How does a finger unlock a door?

At Sensor Expo 2019, Marcia Ratton from TDK InvenSense demonstrates how the UltraPrint Sensor (TCFS-3000) precisely identifies a finger print. Integrated into a door lock, the image from the sensor is displayed on a screen to demonstrate the clarity and details of the image. The ultrasonic fingerprint imaging uses proprietary InvenSense, a TDK Group company, CMOS-MEMS Platform (ICMP) technology with aluminum nitride-based piezoelectric sensing to enable the mass manufacturing of piezoelectric Micromachined Ultrasonic Transducers (pMUT) and transducer arrays. Each transducer element is individually controllable through direct wafer-level interconnect to the CMOS ASIC.

Detailed fingerprint images from the epidermal to dermal layers can be obtained directly through glass or metal, even in the presence of oil, lotions, perspiration or other moisture, and other common contaminants that can pose problems for traditional capacitive fingerprint solutions. Capacitive sensors can only sense through roughly 0.3 mm of glass which creates durability concerns. UltraPrint technology enables the use of thicker glass or metal materials without compromising biometric authentication performance.

The ultrasonic approach provides a highly durable, button-free solution where the fingerprint sensor can be placed behind the cover glass or under metal on the back of phone. Sensor placement can occur without cutting a hole in display glass, aluminum, steel or plastic case material making it attractive for biometric authentication in mobile or many other Internet of Things (IoT) applications.

This enhanced capability allows live finger authentication and guards against spoofing for increased security. Collaborating with GLOBALFOUNDARIES, a leading full-service semiconductor foundry, means that high volume production capability will be available for a wide range of security applications.