Chronaxie and Rheobase Calculator

In neuroscience and clinical electrophysiology, rheobase and chronaxie are two thresholds that describe how nerve or muscle tissue responds to electrical stimulation — rheobase is the minimum voltage needed to trigger a response, and chronaxie is the pulse duration required at twice that voltage. Enter your stimulus strength, stimulus duration, electrode impedance, and pulse width range, then select your measurement type (voltage-duration or current-duration curve). The Chronaxie and Rheobase Calculator returns your rheobase as the primary output, along with chronaxie, 2x rheobase, and charge threshold.

V

Minimum voltage that produces a response

ms

Duration at 2x rheobase that yields response

Type of strength-duration measurement

Ω

Electrode-tissue interface impedance

ms

Range of pulse widths tested

Results

Rheobase

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Chronaxie

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2x Rheobase

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Charge Threshold

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Results Table

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Frequently Asked Questions

What is the difference between rheobase and chronaxie?

Rheobase is the minimum stimulus strength (voltage or current) that will produce a response, representing the asymptotic value of the strength-duration curve. Chronaxie is the stimulus duration required to produce a response when the stimulus strength is set to exactly twice the rheobase value.

Why do voltage-duration and current-duration measurements give different chronaxie values?

The complex impedance of the electrode-tissue interface varies with both pulse width and stimulation voltage. This causes chronaxie values from voltage-duration measurements to be typically 30-40% lower than those from current-duration measurements.

How do I determine the rheobase from a strength-duration curve?

The rheobase is determined by finding the minimum stimulus strength that produces a response. This appears as the horizontal asymptote of the strength-duration curve when plotting stimulus strength versus duration.

What is the clinical significance of chronaxie and rheobase measurements?

These parameters are crucial for optimizing electrical stimulation in medical devices like pacemakers, deep brain stimulators, and functional electrical stimulation systems. They help determine the most efficient stimulation parameters for nerve and muscle activation.

How does electrode impedance affect the measurements?

Electrode impedance significantly influences voltage-duration measurements because it affects the actual current delivered to the tissue. Higher impedance can lead to voltage drops across the electrode interface, affecting the accuracy of chronaxie calculations.

What is the typical range for chronaxie values in human nerve tissue?

Chronaxie values typically range from 0.1 to 1.0 milliseconds for most human nerve fibers, though this can vary significantly depending on the specific nerve type, electrode configuration, and measurement conditions.