Testing shows laser marking is the ideal technology for coding glass vials and syringes.
Abstract: The technology SCHOTT chose for its Smart Container program marks primary packaging containers at the earliest possible point in the supply chain to reap digitization benefits from production to point-of-use. While this laser marking technology is already proven for glass vials, the geometry and processing of syringes present a different set of challenges. SCHOTT therefore undertook a proof of concept to adapt its laser coding solution for glass syringes. This paper discusses the proof of concept results and demonstrates the viability of SCHOTT’s choice in its placement of the laser marking for syringes and radio frequency identification (RFID) were considered.
Inkjet technology – either organic or ceramic -introduces another material to the production process and cleanroom, can increase particle generation through its susceptibility to scratching, and requires additional qualification. The smallest code reproducible via inkjet is not as small as laser and in addition inkjet cannot provide the same accuracy or transparency levels as laser can. These facts may affect the inspection process and create less option for code placement on the container
Organic inks are also less durable and have temperature limitations. On the plus side for inkjet and ceramic inks, larger code sizes and higher contrast permit scanning with a mobile phone camera.
RFID comes with certain security concerns. The tag must be mounted in the cap, which means that traceability necessarily starts at a later point than with ink- or laser solutions in the production process. Furthermore, if the cap is removed, the code and traceability capability are lost, and if the antenna or the chip is destroyed the tag is not readable and traceability becomes impossible.
Laser marking is largely impervious to temperature changes or humidity and is abrasion-resistant and impossible to remove without leaving evidence. In addition, the code can be read accurately from point-of-production to point-of-use. Adopting laser marking does not require complete requalification of the container. Testing also showed laser coding doesn’t affect product inspection or slow the fill-and-finish process. Line speeds of 1,000 units per minute are possible. Applying the code in conjunction with the container-forming process – between the hot-forming and annealing stages – links it to the container at the earliest possible stage.
Technology decision and code placement on vials
Applying a unique code to the glass primary packaging container poses two challenges: What is the optimum coding technology and where should the code be positioned on the container for maximum readability and line efficiency? Smart Container development efforts had already proven that vials could be coded successfully using a laser. Research had also shown that the optimum location for the code was on the bottom of the vial.
Syringe as Smart Container
Although Smart Container technology worked well for vials, syringe geometry is completely different. Additional research had to be undertaken to determine if laser coding was compatible with syringes as well. As syringes lack the flat bottom surface of vials, a different location for the code also had to be determined and evaluated. Here, coding locations were limited to the tubular body (barrel) or the flange.
Since vials and syringes feature distinct geometries, undergo different hot-forming processes, and offer various inner surface treatments, SCHOTT tested two types of pulsed lasers for code application. The results showed the laser used to code vial bottoms didn’t have enough fluence to provide a stable marking process for syringe flanges. A faster diode pumped solid state laser with shorter pulse width was tested and proved to be successful. This laser also could be used to code vial bottoms, but was a less practical option for that application since vials could be coded equally well with lower cost smaller laser systems.
As noted above, the only potential locations for a Datamatrix code on syringes are the barrel or the flange. The barrel provides ample space to place such a code and a good surface for laser marking. The laser-marked code on the barrel proved to be consistently readable with standard reading technology. However, reading the code on the barrel increases line complexity. Syringes must be removed from the nest and rotated to capture the image or positioned before a multi-camera system to capture the code regardless of the orientation of the container. Positioning the code on the barrel also impacts final inspection because it can impede visibility and make it harder to detect product flaws. So applying the code to the flange area was studied.
Figure 1: Datamatrix code laser marked on a syringes flange
The flange of a syringe features variable surface geometries, depending on the flange type (round flange versus cut flange). The narrow 1.5-3.0 mm target area provides a greater challenge to place a code. Due to the space restrictions not only 1 x 1mm Datamatrix (14x14 dots codes were tested, but also 2 x 0.5mm (8x 32 dots) codes to best use the available surface area. Tests showed that codes marked on the top of the flange (as shown in Fig. 1) could be read by standard equipment without removing syringes from the nest. Minimizing syringe handling streamlines operations – a major advantage on fill-and-finish lines. Furthermore, the code on the top of each flange is easily readable throughout the fill-and-finish process and downstream in the supply chain and doesn’t interfere with the visibility of the drug product or graduation dose marks on the syringe itself.
Another concern was whether laser coding would affect container strength since some interactions that a glass container experiences can weaken it if they cause flaws or stresses. Flange strength of the syringes was tested in accordance with DIN ISO 11040-4, examining a total of 300 syringes (as shown in table.1), Results showed, that laser marking had no significant effect on flange strength between coded and uncoded samples.
|3mL round flange
||0.9 x 0.9mm
||14 x 14
||50 pcs coded+
50 pcs uncoded
|1mL short cut flange
||0.9 x 0.9mm
||14 x 14
||50 pcs coded+
50 pcs uncoded
|1mL long cut flange
||0.6 x 2.1mm
||8 x 32
||50 pcs coded+
50 pcs uncoded
Table 1: Overview of test samples
Based on the result of the Wilcoxon-Mann-Whitney and Kolmogorov-Smirnov hypothesis tests, the flange strength result per syringe format are statistically indistinguishable and hence the two batches (reference vs. code) can be considered as identical in terms of their flange strength.
Inline camera technology reads Datamatrix codes on the flange
With the code located on the flange, the laser-marked syringes are readable in the nest, whether it’s moving or stationary, and are read one-by-one without any need for removal or rotation. To read the codes, an array of high-resolution cameras or a linescan camera moves over the nest or alternatively, the nest moves under a high-speed galvo scanner system. Code capture occurs in ~0.05 seconds per code. As with many code-reading applications, proper illumination is essential, but no proprietary equipment is required. Many “plug-and-read” systems on the market can capture laser-etched codes on syringe flanges. Simultaneous reading of all the codes in the syringe nest is under development. Options include aggregating the code from each syringe in the nest and writing this data to an RFID tag on the tub.
Code capture and translation rely on a parallel data management system that contains the data represented by the code. The data management system allows information to be added to the database at each step in the process, interfacing with the critical unit-level Datamatrix code to aggregate data for multiple potential uses across the supply chain for vials or syringes.
The advent of track-and-trace requirements for pharmaceutical products, transition to Industry 4.0, continuous manufacturing, and the benefits of real-time release have challenged primary packaging manufacturers to align technology and data management in new ways. Traceability at batch level is no longer adequate. Marking primary containers with a unique code at unit level is now the basis for tracking and digitization in the context of pharmaceutical manufacturing and beyond.
At a high level, the SCHOTT Smart Container proof of concept for syringes has demonstrated that one laser-based and readout concept can be followed for vials and syringes. SCHOTT’s selected laser technologies have adapted to vials and glass prefilled syringes within the Smart Container framework, and affirmed the choice of laser marking versus alternatives as the best approach for supporting traceability from container production to point-of-use. By identifying and proving the ideal location for the Datamatrix code – the syringe flange – SCHOTT has built on the value delivered by laser technology.
Based on SCHOTT glass expertise, the Smart Container solution for vials and syringes brings together a set of carefully-researched technologies that are ideally suited to setting the new market standard for coding glass vials and syringes.