Biomedical signal? what does it look like?

"Biomedical" covers a lot of territory. What SORT of gear are you interested in? Monitoring WHAT? ECG/EKG? EEG? MRI? CAT scan? Blood pressure? Spirometer? Circadian temperature changes? Borborygm?

CLARIFY!

Sorry Ron. I have a general interest in signals graphics, but I am specifically interested in all types of signal used as "stimuli" in neurological research and/or neural interfaces/ devices research.

There are two types of signal mentioned in neural interfaces research: the first and most common is a "stimulus pulse train", typically used in the established therapeutic devices such as DBS, VNS and so on. I've seen lots of discussion of parameters in the "stimulus pulse train" vs effects (pulse frequency, waveform characteristics including charge balance, whether biphasic or triphasic etc) but have yet to see a good graphic of an ordinary or typical stimulus pulse train.

The second type of signal is mentioned in research on "nerve conduction block" and is referred to as "HFAC". I have not been able to find a clear explanation of this term and don't know what the signal looks like.

Wow - and I hadn't even touched on the signals sent TO the patient! So we could add pacemakers, defibrillators, and so on to the mix, though those don't seem to be your target. I think that confirms my notion that the original question is a bit broad! I can't say that I've seen graphical representations of the various ones you mention, either, but there ought to be overview-type articles in, say, Scientific American, that would have such information.

http://neuroscience-bucharest.blogspot.com/2007/10/wwwthalamusro-updates.html looks like it could be a starting point - look at their "About Us" on the right side! I did a Google image search for "DBS stimulation" - try some similar entries to see if you can find what you want. Not everything will show under images, either, so you'll want to use a text search and look at some of the results, I think. Good luck!

Thanks. I've spent a few hours trolling through Google image searches (awhile ago now) without finding a nice clear representation of the stimulus signal alone.

For example, just now I found pix of experimental stimulus and response (I think) in figures found here: http://cogprints.org/121/0/interval_specific_event.htm and referred to as a "montage".

I think it's typical of biomedical science that the response data is what they're really interested in. I would expect to find some nice clear signal images from the gear itself, in the bioengineering literature, at IEEE for example, but I don't have a subscription.

I see Google at least turns up some descriptions of HFAC, searching "HFAC nerve conduction block". "High frequency alternating current" stimuli are described by Bhadry as charge balanced, continuous sinusoidal waveforms between 10 khz and 30 khz, for starters. Images are of the response! again....

well, duh. I guess 'alternating current waveform' is just that. simple and sinusoidal unless otherwise specified.... the HF part is just the frequency (and they're not too fussy about 'high' , some are starting at 3000 hz)

Some HFAC medical research is being modestly funded under HSS/recovery, described here.

as to my question of images, the sports people, as usual, have the goods on the transcutaneous systems.

http://www.medco-athletics.com/lectureseries/neuro.html . Not entirely explained, but they do list parameters, image waveforms, and nifty 'wavenames' like "the russian" (I feel manly just thinking about it!) and a nice graphic of response levels, from 'subsensory' to 'noxious'.

Odd - "The Russian" SAYS that it's sinusoidal, but the single cycle shown as a "closeup" doesn't look like a sine wave to me! More like half of an oval with nearly equal axes. It would seem to need a waveform generator to produce, whereas straightforward generators & alternators (minus the diodes of automotive ones) will produce a decent sine without effort.

Yeh, all of the graphics there are distinctly something drawn up, not a real signal that came out of a machine and was recorded. Sigh!

You can get more accurate pictures of a sine wave on any mech page.