Parylene Conformal Coating for Medical Use
Posted by Sean Horn
Friday, March 20, 2015 9:29
@ 9:29 AM
Parylene conformal coatings have protected medical device components with an extended range of applications for over 40 years. They offer both patients and medical personnel the most reliable level of uniform, biocompatible device-security for cardio- logical and surgical procedures. Their value and application proliferate, as technology develops.
Organic Polymers used as Coatings
The overall generic name parylene designates a unique set of organic polymeric coating materials with innumerable applications. All commercially applied parylene configurations are polycrystalline and linear in nature.
In general, parylene materials possess properties similar to polytetrafluoroethylene (PTFE), better known as Teflon. However, they long ago have proven themselves superior to Teflon for most medical purposes and for other industrial/product uses. The carbon-fluorine molecule model typical of Teflon does not apply for the basic parylene format. It is replaced by carbon-hydrogen for parylene C; parylene N replaces selective hydrogen atoms with chlorine.
The resulting substances are simultaneously linear and polycrystalline. Clear and colorless, parylene possesses no pigment or similar properties that might:
- Irritate or infect internal tissues or organs
- Leak into the human system during application and interfere with medical instruments’ measurements or readings.
The fact that parylene is chemically inert further adds to their safe use as coatings for medical equipment, and for the same reasons, minimal potential for infection or causing altered data readings.
The exceptional biocompatibility of parylene coincides well with the development of implementation of contemporary, minimally-invasive implant-technologies and surgical procedures. Parylene’s barrier properties provide unmatched moisture and chemical protection, while generating peerless surface lubricity. Its dielectric capacities insulate the medical device while within the body, simultaneously transmitting electric current without conducting it.
Parylene has no negative impact on bodily functions, and generally are used with medical devices that enhance organ/tissue performance, as well as ensuring the device’s own acceptance within the body during use. This beneficial quality has been demonstrated by their generally outstanding hemo-compatibility and minimal fibrous capsule formation when utilized; nonexistent toxicological responses have been recorded in virtually all cases of use.
With these characteristics, parylene conformal coatings are adaptable for many product uses, and possess superb qualities for medical device applications.
Medical Product Applications of Parylene
Biocompatible, parylene conformal coatings protect medical devices from chemicals, fluids, and stray electrical charges. Parylene ensures
- Patients are not infected by a device implanted within the body for medical purposes, while
- Protection from contamination by bodily fluids and functions, so the device continues to work as expected.
Parylene has provided this functional-security for more than 40 years.
Parylene’s physical properties play an important role in its medical uses. Applied through a vapor deposition process, the substance retains compositional stability and performance consistencies in the presence of bodily fluids and tissues. While many other substances can generate similar characteristics, parylene is unique in providing the thinnest effective coating application available.
Thus, instruments coated with parylene can be safely situated in less accessible, more-constricted regions of the body than those otherwise coated. The ultra-thin film adds minimal mass to delicate medical components, while retaining the highest levels of protection during use. Low dissipation factors mean extended product durability and longer-lasting functionality; the result is not only enhanced treatment-performance, but safer use for more functions in critical, difficult-to-reach regions of the body.
Parylene coated devices also are suitable for medical application because they withstand most common sterilization methods. Their pin-hole free coatings prevent leakage. These factors, which combine security with durable biocompatible service, generate additional protection from chemical contamination and moisture during internal use.
Superior Medical Product Service
Parylene coatings are noted for their exceptional crevice/multi-layer penetration of surfaces to be protected. Therefore, surface pinholes that lead to leakage are eliminated because parylene conforms precisely to substrate contours.
While protecting devices’ exteriors, parylene also generates excellent dry-film lubricity, which limits the surface modification emerging whenever a medical device has to react bio-actively, as during minimally invasive surgery. Higher levels of surface lubrication produce enhanced device performance and medical care, as well as reducing patient discomfort.
Recommended Parylene Products
Parylene coatings have long provided surface protection for such traditional medical devices as hypodermic needles and syringes, catheters, cannulae, medical bottles, and hearing aids. As time went on, they were effectively applied to coronary stents, and medical probes, electrodes, and circuits/printed circuit boards (PCBs) for medical devices; parylene coatings are used for pacemakers. Orthopedic devices of all kinds also benefit from parylene protection.
Electrosurgical devices (ESU) and pneumatically-powered surgical instruments feature parylene protective surfaces. This is especially true for those using wireless or radio-free (RF) memory communication. Neurosurgery, spinal, ocular and cardiac surgeries increasingly rely on ESU processes. The dielectric properties of parylene are the key enabling technology for ESU implementation.
Equally to the point, parylene applications for microelectromechanical systems’ (MEMS) implantables are expected to grow significantly for a wide range of devices. These include non-coiled guide wires, pacemakers, defibrillators, heart-lung bypass pumps, or intra-aortic balloon pumps. Sensors for diagnostic monitoring of patients’ conditions represent just one product area that will require persistent technological development of parylene coating.
ISO biological evaluations of parylene coated medical devices have found them imminently safe for use in all the cases above. These applications provide only a few examples of a growing list of efficient parylene-based or assisted medical applications.
Parylene’s Unlimited Future
The evidence shows that parylene product applications are already applied to a wide range of cardiological, orthopedic and surgical devices, enhancing their ability to provide treatment and cure. As medical technology develops, appropriate isolation of medical instruments from contact with bodily moisture or gases, corrosive bio-fluids, and chemicals is becoming increasingly important. The application of implanted devices is certain to become more commonplace in the years to come; parylene coatings conform precisely to instruments shape and size, shielding patients from contamination and securing the devices’ functional capabilities throughout the course of the implant.
The mentioned medical uses of parylene coated instruments represent only a fraction of their future potential. In their current format, devices coated with parylene improve treatment options for both the medical community and patients, as well patients” overall options for recovery and comfort during the care process. Leading-edge technological development currently underway should stimulate a wider, more effective range of treatment instruments, devices that reflect the ongoing alliance and convergence of parylene adaptability. Parylene generates the lowest level of negative and potentially infectious surface-to-tissue interaction of any conformal coatings currently available for medical use.