Interdigital transducer

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Two interdigital transducers (shown in black) serve as transmitters (left) and receivers (right) of surface waves in the SAW filter shown.

An interdigital transducer ( IDT for short ) (lat .: inter = between; lat .: digitus = finger; lat .: trans = over, over; lat .: ducere = lead, guide) is a transducer that has finger-like structures . These structures are also known as interdigital electrodes . They look like the prongs of two combs that interlock without touching.

The finger-like structures are usually made of metal and are arranged on a piezoelectric carrier material. If a voltage is applied between the combs, this generates a change in length of the carrier material between two prongs due to the generated mechanical force. If an alternating voltage is applied, this causes the carrier material to vibrate. As a result, surface waves are generated which propagate on the carrier material. Another interdigital transducer can convert these waves back into an alternating voltage using the piezo principle.

Such an arrangement can be used, for example, as a bandpass filter in high-frequency technology and as a pump in microfluidics .

literature

  • Alexander v. Mamishev, Kishore Sundara-Rajan, Fumin Yang, Yanqing Du, Markus Zahn: Interdigital Sensors and Transducers . In: IEEE (Ed.): Proceedings of the IEEE . tape 92 , no. 5 , May 2004, doi : 10.1109 / JPROC.2004.826603 ( Online [PDF]).