“We have validated high level disinfection of silicone components with Glutaraldehyde chemical sterilant/disinfection solutions. In researching standards or recommendations for safe GLUT residuals in these devices we have found very little information available. OSHA and NIOSH have published or recommended some limited information on worker “exposure” to GLUT in the hospital and the work place. These include values in ppm that are sampled or pulled from the immediate atmosphere and recommendations related to direct contact, which can result in skin irritation issues. Does NELSON have defined tests for measuring patient or worker exposure to devices that have residuals of GLUT?”

I would actually take a slightly different approach and have the component tested at a biotesting company, such as NAMSA. In the past I have run evaluations using test method C0020 USP Physicochemical tests, which is a leachables and extractables test in water. This would pick up and identify the value in ppm of residual on the substrate. They do offer a test, C0046 Glutaraldehyde Analysis in Aqueous samples, which can be collected by rinsing the part in water, capturing the water, and sending it in for analysis. I expect that this C0046 test method has defined limits of what is allowable for patient contact, but a call into NAMSA would define the test further.

Safety biotesting, chemical safety, GLUT, Glutaraldehyde

“What type of adhesive would I use to bond latex and latex-free rubber to brass?”

Latex rubber can usually be bonded with cyanoacrylate, commonly referred to as super glue. In most cases cyanoacrylates have excellent adhesion to brass. Latex-free rubber can include any number of types of rubber, from synthetic rubber, butyl rubbers, and isoprene, to even silicone, so I can not make a recommendation right now. However, cyanoacrylates would be a good starting place. Cyanoacrylates come in different viscosities such as low water-like viscosities of 20 or 50 cP, higher viscosity materials like 500 cP or 1,000 cP, and all the way up to GEL viscosities. Cyanoacrylates also come in different grades like low odor, low bloom, surface insensitive, and rubber toughened for better impact resistance. DYMAX 222/100, which is a low odor/low bloom cyanoacrylate, might be a good place to start, and then you can refine the adhesive selection from there.

Adhesives, Cyanoacrylates adhere brass to rubber, Adhesives, bonding rubber, Cyanoacrylates, industrial adhesives, metal bonding

“Do you have a list or can you point me to a list of adhesives and epoxies that are compatible with mineral oil? These would be ones that do not break down or release their adhesiveness when mineral oil passes over the adhesive/epoxy. Along those lines, which materials are better/best for tubing carrying mineral oil?”

The table below was provided courtesy of Cole Parmer. There may be other chemical compatibility charts available. You can rank various adhesives into different chemical categories, such as urethane, epoxy, or silicone, and should follow the basic trends listed below. For Example: DYMAX 1187-M light-curable adhesive is classified as a Urethane Acrylate adhesive family of chemicals. Evaluation of specific adhesives for a given set of substrates should be evaluated fully.

Explanation of footnotes
1. Satisfactory to 72°F (22°C)
2. Satisfactory to 120°F (48°C)

Ratings - Chemical Effect
• A = Excellent
• B = Good - Minor effect, slight corrosion or discoloration
• C = Fair - Moderate effect, not recommended for continuous use. Softening, loss of strength, swelling may occur
• D = Severe effect - Not recommended for ANY use
• N/A = Information not available

Adhesives Adhesives, Epoxies, epoxy, mineral oil compatibility, UV Light Curing Adhesive

“About ten years ago I worked for a start-up electronics manufacturer. In the lab we had a machine that dispensed UV-curable epoxy and had a UV spot lamp attached to the dispenser. It was all controlled by a foot switch for both adhesive dispensing and light control. We used it for numerous tasks such as bonding modification wires to the board as well as bonding components to the board. Does DYMAX offer anything like this or do you know of anyone who does?”

This unit was called the DYMAX PC-3D, with a dispensing system on one side, and a UV-curing system on the other. While there might be a few available units floating around eBay, these units are not manufactured anymore. At this point, they are stand-alone units. DYMAX can offer the individual lamps and air/pressure dispensing systems separately, but we do not have a combination unit like the PC-3D available anymore. I am not aware of anyone on the market making a unit like this currently. Sorry!

Curing Equipment adhesive dispenser, Curing Equipment, DYMAX PC-3D, light-curing equipment, uv curing lamps

"Can you cure DYMAX Ultra Light-Weld^® 1161-M adhesive with just heat or does the adhesive need to be exposed to UV/Visible light?"

Unfortunately, products like Ultra Light-Weld^® 1161-M are designed to cure with UV and visible wavelengths of light only, and heat will not cause this material to cure. There are families of DYMAX products that are considered Multi-Cure^®, which have both UV/Visible light-curing capability as well as thermal-cure capability. I would recommend calling a DYMAX Applications Engineer to discuss the specifics of your application, so that we can recommend the right Multi-Cure^® adhesive for your application.

Medical DYMAX 1161-M, heat cure, medical device adhesive, thermal cure, uv light cure, visible light cure

"Hello, I am using DYMAX 140-M to bond ABS to stainless steel. The product will be sold sterile in a Tyvek and LDPE/PET laminate pouch. Is there any data that shows the adhesive will not interact with the packaging in a way that could compromise the sterile barrier as the product sits on the shelf?"

