Thick Film Heater Elements In Medical Applications

Thick film heater element are used in a wide variety of applications including incubation of cultures, to heat fluids before injection, DNA analysis and diagnostic equipment. These applications require controllable heat to be delivered to a specific area, often over an extended period of time, with a uniform steady state.

Conventional wire wound and other heaters are often difficult to fit in areas that are difficult to access or where space is limited. The high heat output per unit area makes thick film a better choice for such applications. Thick film heaters are ideal when heat output needs to be profiled across the surface, or in high watt-density applications.

Thick film technology is robust and offers high levels of moisture and chemical resistance. The thick film ink can be applied in various patterns and densities concentrating power exactly where it is needed.

Thick Film Heater Elements Material Considerations

In all cases the general thick film manufacturing process applies with the substrate material and the tracking pattern varied according to the application and target cost. Stainless steel, Aluminium, Alumina (or Aluminium Oxide ..ADS96R ) and Aluminium Nitride are common substrate materials.

Aluminium Nitride is suitable for applications requiring a clean, non-contaminating heat source that is mechanically robust. As the material has excellent dimensional stability it can be used to ensure consistent part-to-part thermal contact during heating cycles. AlN’s high thermal conductivity prevents cracking in high temperature applications. Stainless steel tends to be used in high operating temperature environments.

Heater Element Design And Manufacture

In general, medical applications require very high reliability devices that are customised to meet the needs of the application in relatively low volume. Each heater design is based on careful analysis of the specific application requirements. Often, a number of prototypes will be constructed to test design assumption are correct and to A/B test before committing to production.

A close working relationship is required between the supplier and the engineers and purchasing professionals of the end user to ensure a device is delivered that is fit for purpose at an appropriate price.

Thick Film heater elements therefore have some real advantages in medical applications but the choice of the correct substrate material and the design is critical to success. A supplier with both technical expertise and the capability to manufacture in low to medium volume is required.

RELATED POSTS

How to specify custom heater resistors.

 

TSEC's blog