this post was submitted on 16 Jul 2024
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Your body doesn't all die at once. The parts that need a constant flow of oxygen die within minutes, while some parts take hours. Tissues like skin, tendons and heart valves are viable for harvest for as long as 48 hours after death.
https://australian.museum/about/history/exhibitions/death-the-last-taboo/decomposition-body-changes/
I don't know how long a fingerprint would work after death though. I imagine it depends on the type of scanner. An optical scanner would probably not care. I'm not sure about ultrasonic. Thermal and capacitive would probably stop working within minutes of death.
Lol not that. I'm well aware of that. I meant a source for "fingerprint readers are looking for an electrical signal too" as I'm very sure I've heard about them being defeated with a high enough quality reproduction of the finger (read: not flesh at all, let alone alive)
Oh, I did a dumb. Capacitive readers use the body's natural electrical signal to form an image of your fingerprint. You can trick them by using something conductive and running the right amount of electricity through.
Dead people don't work though. Not for very long at least.
Capacitive sensors are looking at capacitance of a material, everything has this not just living things and it certainly doesn't require putting current through the material. You can for example get capacitive sensors for sensing the presence of cardboard, and they're often used for detecting metal parts (obviously tuned to the specific material). This is also why water droplets mess up touch screens (and the biometric sensor), because it's close enough to the capacitance of a finger (we're mostly water after all) to trick it and create false triggers.
Capacitive sensors don't measure the body's signals. Capacitance is a physical property of a material. The sensor puts out a signal and measures the response.
I can use a gallon of milk to scroll my phone. Just tried.