Making the Dune “Pain Box” a Reality

If you are unfamiliar with Dune, then you may not know what the pain box is. The pain box is a fictional device that produces an excruciating burning sensation without causing any actual damage. [Bryan] has been working on a project to duplicate this effect in the real world. It sounds like he may be on the right path by using the “thermal grill illusion”.

The thermal grill illusion is a sensory trick originally demonstrated back in 1896. The trick is made up of two interlaced grills. One is cool to the touch, and the other is warm. If the user touches a single grill, they won’t experience any pain because neither temperature is very extreme. However if the user places their hand over the interlaced grills simultaneously they will immediately experience a burning heat. This usually causes the person to pull their hand away immediately. It’s a fun trick and you can sometimes see examples of it at science museums.

The thermal grill illusion sounded like the perfect way to make the pain box a reality. [Bryan] has set specific constraints on this build to make it more true to the Dune series. He wants to ensure the entire package fits into a small box, just big enough to place an adult hand inside. He also wants to keep safety in mind, since it has the potential to actually cause harm if it were to overheat.

[Bryan] has so far tried two methods with varying success. The first attempt involved using several thermoelectric coolers (TECs). [Bryan] had seen PCBs etched a certain way allowing them to radiate heat. We’ve seen this before in 3D printer surfaces. He figured if they could become hot, then why couldn’t they become cold too? His idea was very simple. He etched a PCB that had just two large copper pours. Each one branched out into “fingers” making up the grill.

Each side of the grill ultimately lead to a flat surface to which a TEC was mounted. One side was cold and the other was hot. Heat sinks we attached to the open side of the TECs to help with performance. Unfortunately this design didn’t work. The temperature was not conducted down to the fingers at all. The back side of the PCB did get hot and cold directly under the TECs, but that wouldn’t work for this illusion.

The latest version of the project scraps the PCB idea and uses small diameter copper tubing for the grill. [Bryan] is working with two closed loop water systems. One is for warm water and the other is for cold. He’s using an aquarium pump to circulate the water and the TECs to actually heat or cool the water. The idea is that the water will change the temperature of the copper tubing as it flows through.

While the results so far are better than the previous revision, unfortunately this version is having problems of its own. The hot water eventually gets too hot, and it takes over an hour for it to heat up in the first place. On top of that, the cold water never quite gets cold enough. Despite these problems, [Bryan] is hopefully he can get this concept working. He has several ideas for improvements listed on his blog. Maybe some Hackaday readers can come up with some clever solutions to help this project come to fruition.

55 thoughts on “Making the Dune “Pain Box” a Reality

        1. Actually I’m pretty sure microwave energy falls under the Convention on Conventional Weapons protocol 3 making it next to impossible to legally use against anything other than uniformed soldiers.
          And secondly using these on U.S. soil mean against U.S. citizens and that would be so ridiculously illegal that even Vladimir Putin would go “Woah”.
          So no, millimeter wave weaponry is just part of the same Military Industrial Complex circle jerk that spawned the OICW program.

          1. Wrong. 1) Raytheon has been selling a smaller version to law enforcement. LA county jail has one mounted on it’s ceiling to control prison riot situations.
            2) NATO findings concluded the Active Denial System was more effective and less dangerous than CS gas, mace, or Tazor technologies in controlling combatants. NATO has approved it for use in war to control unwieldy civilian populations and wartime combatants.
            3) Putin has no problem using this type of device on citizens. Putin has publicly announced an equivalent device, and talked about the new weapon as “an instrument for achieving political and strategic goals.”

        1. Define “no actual damage” using the recommended duration of microwaves may not cause damage but how often do you see Police and Solders in a stressful scenario use the minimum amount of force?

          Pepper spray is supposed to do “no actual damage” when used correctly but tell that to the protesters who have it applied with a cotton swab directly to their eyeballs.

