Janpu Hou

Mass Sensitivity of Plate Modes in Surface Acoustic Wave Devices and their Potential as Chemical Sensors

It has been found that, in contrast to gas sensors, a SAW device operating in a pure Rayleigh mode cannot be used as a sensor in a liquid medium. The reason is that the top surface liquid loading severely attenuates the Rayleigh wave transmission. Theoretical and experimental studies have been performed on SAW delay lines on different wavelengths to thickness ratios. We conclude that if the Rayleigh mode is strongly coupled to the plate modes then the SAW delay line works as a liquid phase sensor. We propose a new type of SAW sensor which utilizes the different plate modes that are generated by an interdigital transducer. There are two advantages of this type of sensor. First, the surface liquid loading will not severely attenuate the acoustic wave transmission. Second, we can use the back surface of the device as a sensing surface without interfering with the surface electrodes. The water loading sensitivity for different plate modes are given.

Common electro-optic interface module for decoding dissimilar input parameters

A common electro-optic interface (EO) has been designed and tested with a new optic sensor decoding architecture. The new EO module converts Wavelength Division Multiplexed (WDM) position, temperature and pressure signals using the same circuitry. This module uses the combination of Digital Signal Processing (DSP) technology along with a new temperature and pressure sensing technology. This approach results in common circuitry for processing three dissimilar inputs. The new architecture was made possible by advancements in two major areas, DSP and growth of advanced materials with tailored optic properties. This paper will discuss both the top level architecture of sensors and EO module and the performance advantages.