Catheter bonding process improvements with high-intensity ultraviolet curing systems
Author: María del Mar Ortega-Meléndez
Advisor: Iván M. Avilés, Ph.D., P.E 
Graduate School
Abstract Methodology Results and Discussion Conclusions
Ultraviolet (UV) curing is a common process used in medical devices This test study challenges the lower limits of our time and intensity
All test parts evaluated for the completed experiments, met or exceeded Is the process output complaint with the required specification of
manufacturing for bonding operations. Light-curable adhesives provide parameters and their impact on tensile values. The effectiveness of the the required tensile strength output of >3.38 lbs. All samples were >3.38lbf? Is the process capable of absorbing process variation in curing
rapid cure, great adhesion, and good chemical resistance for cure will be measured based on the ability to meet the design spec of inspected for surface defects and no signs of voids, bubbles, or uncured time, UV intensity, material changes, and still meet the required tensile
sterilization processes. This project studies the effect of the 3.38lbf for the bonded joint tensile strength. The test will be conducted adhesive was found. By analyzing the DOE results P-value for all factors output? The answer to these questions is yes. The Feasibility and Edge of
implementation of a new UV curing technology for manifold catheters in the same clean environment that current manufacturing for catheter are 0.00; this means that there is strong of significant association between Failure testing proved that the new equipment is capable of successfully
manufacturing. The upgrade consists of moving from the current assemblies occurs. The study will feature three (3) different catheter the response variable and the term. This confirms that the material curing the adhesive while meeting the tensile and surface defects
mercury light bulb UV to an LED bulb. Benefits from improvements manifold parts, purple, grey and clear. For which the purple manifold, colorant affects the process output due to the UV filtering capacity. requirements. The Key Process Inputs (KPIs) were determined to be UV
include energy savings, improved process performance, and reduction will simulate a worst-case scenario during challenge testing since it can Intensity and Curing time. The use of nitrogen in this case was proved to
of maintenance activities. Process performance is evaluated by its filter up to 85% of UV Light source. A Full Factorial DOE for the have no impact into the adhesive curing, so this variable could be an item
capability of meeting the tensile force design spec of 3.38lbf. Key Feasibility Test with two factors, UV Intensity with five (5) levels and to evaluate in the future. Elimination of the nitrogen use can potentially
Process Inputs (KPI) that affect the tensile strength output are UV Product Color with three (3) levels against the tensile strength output of provide big cost savings to the catheters manufacturing process. This
Intensity and Process Cure Time. A Design of Experiments explored the minimum 3.38lbf. DOE for UV intensity Feasibility Test for will be run research was successful in characterizing and establishing the new process
lower and upper limits of adhesive curing time and intensity three (3) times for a total of 45 samples, with n=15 for each manifold parameters for the Dymax LED UV cure system. The research
parameters, and their impact on tensile values. color. A second run of n=30 samples for the purple manifold will contributions for improved equipment reliability, process performance is
evaluate curing time variation against the worst-case material. Edge of evident with the equipment upgrade that the new Dymax Blue Wave offers
Introduction in comparison with the current manufacturing process. One of the majorFailure test will be run one (1) time for a total of 90 samples, with n=30 items in terms of cost and time is the equipment maintenance activities,
for each manifold color. The two experiments described on Table 1,
this new equipment provides longer UV lamp life which directly impact
will define Normal Operating Conditions (NOC) and Edge of Failure
This project will study the effect of the implementation of a new the labor and costs incurred in maintenance work orders.
(EOF) for the manifold catheters bonding process.
ultraviolet (UV) curing technology for epoxy adhesive curing of
catheters manufacturing. The current curing process uses American Table 1: Experiments Objective and Test Parameters Future Work
Ultraviolet Lesco MKIII SuperSpot. This equipment is determined to Experiment Parameters
be upgraded to the Dymax MX-150 Spot Cure system. The UV UV Cure Time Adhesive 
fundamental difference between the two systems are the source of UV Test Name Test Objective/Purpose Intensity Intensity (sec) Amount The manifold color variant was a variable identified during this processFigure 3: Feasibility Test Process Capability Results for Purple Manifold
(W/cm2) Value (cc)
energy. The Lesco uses a 100W Mercury bulb to produce a wide that proved to impact tensile output due to its ability to filter UV light.(%)
Table 2: Edge of Failure Test Results Summary
spectrum of UV light (320-460nm), while the Dymax system uses an However, manifold design is a variable that cannot be changed ofFeasibility Verify that at the lower limit for
Tensile 
LED bulb that produces a narrower band of UV light (~365nm). Testing variable UV intensity, the units 10, 30, adjusted for the current product design and process, nor is within the
pass attribute testing and are 1.0 50, 70, 8 30 Manifold-Edge Output Distribution P-Value Ppk
Additionally, the Dymax system has an integrated user interface that scope of this study. The purple manifold product, D-120, is the catheterstatistically capable for variable 90 Mean (lbf)
allows for recipe control and will make the process easier to operate. with the lowest tensile strength output. A potential future research cantesting. Purple-Low 4.031 Normal 0.681 1.49
Edge of Test parts around the perceived involve identifying a new manifold material or colorant that stillPurple-High 5.05 Normal 0.528 1.93
Failure low end and upper limits of the provides the cosmetic design needs (purple color) but that has a lower
Background Grey-Low 5.18 Normal 0.272 3.28process range to give insight to Low 1.0 Low 8 Low 10 30
Upper 10 Upper 80 Upper 30 Grey-High 10.22 Normal 0.232 1.85 UV filter capacity. In general, polycarbonate materials like thethe tensile strength at lower and
higher UV doses. Clear-Low 23.52 Normal 0.969 1.41 manifold in this study affect the curing performance, if the colorant
Sealants and adhesives are used in many industries, their main purpose
Clear-High 33.79 Normal 0.357 1.46 variable can be addressed process capability can be improved and it can
is to bond and or seal joints of materials; these can also provide open the process to be applied in other catheter product families.
vibration damping and corrosion protection. The need to reduce cure When analyzing the failure modes, it is expected to see an adhesive
times and energy consumption opened the door to new technologies failure, this means the bonded joint area broke at the documented tensile
Joint Bonding Area
using the light electromagnetic spectrum sources to initiate and force. However, some tensile failures occurred due to the exhaust tube Acknowledgements
breakage instead of the bonded joint. Failures due to a break in the
accelerate adhesive cure. Recent research studied the differences
exhaust tube, occurs prior to adhesive failure, which means that the
between LED lamp and mercury lamps for UV curing. The results
limiting factor in this build was not the quality of adhesive curing, but The investigation and completed project presented in this poster is
showed that a homogeneous light distribution allows a higher photonic
rather the tensile strength of the proximal exhaust tube. These experiments based upon the work supported by Boston Scientific. Thank you to
efficiency. LED lamps, provide an improvement to light homogeneity
were successful in showing that even under worst case conditions, my fellow classmates for your constant support and motivation
and energy efficiency, creating higher curing rates. The characteristics exhaust manifold adhesive curing is still capable at meeting required tensile values. throughout this entire process. Assistance and mentorship
of the material to be bonded can affect cure, at least one of the
provided by Dr. Miriam Pabón and Dr. Iván Aviles.
components to be bonded must be translucent within the adhesive’s
absorption range. UV bonding process for this study is comprised of a
UV light source, cure box, nitrogen purge box, and light-curable acrylic Figure 2: Manifold to Exhaust joint bonded assembly example References
Loctite adhesive. Compress nitrogen, removes oxygen from the area
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