Less than 10-nm Gap Silicon and Polysilicon Electrodes for Sensing pH and Yeast Concentration

Silicon and polysilicon based nanogap electrode devices have been developed. The devices are able to detect lower concentrations of yeast at various pH values. Nanogap electrodes sense subtle changes due to molecular species perturbing the electrochemical signals across the gap. Two different materials and size of the nanogap electrodes were used to detect the biochemical solutions. Silicon and polysilicon nanogaps electrodes were characterized electrically by measuring the current-voltage and by optical imaging using SEM and FESEM. The capacitance, permittivity and conductivity were measured using a dielectric analyzer to sense and to profile pH under a simple and complex background. Polysilicon based electrode showed slightly higher sensitivity to the permittivity and conductance as compared to silicon based electrode over the same range of concentration. The data suggest that these electrodes can be used as low cost electrical devices for biomolecular sensing while consuming very low power (voltage).