Helium in the air kills iOS devices? (MEMS oscillator vulnerability) - Page 1
Forum section: electronics / general

author: RickBrant
author_rank: Unknown
timestamp: October 14, 2018, 04:30:00 pm
content: Well, according to this reddit thread, yes.https://www.reddit.com/r/sysadmin/comments/9mk2o7/mri_disabled_every_ios_device_in_facility/It appears that helium (at ordinary temperatures and at concentrations you might get during an accidental release when bringing up a new MRI scanner) devastatingly affects MEMS oscillator chips, changing their frequency enough to be out of useful range.I think David should get some MEMS oscillators and test this!edit: changed title to make EE(vblog) relevance more apparent.edit: Added the following - here is a link to a paper that describes helium vulnerability in MEMS devices. It's in the reddit thread but it's buried a bit...https://file.scirp.org/pdf/JST_2013122009560886.pdfNote that ceramic and metal-packaged MEMS devices were not found to have problems.

author: German_EE
author_rank: Super Contributor
timestamp: October 15, 2018, 06:46:23 pm
content: This is fascinating. It appears that the helium molecule is so small that it is able to penetrate the seals on some components that hold parts in a vacuum. One of those 'oooh, we never thought of that' moments.

author: langwadt
author_rank: Super Contributor
timestamp: October 15, 2018, 07:43:06 pm
content: I'm skeptical the helium had anything to do with it, super magnets have vents to the outside so you don't suffocate people if you have a quench. The article talks about putting a mems device in 415kpa helium for days, something even remotely like that obviously didn't happen because people would die

author: wraper
author_rank: Unknown
timestamp: October 15, 2018, 08:04:39 pm
content: I don't think helium has anything to do with this. First of all helium is naturally present in the air in small quantities. Secondly, helium is not THAT leaky that somewhat increased amount of it would penetrate vacuum seals in less than one day and destroy the device.

author: thm_w
author_rank: Super Contributor
timestamp: October 15, 2018, 08:07:53 pm
content: QuoteWouldn't an iphone have secondary independent circuit to control charging? Although it depends if there is any way to visibly see if an iphone is charging without the screen on, which I don't know.QuoteSo TVs and laptops were also affected, but not clear if its permanent damage or crash/reset due to EMI.QuoteInteresting anecdoteQuoteFrom that linked PDF, the resonator drifted by 0.2% after many hours in a high He environment. Is that enough to cause something not to even power up?

author: RickBrant
author_rank: Unknown
timestamp: October 16, 2018, 09:50:45 am
content: Quote from: German_EE on October 15, 2018, 06:46:23 pmThey certainly should have thought of it. Containing helium is well known as a difficult problem. Helium toy balloons collapse much faster than air ones. The metallized Mylar balloons, though, hold helium much better as the metallization helps make a better barrier (and they're generally not at any significant pressure).In the early days of HeNe laser tubes, a common failure was that the stuff would "migrate" around the glass/metal seals, leaving the wrong mix of He and Ne behind. And you could fix them by putting them in an aquarium, turned upside down, and filled with "helium" from a balloon gas bottle. STP is far higher than the needed He partial pressure in the tube, and only the He can do that trick, so it didn't matter how much other junk was in the gas. You didn't even have to remove the tube from the laser housing (assuming the unit was small enough to fit under the aquarium), and you could monitor progress by powering it up during the "refill".

author: RickBrant
author_rank: Unknown
timestamp: October 16, 2018, 09:53:23 am
content: Quote from: langwadt on October 15, 2018, 07:43:06 pmI'm skeptical too... again, this sounds like fine material for a Dave video

author: amyk
author_rank: Super Contributor
timestamp: October 16, 2018, 11:51:59 am
content: I suspect it was an EMP event too --- if you read the Reddit comments he mentions other devices affected, and I doubt the helium would've been in sufficient concentration to have any effect (as that linked paper shows.)

author: wraper
author_rank: Unknown
timestamp: October 16, 2018, 12:09:55 pm
content: Quote from: amyk on October 16, 2018, 11:51:59 amYep, it was tested at 2.8 atm pressure, thus seal experienced 2.8 more pressure than normally. If there was such helium concentration to kill the component this fast, people would have health issues or even die due to oxygen deprivation in the first place.

