Gel-cast—A promising technique to develop highly sensitive temperature sensor

• A promising low-cost technique for developing MWCNTs/Al2O3 nanocomposite film.
• Temperature sensor is prepared from this self-supporting film.
• FESEM observations reveal uniform dispersion of MWCNTs in the alumina matrix.
• Electrical characterizations show high sensitivity and excellent repeatability.
• This technique also proves its candidature for use on commercial scale.

Higher thermal coefficient of resistance (TCR) for any sensing element is prerequisite to ensure best sensing performance, because the rest of the sensor parameters just follow the suit. In this paper, we report a simple, low cost technique, called ‘gel-cast’ for the preparation of tape/film from multi-walled carbon nanotubes (MWCNTs)-Alumina (Al2O3) composite and its potential use as temperature sensor. The composite was prepared by uniform dispersion of MWCNTs in alumina sol, prepared by sol-gel route. Sensors with varying concentration were subjected to moderate to high temperature ranges. Results show excellent sensing performance in terms of response-recovery time, sensitivity, and resolution. Sensor with 2% wt MWCNTs was found to have TCR value of around −0.87%/°C which is quite high in comparison to works reported so far on MWCNTs-ceramic composite film deposited by other techniques. Besides, cyclic studies show good thermal stability without any significant thermal hysteresis loss and compositional breakdown.

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