          Millimeter wave weapons may do “no actual damage” if used correctly but what about when you press it against a struggling captive and hold the weapon active for 5 or 10 min?

          1. Pepper spray is not applied with a swab in the US, that is just a ridiculous statement. It would defeat the purpose of using a spray that allows you to put a safe distance between the target and yourself. It would also have no additional effect on the target compared to being sprayed in the eyes.
            The Active Denial System is a “large standoff” device. It is several hundred pounds (at minimum), and it’s best attribute is the ability to cause a reaction from a distance. There is no reason to approach the target.

      1. How would the UN pass such a resolution against the US’s wishes?

        Even if they did, who would stop the US from using it to defend embassies or whatever? Europe has all but dismantled their force projection capability not because they no longer need it, but because the US backs them up. There’s all sorts of things they *could* do–sanctions, withdrawing support for this or that project, etc–but very little they actually would.

        it baffles me that people who (presumably) know about the torture programs the US has run on foreign soil, all the spying they’ve done on allies, the wars they’ve started, and so on, and seen how little has come of it (again presumably), could possibly thing *this* is the issue that will spark the UN to step in and take meaningful steps.

  1. Would it be not be easier, and safer to implement this without using electricity. One metal box filled with water at 40 degrees centigrade (2 parts boiling water to 3-4 parts water at room temperature would probably get the temperature close).
    And a second metal box filled with ice cubes (and maybe a few grains of salt, would need to do a few tests, too much salt and it could get to some dangerously low body damaging temperatures).

    And each box has metal bars connected that are spaced such to allow them to be interlaced when fitted together.

    [hot] —–[cold]
    [hot]—– [cold]
    [hot] —–[cold]
    [hot]—– [cold]
    [hot] —–[cold]
    [hot]—– [cold]

    You could just solder the bars onto the metal boxes.

  2. Seems overcomplicated to me.

    I would just have a peltier plate in the box.
    When you add current, one side gets warm while the other side cools.
    Add a few heat pipes and a limited current battery, and you have both hot and cold contacts with a single circuit.

    1. Agreed. Use a single copper plate with TEC for each hot and cold. I’ve done something very similar with a copper cooling “finger” attached to a TEC, and found only a couple degrees variance over a few inches, and that’s with a heat load of 15W on the far end too. It would be interesting if he could find a way to make it work with only one TEC though. Not have to worry about providing two extra best sinks for the waste sides of the TECs.

    2. May be he should look into using heat pipes for the grill as it has copper tube on the outside and conduct heat very well. This do away with the pump and long heat up time. Use TEC for the cold pipes and resistors for hot side so that both can be regulated separately with PID controller (which can be done with firmware).

    3. The magic of a TEC is just that it uses two dissimilar metals. He could just skip the formal TEC and make the grill itself a larger scale thermopile:

      Then of course, some tweaking of dimensions is needed to self-regulate the temperature using the hand itself as a heatsink.

      Also certain metals will conduct the heat away from the hand very quickly making it feel cool to the touch and another could conduct slowly. I would think (without having experimented) that the trick is in the temperature differential being a certain amount, not the actual temperatures.

      1. For example, one experiment could use very thin capillary tubes. One has flowing water and the other has water kept at pressure. The flowing water would draw heat away from the hand cooling it, and the other would quickly heat up to the skin temperature.

        Focus the contact points on the AVAs (arteriovenous anastomoses) veins in the hand. Reference the “Cooling Glove” experiments:

        And of course, there are also chemical reactions. For example, pouring alcohol on the skin makes the skin feel cool very rapidly because of it’s low boiling point. Running alcohol or ammonia through a very thin aluminum radiator would chill the skin very quickly.

        I suspect that the temperature differential just between making an area of the skin feel too cold versus body temperature would create this effect.

        Lots of things to try.

        1. You would need two “active” temperature components I would think. They wouldn’t both have to be active in that one heats and one cools, but I don’t think you could simply cool selective regions without some sort of thermal “resistor”. Think of a set of copper fins that would maintain the heat of the hand while the rest was cooled.