author: BravoV
author_rank: Super Contributor
timestamp: October 16, 2018, 12:14:02 pm
content: As Hydrogen is smaller than Helium, wonder if a simple home experiment, generate H gas with simple water electrolysis, submerge the MEMS into the pure H gas chamber, and measure the drift ? Just guessing.

author: RickBrant
author_rank: Unknown
timestamp: October 16, 2018, 01:54:17 pm
content: Quote from: BravoV on October 16, 2018, 12:14:02 pmActually no. H atoms are larger than He.* And H always comes as H2 molecules, and it's very reactive, so it "sticks" to things. Helium comes as individual atoms and is unreactive with just about everything, so it's very "slippery". It's far harder to contain than hydrogen.(*http://www.batesville.k12.in.us/physics/PhyNet/Quantum/atom_quantum/answers/ch38_assignment.htm,item 30)

author: SeanB
author_rank: Super Contributor
timestamp: October 16, 2018, 06:56:41 pm
content: The standard leak test is to use helium, as it pretty much will migrate through most things regarded as being good sealing materials. This is used to check semiconductors during manufacture, by allowing them to stand for a time at pressure in a helium atmosphere and then either measuring the change in mass, or checking for the gas diffusing out again. Even hermetic welded parts show some diffusion of helium through the metal and glass seals, and plastic packaged items are a lot worse than this.

author: 2N3055
author_rank: Super Contributor
timestamp: October 16, 2018, 07:36:51 pm
content: My electronic device stopped working next to 10 Tesla magnetic field... I think it is logical that reason for that is helium....I'm not saying saturating devices in helium atmosphere cannot have influence..But would start first with EMP level magnetic fields first as my first suspect..

author: raptor1956
author_rank: Frequent Contributor
timestamp: October 17, 2018, 01:55:31 am
content: Quote from: SeanB on October 16, 2018, 06:56:41 pmHaving worked in the semiconductor industry and used helium leak detectors the basic kit involves a kind of mass spec and a vacuum pump and you connect to the thing you want to leak check then you go over the thing with a wand that emits small amounts of helium. Usually an o'ring or fitting, but sometimes the chamber itself is cracked.Brian

author: tooki
author_rank: Super Contributor
timestamp: October 17, 2018, 08:58:07 am
content: Quote from: 2N3055 on October 16, 2018, 07:36:51 pmIIRC the report says that the devices started working again after a week or so. I assume EMP damage would be permanent. Whereas the resurrection after a week does make sense if the absorbed helium can dissipate, as they’re saying.

author: 2N3055
author_rank: Super Contributor
timestamp: October 17, 2018, 09:11:44 am
content: Quote from: tooki on October 17, 2018, 08:58:07 amReport said they will get replacement devices. GE tech said it SHOULd start after a week. I didn't see any word if that happened.

author: StillTrying
author_rank: Super Contributor
timestamp: October 17, 2018, 09:57:20 am
content: Quote from: RickBrant on October 14, 2018, 04:30:00 pm"Initially I thought this only impacted users on one side of the building, but from what I've heard today it seems to be multiple floors across the facility."I think it's EMI, anyone nearthe sourcewould have been speaking in a high pitched voice.

author: wraper
author_rank: Unknown
timestamp: October 17, 2018, 10:10:37 am
content: Quote from: tooki on October 17, 2018, 08:58:07 amMuch more sens would be that electronics hanged in a certain way and resumed working properly once battery discharged.

author: tooki
author_rank: Super Contributor
timestamp: November 01, 2018, 03:26:03 am
content: So it conclusively is NOT EMI: the dude ran experiments using helium and was able to reproduce the problem.https://arstechnica.com/gadgets/2018/10/helium-implicated-in-weird-iphone-malfunctions/

author: Piotr Niemojewski
author_rank: Newbie
timestamp: November 04, 2018, 02:45:03 pm
content: https://tf.nist.gov/general/pdf/906.pdf"The background pressure of helium inside the resonator enclosure can significantly increase if thevacuum enclosure is glass and the resonator is operated in an environment with large amounts ofhelium. A typical helium leak rate for a glass enclosure operating at 80°C in a pure heiium environmentis 5 x 10-3Pa/s."

