# COMMUNITY : FORUMS : BURNING QUESTIONS

## Inflatable iPhone Case that opens upon Impact

Hello everyone,

I am not sure if anyone has made something like this but I thought it might be a cool idea for a weekend project or product. Here's the pitch:

Have you ever dropped your precious iPhone in the water or on the ground? Wouldn't it be great if someone could create a simple case that inflates like an airbag before the phone hits the ground or water. The case could read accelerometer data from the phone and when it detects free-fall, if could use a Co2 cartridge to inflate an air bag type device that saves the device from sinking into the water or hitting the hard sidewalk.

It's just an idea. If anyone wants to discuss this idea, feel free to comment below. I'll let you have all of the rights to this idea if you want it.

Kyle

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kelseymh5 years ago
Instead of a heavy CO2 cartridge, I think you'd want a small charge of a powder which could evolve gas quickly. You could do some sort of fancy electronic trigger (accelerometer circuit) like airbags use.
5 years ago
Bi carbonate of soda + vinegar???
5 years ago
That might work. The question is how fast does it work?

As with car airbags, you don't have a lot of time from when a phone leaves your hand to when it bounces. If the phone is falling from rest (you dropped it, you didn't throw it down in disgust :-), the relationship between distance, time and acceleration is d = a t2/2, so t = sqrt(2d/a).

Assume the phone is 1.5 meters above the ground (around shoulder level), and a = g = 9.8 m/s2. Then t = sqrt(3/9.8) = 0.55 s.

Looking at a nice demo video (http://www.youtube.com/watch?v=4w7BHrXXTxM), it appears that some inflation (enough for a cell-phone airbag) takes about 3 seconds (from 1:26 to 1:29).

It would require some experimentation to be sure, but my guess is that the baking-soda/vinegar mix isn't fast enough for this application.
5 years ago
Speed doesn't matter so much if it's dropped in water - the chemicals fizz and the phone gently bobs to the surface.

(Actually, for a water-based device, that's not a bad idea.)
bestburglar5 years ago
soz, didnt mean to yell :)
bestburglar5 years ago
yes, along the lines of an inflatable life vest (PDF1) ALOT OF THE NEWER ONES INFLATE UPON CONTACT WITH WATER
Goodhart5 years ago
The problem I see is "before it hits the ground". Building in a sensor would prevent you from actually carrying it :-)
robotkid249 (author) 5 years ago
Yea, you would need to reload it every time the air bag on the phone expands, which could become tedious. Maybe the case could use electricity from the battery and power a small fan that expands the bag.
5 years ago
Given the small size of a cellphone, you could just have spring loaded plates that expand inside of a bladder. Press it back in to reuse.
5 years ago
LOL I can see it now......BOING....drat....now I can't get it out of my pocket....
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