Industrial Automation



Now that UDI has arrived, medical device manufacturers and labelers are under new obligations from the U.S. FDA to meet specific device coding and labeling requirements for their devices – and it’s not just for device labels and packaging anymore. Beginning this September, (September 24, 2016 to be exact), the FDA rolls out the first deadline for permanently marking UDI codes onto medical devices themselves. With this deadline only months away, and little finalized in terms of FDA requirements for UDI marking, many manufacturers are left scrambling to understand what permanent marking is and how to implement it according to what information exists today. At Microscan, we are beginning to see a flurry of requests for technology that can verify permanent marks for UDI compliance using FDA issuing agency specifications (like those regulated by GS1, HIBCC, or ICCBBA). Before marks are made permanent across their devices, manufacturers need to know that their encoded data is accurate to their specifications and that marks are made with the utmost quality to reliably convey the information on devices throughout their lifecycles (readable from manufacturer to consumer).

Although no one (not even the FDA) has all of the answers about final implementation requirements for UDI marking, Microscan comes to the table with three-odd decades in the business of reading and verifying codes (linear barcodes and 2D symbols), with leading algorithms especially aimed at deciphering direct part marks (DPM) – and it just so happens we are also in the barcode verification business. So to help ease some of the panic surrounding UDI permanent marking, our experts have put together a bit of knowledge in this blog about what to expect. 

To start, if you are in the medical device business (or simply a fan of the FDA’s work), I would recommend reading my previous blog outlining the basics of the FDA UDI regulation: UDI Has Arrived: What Do You Need to Know?  

So, what MORE do you need to know…? 

The UDI regulation does not stop at packaging. That’s because, in most cases, your medical device’s utility does not end shortly after it’s unwrapped from its packaging (unless perhaps it’s a bandage or rubber glove). It’s the FDA’s goal to ensure the safety and traceability of all medical devices for as long as they are in use, and that means ensuring UDI codes are identifiable on devices from the time they are manufactured to the time they are disposed of – regardless of how many times they are washed, rinsed, and repeated along the way. 

Understanding that some medical devices will require some level of reprocessing (as the FDA calls it), and that it is unlikely that a package or label bearing a printed UDI code will survive much reprocessing, the FDA has set forth additional requirements for devices to be permanently marked with a UDI in cases where reprocessing is necessary. This ensures that the UDI isn’t lost before its usefulness has expired. The trouble is – although prevalent in many industries with harsher manufacturing conditions like electronics or automotive (where printed codes are unlikely to survive) – the process of permanently marking devices with codes may be relatively new for medical device manufacturers, and now there are federal regulations dictating coding and marking requirements to boot. 

So let’s start with the basics…

What is permanent or direct part marking (DPM)?

Direct part marking (referred to in the “biz” as DPM), is a process of abrading a code (usually a 2D symbol like a QR Code or Data Matrix) onto a part surface in a manner that cannot be discarded, torn, obscured, wiped off, or easily degraded. An example of an impermanent mark (not permanent) is an inkjet code on a paper label or package, which can be removed from the device, damaged by physical contact, or distorted by moisture, temperature, or other elements. An example of a permanent mark or DPM is a code that is etched directly onto the surface of a device, by a laser for example, which removes the surface layer of the substrate of a device to expose the code in a varying color or contrast. 

With a code permanently marked onto its surface by DPM methods, a medical device can be properly identified and traced throughout reprocessing using encoded UDI identifiers. See the laser-etch DPM symbol on the surgical tools below – this permanent mark ensures UDI code data is available even through regular reprocessing like sterilization. 

Remember: the point of the UDI regulation is to ensure safety in medical device applications by enabling transparency about where a device has come from and where it is being used, in case of any adverse events such as a product recall. It is important that a medical device always bear a UDI until the point that it is no longer fit for use with human patients and is discarded.  

The FDA certainly takes this seriously, and there are bound to be consequences for any medical devices left unidentifiable during use. Regulations surrounding permanent marking for long-term device identification must be strictly observed with the knowledge that a direct part mark is typically the only identifier of your device after it is taken out of the package. 

What are the FDA’s current direct part marking requirements?

