Materials for Biosensors.

Gwent Electronic Materials aims to provide both the materials for the manufacture of bio-sensors and a prototyping facility so that our customers and collaborators may obtain quantities of fabricated sensors for small scale distribution or pilot scale production and validation. Please see our section "Services" Materials for the bio-sensor market may be split into three segments. Medical Diagnostics Industry. A typical example is the blood glucose sensor used by diabetics. Environmental Sensors. Examples of this type of sensor would be the Organo phosphate sensor used for detecting pesticide levels in water, the detection of Chloride or other analytes. The "Agri-Food" Industry This market is interested in the same analytes as the Medical Diagnostics Industry and the Environmental Industries ie. Sugars, Alcohol, contaminants etc. Note:- in this area we have addressed this market by developing a complete sensor system including the instrumentation for testing sugar levels in fruit and vegetables. This entire system is distributed by our sister company Gwent Sensors Ltd. In the medical diagnostic industry our principle customers print and process their own electrodes, however we do offer prototype-printing facilities. Our primary intention in this sector is to sell materials for onward processing and not to fabricate complete sensor systems. At GEM Ltd. most of our developments have been centred on electrochemical sensor materials. We have developed a complete portfolio of materials that should meet all of our customers needs. This included products suitable for a variety of application techniques including screen-printing and flexographic printing. The materials illustrated below have been designed to print onto a variety of support materials both polymeric and ceramic. The most common support materials used are polyester, PVC and 96% alumina. See Ceramic Sensors and Polymeric Materials

Generic Sensor Materials.

We have custom developed many systems to meet individual customer needs. However, these materials can be differentiated into various functions within the electrochemical sensor these are: -

Working Electrode Pastes.

Carbon/Graphite Systems.

We offer three different ranges of Carbon/Graphite Systems.

Platinised Carbon / Carbon Graphite Pastes.

The first range is based on Carbon/Graphite systems mixed with Platinum. In these systems the platinum acts as an electro catalyst.

The formulation that meets most customer needs for manufacturing Platinised Carbon/Graphite electrodes is found in our latest information pages

For Additional information see our latest data

Mediated Carbon Graphite Pastes.

The second range is based on mediated systems. We can offer a wide range of mediated Carbon/Graphite pastes the two most popular formulations are:-

• 
  An ink containing a mediator that makes the electrodes specific to NADH. These electrodes when used in conjunction with specific dehydrogenase enzymes enables the detection of many analytes.
• 
  An ink containing an additive, is used for electrodes where the detection of Hydrogen Peroxide is required. This electrode allows Oxidase enzymes to be used.

For Additional information see our latest data

Standard unmodified Carbon/Graphite Pastes

For optimum electrochemistry the material co-developed with the University of the West of England, Bristol

• 
  This material gives the highest responses, however for good response coupled with good precision and screen-printing characteristics,
• 
  however we have a prefered formulation found in our latest information.

For Additional information see our latest data

It should be noted that all these paste formulations are available with a variety of organic carrying systems. These resins and solvents may interact with specific bio molecules. Our code numbers will alter with each change in the overall formulation. It is therefore advisable to check specific details with technical personnel before placing orders for materials.

Precious Metal Systems.

Precious metal working electrodes are also available. These are generally high temperature materials for ceramic substrates such as alumina.

High Temperature Systems

See Ceramics Sensors

For Gold working electrodes

For Silver working electrodes

For Platinum

For Additional information see our latest data

 

Low Temperature Systems

For low temperature precious metal working electrode pastes we would recommend:

For Silver working electrodes

• A good screen printable material

• For lower cost a Silver / Carbon working electrodes.

However other conductor materials can be used. These tend to be for specific customer requirements.

For Additional information see our latest data

Reference Electrodes

All of our reference electrode materials are based on Silver/Silver Chloride. These are supplied in various ratios to meet specific customer needs for response and conductivity.

These range from the highly conductive high Silver to Silver Chloride ratio materials, to the more resistive low Silver to Silver Chloride ratio materials. The most popular material in this range is the 60:40 paste formulation. The range includes:

• 90:10 Silver:Silver Chloride
• 85:15 Silver:Silver Chloride
• 80:20 Silver:Silver Chloride
• 70:30 Silver:Silver Chloride
• 60:40 Silver:Silver Chloride
• 50:50 Silver:Silver Chloride
• 40:60 Silver:Silver Chloride

• For Additional information see our latest data

Pseudo reference or guard electrodes can be made from either working electrode materials or reference electrode materials depending upon the individual system requirements.

Passivation or Dielectric Materials

The following list is just a small selection from our large range of polymer dielectric materials. These are usually used to define the working electrode area or to isolate sensitive parts of the circuit.

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  A a rubber based material offering high water resistance. This is especially useful for devices that will be immersed in water for extended periods of time.
• 
  A highly flexible methacrylate based material that gives a pinhole free surface and good print definition.
• A hard acrylic dielectric that gives good adhesion on to ceramic and polymeric substrates.

• For Additional information see our latest data

This list is not meant to be comprehensive as the number of variations of bio-sensors in great. For further help and advice please contact us.

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