Charge-based chemical sensors: a neuromorphic approach with chemoreceptive neuron MOS (C(nu)MOS) transistors

A novel chemoreceptive neuron MOS (C(nu)MOS) transistor with an extended floating-gate structure has been designed with several individual features that significantly facilitate system integration of chemical sensing. We have fabricated C(nu)MOS transistors with generic molecular receptive areas and have characterized them with various fluids. We use an insulating polymer layer to provide physical and electrical isolation for sample fluid delivery. Experimental results from these devices have demonstrated both high sensitivity via current differentiation and large dynamic range from threshold voltage shifts in sensing both polar and electrolytic liquids. We have established electrochemical models for both steady-state and transient analyses. Our preliminary measurement results have confirmed the basic design and operations of these devices, which show potential for developing silicon olfactory and gustatory units that are fully compatible with current CMOS technology.