Miniature pressure sensor and micromachined actuator structure based on low-temperature-cofired ceramics and piezoelectric material

Abstract

A novel method to fabricate pressure sensors using low-temperature-cofired ceramics (LTCC) and polyvinylidene fluoride (PVDF) piezoelectric polymer is presented. The basic structure consists essentially of two LTCC substrates with an interlayer of PVDF sandwiched between them. For the top and bottom electrodes, a thin conductive film is deposited on both sides of the PVDF layer, but simultaneously PVDF layers with pre-deposited electrodes are also utilized. The PVDF polymer is normally polarized and has a remnant polarization; therefore, no further electrical poling is required till further processing is done below 80°C. An adhesive layer is selectively provided on each electrode for the attachment of the LTCC substrate on the top and bottom of the interlayer and in realizing the sensor structure. The electrical connections are realized through vias, and these via openings also expose the sensing layer to the external pressure. In a parallel effort, an actuator structure developed using laser micromachining for later coupling with the sensor device has also been briefly described. The initial experiments indicate that the LTCC technology can be used to fabricate actuator structures and when combined with PVDF polymer it can lead to fabrication of sensors in a simplified manner.