Synaptics announces optical-based fingerprint sensors for smartphones

Natural ID

The news from Synaptics is that it has created an optical-based fingerprint sensor for smartphones that provides secure authentication, through 1mm thick cover glass. The high resolution scanning through cover glass, will enable new clean looking button-free designs, from side to side and from top to bottom.

The newest edition to the family of Natural IDTM biometric authentication solutions is the Synaptics FS9100. This will go into mass production in Q2 2017, leading to speculation that it may be used on the Samsung Galaxy S8.

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While this may or may not be true, Synaptics has confirmed that the FS9100 fingerprint sensor will arrive in Q2 and will be affordable enough for use in both flagship and mainstream smartphones.


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The cutting edge design breaks through the technical barriers required, to form ultra thin form factors that use minimal power consumption. The fingerprint sensor can be positioned under 2.5D glass and will help OEMs avoid button cutouts or glass thinning processes, which are required by capacitive under-glass sensors.

Optical fingerprint sensors

This enables a more robust solution where the sensor is protected by durable waterproof and scratch proof glass. The solution also works with wet fingers, making it an even more practical solution.

Synaptics’ vice president of marketing for the Biometrics Product Division, Anthony Gioeli, said that the FS9100 optical fingerprint sensor would enable “OEMs to provide highly durable, button-free cover glass and more easily provide water resistant products while eliminating low yield glass processing.”

How secure is fingerprint security on smartphones

This new fingerprint sensor uses Synaptics’ SentryPointTM technology which provides a range of highly secure authentication features, such as Quantum MatcherTM with PurePrintTM anti-spoof tech. PurePrintTM uses AI technology to examine fingerprint images in order to distinguish between actual and fake fingers.

It is possible to create 100% accurate fingerprint security but for smartphones, in most cases, this is neither practical nor desirable. 100% accuracy would come at the cost of a high battery consumption and the number of false rejects would make the consumer experience unpalatable.

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Instead, a common design goal is adhered to, which balances cost, power consumption and security. Typically a live finger will be rejected in about 1 in every 300 scans (0.35%), while a fake finger would be accepted in about 1 of every 16 fake finger scans (6%).

It is important to note here that the fake finger under question here is created, for example, by stealing a copy of your fingerprint and then creating a physical fake finger using a 3D printer and then coating this in graphite powder or a conductive ink or paint. 

The future of fingerprint sensors for smartphones

Synaptics is collaborating with OXi Technology to bring these optical solutions to the mobile market as quickly as possible. Currently, the new technology places the optical sensor under the glass in the bezel area of the phone.

The next stage of development will be to engineer a fingerprint sensor that can be placed underneath the lighted part of the display. Once this happens, it will enable smartphone OEMs to create displays where the lighted area completely fills the front face.

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Written by: Michael Brown