Surface acoustic wave (SAW) devices are attractive for sensing of the physical, gas, liquid or biological
environment because the device has many parameters which can be adjusted for various applications. The temperature
coefficient of delay can provide temperature sensing, coupling to liquids, gases or applied films can be controlled by
choice of mode, and putting the device under stress or strain can measure pressure or vibration. In addition, there are
many substrate choices to attempt to optimize a given measurand. Finally, substrate choices allow sensing from
cryogenic to high temperatures (1000°C), which has the potential for use in a wide spectrum of space applications.
This paper will describe a novel SAW sensor platform for sensing of various measurands which is passive and
wireless, and has several levels of coding available for providing identification. The paper will describe the concept of
orthogonal frequency coding used in the device identification and its advantages in communications and sensing, and
the mechanism for implementation using reflectors in a SAW sensor. Results of measured SAW device performance
versus the coupling of mode (COM) model predictions show excellent correlation for a 250 MHz device on a lithium
niobate substrate. The approach presented uses frequency selective reflectors in a differential delay line to measure
temperature; measured from cryogenic temperatures to 150°C with the same device. A discussion of substrate materials
and device parameters will be presented to exemplify the versatility and practicality of these devices to a wide range of
Wavelength tuning is demonstrated in an antenna-coupled infrared microbolometer. With a 300-mV control voltage, we observed a tuning range of 0.5 µm near 10 µm. A metal-oxide-semiconductor capacitor underneath the antenna arms causes the shift of resonance wavelength with applied voltage. We develop a device model that agrees well with measured results.