Although FDA regulations regarding directly-marked UDI have not been finalized, they do offer guidance to tide us over for the initial UDI DPM rollout.

Unique Device Identification: Direct Marking of Devices Draft Guidance:  

The FDA’s draft guidance states that all devices that are intended to be implanted or sterilized and reused must have permanent marks. This will require medical device manufacturers (or third-party providers of medical device coding and identification) to begin to incorporate direct part marking methods into their operations to ensure UDI compliance for permanent marks. Care should be taken to ensure both mark accuracy (the proper format of data within the UDI code that is marked on a device) as well as mark quality, since the legibility of a mark over time will be paramount to ensuring devices can be identified, logged, and located throughout their lifecycles. 

What are the deadlines for permanent marking of medical devices?

Medical device manufacturers for the following device classes must submit their DI (Device Identifier) to the GUDID, as well as mark their UDI permanently to their devices, by:

• Implantable, Life- Supporting ad Life sustaining Devices – September 24, 2015 (Already implemented UDI marks? Any advice for our readers?) 
• Class III – September 24, 2016 
• Class II – September 24, 2018 
• Class I - September 24, 2020

For a complete timeline of UDI implementation deadlines, visit:

What are the best practices for marking a medical device?

First of all, you need to know the class of your device in order to know if and when permanent marking will become a requirement. If you are uncertain of the classification of your device, visit the FDA’s Product Classification Database, where you will be allowed to search by the device name or the device panel (medical specialty) to which your device belongs. This database includes a list of all medical devices with their associated classifications, product codes, FDA premarket review organizations, and other regulatory information.

FDA Product Classification Database: 

Second, check with your UDI issuing agency to see what their guidelines are for permanent marking for your device. It is important to note that UDI marking requirements vary across manufacturers and device classes, including product lines, manufacturer sites, and business units. Depending on these factors, a UDI may need to comply with a unique format or include specific encoded data as determined by the UDI issuing agency. 

Third, and to make matters a tad more complicated, keep in mind that parameters used to assess UDI labeling and packaging compliance are not identical to those used for device marking. It is important to look specifically at guidelines for direct mark verification to ensure your UDI marks are produced to meet your issuing agency’s specifications and avoid production waste or compliance issues that may result in fines and legal action if an improperly-marked product is released to the market. It is a best practice to first print a newly-created code and verify its data content for UDI compliance before ever reaching the marking stage. This provides assurance that the data in your UDI code is formatted appropriately to your specifications prior to the investment of material and time implementing UDI DPM. No one wants to scrap a batch of medical devices due to an incorrect date format or a UDI that has an incorrect check digit. Especially when verification of the encoded data can be done quickly and accurately using barcode verification equipment at the code creation stage to verify the proper UDI code data structure for specific application standards. 

As a side note: Be careful to leave your newly-created, verified UDI code unchanged along the way to the marking stage. If you verify a symbol and then re-size or adjust the symbol prior to applying a permanent mark, the mark may fall out of compliance with the quality specifications of your issuing agency, impeding its long-term legibility. Verifying the symbol after all adjustments have been made, as well after the first product is marked, is also recommended to avoid unnecessary loss of time and material. 

You can learn more about how to minimize waste in UDI implementation in Microscan’s white paper, “Three-Step Verification for Lean Product Labeling.”

What kind of data carrier is recommended for UDI DPM?
Two-dimensional symbols such as Data Matrix are the most common UDI “data carriers” used for DPM due to their small size, data capacity, and error correction. Data Matrix symbols are extremely reliable and can be read in any orientation, at low or high contrast, and even when errors are present. As a result of error-correction, Data Matrix symbols with damage, distortion, or minor defects can still be decoded accurately, even if more than twenty percent of the symbol is obscured. 

What are the available methods for direct part marking?
Direct part marks are made by altering a part surface to expose a pattern in contrast to the default surface reflectance or color. The area of the alteration is called the “mark.” The combined marked area and surface area that make up the background of the mark (when creating a pattern of dark andlight elements in a machine-readable pattern) is called a “symbol.” An example is the laser-etched linear barcode symbol on the PCB to the right, where the laser has exposed the light elements of the barcode in contrast with the color of the surface of the PCB (the dark elements). 

