---
title: "Parylene C Biocompatibility: Properties, Safety, and Medical Use Cases"
description: Parylene C is biocompatible, meeting USP Class VI and ISO 10993 standards. See how it compares to silicone, Teflon, and other medical coating materials.
---

[Thin Film Coating Blog ](https://hzo.com/blog)

# [Parylene C Biocompatibility: Properties, Safety, and Medical Use Cases](https://hzo.com/blog/parylene-c-biocompatibility-properties)

 Written by [Mallory McGuinness-Hickey](https://hzo.com/blog/author/mallory-mcguinness-hickey) | September 24, 2024

## Overview & Key Takeaways

Parylene C is biocompatible and meets USP Class VI and ISO 10993 standards — the two primary benchmarks for medical device materials. It is the most widely deployed variant in the Parylene family for medical and implantable device applications. Its chlorinated para-xylylene structure delivers superior moisture barrier performance and chemical resistance while maintaining full biocompatibility with human tissue and fluids. Engineers evaluating Parylene C should weigh its exceptional protective properties against its mechanical limitations relative to bulk structural materials.

- **USP Class VI and ISO 10993 compliance:** Parylene C meets the two primary biocompatibility standards for medical devices, including passing cytotoxicity, sensitization, genotoxicity, and implantation tests. Independent third-party testing confirms it causes no measurable harm to tissues or body fluids.
- **Chemical inertness:** Parylene C does not leach plasticizers, solvents, or catalysts into surrounding tissue. Deposited as a pure polymer with no additives, it resists bodily fluids, enzymes, and varying pH levels without degradation over time.
- **PFAS-free formulation:** Unlike Teflon (PTFE), Parylene C contains no per- or polyfluoroalkyl substances and is both REACH and RoHS compliant — a meaningful differentiator for manufacturers navigating tightening PFAS regulations.
- **Pinhole-free conformal barrier:** Chemical vapor deposition produces a continuous, void-free coating at thicknesses as low as 1 micron, conforming to complex geometries and fine features while fully isolating device surfaces from biological environments.
- **High dielectric strength:** Parylene C achieves up to 7,000 V/mil, providing reliable electrical insulation for implantable electronics, sensors, and active devices operating in the body.
- **Tradeoff vs. structural materials:** Parylene C is not suitable as a load-bearing or structural material — its tensile and yield strength are lower than metals and ceramics. Applications requiring mechanical strength must pair Parylene with a rigid substrate. CVD application also requires specialized equipment and process integration not needed for simpler liquid coating methods.

**Parylene C is widely considered one of the most [biocompatible](https://hzo.com/blog/biocompatible-coatings) conformal coatings used in medical devices.** It forms a chemically inert, pinhole-free barrier that protects both the device and the human body from harmful interactions.

Because of its stability, low permeability, and proven safety profile, Parylene C is commonly used in implants, surgical tools, and wearable medical electronics.

 

## What Does "Biocompatibility" Mean for Parylene C?

Biocompatibility refers to a material's ability to perform safely in contact with the human body without causing adverse reactions such as toxicity, inflammation, or immune response.

Parylene C achieves this by acting as a **non-reactive, [protective barrier](https://hzo.com/blog/waterresistant-waterrepellent-waterproof-whats-difference)** between device materials and biological environments. It prevents leaching, corrosion, and chemical interaction — key risks in medical applications.

 

## What Biocompatibility Standards Does Parylene C Meet?

Parylene C satisfies both primary biocompatibility standards used by medical device manufacturers and regulatory bodies:

- **USP Class VI** — the highest classification in the U.S. Pharmacopeia's plastics testing protocol, requiring [passing results](https://www.nes-ips.com/usp-class-vi-testing-what-is-it/) for systemic injection, intracutaneous injection, and implantation tests
- [**ISO 10993**](https://en.wikipedia.org/wiki/ISO_10993) — the international standard series for biological evaluation of medical devices, covering cytotoxicity, sensitization, and genotoxicity, among others

Independent testing confirms Parylene C passes both standards. Its chemical inertness — meaning it does not react with bodily fluids, enzymes, or varying pH environments — is the primary reason for its compliance.

 

## Why Is Parylene C Considered Biocompatible?

- **Chemically inert:** Does not react with bodily fluids or tissues
- **Pinhole-free coating:** Provides complete, uniform coverage with no gaps or voids
- **Low permeability:** Blocks moisture, gases, and contaminants
- **Non-toxic barrier:** Prevents harmful substances from leaching into the body
- **PFAS-free:** Contains no per- or polyfluoroalkyl substances — REACH and RoHS compliant

Parylene C's ability to create a continuous, defect-free film is critical. Unlike liquid coatings, it forms a uniform layer even on complex geometries, reducing exposure risks.

[Download datasheet](https://hzo.com/resources/downloads/guardian-plus-datasheet)

## Key Properties That Enable Biocompatibility

### 1. Exceptional Barrier Protection

Parylene C has [extremely low permeability](https://hzo.com/coatings/parylene-coating/properties/) to moisture and gases, which helps prevent corrosion and contamination in harsh biological environments.

### 2. Chemical Resistance

It [resists a wide range of chemicals](https://hzo.com/blog/parylene-chemical-resistance-properties-overview), ensuring long-term stability when exposed to bodily fluids, enzymes, and varying pH levels.

### 3. Electrical Insulation

Parylene C has a dielectric strength of up to 7,000 V/mil, making it ideal for implantable electronics and sensors that must function reliably in the body.

