proprietary circuitry to completely compensate pipette capacitance with only one control adjustment, for unequaled ease-of-use.
In contrast, most patch clamps require independent adjustment of four separate controls to achieve similar performance under varying pipette geometries and immersion depths.
Outputs, controls, and telegraphs
Im - Scaled pipette current, with selectable scaling factors of 0.05mV/pA through 5mV/pA. Im can be selectively filtered with an internal 4 pole lowpass Bessel filter.
Vm - Pipette voltage X 10
Ext Drive - Digital input/output port through which Mode, Gain, Filter, and Rs compensation range can be set and/or monitored using an external computer. This port also enables the amplifier to be dynamically switched between Current clamp and Voltage clamp under software control.
Telegraph outputs (with optional Telegraph unit)- Separate analog outputs encode the mode, gain and filter panel switch settings. The telegraph outputs allow popular electrophysiology acquisition software to automatically record these panel switch settings.
LED Panel meter - Meter displays pipette voltage in mV.
