Have iPhone found allergic to helium

Original author: Kyle Wiens
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This story is not heard every day. Eric Wooldridge is a specialist in complex systems at the Morris Hospital near Chicago. When he installed a new machine for MRI from GE Healthcare, he began to receive complaints about non-working phones. Then people began to fail Apple Watches.

“I immediately thought that an MRI was emitting some kind of electromagnetic radiation, as a result of which we might have a lot of problems.” But the EM impulse would also have disabled the hospital's medical equipment - and at the same time everything worked perfectly! He began to study this question, and found out that absolutely all the devices affected as a result of this case were made at Apple - while the Android-based phone itself worked perfectly on the device itself. In addition, this incident has spread quite widely, affecting the work of 40 different devices. What the hell?

In my lifetime I have seen many strange glitches, but I have never heard of anything like that. Like Eric. “The devices behaved quite strangely. Most of them are completely out of order. I plugged them into the outlet, and did not see any signs that they are charging. Other devices turned on, but they had problems with the cellular signal. WiFi worked quickly and clearly, but the cellular connection was once. ”

Then he wrote a post on Reddit about his problem, and other sysadmins began to reason that this problem could be caused by liquid helium used to cool MRI. He investigated and found a leak of helium, which then spread through the building.

“I discovered that a helium leak occurred when a new magnet was being prepared for cooling. In 5 hours, about 120 liters of liquid helium evaporated. The car had a valve that worked, but probably leaked. A room with an MRI does not belong to a system with insulated heating and ventilation, so the air from it is mixed with the air of a large part of the building. We do not know which part of the helium leaked out and which part got inside. Moving from a liquid to a gaseous state, helium expands 750 times, with the result that we had a lot of helium (90,000 liters). ” I bet that the nurses' voices sounded higher that day!

After the initial incident, the devices began to recover slowly, but could not do it completely. “We had a few abnormally-behaving devices. One phone had serious problems with repairs, and some smart watches continued to work, except for problems with the touch screen (even a few days after that). ”

He sorted the devices by type. “IPhones of version 6 and above, as well as Apple Watches version 0 and above, have suffered. We are aware of the presence of one iPhone 5 in the building that day, and this had no effect on it. The question was: what happened, why did Apple's devices break down? ”

It sparked my interest, and I contacted friends working in the production of microelectromechanical systems(MEMS). This is one of the smallest mechanical devices in the world. Each phone has gyroscopes and accelerometers with dimensions of the order of micrometers thick. First, I had a theory (coinciding with the opinion of one of the users of Reddit) that the helium molecules, being small enough, penetrated these chips and began to interfere with the operation of the mechanical parts.

But this idea has two problems: first, not only Apple uses MEMS gyroscopes - they are in every phone [not in every, but in many / approx. trans.]. Why not hit phones based on Android OS? Perhaps iOS has a bug that causes the system to crash when receiving incorrect data from the gyroscope? But the situation also influenced Apple Watche, and they have their own system, WatchOS. In addition, iPhones versions less than 6 are not affected. It is unlikely that this was a new software bug that affected both iOS and WatchOS at the same time.

Inside the iPhone 4 MEMS gyro

What else could be the reason? At the heart of every electronic device is a watch. Usually these are quartz oscillators.(generators), crystals, vibrating with a certain predictable frequency - usually 32 kHz. When they were first invented, it allowed the creation of the first quartz watch. Now these frequency generators are at the heart of any electronic device.

Without a clock, the system freezes. CPU is not working. The clock is the heartbeat of a modern device.

But quartz oscillators have certain problems. They do not count time very well at high (and low) temperatures, and they have relatively large dimensions — on the order of 1 × 3 mm. And in search of ever smaller device implementations, Apple recently began using SiTime's MEMS oscillators to replace quartz components.

MEMS accelerometer under an electron microscope

Specifically, they useSiT512 , “the smallest in terms of size and energy consumption, an oscillator of 32 kHz in the world”. And if some kind of MEMS device is exposed to helium, this could be our culprit!

The failed oscillator is similar to the symptoms described by Eric as reproduced in the experiment . “I put the iPhone 8 Plus in a sealed bag and filled it with helium. This was not very realistic, since those iPhones were exposed to lower concentrations, but the experiment still supports the idea that helium can disable the device. I left the display on and started the timer. After 8 minutes and 20 seconds, the phone is frozen. Nothing crazy happens - the clock just stops, that's all. The screen remains on. ”

I was able to repeat the experiment in our laboratory. My iPhone 8 lasted about 4 minutes in a helium atmosphere before completely shutting down.

The instructions for the phone and the clock from Apple reported a similar problem:

Do not expose the iPhone to environments containing high concentrations of industrial chemicals, and bring it to evaporating liquefied gases such as helium - this can damage or impair the performance of the phone. If your device has undergone such an impact and demonstrates such symptoms, or does not turn on, it can usually be restored. Leave it without connecting to the charging cable and let it air for a week. Helium must be completely removed from the device, and the battery must be completely discharged. After a week, connect the device directly to the charger and let it charge for an hour. Then you can turn on the phone again.

Hydrogen and helium are extremely difficult to retain due to the small size of their molecules. Apparently, SiTime has been working on this problem for quite a long time. In their FAQI found the following: “How efficient is the sealed enclosure of MEMS oscillators?”

The previous generations of EpiSeal resonators could be affected by high concentrations of gases with small molecules. More modern EpiSeal impermeable to all small molecular gases. Contact SiTime if you plan to use our device near large concentrations of small molecular gases so we can recommend a suitable part for you.

I wondered if gas would affect other types of MEMS devices, and I contacted InvenSense Motion, the company that produces the image stabilization chip for Pixel 3. David Almoslino, senior director of corporate marketing, confirmed the existence of such a problem. He told me that their products “may to some extent be exposed to helium. Helium can leak through the melt-connected substrates and increase the pressure in the cavities. Helium can temporarily degrade the absolute accuracy of our pressure sensors. In gyroscopes, helium can lead to imbalance, which is why the oscillations can temporarily stop. In accelerometers, helium can do little to harm. But all our products must be restored to working capacity after they are removed from the helium-rich environment. ”

Of course, you have never heard of this before because such situations occur quite rarely. However, manufacturers of silicon chips are well aware of this problem and are doing everything possible to minimize it. David told me that "helium leakage is a fairly standard test for MEMS, which most companies are conducting to evaluate leaktightness."

That's what's the matter! Helium molecules, like incredibly small grains of sand, can penetrate into the device, stop the clock, and temporarily turn your phone into a paperweight.

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