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Browse Prior Art Database

Metal Oxide Chemical Sensor for Portable Device

IP.com Disclosure Number: IPCOM000233602D
Publication Date: 2013-Dec-18

Publishing Venue

The IP.com Prior Art Database

Abstract

A chemical sensor and methods of manufactur-ing are described with a layer (11) of a metal oxide ar-ranged between two electrodes (26-1, 26-2, 36-1,36-2) with the electrodes being arranged above and below the layer of metal oxide.

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Metal Oxide Chemical Sensor for Portable Device

ABSTRACT

A chemical sensor and methods of manufactur-

ing are described with a layer (11) of a metal oxide ar- ranged between two electrodes (26-1, 26-2, 36-1,36-2) with the electrodes being arranged above and below the layer of metal oxide.

FIELD OF THE INVENTION

The present invention relates to an integrat-

ed chemical sensor, particularly a gas sensor, using met- al oxide. The sensor is sufficiently small to be located within the exterior shell or housing of a portable elec- tronic device such as a mobile phone, tablet and the like.

BACKGROUND OF THE INVENTION

Portable or mobile devices originally intro-

duced as mobile phones or electronic agendas become more and more ubiquitous. As the processing power of their internal processors grows and equally the bandwidth for communication with stationary processors, such portable devices take on more and more the role of multi-purpose tools available to consumers and specialist users alike.

          It has been recognized that portable device can benefit from the presence of sensors capable of providing a chemical analysis of materials brought into contact or the vicinity of the device. Whilst there are many possible applications for such sensors, it suffices to consider for example the analysis of air surrounding the portable device. Such an analysis can be useful for multiple purposes such as testing for hazardous gases,


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breath analysis for general medical purposes or driving fitness, and the like.

          It is further known to use high-temperature chemoresistors with a semiconducting metal oxide (MOX) as sensitive material. Typically a layer of the sensitive material is deposited onto a pair of metal electrodes. When used as a gas sensor, the gaseous species is ad- sorbed on the metal oxide and acts as an electron donor or acceptor. The related change in conductivity across the layer is measured and analyzed to determine the spe- cies and/or its concentration.

          When applying such a MOX sensor as an inte- grated sensor within a portable device, it is seen as im- portant to provide a sensor with a compact design.

SUMMARY OF THE INVENTION

          Hence, according to a first aspect of the in- vention, there is provided a chemical sensor comprising at least one layer of a metal oxide arranged between two electrodes to determine the resistance across the layer, wherein the electrodes are arranged above and below the layer of metal oxide.

          Accordingly, the electrodes are separated vertically taking the plane of the layer or a substrate onto which the layer is deposited as reference.

          When manufacturing smaller metal oxide sen- sors, it is seen as an advantage to arrange the elec- trodes and the metal oxide as a vertical stack of layers. The advantage can arise particularly from reducing the distance between the electrodes and hence the thickness of the MOX layer to less than 10m or, more preferably, to a range between 2m and 200nm whilst retainin...