As you know last week was the unveiling of the iPhone 5s,it has improved camera,a 64-bit processing,and of course iOS7. But the biggest most talk about feature on the new iPhone 5s is its finger print reader. Its the permanent replacement of the famed home button on the iPhone 5s. To explain the 5s "Fingerprint" reader you have to break it down to its sum of all parts.
How does it work?
The iPhone 5s uses a biometric ID system that has a capacitance reader that leverages a handy property of the users skin. The out portion of the skin (which is your demis) where the finger print is,is non conductive,while the subermal layer behind it is conductive. When users touch the iPhone's fingerprint sensor, it measures the users minuscule difference in conductivity. This is caused by the raised parts of the fingerprint,it then uses those measurements to form a image. The sensor is embedded on the home button, and added is a ring that turns on that helps reduce signal errors.
Howe does the fingerprint get stored?
The biometric fingerprint data is locked and stored in the iPhone 5s A7 chipset, it is never made available to any type of software beyond the Tocuh ID sensor. It's never stored to any of Apple's servers or synced to iCloud,once the data exists,it exists.
What's its made of?
The wafer thin Touch ID sensor measures about 170 microns,it can take 550ppi scans which allows for a good level of detail analysis. The ID Touch ID Sensor has a capacitive and reads the fingerprint at a sub-dermal level. This means it has the ability to read dead skin on the top of your finger, with new and living skin beneath the surface. This makes its less likely to fool fake fingerprints and severed fingers. The Sensor ID can read fingerprints in a 360 degrees motion,meaning according to Apple you don't ever have to hold the device a certain way in order for it read fingerprints,you can hold it anyway you want and it'll still read your fingerprints.
About that home button?
The home button,or what is now an upgraded home button is constructed out of a scratch-resistant sapphire glass lens that protects the assembly and focuses the sensor,there is a color match steel rings that surrounds the button waiting to detect a finger.
How to use it?
You train the Touch ID by repeatedly holding your finger against the Home button,every time you use it it starts to recognize that finger. You can also train the Touch ID to recognize up to 5 fingers. You can even train 5 fingers of your family members and friends.