In multiple applications, fiber optic sensors play a vital part, from guiding surgical procedures to detecting leaks in nuclear power plants. Although the technology has been developed to both identify and relay complex data, the optical fibers involved cannot tolerate severe environments or physical hazards.
Optical fibers must therefore be protected or modified if they are to survive and perform optimally, when they are deployed in such conditions. Failure to protect optical fibers could therefore compromise long-term reliability and risk the project’s integrity.
Polymer coatings are increasingly being turned to by design engineers in order to obtain the kind of multi-environment fiber optic protection needed to maximize the performance of sensors and networks. Using an additional polymer layer, individual optical fibers can be coated over their primary cladding, while a tube or sheath can contain fiber bundles, either as a sensor or a fiber optic cable. This tubing offers physical protection from threats in the surrounding environment.
The scope and efficiency of polymer-based protective coatings and sheathings and constantly increased by research and development efforts. For instance, last year, Zeus and Luna Innovations collaborated in order to assess the possibilities of a new optimized PEEK coating procedure, which had been developed specifically by Zeus for fiber optic applications.
This joint research yielded exciting results. The coating, once applied, was thermally stable and not susceptible to shrinkage, even during large temperature swings. The new PEEK coating was also found to deliver increased resistance to radiation and chemicals, as well as exceeding the performance of uncoated fibers under several other conditions.
Protecting Fiber Optics
It would be an overstatement to imagine a ‘one size fits all’ protective polymer solution. It is imperative to understand the characteristics of the polymers available and the kinds of protection offered by coatings and sheathings.
Zeus created the table below in order to best support engineers as they explore the possibilities of best–match protection for their application. The table details the different advantages and uses of the six principal polymers deployed in fiber optic coatings and sheathings: ETFE, FEP, PEEK, PFA, PTFE, and PVDF.
Though this is not a comprehensive overview, it offers a starting point to guide individual research into which polymers may offer the critical protection needed for user-specific fiber optic innovation.
| Polymer |
Key
Benefits |
Common
Applications |
Industry |
| ETFE |
- Working temperature:
-308 °F to 302 °F
(-189 °C to 150 °C)
- Temperature stability
- Good radiation resistance
- Mechanical integrity
- Low coefficient of friction
- Low water absorption
- Improved strength
- Sterilizable by multiple methods
|
Easily removed coating for crimp and cleave assemblies
in environments with broad temperature fluctuations |
Aerospace
Medical
Nuclear
Telecom fiber
|
| FEP |
- Working temperature:
-328 °F to 400 °F
(-200 °C to 205 °C)
- Temperature stability
- Chemical resistance
- Low water absorption
- Low coefficient of friction
- Good tensile strength
|
High transmittance housing
for fiber optic lighting
Low-friction lead-in tubes.
|
Aerospace
Automotive
Medical
Telecom fiber
|
| PEEK |
- Temperature maximum:
to 572 °F (300 °C)*
- Radiation resistance
- Thermal stability
- Chemical resistance
- Abrasion resistance
- Mechanical integrity
- Tensile strength
- Enhanced pushability
- Sterilizable by multiple methods
|
Strain and temperature sensing in harsh environments
Embedded sensors for structural and composite monitoring
|
Aerospace
Automotive
Energy
Medical
Nuclear
|
| PFA |
- Working temperature:
-328 °F to 500 °F
(-200 °C to 260 °C)
- Temperature stability
- Chemical resistance
- Low coefficient of friction
- Tensile strength
- Low smoke, toxicity
|
Protective housing for aerospace data cables
Pipeline
Monitoring
|
Aerospace
Energy
|
| PTFE |
- Working temperature:
-328 °F to 500 °F
(-200 °C to 260 °C)
- Low coefficient of friction
- Low water absorption
- Chemical resistance
|
Low friction liner for fan-out kits and cables
Cryogenic cables
Temperature sensor delivery
|
Aerospace
Automotive
Medical
Telecom fiber
|
| PVDF |
- Working temperature:
-58 °F to 302 °F
(-50 °C to 150 °C)
- Temperature stability
- Chemical resistance
- Radiation resistance
- Mechanical integrity
- Low coefficient of friction
- Low water absorption
- Tensile strength
|
Cables requiring low flame spread, limited smoke generation
Housing for high radiation environments up to 1000
MRad
|
Medical
Nuclear
Telecom
fiber
|
* Note that the maximum temperature for PEEK coatings ensures it is acceptable for applications that do not require dielectric or insulating properties.
Creating Custom Polymer Solutions
Market needs are constantly changing when it comes to fiber optic technologies. Work is always progressing in order to develop more versatile, stronger protective polymer solutions. These solutions will pave the way towards innovative new fiber optic technologies.
These facts are what drive Zeus towards working alongside their customers in order to develop and test custom polymer coatings and sheathings, which can achieve the specific protection needs of individual fiber optics applications and products. Indeed, the more product design engineers and R&D teams explore polymer protection possibilities, the more wide-ranging fiber optic applications will become, and ultimately the faster their development cycles can be established.
This information has been sourced, reviewed and adapted from materials provided by Zeus Industrial Products, Inc.
For more information on this source, please visit Zeus Industrial Products, Inc.