Arizona Board of Regents, a Body Corporate

Arizona State University

Arizona Baord of Regents

Ian Sorensen

William Glaunsinger

Qingcheng Bao

Michael J McKelvy

Mahesan Chelvayohan

A method and apparatus for rapidly and continuously restoring the sensing capacity of thin film sensing elements includes passing a sufficient electrical current through the sensing element to remove from the element selected components from a fluid sample in contact with the sensing element that have an affinity for and are adsorbed and accumulated onto the surface of the sensing element. The passing of current through the sensing element can be accomplished either by applying a constant voltage across the sensing element or by forcing a constant current through the sensing element. The restoration technique removes the components from the sensing element by a combination of resistive heating of the element and electron bombardment of the components on the surface of the element. Moreover, to prevent possible rupture of the sensing element due to electromigration, the current may be alternated in a first direction and then in a second and opposite direction through the sensing element in sequential runs of equal predetermined time intervals.

Method for regeneration of a sensor

A chemical switch device comprising a film which irreversibly reacts upon exposure to specific chemical components in the environment under the conditions of measurement. The reactions can lead to large changes in the physical and chemical properties of the film which are measurable electrically, optically or by other methods.

Chemical switch for detection of chemical components

A combustible gas sensor having a noble metal sensor element with a surface that is heated above a critical temperature at which the surface is able to dissociate oxygen in a gas stream and adsorb the oxygen onto its surface. The adsorbed oxygen present on the noble metal surface enhances the reactivity of the sensor element and permits it to react with combustible gases that otherwise would have little or no affinity for the sensor element. The balance of adsorbed oxygen and combustible gas species on the sensor surface cause a change in an electrical property that is used to determine the presence or identity of a combustible gas, or to derive a concentration measurement. The electrical property measured to determine the presence, identity, or concentration of combustible gas includes the work function of the noble metal surface, which may be measured by incorporating the sensor element as a component of a variable capacitor contained in an electrical circuit adapted to measure change in current caused by the change in capacitance of the variable capacitor.

Apparatus for sensing combustible gases employing an oxygen-activated

A thin film device having a selectively passivated surface is provided. An embodiment of the device is particularly suited to detection of chemical constituents by selective adsorption, where the selectively passivated surface is inert to the chemical constituent being detected. A method of fabrication of the device is also provided in which the selective passivation is achieved by selectively applying the metallic adhesive to the substrate. The migration of the metallic adhesive through the thin film layer is essentially normal to the surface of the substrate, thereby limiting the passivation of the thin film layer to the surface areas directly overlying the metallic adhesive.

Selected area adhesion and surface passivation of metal films

Method and apparatus for sensing combustible gases employing and

A chemical switch device and method of sensing the presence of a chemical constituent in an ambient environment, the chemical switch device comprising a film which irreversibly reacts upon exposure to specific chemical components in the environment under the conditions of measurement. The reactions can lead to large changes in the physical and chemical properties of the film which are measurable electrically, optically or by other methods.

Growing community of inventors

Phoenix, AZ, United States of America

Ian Sorensen