author: StillTrying
author_rank: Super Contributor
timestamp: November 04, 2018, 03:38:01 pm
content: I'm amazed that He molecules are small and light enough that a few get through the seals. but large and heavy enough to effect the MEMS.https://ifixit.org/blog/11986/iphones-are-allergic-to-helium/

author: BrianHG
author_rank: Super Contributor
timestamp: November 06, 2018, 07:58:24 am
content: It just sounds way too sensitive... unless.... it's that they are trying to drive that 32khz reference crystal so lightly, or just at the edge of tuning, like in some old PIC32 projects I had to patch, that a fraction of a pf on the device seizes the oscillator, and once the phone has a hardwired battery, it can never be power cycled to re-kick the oscillator to run after the fact. Something Apple has passed from phone to watch while Android devices using a different CPU circuit loading the MEMs crystal differently making them much more robust to keep oscillating.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: November 06, 2018, 08:25:35 am
content: Quote from: StillTrying on November 04, 2018, 03:38:01 pmSurely the issue is that the air density is reduced, as helium displaces the air

author: langwadt
author_rank: Super Contributor
timestamp: November 06, 2018, 08:32:20 am
content: Quote from: mikeselectricstuff on November 06, 2018, 08:25:35 amI believe they are vacuum inside, which would also explain how the helium gets in

author: Wolfram
author_rank: Frequent Contributor
timestamp: November 06, 2018, 11:56:42 am
content: Quote from: langwadt on November 06, 2018, 08:32:20 amDiffusion only depends on the differential partial pressure. In other words, the helium will diffuse in at the same rate whether there are other gases or not. This is the reason Helium can leak out of HeNe laser tubes even if the helium pressure inside the laser tube is less than 1/100 of the air pressure on the outside of the tube.If the packages are permeable to helium, then the helium pressure inside the package will be the same as the helium partial pressure on the outside of the package. This is around half a pascal with normal air, due to its 5 ppm helium content. An increase of helium concentration beyond 5 ppm in the surrounding air will also lead to a corresponding increase in the internal helium pressure. From the videos of iPhones being exposed to helium, it seems that this process has a time constant on the order of minutes.As other gases are likely unable to diffuse through the MEMS oscillator package, the total internal pressure will be equivalent to the external partial pressure of helium (plus maybe hydrogen), in addition to whatever gases were left from incomplete evacuation during the manufacturing process. It therefore takes very little extra helium in the surrounding air to drastically change the pressure inside the package)

author: cdev
author_rank: Super Contributor
timestamp: November 06, 2018, 01:20:06 pm
content: Why do sealed plastic bags sometimes expand with trapped gases inside over time?

author: DenzilPenberthy
author_rank: Frequent Contributor
timestamp: November 06, 2018, 02:34:36 pm
content: Quote from: cdev on November 06, 2018, 01:20:06 pmMaybe due to atmospheric pressure decreasing over that time period, or changing temperature?

author: TheSteve
author_rank: Unknown
timestamp: November 06, 2018, 05:40:45 pm
content: A friend of mine has had his Apple watch replaced twice due to helium exposure.edit - I should add that he does work around helium at times, the sensors are very sensitive.

author: StillTrying
author_rank: Super Contributor
timestamp: November 06, 2018, 08:32:02 pm
content: "This is around half a pascal with normal air, due to its 5 ppm helium content. An increase of helium concentration beyond 5 ppm in the surrounding air will also lead to a corresponding increase in the internal helium pressure."I know helium is strange, but I still find this MEMS problem hard to believe!

author: Red Squirrel
author_rank: Super Contributor
timestamp: November 07, 2018, 07:36:47 pm
content: I bet everyone in that room was talking pretty funny too.

author: StillTrying
author_rank: Super Contributor
timestamp: November 13, 2018, 10:02:14 am
content: Quote from: cdev on November 06, 2018, 01:20:06 pmFumes from the plastic itself ?

author: BrianHG
author_rank: Super Contributor
timestamp: November 16, 2018, 04:22:17 pm
content: Tested true here:I bet they are just driving that crystal too weakly, or just at the edge of it's tuning capacitance.

author: ruffy91
author_rank: Regular Contributor
timestamp: November 19, 2018, 04:31:07 am
content: Quote from: BrianHG on November 16, 2018, 04:22:17 pmMEMS oscillators do not use quartz crystal which is piezoelectric. They use polysilicon in a electric field. They are much worse than quartz (25ppm/K temperature dependency). But there is 1 big advantage. You can make them very small and you can make them out of the same silicon as the rest of an IC, they are much smaller even including drive circuitry and temperature compensation than a quartz.I think Apple devices are more affected because they use MEMS oscillators for all devices while most Android devices still use quartz.