Human Geiger Counter
So, in my wandering biohacking thoughts, I started to think about what all of our projects here do. Magnets allow us to sense EMF and biothermals let us detect internal temperature. I would put RFID and NFC in a separate category because they don't add a new sense to the body. In thinking about this, I was trying to figure out other things we could sense and I came up with radiation. I don't know what it would precisely be used for, but I find the idea of being aware of levels of radiation to be interesting. The basic concept I'm thinking of is a subcutaneous light or tattoo that is inside the forearm and emits light proportionally to the amount of radiation around it. The reason I chose a light instead of a click or electrical signal is because there are already types of radiation detectors that use scintillation, so it may be easier to adapt one of those methods than to create our own.
The main scintillation detector used is Sodium Iodide (NaI) and Thallium. An example of their brightness can be seen at 4:30 in this Youtube video. Sodium Iodide is activated by the Thallium and releases photons when stimulated by ionizing radiation (Gamma waves) in its environment. Most detectors then detect this light and change it into an electrical charge which can then be measured and turned into a reading or click.
NaI itself is an irritant to the human body and may cause birth defects, but I doubt any subcutaneous tests have been run on it except where pertinent in radiation therapy. It's also edible and used as an Iodine supplement for deficiencies.
The other option I found is plastic scintillation. Sadly, even though plastic is supposed to be the cheaper and more available of the two options, I can't seem to find crap for information on them. All I have is this link to a place that sells plastic, liquid, and fiber scintillators, but I can't be sure this is even what I'm looking for. The plastic detectors are supposed to be organic (or have organic activators), but I can't find any proof or info on them or their chemistry other than the data sheets under "specifications" that I have no idea how to read.
I'm leaning towards the plastics because having thallium inside my body sounds less than preferable and they're the cheaper option. I don't know how bright they are, however, and I'm unsure whether we could make a coating that allows light through both itself and then the skin.
Thoughts?
The main scintillation detector used is Sodium Iodide (NaI) and Thallium. An example of their brightness can be seen at 4:30 in this Youtube video. Sodium Iodide is activated by the Thallium and releases photons when stimulated by ionizing radiation (Gamma waves) in its environment. Most detectors then detect this light and change it into an electrical charge which can then be measured and turned into a reading or click.
NaI itself is an irritant to the human body and may cause birth defects, but I doubt any subcutaneous tests have been run on it except where pertinent in radiation therapy. It's also edible and used as an Iodine supplement for deficiencies.
The other option I found is plastic scintillation. Sadly, even though plastic is supposed to be the cheaper and more available of the two options, I can't seem to find crap for information on them. All I have is this link to a place that sells plastic, liquid, and fiber scintillators, but I can't be sure this is even what I'm looking for. The plastic detectors are supposed to be organic (or have organic activators), but I can't find any proof or info on them or their chemistry other than the data sheets under "specifications" that I have no idea how to read.
I'm leaning towards the plastics because having thallium inside my body sounds less than preferable and they're the cheaper option. I don't know how bright they are, however, and I'm unsure whether we could make a coating that allows light through both itself and then the skin.
Thoughts?
Comments
One coating that would allow light through would be silicone. The silicone used on the Circadia looked pretty transparent, as I recall. Bio-glass, of course, comes to mind, but that's not something we can do without a fair bit of equipment, right?
So... yeah. This stuff when mixed together should glow under radiation. Who wants to put it in a pill under their skin (or a mouse's) for science?
That said, bio issues aside, I don't think the physics of this project will work. NaI(Tl) and plastic scint crystals produce photons when struck by radiation, and these cause fluorescence which shifts the wavelength into visible or at least closer to visible light frequencies.
Scints do not produce a lot of light in response to radiation. The first YouTube video you post shows her irradiating a scint with an X-ray machine. That's a very intense (but short duration) radiation exposure, and you could not legally own (nor would it be advisable to own!) a source that could make a scint light up like that. Also note that it was filmed in a dark room, and the scint in question was large. Large scint = more interactions with radiation = more light, but at the same time, something that large is too big to be implanted. The second YouTube video of BC-412, according to the description, shows a scint exposed to UV. In that case, you're observing the fluorescent properties of the scint, not the radiation sensitive properties.
