Three Steps to Reliable Fiber Optic Medical Devices: Inspect, Clean and Inspect

Author: Jay Tourigny, MicroCare Sr. Vice President

The use of fiber optics in the medical industry is steadily rising. As the population grows and ages, healthcare providers are using fiber optic devices to provide improved patient diagnosis, monitoring and treatment. Today fiber optics have many uses within the medical sector including for minimal invasive surgeries (MIS), in single-use endoscopic sensors or for real-time MRI, CT, PET, or SPECT diagnostic imaging.  

Like most medical devices, cleanliness is vital to the performance of fiber optic instruments.  It is essential that the device performs without fault. One of the main causes of fiber optic instrument failure is contamination of the fiber optic cable connectors, also known as ferrule end faces.  It may be intuitive to wipe ferrule end faces on a gown or a cloth, but those items carry a variety of contaminants that could soil the ferrule end face connectors. Also, allowing connectors contact the floor or even touching the end faces with a finger can cause them to be significantly dirtied with dust or skin oil.

Dirty fiber connectors can cause a host of problems ranging from intermittent device performance to ruined instruments. That is why cleaning the fiber ferrule end faces, both during manufacturing and before use, is crucial to ensure the reliable operation of fiber optic medical devices.

The Contaminant Challenge

One of the biggest challenges of ferrule end face contamination is that it cannot be seen with the naked eye. Microscopic dust particles or fingerprint oils on end faces are typically only seen at 200x or 400x magnification. A close examination of the connectors, using a specialty fiber optic inspection scope is critical to confirm no particles or residue are present on the end faces.  This ensures that the fiber optic connections are clean and functioning properly.

Inspect to Ensure Compliance

Every fiber optic cable manufacturer strives to produce fiber cables with pristine, zero-contamination ferrule end faces. But in the real world, this lofty goal is impossible to achieve. Even the best manufacturers have fiber optic cables leave their factories with contaminants on the end faces. So, it is necessary that all fiber optic end faces, even brand-new ones right out of the packaging, be inspected with a scope for cleanliness prior to use.

Digital inspection scopes are commonly used in both production facilities and in the field to inspect ferrule end faces and ensure IEC compliance. As a matter of background, the International Electrotechnical Commission (IEC) published the fiber ferrule end face specification 61300-3-35 as a way to guide the fiber-optic industry in identifying the types of contaminants to be found and how to best remove them. Section 5.3 of IEC 61300-3-35 recommends using a three-step process of inspect, clean, inspect for ferrule end faces.

Inspect, Clean, Inspect

First, inspect the connector end faces to identify the amount of contamination. Second, clean the end faces, if necessary, to remove contamination. Finally re-inspect the end faces to ensure they are free of contaminants. Repeat this process until absolutely certain the instrument’s ferrule end faces are clear of all contaminants.

Most digital inspection scopes employ automated, software-driven algorithms to accurately compute the size, area, and location of end face contaminants. The total inspection process, using a digital ferrule scope, takes less than five seconds for an accurate analysis. Also, most modern digital scopes capture an image of the ferrule end faces, allowing the inspector to see and document the end faces’ condition both before and after cleaning.

Static Makes Things Worse

Static charges on the ferrule end faces attracts and holds particulate debris on the end faces for days or even months. The debris remains bonded to the end faces until the static charge finds a conductive path for it to dissipate. Introducing a cleaning fluid temporarily creates that conductive path, dissipating the static and making it easier for the device user to physically wipe the debris away.

Fluid Engineered for Fiber Cleaning

When cleaning fiber end faces, be sure to use a fluid specifically engineered for fiber cleaning.  Avoid using aqueous (water-based) cleaning solutions or pure isopropyl alcohol (IPA). Aqueous products are slow to dry and can leave moisture on the end faces. If the moisture is not completely removed before the fiber cables are connected, the laser-energized fiber can instantly vaporize the remaining liquid into a gas, causing an explosion through a sudden expansion of the vapors. This ultimately causes irreparable damage to sensitive and expensive diagnostic or procedural equipment.

As with water-based cleaners, IPA may explode or catch on fire when left on highly energized fiber end faces. IPA also typically leaves a hazy film behind when it dries. Using a fast-drying, high-purity fluid engineered specifically for cleaning fiber optics helps eliminate that problem.

The Contaminant Trifecta

Particulate, oils, and salts are the three basic types of contaminants found on the end faces, all of which require their own cleaning tools and methods.

Particulates are solids held onto the end faces by static attraction. The best way to clean particulates is to dissipate the static charge that attracts and holds the particulate in place. This is typically performed using a specialty fiber optic cleaning fluid. The cleaning fluid also dissolves any oils found on the end faces.

Salts, typically left from fingerprints, are not fully removed by cleaning fluids alone. While cleaning fluids may quickly rinse away the oils, they tend to leave salt remains behind in the form of a white residue that can be very difficult to remove. Adding mechanical cleaning action with a cleaning swab or wipe helps to fully eliminate oil and salt left on the ferrule end faces.

Beware of Presaturated Wipes

High-purity cleaning fluids can be used with both specialty fiber cleaning wipes and swabs. However, beware of presaturated cleaning materials. Presaturated wipes and swabs often contain microscopic contaminants drawn from the plastic packaging, which transfers to the end faces during the cleaning process and can result in adding even more contamination.

Instead, carefully apply a small amount of high-purity cleaning fluid on the corner of an optical grade dry wipe or to the tip of a specialty fiber optic cleaning swab. Then apply the moistened wipe or swab to the fiber optic end faces. Be sure not to touch the moistened area of the wipe or swab with fingers or clothing to avoid contamination and do use a fresh swab or wipe for each end face cleaning.

Fiber Cleaning for Better Outcomes

Using flexible, minimally-invasive fiber optics inside catheters and surgical scopes makes it easier for healthcare providers to give more accurate diagnoses, improved medical treatment and better surgical outcomes. All with more patient comfort.

Proper ferrule end face cleaning is an important step ensure reliable fiber optic medical device performance. To help safeguard fiber optic device reliability, use specially-engineered fiber optic cleaning products and closely inspect, clean and inspect all ferrule end faces before connecting. These simple steps help ensure the fiber optic device always operates as intended and without fault.

For those looking for help in selecting medical fiber optic cleaning tools and fluids, partner Sticklers™. We specialize in fiber optic cleaning and can provide advice on the best cleaning solutions and methods for your success.