has shown EEG oscillations that constituted EEG states were characteristic for 13 different groups of conditions in accordance to oscillations’ functional significance 23.
EEG has also been studied for its potential for biometrics 22, and Fingelkurts et al. ECG-based technology has been reported as a biometric feature that provides strong liveness evidence 20, 21. For example, electroencephalography (EEG) and electrocardiogram (ECG) have been considered as new biological features in biometrics research. In recent years, new approaches such as biomedical engineering technologies have been proposed to provide non-image-based frequency or time domain information. Many novel and unconventional features, such as ear contour 9, palm print 10, 11, nose pore 12, 13, vein patterns 14, 15, finger-knuckle-print 16, 17, and multimodal approaches have been adopted for development as new biometrics methods 18, 19. Under these challenges mentioned above, researchers have been seeking new alternatives to existing methods. Overall, current biometrics technologies could not reach a balance between counterfeiting and usability, and therefore, its popularization remains limited 8. Recently, the feasibility of some attacks have been reported, and it is actually possible to trick the iris recognition system with a printed iris, photo iris, and well-made color lens 7. There are also potential threats for iris-based systems. For example, it is possible to spoof the fingerprint scanner by using a printed gelatin mold over a real finger because this technology can fail to discriminate an artificial fingerprint 6. For example, some image features, such as those of the fingerprint and iris, which are used in a wide variety of applications ranging from smartphones to immigration identity authentication, could be easily spoofed and its anti-fake performance is threatened 5. However, the image-based biometrics methods also have their weaknesses 4. Most current biometric technologies are based on the structural features of acquired images, which have many advantages such as convenience and simplicity 3. Biometric systems play an important role in personal, national, and global security by significantly improving personal identification and authentication 2.
Overall, our ratiometric analysis of impedance improved the classification accuracy of 41 subjects and reduced the error rate of classification from 29.32% to 5.86% (by a factor of 5).īiometric authentication relies on the individual unique biological characteristics (fingerprint, vein, iris, retina, face, etc.) of a person 1.
By calculating the ratio of impedances, the difference between individual subjects was amplified and the spectral patterns were diversified. This study shows that the ratiometric features of the impedance of fingers in 10 different pairs using 5 electrodes at the fingertips can reduce the variation due to undesirable factors such as temperature and day-to-day physiological variations. In comparison to the traditional biometrics that relies on acquired images of structural information of physiological characteristics, our biological impedance approach not only eliminates any practical means of making fake copies of the relevant physiological traits but also provides reliable features of biometrics using the ratiometric impedance of fingers. We present a novel biometric authentication system enabled by ratiometric analysis of impedance of fingers.