Unfortunately we do not have data as specific as this. With so many applications around the world, and with so many substrates and packaging options being used, we have not attempted to determine the effects of cured adhesive in contact with the device packaging. The medical adhesives are usually tested for contact with blood, skin, muscular implant, etc., per ISO 10993/USP Class VI procedures, all with good results. If the material is cured properly, then after cure it is considered a solid plastic (urethane/acrylic type). We do not use any type of plasticizers or migrating materials that could compromise the integrity of the sterile barrier.

Adhesives, Medical adhesive compromise sterile barrier packaging, bond ABS to stainless steel, device packaging, ISO 10993, medical adhesives, migrating materials, packaging substrates; cured adhesive, plasticizers, USP Class VI

"We use a lot of RTV adhesives. Every lot is tested by QA. Last week we found out that in one of our components the adhesive did not cure at all. The RTV is one component and it adheres metal to ceramic. It has holes for air to penetrate. Even after opening the bond and exposing it for one week it still did not cure. What could be the reason for not curing?"

RTV silicone adhesives rely on moisture and humidity in the air to cure properly. Generally the conditions have to be 40-60% RH, but can extend down to 20%, and up to 70% in certain cases. The moisture in the air reacts with the stabilizer in the RTV, and once the stabilizer is removed, the adhesive can cure fully. In a very high-humidity environment, the humidity in the air can saturate the surface of the RTV, and effectively seal it off, limiting the penetration of the humidity to deeper levels. If you have a thick bond line or cross section of material, it may take longer than one week to cure fully. The silicone manufacturers generally set a 5-7 day cure schedule for RTV’s before they can test the physical properties in a thick slab of material, and that’s with the condition of 40-60%. If you have a 70% RH condition during the summer time, it may take longer, or disrupt the cure enough to appear gummy or semi-cured. Acidic surfaces may also cause problems with the cure mechanism.

Another avenue to explore: Was this failure linked to just one lot of material? And was it 100% failure for this lot, or 1% failure of one tube within the lot? These answers can lead the manufacture of the RTV to help determine the root cause of the failure.

Adhesives, Medical 40-60% RH, acidic surfaces cure mechanism, adhere metal to ceramic, bond, bond failure, fully cure, gummy, high-humidity, humidity cure, moisture cure, one component, RTV adhesive, RTV silicone adhesives, RTV stabilizer, semi-cured

"I have a lead wire containing a polyimide jacket. I need to bond the polyimide jacket to a titanium housing. The bond needs to provide a strain relief, and more importantly a fluid-tight seal. The adhesive needs to be rated for long-term implant use. Can you make an adhesive recommendation for this application?"

There are relatively few long-term implant adhesives on the market. NuSil Technology offers MED-2000, which is a one-component silicone RTV adhesive, and MED1-4213 is a two-component addition-cure silicone adhesive. Applied Silicone also offers long-term implant adhesives, such as P/N 40064. Since both companies offer other alternatives besides these, I would recommend contacting their respective sales/technical departments to discuss further.

Adhesives, Medical addition-cure silicone, Applied Silicone, bond polyimide to titanium, fluid tight seal, long-term implant adhesive, long-term implant adhesives, NuSil Technology, one component adhesive, silicone RTV adhesive, strain relief, two component adhesive

"I need inert and non-water absorbent adhesive film, with good sealing properties, to cover a surface (ceramic) already covered with a suspension of bacteria (dried). This set will be placed in a stomacher bag that contains culture media and the bacteria should be able to pass from the adhesive film to the media. It must be sterile or be able to be sterilized."

There are a few different options, depending on whether you want it to be sticky or non-sticky, or somewhere in between. Various silicone manufacturers or converters may offer cured silicone sheet in various durometers that would be inert and non-water absorbant. The lower the durometer (A-5 to A30), the better it will seal, but will be soft and “grabby” to the touch. Higher durometer silicone will be slightly easier to handle, but will not be as sticky or grabby as the lower durometer materials. You can go with an even lower durometer with silicone gels for better adhesion, but these need to be on a backing (similar to the tacky gel woundcare dressings or ouchless bandaids). Thin film PTFE or PTFE tape may also be an option. Many of these options will be sterilizable.

Adhesives, Medical adhesion, bacteria, cured silicone sheet, durometers, grabby, higher durometer silicone, inert, lower durometer material, non-sticky, non-water absorbant, ptfe tape steilizable, silicone gels, silicone manufacturers, sterile, sticky, thin film ptfe

"We have a segment of uncured adhesive inside a tube encapsulated with the adhesive DYMAX 204-CTH-F-VLV due to UV-opacity of the said tube’s segment. Does contact with uncured adhesive deteriorate properties of cured adhesive?"

Unfortunately, yes. Uncured adhesive will attack the bond line and the cured adhesive. The extent of deterioration is dependent on the area and volumes in contact with each other, and the duration of how long they are in contact. We would recommend sealing the tube, or removing the uncured adhesive if possible.

Adhesives, Catheter Bonding, Medical attack bond line, cured adhesive, deteriorate properties, remove uncured adhesive, sealing, uncured adhesive