I don't usually use vampires as main characters. They're normally supporting characters for more, and yet less, human immortals, but I've decided to flesh them out a bit. I was thinking about advanced, hands free dead man's switches for something else when it occurred to me that none of my vampires could use any of the alternatives I was looking at.

So my question is: What physical parameters could a vampire/ghoul/zombie use for a passive body monitoring dead man's switch?

Assume the creature using the switch in question is otherwise human but has:

  • no pulse
  • no measurable blood pressure
  • a room temperature body

If it makes a difference the switch in question is designed to send a signal pulse. This can be used to trigger either an on-site (like a jacket full of Semtex) or an off-site (like a release of files, or a computer wipe) event.

Note: I've lumped vampires, ghouls, and modern zombies together because they have similar physical characteristics and the same mythological origins even though we tend to differentiate them in modern literature.

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    Dead Mans Switches tend to take different forms for different purposes. What's the use-case you have in mind? – Ruadhan Aug 15 at 11:21
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    What do animated vampires/ghouls/zombies have that unanimated vampires/ghouls/zombies don't? Determine that in your story, and you answer the question. – RonJohn Aug 15 at 14:46
  • Maybe make it based on movement, like a step counter? – alexgbelov Aug 15 at 19:13
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    Do vampires turn to dust in your mythos? – James McLellan Aug 16 at 0:22
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    Even a dead man switch that measures pulse/ blood pressure or a room temperature body won't catch all issues with the normal living humans, and is for that reason also avoided in most real life applications (think of falling asleep) – Ferrybig Aug 16 at 8:33
up vote 12 down vote accepted

Eye-tracking glasses

Your undead have glasses that track their eye movement.

No eye movement -> truly dead
Eye movement -> normal undead

Depending on your undead they don't need to sleep so there is no reason to take them off. If your vampires need to rest during the day you could use the camera to watch their coffin or wherever they are sleeping and change it to a "detect light" mode. Once they are awake again they take on their glasses and turn the correct mode for eye tracking on again.

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    That's really cool, and an excuse for the cool vampires never to take off their shades. – Ash Aug 15 at 12:18
  • How about zombies/ ghouls that lack eyeballs? – John Dvorak Aug 15 at 14:06
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    @JohnDvorak The requirements specifically state that I should assume an average human being apart from pulse, blood pressure and room temperature body. If we start to question what happens if it doesn't have an eyeball we also need to question whether it has a brain and we will quickly land at ghosts being undead creatures, too, without any physical body. I assume an undead without eyeballs is not suited to the task designed to require it to wear a dead-man switch. – Secespitus Aug 15 at 14:08

Measure brain activity.

Most variations of vitally impaired citizens which try to maintain at least a minimum of scientific plausibility either have an active brain or something which replaces the function of the brain. So you should be able to measure brain activity (or at least the activity of whatever replaces the brain).

You can use an Electroencephalograph for that purpose. It is a relatively cheap and compact device which gets attached to the head and measures the electromagnetic activity in it. If you want a higher reliability, make it less visible and don't shy away from intrusive methods, you could alternatively implant the detector into the skull.

You could even give them a more advanced detector which doesn't just check if the person is still alive un-dead but can detect certain brain wave patterns and thus allow the wearer to intentionally trigger the dead man's switch with their thoughts.

If your vitally impaired people don't have brain activity, then there got to be some magic power which controls them. In that case you might be able to somehow measure that magic power.

Another bio-function you could measure is their digestive system. Vampires drink blood, ghouls and zombies eat human flesh. That means they need a working digestive system. The activity of the digestive system might be measurable. This might be easier to do with those vitally impaired people who prefer solid food, because they will need active intestines in order to digest that food. The chunks of flesh moving through their guts should generate measurable movement. Curiously, I can not think of any source of zombie lore which mentions whether or not zombies defecate. Intuitively, I would say they do, because some sources say that zombies must eat to survive and a 100% effective metabolism is implausible. If your zombies consume flesh out of instinct but don't actually get nutrients from it, then their stomachs would quickly burst while eating. While a zombie walking around with an open belly oozing a sludge of stomach acid and half-digested flesh is certainly very zombie-esque*, I can not think of any zombie lore mentioning that this is a particularly common occurrence. Also, zombies shitting themselves certainly makes them even more gross**.

It might be a bit harder for those who consume their nutrients in liquid form. Maybe they have active kidneys and a working bladder?

*I think I got a halloween costume for this year! **Not going to incorporate that into my costume, though

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    Good answer, though the hardware is kinda awkward if you're planning to make it removable at all. I own one of these devices intended as a computer peripheral, it's a flexible headset with three contacts for the forehead and some cabling, you could mount it inside a hat or helmet I guess.. The awkward bit is that it's super unreliable. I wouldn't trust it to govern a lightbulb much less a semtex vest. somewhat simpler if you're just watching for any activity rather than some precise state, but still.. private-sector tech for this kinda sucked 8 years ago when I bought it. Probably better now – Ruadhan Aug 15 at 15:54
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    @Ruadhan2300 I think I may have had the same consumer device. I thought it was very reliable, but it really needed a grounding wire, and I felt rather dumb every time I put it on, winding a grounded copper wire around my toe like I was about to be executed. (Needless to say that particular solution to noise was not an official solution provided by the company, but it worked great!) – Cort Ammon Aug 16 at 4:07
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    Fun EEG info: It only detects electrical field, magnetoencephalograph (MEG) is needed for magnetic field, and they are bulky. For the implanted option, the device is called electrocorticograph (ECoG). – AndrejaKo Aug 16 at 7:39
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    Your deadman's switch based on the digestive won't detect is the subject under test falls asleep – Ferrybig Aug 16 at 8:35
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    "Curiously, I can not think of any source of zombie lore which mentions whether or not zombies defecate." -- This made my day! – Vilx- Aug 16 at 14:23

