The present invention provides an apparatus for sensing biometric
information in a finger with piezo ceramic elements. In one embodiment,
the apparatus includes an array of discrete piezo ceramic elements and
filler. The array of discrete piezo ceramic elements is responsive to
acoustic characteristics of parts of the finger. The filler is
distributed between the discrete piezo ceramic elements and provides
acoustic attenuation and electric isolation between the discrete piezo
ceramic elements. A protective layer can receive a ridge pattern of the
finger positioned proximate to the array. Air in valleys between ridges
of the ridge pattern of the finger acts as an acoustic barrier. A backing
layer (air or foam) can also be provided.