Novel ultrasensitive millimeter-wave pressure transducer utilizing a Si membrane and a stacked-patch configuration

A new highly sensitive radio frequency pressure transducer has been designed to operate in the millimeter wave frequency range that can be seamlessly integrated with other RF circuits in the LTCC multilayer packaging technology. The resonator consists of a stacked-patch based on LTCC multilayer packaging technology, having an air cavity embedded by a silicon (Si) diaphragm that deflects due to pressure change. Furthermore, the RF transducer presented here, operating in two frequency bands between 30-55 GHz, serves as both a wireless communications link and a remote sensing differential pressure indicator. This device can simultaneously simplify the design process, reduce the device's size, and reduce power consumption of the sensor at device level, providing a sensitivity of 116 MHz/um with respect to the diaphragm deflection due to pressure change. The pressure inside the air cavity can be calibrated to detect differential pressure anywhere from zero to several bars. The transducer can be directly employed in a typical remote sensing / radar system without the need for additional circuits such transceivers required in traditional wired transducers. Thus, it significantly reduces the power consumption and greatly minimize the sensor. Due to its high sensitivity and portability, in future work the RF transducer design will be modified to use multilayer organics, such as LCP so that it may be utilized as wireless implantable sensors for biomedical applications and conformal structural health monitoring devices. A prototype of the RF transducer will also be presented to demonstrate the operation of the device.