Self-heating effects in large arrangements of randomly oriented carbon nanofibers: Application to gas sensors

• Self-heating effects in large arrays of randomly deposited carbon nanofibers are shown.
• Self-heating reduces power consumption from mW to μW.
• Self-heating in randomly deposited carbon nanofibers devices can be calibrated using a fast 2-point procedure.
• Humidity sensing is proven to be equivalent in external heater and self-heating operation, without changing the transduction sensing mechanism.
• NH3 and NO2 gas response modulation by self-heating is also shown.

Herein, we prove that self-heating effects occur in sensor films made of randomly oriented nanoparticles (electro-sprayed, drop-casted and paint-brushed films of carbon nanofibers). A 2-point calibration method, reliable enough to overcome the lack of reproducibility of low cost fabrication methods, is also proposed. Self-heating operation makes possible reaching temperatures up to 250 °C with power consumptions in the range of tens of mW. For certain low-temperature applications (<100 °C) typical power consumptions are as low as tens of μW. The method is suitable to modulate the response towards gases, such as humidity, NH3 or NO2. This approach overcomes the complex fabrication requirements of previous self-heating investigations and opens the door to use this effect in cost-effective devices.