Carbon nanofibres (GANFG) decorated with metal nanoparticles were deposited over Kapton, a polymide flexible substrate, onto which an array of four interdigitated electrodes in one side and a common heater in the backside were printed using inkjet printing technique. The control over metal type and the decoration percentage have given us the possibility to improve the sensor sensitivity and also enhance the selectivity by taking advantages from the difference interaction behaviors of tested target gas molecules with different hybrid materials at room temperature.

a b s t r a c t 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 W. The method is suitable to modulate the response towards gases, such as humidity, NH 3 or NO 2 . This approach overcomes the complex fabrication requirements of previous self-heating investigations and opens the door to use this effect in cost-effective devices.

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We present a simple and inexpensive method to implement a Griess-Saltzman-type reaction that combines the advantages of the liquid phase method (high specificity and fast response time) with the benefits of a solid implementation (easy to handle). We demonstrate that the measurements can be carried out using conventional RGB sensors; circumventing all the limitations around the measurement of the samples with spectrometers. We also present a method to optimize the measurement protocol and target a specific range of NO concentrations. We demonstrate that it is possible to measure the concentration of NO from 50 ppb to 300 ppm with high specificity and without modifying the Griess-Saltzman reagent.