A personal care appliance (10) comprises a handle (12), an attachment (14), and a controller (16). The handle (12) includes an actuator (20) and drive shaft (22). The attachment (14) has a body (30) with a principal axis (32) extending between a proximal end and a distal end thereof, wherein the proximal end couples to the drive shaft. The attachment (14) further includes a mass-spring identifiable assembly (40) having at least one identifiable resonant frequency in response to a given excitation, wherein the at least one identifiable resonant frequency comprises a resonant frequency selected from at least two different resonant frequencies. The controller (16) is configured to control the attachment (14), via the actuator(20), over a predefined range of frequencies that includes the given excitation. The controller (16) is further configured, in at least a detection mode, to uniquely recognize the attachment (14) via detecting a presence of the at least one identifiable resonant frequency of the mass-spring identifiable assembly (40) of the attachment (14) in response to the given excitation.
