According to some embodiments, an authentication server may receive first and second biometric user data from a writing device. The writing device may, according to some embodiments, have a plurality of spatially alternating sensors, including a plurality of sensors of a first type to read the first biometric user data and a plurality of sensors of a second type to read the second biometric user data. The authentication server may also receive a user identifier input by the user via the writing device and verify that the first and second biometric user data are consistent with the user and that the user has a payment account associated with the user identifier input. The authentication server may then determine a payment identifier associated with payment account and transmit a payment authorization indication associated with the determined payment identifier.