Methods of direct part marking include: 

• Indenting
• Embossing 
• Coining 
• Abrasive blasting 
• Adhesive dispensing 
• Cast, forge, or mold 
• Dot peen 
• Scribe 
• Electro-chemical etching 
• Vibro etching 
• Embroidery 
• Engraving/milling 
• Laser marking 
• Laser peening 
• Liquid metal jet 
• Manual metal stamping 
• Stencil (mechanical cut, photo process, laser cut) 

Manual metal stamping, vibro etching, and embossing are not suitable for successfully applying micro-sized (as small as 1/32- to 15/64-inch square), high-density machine-readable symbols, and therefore may not be applicable to medical devices, which usually have limited surface areas for marking. Indenting, embossing, and coining are common methods for high-speed direct part marking, specifically for human-readable data like text on data tags. Laser, scribe, and dot peen marking methods are incapable of keeping up with high-volume production and are less ideal for applications that require high-speed marking. 

More information on direct part marking methods can be found in Microscan’s white paper, “How to Select the Best Direct Marking Method for Your Part.”

What marking method should be used for your medical device?

The routine response to direct part marking questions (and the key to the delay of final FDA regulations for permanent UDI marking and verifying procedures) is: “It depends.” There are a number of factors that determine the appropriate marking method for a device, such as: 

• Part function: Non-intrusive marking methods are recommended for parts used in safety-critical applications like balloons or catheters or high-pressure and high-stress systems. 
• Part geometry: It is more difficult to mark a symbol on a curved surface than it is on a flat surface. 
• Surface: Highly-polished metal surfaces should be lightly texture to reduce glare prior to marking. The textured area should extend the width of one symbol beyond the borders of the area to be marked. 
• Part size: Small devices require small marks. In most cases,   when a 2D symbol (like QR Code or Data Matrix) is used, the size of the part is irrelevant since these codes can be made so small, the required marking area can be reduced to below 1/4; inch square. 
• Application environment / lifespan: A mark must last as long as the device is used.Wherever the device is used, the mark must also be able to withstand the environmental conditions and remain readable for the lifecycle of the device. 
• Surface roughness / finish: If a device surface is too rough, the data elements of a symbol may be difficult to distinguish from the features of the device, making it illegible to decoding equipment. Surface roughness should be limited to 8 micro-inches for dot peen marking. Laser and scribe systems can produce a readable mark in rougher surfaces. This is because laser systems first burn a "quiet zone" (smooth,blank area on the surface of the device where the symbol will be marked) and then mark the symbol inside the quiet zone. The scribe method creates a high-resolution symbol that makes the mark reliably readable in most rough surfaces. 
• Surface thickness: Surface thickness must be taken into account when applying intrusive marking methods to prevent deformation or excessive weakening of the part. In most applications, the marking depth should not exceed 1/10 the thickness of the part to avoid compromising the safety of the device.

How can you make sure your code is compliant with UDI regulations? 

Assessing the accuracy of encoded data (validation) and the quality of a symbol for long-term legibility (verification), requires specialized barcode verification equipment. Barcode readers and scanners cannot be used for verification or validation of your code, and here’s why: While you may be able to extract data from a marked code using a barcode reader, a reader will only tell you what it reads, not on how well it was able to read it. 

A barcode reader will:

• Recognize the barcode symbology (UPC, Data Matrix, QR Code, etc.) 
• Extract the content of the symbol (decode it) 
• Transmit data to a connected device, like a PC (communicate what it decoded) 

Are you reading (extracting encoded data), or verifying (checking the accuracy of encoded data and quality of the symbol)?

To actually analyze the data that is within a code, and asses the physical properties of the mark to determine quality and readability, you need equipment with the ability to compare what it sees with an expected result. Barcode verifiersoffer built-in software programmed with barcode evaluation parameters, both for checking the syntax of encoded data as well as grading the physical properties of the mark in comparison with the properties of an ideal, high-quality symbol. Some barcode verifiers, like Microscan’s LVS® Barcode Verification Systems, are engineered with UDI issuing agency specifications. To grade a UDI code using this software, a manufacturer must simply select their application standard in LVS-95XX Software and the verification system will automatically recognize the code type and apply the complete set of data formatting and code legibility specifications to evaluate the code based on issuing agency requirements from GS1 or HIBCC. For example, LVS-95XX Software can automatically separate the segments of a UDI code into GS1 application identifiers (AI), ensure that all AI are valid, and ensure that the encoded data matches the prescribed format (for instance, 14 characters required for a GTIN). 

