Interdigitated nanoelectrodes for nanoparticle detection

Experimental results on the electrical detection of metal nanoparticles adsorbed on interdigitated nanoelectrode based devices are presented. By adjusting the gap between these electrodes to the diameter of the nanoparticles, we demonstrate that efficient bridging of the electrodes can take place. This phenomenon leads to a strong modification of the conductance of the device. The capability of the nanoelectrodes to detect single adsorption events electrically is demonstrated and reveals that the sensitivity reaches the individual nanoparticle level. This result is proven by current-voltage measurements at room temperature performed in solution during the adsorption of the nanoparticles and after the deposition process and surface drying. The capability of the devices to perform quantitative measurements is also addressed. Even if individual adsorption events could be detected one by one in solution, current-voltage measurements performed after the deposition and drying show that a correlation between the number of particles immobilized on the sensing area of the devices and the electrical characteristic remains difficult. The current flow is dominated by tunnel transport through the junctions formed between the nanoparticles and the nanoelectrodes and the dispersion of the electrical characteristics of the junctions is a limitation for quantifying the number of nanoparticles involved in the electrical response.