Ring oscillator based chemical sensor

A chemical sensor comprising:

• an active material that changes temperature in response to a change in a chemical condition of an environment to which it is exposed;
• a first ring oscillator defined by a first plurality of microelectronic inverters connected electrically in series, said first ring oscillator being coupled to said active material wherein a frequency of said first ring oscillator changes digitally in correspondence with the temperature of said active material;
• a second ring oscillator defined by a second plurality of microelectronic inverters connected electrically in series, said second ring oscillator being matched to said first ring oscillator wherein said second plurality of microelectronic inverters is identical in number and gate dimensions to said first plurality of ring oscillators, said second ring oscillator exposed to said environment in proximity to said active material wherein a frequency of said second ring oscillator changes digitally in correspondence with a temperature of said environment;
• and
• a processor coupled to said first ring oscillator and said second ring oscillator for generating a frequency difference between said frequency of said first ring oscillator and said frequency of said second ring oscillator, wherein said frequency difference is indicative of said change in said chemical condition.

A monolithically integrated chemical sensor comprising:

• a substrate;
• a first ring oscillator monolithically formed upon said substrate and defined by a plurality of microelectronic inverters connected electrically in series;
• an active material exposed to an environment and capable of participating in a chemical reaction with agents in said environment such that said active material experience a temperature change in response to said chemical reaction, said active material being monolithically formed and operably coupled to said first ring oscillator, wherein a frequency of said first ring oscillator changes digitally in correspondence with said temperature change of said active material;
• a second ring oscillator monolithically formed on said substrate matched to said first ring oscillator in terms of numbers of microelectronic inverters and associated gate dimensions thereof, said second ring oscillator positioned in proximity to said first ring oscillator, wherein a frequency of said second ring oscillator changes digitally in correspondence with the temperature of said environment;
• and
• a processor monolithically formed on said substrate and coupled to said first ring oscillator and said second ring oscillator for generating a frequency difference between said frequency of said first ring oscillator and said frequency of said second ring oscillator, wherein said frequency difference is indicative of the presence of said agents.