Regardless of whether a manufacturer is applying a UDI code to a label by impermanent methods, or directly to a device by permanent marking, it is best practice to always validate the content of the UDI code in print before application. This can be done by simply printing a newly-created UDI code on a desktop printer and using a barcode verifier to check that the contents are correct. Accomplishing this step before application can reduce the risk of time and material waste caused by applying an incorrect or noncompliant UDI code to devices on a wide scale. 

Once encoded UDI data strings are validated for the correct information in the correct format, the code can be applied by permanent marking methods to a medical device. 

Verifying mark quality is a separate matter, and requires the evaluation of physical properties of the mark (height, skew, element size and consistency, etc.) against barcode quality standards like those regulated by ISO. If you are already verifying the quality of your printed UDI codes, you may be familiar with ISO/IEC 15416 for linear (1D) barcodes like Code 128 or UPC, and ISO/IEC 15415 for 2D symbols like QR Codes and Data Matrix. These standards provide the basic grading parameters to determine printed code quality, and are also employed in DPM verification standards for marked codes (with some additions). 

LVS-95XX Software applies parameters of the ISO/IEC 15415 barcode quality standard to this Micro QR Code, which receives an “A” grade for its print quality.

What about DPM codes?

Direct part marks pose special challenges for both barcode reading and verification because – as discussed earlier – they are applied in a variety of ways to a variety of surfaces with different reflectiveness, contrast, color, texture, and curvature. These conditions produce unique reflections of light and can cause glare or shadows that may obstruct areas of the code or yield poor contrast, making it difficult for barcode readers and verifiers to distinguish the codes against device surfaces.

The key to both reading and verifying directly-marked UDI codes is lighting. When a device is illuminated, light reflects off of its surface in different ways based on the material and any abrasions (like a marked symbol) on the device surface. Ensuring that a barcode reader or verifier can distinguish the light and dark elements of a marked symbol on a surface requires the uniformity of light reflecting from the surface back to the reader or verifier. However, since light reflections vary based on the surface or marking method, it is difficult to obtain a “controlled” environment in which to read and verify codes across all marking methods and substrates.

To give an example, think about taking a photo with a camera that has its flash on. If the object or surface that you are photographing has “specular” reflectance (mirror-like reflectance), what does your photo look like? Can you make out any details in the object or are they obscured by the reflection of light? 

Using different lighting angles and geometries (backlight, diffused light, dark field light, and other configurations) is key to illuminating an object in a way that reflects light back to the camera so as not to “blind” it, but instead to emphasize important details in clarity. If you are trying to take a photograph through a window (which has a lot of specular reflectance), you would likely turn the flash off. If there is a light on behind you as you are taking the photo, causing a reflection of light in the window, what angle would you use to alleviate glare? 

The same goes for reading and verifying marked codes on different surfaces. If we position a verifier at a slightly different angle, or apply different geometries of lighting, the mark appears in different clarity to the verifier – either light is reflected back to the verifier in a way that obscures the mark’s features from the verifier, or it is reflected back in a way that emphasizes the details of the mark in high contrast. These subtle variances in lighting and angle affect the ability of the verifier to accurately evaluate the quality of the mark, just as lighting and angle affect your ability to take a clear photo through a window if you move your camera position or change the flash. 

Based on your angle, or the angle of the object in relation to light, the appearance of the object will change as well. 

So how do you verify a UDI direct part mark?

Here again we reach the standard conclusion for these kinds of DPM quandaries: “It depends.” The FDA is still working on guidelines for UDI marking to find the best method to cover the greatest range of potential DPM factors, from marking methods to reading environments to device types. Until the FDA provides their final verdict on how they would like UDI marking to be done, barcode quality standards organizations (like ISO) and UDI issuing agencies (like GS1) wait with bated breath to receive their directives so that they, in turn, can formulate their mark quality specifications to support the conditions of the latest FDA regulations. 

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