PRINTED ELECTRONIC SENSORS FABRICATED FROM POLYMER COMPOSITES CONTAINING CARBON NANOTUBES
Małgorzata Jakubowska, Maciej Sibiński, Marcin Słoma, Anna Młożniak, Daniel Janczak
Quarterly No. 4, 2010 pages 392-397
DOI:
keywords: carbon nanotubes, printed electronics, temperature sensors, pressure sensors
abstract Paper presents results of experiments related to fabrication of polymer compositions filled with carbon nanotubes. This type of materials were used for production of printed electronics sensors, which is a new trend in production of electronic devices and circuits for elastic and disposable electronics. Nanotube amount in compositions was evaluated in relation to electric properties of screen printed layers. Obtained polymer-nanotube layers demonstrate favourable electrical properties and high mechanical durability, what inspired authors to use that potential in production of various types of sensors including temperature and pressure sensors. Compositions are optimized for production of printed electronics elastic structures where key aspect is to obtain highly durable layers especially resistant to mechanical fatigue. Low temperature (5÷273 K) measurements demands to preserve measurement stability in cyclical temperature drops and raises. Specially developed pattern of screen printed silver paths and carbon nanotube areas was fabricated for pressure measurement through contact resistance changes. It is widely used method in application such as electronic foil keypads, potentiometers or pressure sensors. Investigated samples demonstrated over thousandfold change in measured contact resistance. This is way above resistance changes measured for other carbonic filling material such as fine grained graphite or carbon black. Compositions with 0.1÷1 wt.% of carbon nanotubes allows to fabricate conductive layers with resistance range 103÷106 Ω adequate for resistive temperature sensors. By special manufacturing technology and thermal processes stable and linear characteristics were obtained. By employment of carbon nanotubes as the active material, parasitic tensometric effects were eliminated. Ability to print various patterns allows to manufacture sensors adjusted to complicated shapes of objects, what makes measurements more precise. This type of sensors can meet the conditions of elastic skin temperature sensors for textronic applications.