Sensing Changes in Medical Electronics
By Kerem Durdag
Overview of the Wave Sensor
Further, these characteristics are complemented by another outstanding property of SAW devices which is particularly pertinent to medical devices; namely, their ability to operate with no wire connection or battery. They are connected only by a radio frequency link to a transceiver or reader unit. This is due to the SAW devices operating at very low input signal levels and high electrical efficiency.
A high-frequency electromagnetic wave is emitted from an RF transceiver and is received by the antenna of the SAW sensor that is fabricated onto the sensor surface using standard semiconductor techniques (Figure 3). The antenna is connected to the IDTs leading to the conversion of the received signal into an acoustic wave, which propagates along the sensor similarly to the previous description. Depending on the construction of the device, the IDTs can retransmit to the receiver. The received signal is amplified, converted to a baseband frequency in the RF module, and then analyzed by a signal processor for appropriate translation and display. Because the operating frequencies are in the GHz range, SAW sensors are well protected from electromagnetic interference that often occurs in the vicinity of industrial equipment, such as motors and high-voltage lines.
Kerem Durdag is the director of business development for SenGenuity at Vectron International. In this role, he is responsible for business and sales channel development activities regarding solid-state acoustic wave (fluid, physical, and gas) sensors to a variety of markets and applications. Durdag can be reached at 207-856-6977, x106 or firstname.lastname@example.org.