System Description
The TempTrackr™ Wireless Multipoint Wireless Measurement System is a SAW based temperature sensing solution that has the capability of wirelessly interrogating six to twelve wireless temperature sensors. The key advantages of the system are:

• Wireless Passive Temperature Sensors (no batteries, no energy harvesting)
• −40°C to 220°C Sensor Operating Range
• 428 MHz to 439MHz RF Operating Range
• Scalable System Configurations:
• 6 Sensor System
• 9 Sensor System (with sensors partitioned into electrically isolated compartments)
• 12 Sensor System (with sensors partitioned into electrically isolated compartments)

The TempTrackr™ Multipoint System is ideally suited for a wide variety of applications including High Power Switchgear, Rotating Machine Components and Wireless Food Probes. Any application that requires an electrically non-invasive temperature sensing solution or any application, where access is limited would greatly benefit from the passive, wireless temperature sensing capabilities of the TempTrackr™ Multipoint system. One of the best ways to evaluate the TempTrackr™ system is to obtain a Starter Kit.

Solution Differentiator
Traditional methods of measuring temperature have relied on the temperature dependence of resistance (thermisters or Resistance Temperature Detectors - RTDs), the temperature dependence of fluid expansion (thermometers), the temperature dependence of a diode junction (silicon), or the emission of infrared radiation from heated objects (IR thermometers). SAW based temperature sensors take advantage of the controlled change in material properties of a crystal, converted to an electrical signal via the piezoelectric effect. The sensing mechanism involves electrically inducing a surface acoustic wave into a piezoelectric material and then reconverting the energy of the wave (influenced by the temperature to which the sensing element is exposed) back into an electrical signal for temperature measurement. One significant advantage of SAW devices is their passive operation, which makes them very amenable to operation in harsh environments via wireless interrogation. A wireless SAW based temperature sensing solution consists of a reader (RF Transceiver) electromagnetically linked to a SAW sensing element as shown in the Figure below.

Figure: Wireless SAW Temperature Sensing System

A typical interrogation cycle includes the following steps:

• The wireless interrogator generates a Radio Frequency (RF) signal which is transmitted by the interrogator antenna.
• This signal is received by the sensor antenna and is used to induce a surface acoustic wave in the piezoelectric sensing element via an Interdigital Transducer (IDT).
• The resonant frequency of the surface acoustic wave resonator is influenced by the temperature to which the sensing element is exposed. It is this phenomenon that is exploited to obtain a temperature measurement.
• The IDT converts the natural oscillation of the surface acoustic wave resonator into an RF signal, which in- turn, is transmitted back to the interrogator via the same antenna set.
• A change in the frequency of the received RF signal is indicative of a change in the measured temperature.

Applications of Wireless Temperature Measurement Using SAW Resonators