Electrical noise in gold nanoparticle chemiresistors

We studied electrical noise of gold nanoparticle chemical sensors with the intent of improving their limit of detection. All the sensors exhibit 1/f-type noise at low frequencies. The magnitude of the noise is found to be strongly dependent on the thickness of the films. The sensors containing a single monolayer of nanoparticles had the highest resistance and the worst noise performance. By making the films thicker, we were able to lower the 1/f noise by five orders of magnitude. The nanoparticle deposition of the thicker films was done with a micro-dispensing system, which resulted in highly non-uniform, coffee-stain patterned films. To get films of different thicknesses, we varied the number of drops deposited on each sensor. The noise prefactor extracted from different devices scaled linearly with the resistance of sensors. The effects of electron beam cross-linking were also studied and found to lower the noise of the sensors.