Low Noise & High Stability
Quiet baselines and stable feedback for precise TER/Isc and current recordings.
Morsetti di tensione
Il voltage clamp viene utilizzato dagli elettrofisiologi per misurare le correnti ioniche attraverso una membrana neuronale mantenendo la tensione di membrana a un livello impostato. Le membrane neuronali contengono molti tipi diversi di canali ionici, alcuni dei quali sono voltaggio-dipendenti. Il voltage clamp consente di manipolare la tensione di membrana indipendentemente dalle correnti ioniche, consentendo di studiare le relazioni corrente-tensione dei canali di membrana.
Il concetto di voltage clamp si deve a Kenneth Cole e George Marmount negli anni '40. Cole scoprì che era possibile utilizzare due elettrodi e un circuito di feedback per mantenere il potenziale di membrana della cellula a un livello impostato dallo sperimentatore.
Alan Hodgkin capì che per comprendere il flusso di ioni attraverso la membrana era necessario eliminare le differenze nel potenziale di membrana. Dopo esperimenti con il voltage clamp, Hodgkin e Andrew Huxley delinearono le cause ioniche del potenziale d'azione nel 1952, per le quali condivisero il premio Nobel per la fisiologia o la medicina nel 1963.
Voltage Current Clamps ( VCC )
Our voltage current clamp amplifiers pair precise control with low-noise measurement for epithelial transport and electrophysiology workflows. Each unit provides voltage-clamp and current-clamp operation for mapping I–V relationships, measuring short-circuit current (Isc) in Ussing chamber studies, and integrating cleanly with data acquisition and Ag/AgCl electrodes.Voltage/Current Clamps for Electrophysiology
A voltage current clamp (voltage-clamp and current-clamp amplifier) lets researchers hold membrane voltage or inject defined current to quantify ion transport and membrane excitability with low noise and fast response. In epithelial studies and Ussing chambers, clamps enable precise short-circuit current (Isc) control and high-fidelity recordings for transport and barrier research.
Voltage Current Clamp Modes and Applications
| Mode | Primary Application | Highlights |
|---|---|---|
| Voltage Clamp (V-Clamp) | Hold membrane/epithelial potential and measure ionic currents | Stabilizes Vm via feedback; ideal for IV curves, channel kinetics, and transport quantification |
| Current Clamp (I-Clamp) | Inject defined current and record voltage responses | Characterize excitability, resistance, and time constants; bridge/offset tools improve accuracy |
| Two-Electrode Voltage Clamp (TEVC) | Large cells/epithelia with separate sense and drive electrodes | Excellent stability; compatible with Ag/AgCl electrodes and low-noise bath references |
| Short-Circuit Current Clamp (Isc) | Ussing chamber studies at ~0 mV transepithelial potential | Direct Isc measurement for transport assays, drug response, and barrier integrity work |
Why Choose Our Voltage/Current Clamps?
Fast Response & Bandwidth
Rapid settling for accurate steps, pulses, and dynamic protocols.
Flexible Modes & Ranges
Voltage-clamp, current-clamp, TEVC, and short-circuit clamp in configurable ranges.
Electrode Compatibility
Integrates with Ag/AgCl half-cells, reference electrodes, and Ussing chamber hardware.
Acquisition-Ready Outputs
Scaled analog outputs for current/voltage; easy hookup to data acquisition and analysis.
Safety & Reliability
Appropriate compliance voltage, protection, and calibration for repeatable results.
Best Practices & Setup
- Electrode Prep — Use fresh Ag/AgCl electrodes; check offsets and impedance before each run.
- Offset & Bridge — Zero electrode/bath offsets; in I-Clamp, set bridge balance and capacitance neutralization.
- Series/Leak Compensation — Use appropriate compensation in V-Clamp; avoid oscillations by increasing gradually.
- Filtering — Apply minimal low-pass filtering needed for SNR; document filter and sampling rates.
- Grounding — Maintain a single, stable bath ground to reduce hum and ground loops.
- Validation — Verify gain/scale using known resistors or test cells; record baseline drift over time.
Following these steps improves signal-to-noise, measurement accuracy, and reproducibility in voltage-clamp, current-clamp, and Isc assays.
Frequently Asked Questions
What is a voltage current clamp?
Answer: A voltage/current clamp is an amplifier that operates in two modes: voltage-clamp holds membrane voltage and measures ionic current, while current-clamp injects defined current and records the resulting voltage.
When should I use voltage clamp vs current clamp?
Answer: Use voltage-clamp to isolate conductances, generate IV curves, and quantify transport; use current-clamp to study excitability, membrane resistance, and time-dependent voltage responses.
What is TEVC and short-circuit (Isc) clamp?
Answer: TEVC uses separate electrodes to sense voltage and drive current for stable control in large cells or epithelia. Short-circuit clamp holds transepithelial voltage near 0 mV in Ussing chambers to measure Isc directly.
Which specifications matter when selecting a clamp?
Answer: Key specs include bandwidth/settling time, noise, gain ranges, compliance voltage, stability/oscillation behavior, output scaling, and compatibility with your electrodes and DAQ.
Are your clamps compatible with Ussing chambers and electrodes?
Answer: Yes. Our voltage/current clamps interface with Ag/AgCl and bath reference electrodes and integrate with standard Ussing chamber hardware for TER and Isc studies.
How do I calibrate and zero the clamp?
Answer: Before each run, zero electrode offsets, verify gain/scale with a known resistor or test circuit, confirm polarity, and document filter/sampling settings for repeatable results.
Resources and Support
Ussing Chambers — pair with short-circuit clamp for epithelial transport studies.
Electrodes & Accessories — Ag/AgCl electrodes, reference leads, and cables.
Acquire & Analyze — data acquisition and analysis tools for clamp outputs.
Talk to an applications specialist — get help selecting the right clamp and setup.