Ultrasonic Fingerprint Sensors

Research shows that biometric image quality is one of the most significant variables affecting biometric system accuracy and performance. Some imaging modalities are more susceptible to poor image quality than others, caused by a number of factors including contamination found on the finger and/or platen, excessively dry or moist fingers, ghost images caused by latent prints, and so on.

Optical fingerprint scanners, which rely on a concept called Frustrated Total Internal Reflection (FTIR), are vulnerable to inaccurate fingerprint imaging. Although optical fingerprint technology advances, we find most of these advances pertain to product features, and the limitations associated with the physics of FTIR can never be overcome. In response to FTIR issues causing suboptimum performance, a new imaging modality has been pioneered using ultrasonic imaging for livescan fingerprint applications. Ultrasonic imaging has demonstrated much more tolerance to external conditions that cause poor biometric image quality in optical systems, such as humidity, extreme temperatures, and ambient light. Although there is still a variable that cannot be overcome, that is, poor quality fingers, ultrasonic imaging has managed to minimize the impact of these types of fingers on overall system performance.

In addition, many biometric system inaccuracies are beyond the scope of most inhouse biometric vendor system testing facilities, creating a performance gap that exists today between laboratory biometric system prediction and real-world conditions. To resolve this performance gap, new biometric image quality metrics are needed to drive more precise biometric industry standards, baseline performance, and serve as the catalyst that could jumpstart an industry that has failed to meet many expectations for decades.