Utility of resistance and capacitance response in sensors based on monolayer-capped metal nanoparticles

We investigate the utility of resistance and capacitance responses, as derived by impedance spectroscopy, in well-controlled and real-world applications of monolayer-capped metal nanoparticle (MCNP) sensors. Exposure of the MCNP films to well-controlled analytes showed stable sensing responses and low baseline drift of the pertinent capacitance signals, when compared with equivalent resistance signals. In contrast, exposure of the MCNP films to breath of chronic kidney disease patients under dialysis, as a representative example to real-world multicomponent mixtures, showed low baseline drift but relatively scattered signals when compared with the equivalent resistance response. We ascribe these discrepancies to the level and fluctuating concentration of water molecules in the real-world samples.