UV Curing for Lubricious Hydrophilic Coatings on Catheters and Guidewires

Catheters and guidewires carry hydrophilic or hydrogel coatings that become slippery when wet, so the device can be advanced through the vasculature with less force and less trauma. The coating is dipped or sprayed onto the shaft and then cured with UV light; how well it is cured decides the friction the clinician feels, how long the coating survives repeated passes, and whether particles shed into the patient.

Oxygen is the problem. At the exposed surface of the coating, atmospheric oxygen quenches the free radicals that UVA generates, so the outermost layer stays under-cured while the bulk beneath it hardens normally. The result is a tacky skin: higher friction than the formulation should give, poorer abrasion resistance, and a coating that can pick up debris. Extending the UVA exposure does not fix it — the oxygen at the surface is replenished as fast as it is consumed, so longer cycles cost throughput without curing the skin.

A two-stage exposure. First a high-intensity UVA cure in the 320–405 nm range brings the bulk of the coating to full conversion. Then a short, low-level exposure in the UVC range (200–280 nm) finishes the surface: the shorter wavelength is absorbed in the top few micrometres and drives the skin through the oxygen-inhibited layer. Because the second stage only has to treat the surface, it is brief and adds little to the cycle.

From the ETIA catalogue, the UVA stage is covered by the OmniCure AC Small series — AC4 at 365/395 nm or AC5 at 395/405 nm — mounted over the coating line. For the UVC-containing stage, the OmniCure S2000 Elite fitted with the 250–450 nm filter cartridge passes the UVC band of its continuous 250–600 nm lamp output; ETIA does not currently list a dedicated UVC LED head, so a customer specifying one should raise it with ETIA before design-in rather than assuming an equivalent.

OmniCure® AC Small (AC4 / AC5) is recommended for the UVA bulk cure and the OmniCure® S2000 Elite with its 250–450 nm filter cartridge for the UVC-containing surface pass, with the R2000 Radiometer used to fix and re-verify the dose of each stage.

As an authorized OmniCure® distributor, ETIA supports application review, product selection, genuine supply, installation, training, troubleshooting, and long-term service.

ETIA helps customers translate UV curing requirements into practical, reliable production solutions.