Oxygen-chemical agent sensor
AssigneeApplied Nanotech Holdings, Inc.
InventorsThomas Visel, Prabhu Soundarrajan
Life of this patent
Estimating the term…
Abstract
A gas sensing mechanism and a gas sensor based on a semiconducting carbon nanotube diode structure are disclosed. The gas sensor operates by detecting the change in conductivity characteristic of the current vs. voltage behavior of an I—N, or I—P junction, in the carbon nanotube. In the presence of electrophilic gas species at the I—N junction, or nucleophilic gas species at the I—P junction, a P—N, or N—P, junction is created by doping of the carbon nanotube by the respective gas species. The resulting change from the undoped, instrinsic i-type to p-type, or n-type, creates a diode structure whose conductivity characteristics can be measured with high accuracy and selectivity.
Claims16
A gas sensing device for selectively detecting electrophilic species comprising:
- an insulating substrate;
- two conducting electrode pads deposited on said substrate, separated by a gap greater than about 10 nm;
- and
- semiconducting carbon nanotube material deposited on said two electrode pads forming a conduction path, wherein about one half of said carbon nanotube material is in an undoped, instrinsic i-type electronic state and the remaining portion of said nanotube material is doped with a nucleophilic species to form an n-type semiconductor, such that an I—N junction is formed, wherein a P—N junction diode is formed in the presence of said electrophilic species;
- and
- circuitry connected to said electrode pads for measuring the conductivity characteristics of the diode structure,
- wherein the circuitry is configured to detect the presence of said electrophilic species by detecting the presence of a knee in a current-voltage curve for the semiconducting carbon nanotube material.
A gas sensing device for selectively detecting nucleophilic species comprising:
- an insulating substrate;
- two conducting electrode pads deposited on said substrate, separated by a gap greater than about 10 nm;
- and
- semiconducting carbon nanotube material deposited on said two electrode pads forming a conduction path, wherein about one half of said carbon nanotube material is in an undoped, instrinsic i-type electronic state and the remaining portion of said nanotube material is doped with an electrophilic species to form a p-type semiconductor, such that an I—P junction is formed, wherein an N—P junction diode is formed in the presence of said nucleophilic species;
- and
- circuitry connected to said electrode pads for measuring the conductivity characteristics of the diode structure,
- wherein the circuitry is configured to detect the presence of said nucleophilic species by detecting the presence of a knee in a current-voltage curve for the semiconducting carbon nanotube material.
Dependencies are inferred from the claim text.