          Or, you may need to increase the heat a tiny bit as the other cools it. The effect may work because the brain is trying to “correctly” resolve two normally conflicting sensations; one nerve says that it feels warmth, and the other (right next to it) says it feels cool. If the distance between the two points is too small, the brain will decide that it is one source.
          You can see this by taking two drinking straws, one that will slide inside the other. Cut a slit in the larger straw. Put a straight pin through the smaller straw, and allow it to stick out the slit. Now put another pin through the end of the larger straw, parallel to the first pin. You can slide the pins closer and farther, and lightly apply them to the skin. At a certain distance, you will stop feeling two pin pokes, and feel only one. It might be a useful tool for determining how close the hot/cold areas can be.

    4. As others have pointed out, heat pipes could be used. Attach to opposite sides of the Peltier and interleave the pipes.

      Since you’re injecting power into this system without a good was to dissipate the injected heat/power, you still need a heatsink and fan on the hot side to let the cold side get cold.

      The fan needn’t run all the time. Monitor the hot side temperature, and turn on the fan to control it to about 40C. The cold side will go to about 30C below the hot side.

      Need a larger temperature change? You will have to use 2 Peliers, stacked one on top the other. 35C is about the maximum temperature drop a single module can generate.

  3. “I must not fear.
    Fear is the mind-killer.
    Fear is the little-death that brings total obliteration.
    I will face my fear.
    I will permit it to pass over me and through me.
    And when it has gone past I will turn the inner eye to see its path.
    Where the fear has gone there will be nothing….only I will remain”

  4. TECs are a wonderful and strange beast. I work with dew point sensor systems, and it’s incredible what a well designed multi-stage TEC can achieve, albeit with shockingly high power consumption.

    If you are trying to pump any serious amount of thermal energy about a system, you begin to need some serious current. I’ve run a series-connected triple stage TEC with an additional backing TEC, on two separate PID control loops, all mounted to a forced-air cooled heatsink that has approx. the same area as a standard eurocard.

    This setup runs at about 100W, all to cool a gram or two of metal down to -100 C or so. This is far beyond what is being approached here, but I see a few more revisions before this design is successfully achieved using peltiers.

    I’d be looking at some TECs designed for mounting to DFB laser packages. They are finger-shaped, and could be mounted interleaved with each other, with hold and cold sides alternating orientation. This would depend on how locally the temperature differential must be applied to experience the effect though!

  5. Personally I’d start with a smaller and simpler setup, using this layout:


    With the inner two heatsinks positioned so that their fins are interleaved, and the side of them being the contact point for the illusion.

    Version #1 failed not just because of the thinness of the copper. Look at the PCB layout. There’s only one small strip of copper running down each side, maybe 1/4″ wide, expected to carry heat/cool to the large surface area of all the individual fingers! If the end of each finger ran directly underneath the TEC, or at least to a large copper pour near the TEC, it would have worked much better; though perhaps still not good enough.

    Version #2 has multiple problems, all of which [Bryan] identified. But the biggest is that [Bryan]’s TECs produce 69.6W of heat at full rated power. Those little ~1″ fans and heatsinks have no chance of keeping up, even at reduced power. You don’t necessarily need a fancy (and expensive) Arctic product with heatpipes and whatnot, but you do need a lot of surface area and airflow.

  6. My first thought when I read the title was a miniature version of the 1cm wave [microwave] “non-lethal” weapon that was shown off a few years back. (along with various things like stun gun bullets and a few things to be publicised a bit later by the whole Snowden thing. (I thought it was commonly denied knowledge myself but who knows)
    Anywho, I still think a mini microwave gun in a box could be interesting, that is if the control software could be make safe enough to regulate the “safe” minimum dose.
    Getting a suitable power supply to make it portable could make for an interesting experiment. Perhaps a tuned Tesla coil might provide a more energy efficient solution.
    I guess you’d end up with something like a table top tea laser style capacitor at those frequencies.