Hollywood effects

In modern films, many undead creatures die spectacularly, because it makes for good cinema, and hey, why not. Since these are your vampires/ghouls/zombies, you can make their death throes whatever you like.

But, let's say it includes bodily disintegration -- after all, the corpse has been rotting for years and is only held together by the forces of necromancy / dark science / plot convenience.

So the switch is a large, spring loaded contraption embedded in the chest cavity. Kill your vampire, and everyone crowds around to watch the swirly tornado of ash the FX crew are CGI-ing in; someone notices the tips of the probes starting to tear through the disintegrating ribs -- "What's that?", they cry, and lean closer for a better look -- BOOM.

An advantage is that unlike most terrorist style dead men's switches, false positives are unlikely: chest cavity disintegration will always be either a symptom of death, or a cause of it.

Plot-wise, once the living wise up, there are a couple of ways you have a slim chance to override the device -- shove your vampire in an iron maiden, for example.

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    Nice, and accelerated rotting/disintegration is a traditional trope for the death of the unnaturally animate. – Ash Aug 15 at 12:28
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    It would explain why you need to kill them with a stake through the chest! – Daniel Darabos Aug 16 at 14:57

A thin wire and/or mesh

If we assume that vampires can be killed by decapitation, a stake through their heart and by sunlight... ghouls and zombies only by decapitation or massive brain damage.

...and if we assume the character in question is cooperative and has some assistance...

...the solution is to run a thin wire loop/mesh under their skin. Start by wrapping it around their heart, or chest if you do not want to go as deep. Then run it up their neck, a few wraps around the skull, and then down again, ending at the dead man switch activator in the chest, located just under the sternum .

If the wire is cut, this activates the switch.

Vampires have a special version that is also activated if it detects light.

CAUTION: Do not use vampire version of the activator on zombies because zombies are of... "questionable physical integrity". You may choose to forgo to the heart wrap/mesh if you think your character is not particularly bothered by a stab to the heart.

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    This was the only thing I could think of but I couldn't make it really effective; I hadn't thought of using a wrapping or mesh. – Ash Aug 15 at 12:33

Vampires, ghouls and modern zombies have different features, but they all move (if they didn't, well, all horror stories would be pretty boring, or their human protagonists even dumber than today. I mean, leaving the group to enter a dark room alone is already a bad idea. Seeing a still vampire and going into its hug is really, really bad idea.).

Just use an accelerometer to detect movements (a step counter might be enough) and let it act as dead man switch.

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    That's going to be annoying when you lie down to rest. (At least the vampires, when the switch triggers, will already be in a coffin. The rest will just leave a mess.) – Erik Aug 15 at 11:25
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    Hey, that makes killing vampire so much easier! You don't have to impale their hearts or behead them, entangling them in a net, trapping them in a pit or jut tying them to a chair is enough. – Elmy Aug 15 at 11:40
  • I was also thinking accelerometer, but from a different angle. If a vampire which is staked turns to dust or otherwise vanishes, a necklace will no longer be supported and will fall. This is used by Terry Pratchett in Discworld: some vampires carry a vial of blood around their neck with glass thin enough to break when it falls, and the blood restores the vampire to undeath. – Peter Taylor Aug 17 at 10:18

Humanoids (with or without heartbeats) usually have an upright posture. Most muscles and tendons are needed to support this upright posture and you could measure the tension in them. Take for example the muscles and tendons in the legs and at the sides of the spine or in the neck (these are even active while sitting down).

Downside: You would have to deactivate the switch while sleeping / resting and knocking you unconscious could activate the switch.

Another (more sophisticated) possibility is to measure the electrical activity of the brain with a probe like those in modern pace makers. You can implant the device in the chest cavity and place a thin wire with a sensor at its end in the brain. Might not work with typical zombies... Who knows what is really going on in their brains.

You didn't define breathing... assuming it's intentional, consider using that and lung movement for measurement of them being "alive." A gadget planted on the chest, measuring movement in the chest area, or a gadget checking atmospheric pressure from the direction of the mouth.

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    Nice, these creatures do all traditionally breath if only out of habit or to hold a conversation so this could work well. – Ash Aug 15 at 12:17
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    @Ash - or to smell the next victim(s) ? muahahaha! – ivanivan Aug 15 at 22:29

Digit Pressure.

Just like dead man's switches of old, where someone is strapped with explosives and is holding down a detonator device, the loss of pressure on that button is the catalyst for the bomb. This of course assumes rigor mortis doesn't descend in a split second after 'death'.

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