Generally speaking, individual radiation events produce small numbers of photons. Usually, they are optically coupled to a photomultiplier tube (PMT), which turns small numbers of received photons in the visible or near-visible light wavelengths into electrical impulses. And that optical coupling usually requires the crystal face (or for NaI(Tl) which is extremely hygroscopic, the clear face of the can that contains it) to be in direct contact with the PMT, and the gap to filled with an optical jelly. Further, the entire assembly must be kept 100% light tight, or else the PMT will be overwhelmed with stray light.
I can't think of a way that a scint small enough to be implanted could produce light under any reasonable levels of radiation that would escape through the skin and be visible or be countable by a PMT. This just might work in the case of a lethal radiation dose, but you can't exactly test it, and, anyway, it would be hard to see over the light of the mushroom cloud. :-)
I own this watch: http://www.polimaster.com/products/electronic_dosimeters/pm1208m/ I observed that a single CR2032 battery powered the Geiger counter + the micro-controller that runs it + an LCD screen + a standard quartz watch movement for 1 1/2 years. So its power usage is probably within the realm of possibility for implanted electronics.
I suspect they get the long battery life out of it because they only turn the Geiger tube on infrequently, measure the time until the first pulse, or maybe the time between consecutive pulses, and immediately turn it off. You can then do statistics on the result to estimate the radiation dose rate. I can set it next to the most powerful source I own and it often takes about a minute to figure out that it's in the presence of radiation, and even longer to figure out when I've taken the source away.
Here is a dissection of a similar watch: http://xronosclock.com/home/?p=4238
Note the size of the Geiger tube. That appears to be a Russian SBM-21 Geiger tube. Data sheet is here: http://www.gstube.com/data/2399/ So, 6mm x 21mm for the tube alone. It would need to be in a carefully chosen implant site because you really don't want a near-vacuum tube getting crushed internally.
Next, there's the high voltage issue. The tube operates at 350-475V! Now the HV supply requires extremely low current. (So low that you can't directly measure it with a multimeter; the typical 10 MOhm impedance looks like a short when compared to what the tube typically uses when it isn't triggered by a radiation event.) Still, I've been zapped by a Geiger counter power supply, and it is enough to get your attention! I really don't want to know what happens if the coating breaks down and starts shocking the user internally with the full Geiger tube voltage.
All said, this is probably a bad idea. But I'm picturing a user interface where the device could deliver small subcutaneous shocks. It could have several operation modes (which possibly could be switched by tapping it with a finger magnet?):
1. Alarm mode. Default. Deliver shocks when configured radiation dose rate thresholds are reached. Shock pattern indicates which alarm threshold was triggered.
2. Dose indication mode. When prompted, it could use some form of encoding (e.g. Morse code) to send the current dose rate to the user. E.g. ".12u" = 0.12 uSv/h
3. Continuous / sixth sense mode. This would keep the tube powered on, and translate individual counts to shocks. This would use the most power, so it might not be possible for long periods of time.
4. Most important: OFF!
SO if you wnat a gieger counter implant, don't bother with a geiger tube. Things are a pain in the ass, bulky and take a massive amount of power to run if you want any sort of accuracy or sensitivity. Sints are better but you still have issues. Most need a photomultiplier tube to work and incase you've never seen one, most are the size of a lightbulb or larger. A guy I worked with once built a detector by putting silver in a tank of scint fluid. When a neutron hit the silver it would cause ti to decay and the radiation released would cause the scint to light up which was picked up by the photomultiplier tube. If you could somehow boost the signal from the scint you'd be able to detect things. My suggestion is do it electrical but not with a gieger tube. Use a scint with a photodiode next to it. Boost the signal from the diode and transfer the signal to an LED or something. Or a shock. You'll need a much better scint than NaI though. That shit is dim as hell and any moisture destroys it. Trust I've tried. Total pain. Plastics again are better but i like the idea of a bit of liquid encased in a little vial. You won't pick up alphas but gammas and strong betas should make it through your skin to the detector just fine.
you want bc-408 if you're buying from them. Widest range of detection, fairly tight emission band and soluable in most decent solvents so you can form it how ya like. Changed my mind about liquids. They're better for high energy stuff and if you want to know the shape or path of a particle which we don't need here. Stick to plastics.
