The Silicon Olfactory Bulb: A Neuromorphic Approach to Molecular Sensing with Chemoreceptive Neuron MOS Transistors (CnMOS)EPA Grant Number: R830902
Title: The Silicon Olfactory Bulb: A Neuromorphic Approach to Molecular Sensing with Chemoreceptive Neuron MOS Transistors (CnMOS)
Investigators: Kan, Edwin C. , Minch, Bradley A.
Current Investigators: Kan, Edwin C.
Institution: Cornell University
EPA Project Officer: Carleton, James N
Project Period: May 1, 2003 through April 30, 2006
Project Amount: $354,000
RFA: Environmental Futures Research in Nanoscale Science Engineering and Technology (2002) RFA Text | Recipients Lists
Research Category: Safer Chemicals , Nanotechnology
An ideal microsensor for autonomously monitoring chemical and molecular environmental hazards in both water and air should simultaneously have a high sensitivity, a high selectivity, a large dynamic range, a low manufacturing cost, simple calibration/reset protocols, a long lifetime, field reconfigurability, and low power consumption. These requirements arise from considering the rapid deployment and autonomous operation of a microsensor network monitoring a large area. We have developed a Si-based neuron MOS transistor with a novel extended floating-gate structure that permits molecular/chemical sensing. Our sensor, called a chemoreceptive neuron MOS (CMOS) transistor, is expected to simultaneously meet all of these requirements, and can be fabricated by minor modification or simple postprocessing of conventional CMOS integrated circuits. The modular structure and fabrication of this new device permits us to use CMOS devices optimized for high sensitivity and large dynamic range and affords us complete flexibility in the design and composition of the molecular/ chemoreceptive sites. The performance of our new sensor is expected to be vastly superior to that of existing chemical microsensors, such as the ion-sensitive FET (ISFET) and the CHEMFET, in nearly every important respect resulting from the internal transistor gain and much better isolation between the electronics and microfluidics.
We have already established the preliminary process flow and testing of CMOS transistors with generic molecular receptive areas for vapor and liquid sensing (e.g., water, acetone, etc.). Our preliminary measurements have validated most of our assumptions on the performance of these devices. In the three-year proposed effort, we will fabricate prototype arrays of these novel microsensors with various molecular/chemoreceptive surface coatings and characterize their sensitivities. Surface adsorption kinetics will be studied to facilitate fast and reliable coating selection. We will start with polymer coatings that have been used in vapor and liquid sensors through volume expansion monitoring. We will gather a new table of target agents and coatings from CMOS reading to achieve selectivity. We will also develop a micropower neuromorphic electronic interface for such sensor arrays whose structure and function is based on what is known about the olfactory and gustatory sensory systems of animals. This interface, called the silicon olfactory bulb, will provide a distilled set of informative features that can be used by a recognition system to perform analysis and risk assessment.
We expect to be able to develop a complete system, including both a sensor array and the silicon olfactory bulb, that can be fully integrated, perhaps on a single chip, and that will dissipate only a few hundred microwatts of power in total. Such devices could be manufactured in large numbers very inexpensively and deployed rapidly as environmental sensors, running autonomously for long periods of time on either solar power or miniature chemical batteries.