# Sinusoidal to monphasic pulse

I have impedance values for an electrode (used for nerve stimulation) over a wide frequency range using sinusoidal current. Now I have to calculate how much voltage I need to stimulate the electrode at a current of 5mA, using the equation (V=IR). I have to use monophasic pulse train of 5 to 10 pulses, pulse width = 200 micro seconds, inter pulse interval = 5 milli sec and frequency= 20 Hz.
I want to know at what frequency I should take the impedance from the impedance data (obtained using sinusoidal current) corresponding to the frequency of 20 Hz (monophasic pulse train)?

## Answers and Replies

berkeman
Mentor
I have impedance values for an electrode (used for nerve stimulation) over a wide frequency range using sinusoidal current. Now I have to calculate how much voltage I need to stimulate the electrode at a current of 5mA, using the equation (V=IR). I have to use monophasic pulse train of 5 to 10 pulses, pulse width = 200 micro seconds, inter pulse interval = 5 milli sec and frequency= 20 Hz.
I want to know at what frequency I should take the impedance from the impedance data (obtained using sinusoidal current) corresponding to the frequency of 20 Hz (monophasic pulse train)?

Welcome to the PF.

First, is this electrode meant to be used in a human biomedical application? If so, are you designing your circuitry according to the UL 544 safety standard?

Can you please describe the application? What does the electrode get placed on? Depending on the surface, you may not be able to infer monophasic impedance from a balanced AC impedance sweep...

Yes, the electrode is meant for biomedical application. the electrode is placed near the nerve.
I have done the impedance measurement of the electrode now I want to calculate how much voltage is required for stimulating this electrode using monophasic current. if the required voltage is too high than this electrode is not suitable.

berkeman
Mentor
Yes, the electrode is meant for biomedical application. the electrode is placed near the nerve.
I have done the impedance measurement of the electrode now I want to calculate how much voltage is required for stimulating this electrode using monophasic current. if the required voltage is too high than this electrode is not suitable.

For monophasic current, won't polarization at the interface modify the impedance? Why are you using monophasic stimulation? Is that standard for EMG applications (I don't know)?