SBM-21: 6mm x 21mm
LND 716: 5.2mm x 24.5mm
The sensitivity isn't great, but they are still capable of measuring background. Power consumption doesn't have to be high. As I said, I've got one in my wristwatch, and Polimaster quotes an accuracy of ±20% in range 0.1 - 9999 μSv/h which is certainly adequate.
I'm not familiar with scint + solid state detectors, although I know a PIN diode on its own will work as a gamma detector, but it's not terribly sensitive, and that has the advantage of working with much lower voltage.
I don't know where you're getting your info about power consumption of Geiger tubes, but they use extremely low power. They aren't like glowing hot guitar amp tubes. Geiger tubes need a high voltage bias supply, but they don't consume that power when they aren't experiencing a count event. And when a charged particle causes an avalanche, there's a resistor on the anode which limits current flow until the contents of the tube can quench it. The tube becomes insensitive during its dead time period, and the HV supply can use this free time to restore the bias voltage again. There are plenty of ways to make high efficiency switching HV power supplies, especially when you only need them to supply nanoamps of power..
From practical experience: A CR2032 battery contains around 190-225 mAh of power, and my watch lasted for a year and a half on one CR2032 without changing the battery. That powered the Geiger tube, the micro-controller, the LCD, and a standard quartz wristwatch movement. And the Geiger tube was taking readings 24x7 (although I'm sure it's only doing so a small fraction of the time and using statistical sampling to arrive at the dose rate.)
I don't know much about the medical aspects of grinding, but from a purely electrical standpoint, the power requirements for a miniature Geiger tube are extremely low.
Also all the solid state detectors i've seen are far far smaller. They have an array of them at my school and they're paper thin and the electronics are small too.
Now this design has a few problems: It requires complete darkness so the diode doesn't pick up photons but even then to be really good it would require extreme cooling to eliminate thermal noise.
The software powering this device tries to filter the thermal noise and this is the result:
I'm pretty sure tis device wouldn't work under the skin (it's to big anyway). Even if you would use a larger array of diodes the detection rate would be very low. Also I guess you can't detect alpha rays under the skin, no matter how good your detector is, as the upper skin layers are already blocking them (that's why you don't really have to fear alpha rays. The chance of them entering deep skin levels and as a result causing cancer is extremely low). Generally a subdermal detector would detect rays which are passing through the skin only, so the rays it detects can damage your DNA (cause cancer) and as a result you should run as fast as you can when you have such an implant and it really gives you a sense! That said I'm not that sure if such a implant would be useful for daily tasks at all.
Anyway, these are just my 2 cents and I'm all other than an expert in this area so keep on brainstorming! :)
BTW: If anyone is interested in the technical details of the device simply google for "alpha ray visualizer" - the hardware design isn't by me (anyway you should shield not only with foil but also with wax. Wax is a beta ray blocker and even if there shouldn't be such rays when you're working with nuclear things it's always better safe then sorry) - and for the software have a look at github (but please note that the readme is out of date; it does require root rights, for example).
Looks like the perfect size and actually gives great data.
Film badge dosimeter[edit]
Film badge dosimeters are for one-time use only. The level of radiation absorption is indicated by a change to the film emulsion, which is shown when the film is developed.
Quartz fiber dosimeter[edit]
Quartz fiber dosimeters are charged to a high voltage. As the gas in the dosimeter chamber becomes ionized by radiation the charge leaks away, causing the fiber indicator to change against a graduated scale.[7]
Thermoluminescent dosimeter (TLD)[edit]
A thermoluminescent dosimeter measures ionizing radiation exposure by measuring the intensity of visible light emitted from a crystal in the detector when heated. The intensity of light emitted is dependent upon the radiation exposure.
Both the quartz fiber and film badge types are being superseded by the TLD and the EPD."
How to communicate this to the body? Not sure, that's where power is the problem which we've been discussing. I wonder... have a feeling if the body may sense more than what we relise and if we give different things a go we may find that any of these implanted may be sensed in how they are changing, outside of how we normally understand the body. Perhaps maybe even on the skin too.