Abstract: A sensor device having a vibratable surface which can be exposed to variousmaterials and used to determine the presence thereof is disclosed. The device includes a sandwich structure comprising a substrate coated with a piezoelectric material, a pickup electrode joined to the piezoelectric and a drive electrode also joined to the piezoelectric. The piezoelectric material is applied to the substrate as a slurry and when dried forms a ceramic coating which is chemically bonded to the substrate. The sensor is electrically driven to vibrate and depending upon the absence or presence of the material to be detected a characteristic vibrational frequency or amplitude of the sensing surface is observed to indicate contact with such material. Various embodiments are discussed including a rectangular configuration which is cantilevered from a support base and a circular configuration which is held circumferentially by the support base.
Abstract: The construction and method of operating a signal generator which provides an electrical output in response to an input mechanism such as a loading by finger are disclosed. The generator has the appearance of a plate and includes a sandwich structure comprising a conductive substrate, a coating of piezoelectric material and usually a plurality of discrete electrodes joined to the exposed surface thereof. The coating is deposited on the substrate as a slurry and is chemically bonded to the substrate. In order to produce an electrical output signal, prescribed locations on the plate are subjected to a force such as can be applied by the touch of a finger and a voltage is generated across the piezoelectric coating between the point of contact on the substrate and the adjacent electrode. The output signal is used either directly or after being amplified to drive various functionally responsive devices.