Solid state nitric oxide sensor prepared by sol–gel entrapment of iron-diethyldithiocarbamate in a siloxane matrix

In this work we report the synthesis of a solid state nitric oxide (NO) sensor based on the trapping properties of iron-diethyldithiocarbamate. Electron Spin Resonance was used to quantify the number of NO trapped. The sensors were made by entrapping the iron complex within a siloxane matrix using the sol–gel process. Different synthesis parameters such as pH or annealing temperature have been changed and its effect on the sensor properties were analyzed. It is found that the process of solidification can be accelerated using a sensor with small masses, approximately a few micrograms, using an acid environment and aging temperatures above 50 °C. The NO trapped in solid states was found to be more stable than in solution, the NO related ESR signal could be observed even after 14 days. The use of dimethyl formamide was observed to increase the ESR signal related to NO trapping, while improving the matrix structure stability. The sensor can be reused and it is able to measure NO concentrations higher than 0.01 mM.