  7. A small incandescent bulb might also generate enough heat and cooling is more a mater of drawing heat away from the skin than trying to pump cold INTO the skin.

    The temperature differential itself is the trick. So warm some points with grain-of-wheat bulbs and create heatsinks to draw heat away from the skin at the other points.

    In short, don’t get so stuck on trying to use TECs because of the misconception that they ‘generate’ cold. They don’t. They draw heat away from one side which makes the other side cold. And with the human body, you already have a heat source. Draw that heat away and it will cool the skin.

    1. Two problems: the cold temperature is below room temperature and the hot temperature is above body temperature.
      Either a heat pump or a cold storage of something (more likely water) is required. The setup is intended to be portable so a heat pump is probably best. A TEC using the Peltier effect is more compact than a compressor solution and the lack of efficiency isn’t a huge problem for this application.

      But with some regulation one could use expanding gas (CO2?) for the cooling effect and resistive heating for the hot area, the problem is that a failure of the electrically controlled gas valve may quickly cause injuries…

    1. That’s not how a TEC works. You need to draw heat away from the hot side to cool the cool side. Heatinks and fan would be on hot side. It would serve no purpose at all on the cold side.

      If you do not draw enough heat away from the hot side, the whole thing heats up and becomes one temperature until it shorts out and fuses open.

      1. He is not arguing about how TEC works. He just proposes to have a heatsink cooled down by TEC, and a wire in between heatsink’s fin to generate the heat needed.
        He didn’t say anything about TEC’s hot side, which obviously would need its own heatsink. But the idea might work and simplifies things a lot.

  8. Just use a PTC for the hot side and a peltier for the cold side with heat pipes from each.

    PTC heaters are self-limiting so they won’t overheat and you can get them in many different temp ranges, sizes, voltages.

    e.g. this 40C one

    For the peltier you’ll possibly need some active temp control, but you can probably size the peltier so that it doesn’t have the capability to cool the hand to a dangerous level. It’ll need a heatsink and possibly fan on the hot size but a noisy fan blowing out some warm air will probably add to the effect you’re going for.

  9. I think you were on the right track with the first attempt, but there’s really no need to use two different TECs when one generates the differentials you seek – unless you put them in parallel to cover a larger area. Heat pipes might be useful if applied correctly but fitting them to a custom project can be a headache (bending them risks breakage, and you’d need good machining to transfer heat efficiently between heat pipe and TEC), and it’s not clear to me they’ll help much since the distance heat must travel needn’t be very far at all – your TEC can be directly under the grill.

    The problem with the PCB trace approach is that they are paper thin copper, and heat flow is limited by both distance it must travel AND cross sectional area of the heat conduit. If you use large thick slabs of aluminum or copper and machine them so their fingers interdigitate just above the TEC sandwiched between them you should get much better results.

    With TECs the hot side will get much hotter than the cold side produces, due to its inefficiency generating waste heat. So you might want a fan to help cool just the hot side of the device. This should be sized to take away some of the heat, but not enough to take away the temperature differential you need for the effect.

  10. Here’s my idea. Use the wires of an electrical blanket to form a grill inside an esky/ice box with a fan to circulate the cool air. Make a hole in the ice box for your hand to fit into with an elasticized plastic seal to not let cool air escape. Problem solved.
    A safer option though would be to make a mesh glove lined with the electric blanket wires. That way you keep the ice water and electricity completely seperate.

  11. Look to existing technology that creates rapid temperature differentials intended for human senses :D
    An air conditioner compresses and decompresses refrigerant which causes a natural but rapid transfer of heat depending on which way the pressure is changing. This van be varied greatly so you should be able to hit a safe but effective spot for the senses by using more/less compression or refrigerant with higher or lower R value.

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