Sensor Technologies

Fuel Cell Sensors --- Dynamic Performance --- World Class Quality

When selecting your electrochemical fuel cell sensors to drive high performance from your instrument design you want to be sure you have selected top quality sensors with proven reliability, world class quality and consistency. At PAS Systems International, Inc., we understand the dynamics of electrochemistry, sampling technology and instrumentation design requirements that make for the perfect union. In our experience, electrochemical fuel cell sensors knowledge alone is not enough.

We have vast experience in design, development and manufacturing of fuel cell sensors, sampling systems and instrumentation dedicated to breath alcohol sampling, detection and measurement. We work with many companies engaged in Ignition Interlock Device design and manufacturing, passive alcohol sensors, and other hand held breath alcohol instruments across many applications. This breadth of experience means when you select our Fuel Cell Sensors we bring much more to the table than just our substantial fuel cell sensor know-how.

Of course competitive pricing of fuel cells in also important, but QUALITY and APPLICATION EXPERIENCE that can be shared is often more VALUABLE. We make custom fuel cell assemblies that are a perfect match for your design needs. This includes providing the critical components, a selection of fuel cell cases, sampling technology options, and other engineering guidance. Normally you would expect a list of satisfied customers, and there are many; but we perform all or our work in accordance with strict CONFIDENTIALITY OR NON-DISCLOSURE AGREEMENTS. That does not mean we cannot meet your need for assurance of our capabilities and experience. Give us a call or visit our modern facility to see for yourself.

Basic Scientific Principles

A fuel cell sensor is an electrochemical device in which the substance of interest, in this case alcohol (ethanol), undergoes a chemical oxidation reaction at a catalytic electrode surface (platinum) to generate a quantitative electrical response. The position on the catalyst where this occurs is known as an “active site” and is on an intermolecular scale and therfore measured in nanometers.

Whenever a molecule is oxidized it loses electrons. During the fuel cell reaction, the electrons which are lost from the alcohol molecule are transferred to the platinum electrode (the fuel cell anode). From here they flow around the external circuit to the fuel cell’s counter electrode. This flow of electrons through the external circuit constitutes a measurable electric current. The more alcohol molecules that are oxidized the more electrons that are lost to the platinum surface, so the greater the current flow. Also, Hydrogen ions (H+) are freed in the process and migrate to the opposite surface where they combine with atmospheric Oxygen to form water, consuming one electron per H+ in the process. Thus the initial contact surface has an excess of electrons, and the opposite surface has a corresponding deficiency of electrons, and if the two surfaces are connected electrically, a current will flow through this external circuit to neutralize the charge. This means that the electric current which is generated is directly proportional, over a wide concentration, to the alcohol level in the sample.

In summary, as this oxidation of the ethanol molecule takes place a new molecule, acetic acid (ethanoic acid), is produced altering the electrical properties of the electrode. This alteration creates the peak output from the fuel cell. This process is referred to as Heterogeneous Catalysis.

By careful electrode design and catalyst selection, the fuel cell chemistry can be geared to work only with a limited range of fuel substances. This high level of analytical specificity is one of the positive features of our fuel cell sensors.

Pt + H2SO4

C2H5OH-----------------------CH3CHO + 2 H+ + 2 E

(Ethanol) Sensor action Acetic Acid (Ethanoic Acid)

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