Is there a sensor that can be used for detecting a dead human body?

A heart rate monitor would probably tell you if you're dead.

No.

What are you trying to do?

You cannot locate a dead body by heat signals, unless it's freshly deceased. If that's what you're looking for, look up heat sensors.

To find a dead body with little to no heat signal, more than 6 hours after death, it's my understanding the body passes off a number of noxious gasses that causes a bad odor, including cadaverine and putrescine. While I'm not a chemist, but can hopefully help point you in the right direction, if you know one that can tell you what compounds may coincide with those.

Also, WHICH sensor you're using depends on application, like if you're wearing or carrying the gear, if it's automated or remote controlled, etc. This changes if it should resist humidity, and other factors.

As I mentioned in my comment, bodies turn cold usually within 6 hours of death. Since infrafred is based mostly on heat, a dead body would produce little more IR than let's say a tree trunk.

Actually, a tree trunk with sun hitting it would generate more IR, probably.

Thanks for the answers. We're planning to make a system/prototype, something robotic, for our thesis that can be used after a disaster for search and rescue, and also finding dead bodies. We're planning to use image processing that can detect partial body parts (I just realized that I posted in Arduino section) and several sensors like PIR or the d6t for the project. Those may work for finding humans that are still alive but I don't think using image processing alone is sufficient for detecting a dead body. What about using air quality sensor?

How close do you plan to be to where you're searching?

If you plan to be a fair distance to use cameras/image processing, OpenCV is a Python library that does EXCELLENT at customizing it. There's even a couple of facial recognition apps for it (NOT just facial detection!). You can program it to track things such as a ball, even after half of the ball disappeared behind something. It may be of great use for this project! Also, someone else developed a neural network based on Python libraries, which I never linked even though I intended to.... but if you're familiar with coding, you may be able to!

By sensors alone, it still stands you'd need a sensor at least SOMEWHAT specific to what you're trying to find. A general or generic air quality sensor would go crazy usually after let's say some form of storm in example, where there are gas leaks.... which even may have been the CAUSE of some of the deaths of the theoretical dead bodies you're trying to find.

Finding an airborne chemical a dead body releases, other than a carbon monoxide compound, would probably be most imperative to sorting out the surroundings.

As an afterthought, I just remembered, there ARE some nightvision/IR cameras for the Raspberry Pi, which can run the OpenCV library I was talking about. It would require a fair amount of processing power to run OpenCV for multiple limbs though, so you'd not want anything less than the Raspberry Pi 3, in terms of power. The camera for it, regular or nightvision, can be found for about $30. If you're feeling explorative, there's also ways to turn an existing camera into "nightvision", though I've never done so myself.

That's about as far as I think you're going to go with electronics on the consumer market for the time being.

Thanks! I just actually started learning OpenCV last week. Last question. If I am about to use a drone that is as small as possible, is it better (if possible) to just do the image processing on a laptop or computer by using the transmitted video from the drone instead of using a camera connected to Raspberry Pi mounted at the drone?

I think it may be possible. AFAIK, the OpenCV processes on the final image(s), not the stream itself. You'd just have to export the video from the drone into whatever device you plan to run OpenCV on to process the images. Again, that's best to my knowledge, but since OpenCV is about finding certain patterns in images, I don't think it really matters what the source is.

For infrared, I think a dead body stops typically emitting heat within 6 hours. IR is *mostly* a bi-product of heat compared to it's surroundings. That heat mostly dissipates, so for IR to work, it would need to be within a short time of whatever "disaster" you're "relieving". Also note other things can produce IR besides just bodies or heat.... Television remotes in example. I'm not sure how much IR refracts or is absorbed by some materials, but if it does, you may end up looking in an empty building do to refraction. And, again, A log can absorb sunlight and show up on an IR sensor, due to the heat, IIRC. I just feel there's much that can go wrong with attempted something automated with IR alone.... though can can use OpenCV and process the IR images and/or dual screen the video for different feeds simultaneously. I've done such myself, so it shouldn't be difficult if you're already learning it.

Good luck!

https://userpages.uni-koblenz.de/~agas/Documents/Trierscheid2008HIF.pdf I saw these article while researching and will leave it here in case someone in the future would ask the same thing. From what I understood from reading it, it uses NIR camera and says that it can detect human skin even if it is buried with dust or even if the person is already cold and dead since it does not depend on temperature. Sounds really expensive though.

I kind of knew about it, but couldn't find it available for resale, except in bulk/outside "hobbyist" prices, which is why I mentioned "consumer market".
However, if you CAN find it, and afford it, this may be your best bet... Again, depending on distance you plan to be.