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Improving CGM Electronics Designs with Medical Coatings

Mallory McGuinness-Hickey November 20, 2021

A vital issue for continuous glucose monitor development is design and reliability engineering. 

CGM systems, however, will encounter environments that can jeopardize electronics that enable functions, such as sensors, making validation of actual product use difficult. The human body will subject CGMs to perspiration and other bodily fluids, vibration, shock, and the potential for drops.

Additionally, regular use presents threats in varied environments as users always wear the products in various settings. CGM devices are more valued by people with diabetes when they enable ease of use. Using continuous glucose monitoring systems in showers, harsh weather conditions, swimming pools, and humid conditions is often a purchase contingency.

Therefore, the ability to operate reliably through frequent exposure to chemicals and corrosives, including airborne pollution, cleaning fluids, soap, and hygienic products, is a critical feature that, if underestimated, can increase product recalls, repairs, and warranty claims.

CGM technology has exponentially evolved, but it is up to product design teams to evaluate if they are genuinely validating actual product use. If you are a CGM product designer and feel your products are experiencing reliability issues, coating systems, particularly Parylene conformal coatings, may be worth investigating.

Watch our webinar “Design for Reliability.”


Corrosion Resistance is a Mandate for CGM Reliability


CGMs, like all electronic devices, run on electricity and batteries. Without proper protection, one drop in the water can kick off the corrosion process, catalyzing unexpected, premature failure. Parylene’s superior corrosion resistance is one compelling reason to use this CGM coating.

Performing as a barrier to corrosion caused by moisture, biofluids, submersion, and cleaning fluids, Parylene minimizes the impact of factors that affect coating performance and lifetime, including the following:

● Low oxygen permeability for a protective polymer coating
● Minimal absorption of water
● Ionic permeability makes it difficult for salts to pass through the coating
● Parylene’s characteristic pinhole-free coatings

Gas permeability and Water Vapor Transmission rate indicate barrier effectiveness for corrosion resistance; the lower, the better. The chart below illustrates these properties compared to other conformal coatings.

Download HZO’s Parylene datasheet


Polymer Gas Permeability at 25 °C, (cc·mm)/(m2·day·atm) WVTR,(g·mm)/(m2·day)
N2 O2 CO2 H2 H2S SO2 CI2
Parylene C 0.4 2.8 3.0 43.3 5.1 4.3 0.1 0.08
Parylene N 3.0 15.4 84.3 212.6 313 745 29.2 0.59
Parylene F (VT-4) 16.7 0.28
Epoxy (ER) 1.6 4 3.1 43.3 0.94
Polyurethane (UR) 31.5 78.7 1,181 0.93
Silicone (SR) 19,685 118,110 17,710
Ref.: Licari, James J. Coating Materials for Electronic Applications – Polymers, Processes, Reliability, Testing. William Andrew Publishing, 2003 and various companies’ literature.


Watch our webinar on proven methods of corrosion resistance.

Submersion Protection Enables You to Meet any Liquid Ingress Protection Standards


As CGM consumers often base purchase decisions on the ability to meet IP ratings, it might be necessary for your team to meet a particular IP standard. HZO Parylene coatings have been tested for over 1,000 hours of submersion, providing a proven method to meet any IP protection level quickly and conveniently.

Download the HZO IP checklist


Environmentally Friendly Solution with Green Manufacturing Support

Sustainability policies and regulations can have far-reaching effects on your decisions, ranging from material selection through the manufacturing process. The Parylene polymerization process simplifies sustainability, as there are none of the following complications that can inhibit compliance:

  •  No VOCs
  •  No Solvents
  •  No Catalysts
  •  No Disposal
  •  No Pollution Threats

HZO’s Parylene coatings are:

  • RoHS Compliant
  • REACH Compliant
  • Prop 65 Compliant

As a green manufacturer, HZO’s support includes the following:

  • Material oversight
  • Corporate social responsibility
  • Green material usage
  • Preparation for repair, reuse, and recycling
  • Proactive chemical management
  • Responsible end-of-life management


Simplify Design With Parylene's Thinness

HZO Parylene passed IPC CC-830C at 50% thinness of conventional conformal coatings, proving no other coating can perform as well in terms of chemical, moisture, and biofluid barrier properties at its thinness.

Parylene can also provide dielectric barrier protection without signal transfer or loss. Furthermore, its low dielectric constant ensures minimal energy loss in RF signals, and the coating thinness ensures signal transmission integrity. The chart below illustrates suitable Parylene thickness for various applications:


Thickness(μm) Relevant Standards IP Protection Level
0.1 to 5 UT Type in IPC-CC-830C IPX3/IPX4
5 to 12.5 UT Type in IPC-CC-830C IPX4/IPX7
12.5 to 25 IPC-CC-830B IPX7/IPX8


Choose HZO for CGM Coatings

With CGM experience, our engineering team knows how to create business-specific solutions that ensure your product will work in the real world. HZO has eliminated many barriers to Parylene on the manufacturing end by developing cost-cutting equipment that can quickly scale as your business grows. If you want to meet with our applications engineering team for a DFM consultation, reach out today.


Additional Resources

Ensure Your Products Meet Market Claims With Our IP Ratings Checklist

Ensure Your Products Meet Market Claims With Our IP Ratings Checklist

Improve Diabetes Device Designs With Medical Coatings

Improve Diabetes Device Designs With Medical Coatings

How to Develop Medical Devices That Are Consumer-Friendly

How to Develop Medical Devices That Are Consumer-Friendly

Learn How to Enhance the Reliability of Your Medical Device Product Design

Learn How to Enhance the Reliability of Your Medical Device Product Design

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