Parylene Protection for Diabetes Control Devices

Diabetes is a chronic disease that occurs either when the pancreas does not produce enough insulin or when the body cannot effectively use the insulin it produces. Untreated or mistreated, diabetes can lead to serious damage to many of the body’s systems, including nerves, blood vessels, kidneys, eyes, feet, and skin.  
 
The treatment goal for diabetes is to control blood sugar, which is achieved by monitoring blood sugar and regulating insulin. This was primarily done via frequent needle sticks and injections. With technologically advanced diabetes care devices, the condition can be managed proactively without the discomfort of sticks and needles. Continuous glucose monitors (CGM) and insulin delivery devices are body-worn medical devices that respectively track glucose levels in real time and steadily deliver appropriate doses of insulin.
 
The CGM is a small sensor that is inserted under the skin into fatty tissue which is connected to a transmitter that sends information to a receiver or smartphone. The patient can view trends in glucose levels and anticipate and prevent hyperglycemia and hypoglycemia. Some CGM have alert sensors when glucose is too high or low.
 
Insulin pumps are sleek and discreet devices that can deliver insulin continuously or quickly for carbohydrate intake. Insulin is infused into fatty tissue through a cannula that is attached to a reservoir in the pump. Traditional pumps push insulin from a chamber within the pump through tubing to a site on the skin that is connected to a cannula which is a few millimeters long and delivers the insulin underneath the skin. Insulin patch pumps also use a cannula under the skin, but the insulin delivery chamber and the cannula are part of one “pod” that sits in the skin with an adhesive patch that is placed on the belly or arm. There is no external tubing with a patch pump, and it’s controlled wirelessly with a handheld controller.
 
In 2019,the U.S. Food and Drug Administration created a new classification for insulin pumps designed specifically to be interoperable with different devices. The Alternate Controller Enabled (ACE) infusion pumps, also called iPumps, are meant to accelerate regulatory review and pave the way for new connected systems in which patients can choose their pump, CGM, and control algorithm.
 

Why Diabetes Care Devices Need Protection

Despite these advancements, failure of CGMs and insulin pumps can happen. When they do, it can expose patients to significant and potentially fatal hazards. Insulin overdoses can result in severe hypoglycemia, causing seizures, coma, and even death, and underdoses can also result in hyperglycemia and sometimes ketoacidosis.
 
To enhance user safety, manufacturers are well-advised to coat their devices against water, blood, dust, and other environmental contaminants. The criterium is protection with no added weight or compromises.
 
Silicones, acrylics, and epoxies can be unreliable, ineffective, toxic, and costly which makes them unsuitable for diabetes care devices. Thin-film conformal coatings are the first and only logical choice for this application. They consist of a protective polymer layer 12-25µm thick (<20µm typical) that conforms to an apparatuses’ shape. They are made of non-conductive dielectric materials that cover all the electronics to protect components from corrosion and shields them from moisture, blood, fungus, dust, and other contaminations. Conformal coatings also help prevent damage from thermal and mechanical stress as well as rough handling or falls.
 
Of the conformal coatings, Parylene is the protective coating of choice for medical devices and personal wearable devices, including diabetes care devices. Parylene, also known as Poly(p-xylylene), is a protective polymer formed using a chemical vapor deposition (CVD) process, which creates a moisture and dielectric thin-film barrier.
 
The Parylene polymer series was isolated by The University of Manchester research chemist Michael Szwarc in 1947. In the 1970s, Union Carbide Corporation scientist William Gorham developed a deposition process to apply the film, which was the catalyst to commercializing the material and process. Although Parylene has been used for decades on a wide range of products, the high price of raw materials, scalability, manufacturing integration, and device complexity were all factors limiting widespread and high-volume adoption. 
 

A Viable Parylene-Coating Option

Nano-conformal coatings company HZO has developed a means of combining materials, processes, equipment, and experience to offer a viable Parylene-coating option. This was achieved by removing the most critical roadblocks of the material application by designing and deploying high-throughput coating equipment and automated processing systems for efficient manufacturing. The coatings company utilizes CVD to produce uniform and conformal coatings not possible with brushed, dipped, or sprayed liquids applications.
 
The conformal coating process encompasses pre-production to post-production activities. After a planning stage to determine each device product’s protection needs, HZO assesses the manufacturing requirements—including masking considerations—and executes on a production plan. Production occurs when units are loaded onto coating trays and placed into racks inside their custom-designed coating chambers where the coatings are applied. The large, cubed chambers hold hundreds of varying rack-loading configurations, which facilitates scaling of hundreds, thousands, or even millions of electrical components a day.
 
Parylene coating begins with raw material in powder form, added to a vaporizer, and sublimed from a solid to a vapor. The chemicals are then heated to a just-high-enough temperature in a pyrolyzer, which “cracks” the raw material into an activated monomer. At room temperature in the coating chamber, vapor forms a uniform, thin-film polymer barrier around the electrical components being coated. The gas can penetrate layers deep because of its vapor form, protecting areas not even visible in complex printed circuit board assemblies essential for the medical device and wearables industries.
 
The Parylene coating acts like a shield around the components creating an impenetrable barrier against contaminants. Parylene is also considered a “green chemistry”. Because there are no catalysts or solvents involved in the Parylene vacuum deposition process, the coating is pure and free from impurities. Parylene is chemically inert and non-toxic and produces no leachable ingredients.
 
Diabetes is a condition that must be managed by patients their entire life. By safeguarding diabetes care devices with Parylene coatings, diabetes management is made as easy and as safe as possible.
 

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James Tosh,  is the vice president, application engineer, of HZO Inc.
 
Educated in Scotland, James started his career in Engineering working for an Opto-Electronic company in Scotland as a Yield Analyst. He then moved to a Fabless Semi-Conductor company, Wolfson Microelectronics (Acquired by Cirrus Logic) where his role was working as a Failure Analysis Engineer, supporting both internal and external (tier 1) customers. He later moved to Canada to join Research in Motion (Blackberry) working as a Reliability Program Manager on products such as the Pearl, Z10, Z30 & Playbook. In 2014, he moved to join HZO where he now works as the Vice President of Application Engineering where his main role is working directly with customers over the life of their products from ideation to production.