Interdigital electrode

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Basic structure of an interdigital electrode with the electrode pair in black.

An interdigital electrode consists of a pair of comb-shaped, interlocking finger-like (finger: lat. Digitus ) electrodes. Each comb forms a single electrode.

use

Two interdigital transducers (shown in black) serve as transmitters (left) and receivers (right) of surface waves in the SAW filter shown.
A corneometer probe is used to measure skin moisture.

Interdigital electrodes are used, for example, in interdigital transducers which, for. B. serve as a bandpass filter in high frequency technology . Furthermore, they are used in a large number of different sensors that record physical parameters such as strain or chemical parameters, especially substance concentrations . For example, they can be built into moisture sensors, with AC moisture sensors for determining skin moisture also being called corneometers . The application areas of the sensors are in biomedicine, environmental monitoring or in industry.

Details on materials, construction and manufacture

Electrodes made of inert materials are required for chemical sensors. Therefore, the electrodes are often made of carbon or the precious metals gold or platinum , or nickel electrodes are gold-plated. The substrate should also be possibly inert. Often, glass , glass ceramics or silicon is used. Plastics are also used as substrate materials, especially polyimide , polydimethylsiloxane (PDMS), polyethylene (PE) or polyvinyl chloride (PVC).

Usual electrode spacings for electrochemical sensors are in the micrometer range, for example 5 µm, 10 µm or 20 µm. The width of the electrode strips connected to one another is also often in the range of 10 μm; 100 µm was also used. An electrode strip that is 10 microns wide can, for. B. be 2 mm long. In the case of strain sensors, the electrode distances and widths can also be in the millimeter range. The electrodes can also run in a ring.

The structure of the electrodes can either be produced with the aid of lithography , or screen printing processes are used.

Individual evidence

  1. ↑ a b AV Mamishev, K. Sundara-Rajan, Fumin Yang, Yanqing Du, M. Zahn: Interdigital sensors and transducers . In: IEEE (Ed.): Proceedings of the IEEE . tape 92 , no. 5 , May 2004, ISSN  0018-9219 , p. 808-845 , doi : 10.1109 / JPROC.2004.826603 ( ieee.org ).
  2. ↑ a b c d e Nasrin Afsarimanesh, Anindya Nag, Md. Eshart E Alahi, Tao Han, Subhas Chandra Mukhopadhyay: Interdigital sensors: Biomedical, environmental and industrial applications . In: Sensors and Actuators A: Physical . tape 305 . Elsevier, April 2020, p. 111923 , doi : 10.1016 / j.sna.2020.111923 .
  3. ↑ a b Christopher E. Chidsey, BJ Feldman, C. Lundgren, Royce W. Murray: Micrometer-spaced platinum interdigitated array electrode: fabrication, theory, and initial use . In: Analytical Chemistry . tape 58 , no. 3 , March 1986, ISSN  0003-2700 , pp. 601-607 , doi : 10.1021 / ac00294a026 .