|Posted on Saturday, April 08, 2006 - 03:40 pm: ||
Very interesting project you are working on. Give me a private e-mail and I'll refer you to the right person to inquire about constituent levels in fingerprints.
|Posted on Thursday, April 06, 2006 - 03:15 am: ||
Ah, here's an idea: Maybe you can give an upper estimate for the mass of a fingerprint?
E.g. suppose that guy that ran just across the street, hadn't washed his hands since breakfast, and touched a glass surface real hard, leaving a nice fingerprint... or any other scenario, you name it... any value might help, really.
|Posted on Thursday, April 06, 2006 - 02:58 am: ||
thanks for you answer :-) Well, I thought it would be vague, but I didn't expect it to be *that* vague... *g*
I'll explain my problem: I work with an mega-cool ultra-sensitive radioactivity detector. (We actually claim to have one of the three most sensitive detectors in the world...) Suppose somebody touched the detector during the production process with bare hands and left an average (here it is again... ;-) ) fingerprint. That fingerprint would probably contain sweat, thus potassium, thus potassium-40 which is radioactive, and might thus mess up our measurements.
And the actual question is: How much would that mess up the measurements? I.E. how much potassium is in a fingerprint?
Of course, since we have this ultra-sensitive detector, we could just try it out, and I'm quite sure we would find the answer. Unfortunately, after that, my boss would kill me, since that would most certainly screw up the thing and ruin the detector, quite expensive trial-and-error indeed...
Still, I'm curious, so I'd like to know a bit more about fingerprints.
|Posted on Wednesday, April 05, 2006 - 07:00 pm: ||
You are right... there are numerous variables that makes the definition of an "average" touch very difficult. In fact, you will probably not get many answers to your questions simply because there are too many variables. However, having said that, I will take a rough crack at some vague and general answers.
How much could vary from nothing all the way to an entire wet impression. Measure that how you will; volume, area, weight, or other.
The second answer depends on what you have recently touched. If you have run your finger through your hair, touched your face, or rubbed your shoulder, the impression is likely to contain a higher percentage of oils and fats. If you have washed your hands and have only sweated from the pores on your friction ridges, then it will consist mostly of eccrine deposits, which are about 99% water along with a host of amino-acids, polypeptides, salts, and other minerals.
Hope this vaguely answers your vague question, but you have one thing going for you... you knew it was a vague question, so there is no suprise at a vague answer.
|Posted on Wednesday, April 05, 2006 - 11:15 am: ||
suppose you're touching your computer monitor as you read this. Clearly, you leave a fingerprint. How much and what kind of material does now stick to the computer monitor?
OK, here's my two cents:
How much - well, that will of course depend on how dirty your hands are, how strongly you sweat, when you've washed them the last time, how smooth the surface is, and probably lots more. So, let's just assume it's your average finger touching an average screen.
What kind of materian - well, once again, I'm sure this will depend on the above parameters as well. But is it mainly sweat? Fat? Old skin?
Thank you very much!