Hi, im trying to make a biomedical machine , the idea is to locate the nerve by supplying a current like 2mA or 0.2mA , so does i need to feed the nerve a 100V with a low current using a transformer ? or a transistor , i dont know really the idea ..

 

Is the person alive or dead?

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hehe, 2mA can kill ??
i think over 20mA can kill , anyway u didnt tell me the idea -_-

 

They do make equipment that does what you describe. I had testing done to help verify that my back was the cause of leg/foot problems. Leads were pasted on various locations - and a pulse was fired resulting in a brief muscle contraction. I've had people tell me how much pain they experienced with a test like this - while not pleasant I found it quite tolerable for a short period of time.

I'd expect that the information you need is in a biomedical reference book. I would expect that anything used on people would be designed so that it can't hurt someone - normally or if failures occur.

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You probably should look up the term: electromyelography and its variants, such as electromyelogram. Just search on EMG and you will get plenty of hits regarding testing nerve conduction.

As for mapping nerves, you need to define the question considerably more. Are you talking about deep nerves, peripheral nerves, which nervous system, and why?

John

 

Dentists use a "nerve locator" during a tooth's root canal. It is probably a very low current. 2mA would blow the patient's head off.

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It depends on the prerson and where the current is introduced.

I've never heard of anyone being killed by 2mA, it'd probaly only kill if it was directly introduced intot he heart.

I can't feel 1mA with my fingers, 2mA would probably ony cause a slight tingling sensation.

Dentist probably use a much lower current as the nerves in the mouth are more sensitive. The open circuit votage is also pretty low, <60V as the mouth is pretty conductive.

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You need to build an adjustable current source with an open circuit voltage of >200 v.

DC?
AC?
What freq.?
I haven't a clue.

 

Go with DC - it's much safer.

A disposable cemera flash unit would probably do it.

Use a resistor to limit the short circuit current to above 1mA (below 1mA you probably won't be able to feel it) and under 5mA (the maximum current deemed to be harmless, according to Wikipedia and other sources), about 2mA is probably a safe bet, make sure the resistor is rated for the voltage (for safety's sake use two in series) and power.

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thanks for the posts ,,
Is 200V will be harmfull ??
So what i only need is a transistor as a current source ?? and its VCC will be 200V ? and with calculations i will make a 1mA current ?
also another question , what is the ground of the human body ?? to test it , the 1mA should flow in the body , then there should be a ground and a positive terminal , where i will connect them ??

 

200V won't be harmful if the current is limited to a safe level.

There's a 1kV insulation tester at work and it doesn't even hurt me because the curent is limited to 1mA.

You just have to make sure that no single failure can allow more than 5mA to flow. Supose you use 200V and two 51k resistors in series, the normal short circuit current will be 1.96mA and if one of the resistors goes short circuit the current will be 3.92mA which would hurt but not kill. Using a transistor current source is more dangerous because if the transistor emitter collector goes short circuit then a potentially lethal current could flow.

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Thanks , and from where to get this high voltage 200V ?! dc to dc converters ?

 

I've already told you - a disposable camera flash unit.

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thanks , so where is the ground in the human body and the live wire ?

 

Why on earth would anyone want to build such a device? Who would let them hook it up to them?
Yea I got the design from the internet

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