### 4. Conformal Coverage

The [chemical vapor deposition](https://hzo.com/coatings/parylene-coating/process) (CVD) process allows Parylene to coat intricate surfaces evenly at [thicknesses](https://hzo.com/blog/parylene-coating-thickness-how-much-is-enough) as low as 1 micron, eliminating gaps that could compromise safety or device performance.

 

## How Does Parylene C Compare to Other Medical Coating Materials?

| Property | Parylene C | Silicone | Epoxy | Teflon (PTFE) |
| --- | --- | --- | --- | --- |
| Biocompatibility Standard | USP Class VI, ISO 10993 | ISO 10993 | Moderate | ISO 10993 |
| Moisture Barrier | Excellent | Moderate | Good | Good |
| Conformality | Complete coverage | Limited | Limited | No |
| Thickness Control | Precise (micron-level) | Variable | Variable | 12–25 µm |
| PFAS-Free | Yes | Yes | Yes | No |
| Dielectric Strength | Up to 7,000 V/mil | ~500 V/mil | ~400 V/mil | ~2,000 V/mil |

 

This combination of properties is why [Parylene C is often selected](https://hzo.com/blog/what-is-parylene-used-for-is-it-right-for-my-project) for **critical medical and implantable applications** — particularly where Teflon alternatives are needed due to tightening PFAS regulations.

 

## Common Medical Applications of Parylene C

- **Implantable devices** (pacemakers, stents, cochlear implants)
- **Cardiac assist devices** — [reduces thrombogenicity](https://pmc.ncbi.nlm.nih.gov/articles/PMC10318457/) without altering device geometry
- **Needles and cannulas** — reduces friction for easier insertion and improved patient comfort
- **Wearable medical electronics**
- **Surgical tools and instruments**
- **Microelectromechanical systems (MEMS)**
- **Drug delivery devices**

The global Parylene market was valued at [$98.38 million in 2023 and is projected to grow to $118.52 million by 2030](https://www.verifiedmarketresearch.com/product/parylene-market/), driven in large part by expanded medical device applications.

 

## Does Parylene C Improve Device Safety?

Yes. Parylene C enhances safety in two critical ways:

- **Protects the body:** Prevents exposure to device materials and potential toxins by creating a chemically inert barrier between the substrate and surrounding tissue
- **Protects the device:** Shields electronics from moisture, corrosion, and biological degradation — extending functional lifespan in demanding in-vivo environments

 

## What Are the Limitations of Parylene C in Medical Applications?

While Parylene C is highly biocompatible, it is not universally ideal for every application:

- **Mechanical load-bearing:** Parylene's tensile strength is lower than metals and ceramics — it is not appropriate for structural applications without a rigid substrate
- **Adhesion on certain substrates:** Some materials require surface preparation or adhesion promoters before coating
- **Application process complexity:** CVD requires specialized equipment and [batch processing](https://hzo.com/blog/parylene-masking-general-concepts-explained), unlike simpler dip or spray coating methods

These challenges are [typically addressed](https://hzo.com/blog/how-do-you-remove-parylene-coating) through proper engineering and process optimization — and in most cases, Parylene's performance advantages justify the added process complexity.

 

## FAQ: Parylene C Biocompatibility

### Is Parylene C safe for implantable medical devices?

Yes. Parylene C meets USP Class VI and ISO 10993 biocompatibility standards — the primary requirements for implantable and body-contact medical devices. It is non-toxic, physiologically non-reactive, and has a decades-long track record in implantable applications, including pacemakers, stents, and cochlear implants.

 

### Is Parylene FDA approved?

Parylene itself is not an FDA-approved material — the FDA approves devices, not coating materials in isolation. However, Parylene C is widely used in devices that have received FDA clearance or approval, and its USP Class VI and ISO 10993 compliance makes it well-suited for inclusion in FDA submissions.

 

### Does Parylene C prevent corrosion?

Yes. Its low permeability, pinhole-free structure, and chemical inertness make Parylene C highly effective at preventing corrosion caused by moisture, bodily fluids, and enzymatic activity.

 

### Is Parylene PFAS-free?

Yes. Parylene C contains no per- or polyfluoroalkyl substances (PFAS) and is both REACH and RoHS compliant — unlike Teflon (PTFE), which is classified as a PFAS material. This makes Parylene a strong alternative for manufacturers navigating tightening PFAS regulations.

 

### How does Parylene compare to silicone coatings?

Parylene offers better moisture resistance, more precise thickness control, and more uniform coverage — especially on complex geometries. Silicone coatings are applied at significantly greater thickness and cannot achieve the pinhole-free conformality Parylene delivers via CVD.

 

### How is Parylene applied to medical devices?

Parylene is deposited via chemical vapor deposition (CVD) — a room-temperature process that conformally coats all exposed surfaces regardless of geometry. The process leaves no liquid residue and requires no curing step.

[Read about how to incorporate Parylene into your process](https://hzo.com/resources/downloads/incorporate-cvd)

 

## Learn More About Parylene Coatings

If you're evaluating Parylene for medical or high-reliability applications, understanding its advantages and limitations is critical.

Explore more about [Parylene coating properties](https://hzo.com/coatings/parylene-coating/properties/) or learn how it compares to other materials in our [Parylene vs. liquid coatings guide](https://hzo.com/blog/parylene-vs-liquid-coatings).

[Learn more in our webinar, Parylene: Pros, Cons, and Practicalities](https://hzo.com/resources/webinars/parylene-pros-cons)

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