While water vapor transmission rate (WVTR) measurement is standardly used to assess material permeability, a system able to quantify liquid water transmission rate (WTR) measurement is highly desirable for implantable thin film barrier coatings. Indeed, since implantable devices are in contact or immersed in body fluids, liquid WTR was carried out to obtain a more realistic measurement of the barrier performance. Parylene is a well-established polymer which is often the material of choice for biomedical encapsulation applications due to its flexibility, biocompatibility, and attractive barrier properties. Four grades of parylene coatings were tested with a newly developed permeation measurement system based on a quadrupole mass spectrometer (QMS) detection method. Successful measurements of gas and water vapor and the water transmission rates of thin parylene films were performed and validated, comparing the results with a standardized method. In addition, the WTR results allowed for the extraction of an acceleration transmission rate factor from the vapor-to-liquid water measurement mode, which varies from 4 to 4.8 between WVTR and WTR. With a WTR of 72.5 µm g m⁻² day⁻¹, parylene C displayed the most effective barrier performance.

Recent developments in urological implants have focused on preventive strategies to mitigate encrustation and biofilm formation. Parylene, a conformal, pinhole-free polymer coating, has gained attention due to its high biocompatibility and chemical resistance, excellent barrier properties, and low friction coefficient. This study aims to evaluate the effectiveness of parylene C in comparison to a parylene VT4 grade coating in preventing encrustation on a urinary bladder pressure MEMS sensor system. Additionally, silicon oxide (SiO_x) applied as a finish coating was investigated for further improvements. An in vitro encrustation system mimicking natural urine flow was used to quantify the formation of urinary stones. These stones were subsequently analyzed using Fourier transform infrared spectrometry (FTIR). Encrustation results were then discussed in relation to coating surface chemical properties. Parylene C and VT4 grades demonstrated a very low encrustation mass, making them attractive options for encrustation prevention. The best performance was achieved after the addition of a hydrophilic SiO_x finish coating on parylene VT4 grade. Parylene-based encapsulation proved to be an outstanding solution to prevent encrustation for urological implants.

Purpose: This paper aims to categorize the mechanical properties of eight percutaneous transluminal coronary angioplasty (PTCA) balloon catheters and translate them into clinical needs. Method: Objective bench tests quantified PTCA balloon catheters' mechanical properties, including tensile strength, kink resistance, bending, torsional behavior, friction, radio-opacity, pushability, and trackability. The results were compared against each other and supplemented by a survey of interventional cardiologists. Results: Clinical needs with respect to deliverability, dilatation efficiency, and crossability were assessed for each catheter. Results indicate that SC Maverick2 excels in deliverability and crossability but lags in dilatation efficiency compared to NC catheters, though it is rated best to fulfill clinical needs. SC EasyT outperforms Maverick2 in dilatation efficiency but has inferior deliverability, similar to NC catheters. The NC balloons were comparable. However, Accuforce exhibits highest deliverability, Pantera LEO shows superior dilatation efficiency, NC Emerge shows best crossability, and Sapphire NC24 exhibits lowest performance. According to the survey, Accuforce, Sapphire NC24, and NC Trek are favored over NC Emerge and Pantera LEO. OPN NC offers limited deliverability but can treat lesions where standard NC catheters fail due to its unique rated burst pressure. Trackability and pushability estimates align better with survey results than those obtained from simulated use-case tests, except for Sapphire NC24 and OPN NC. Torquability measurements show discrepancies with survey ratings, indicating additional influences and rating challenges. Conclusion: Our study comprehensively analyzes PTCA balloon catheters, emphasizing the importance of integrating mechanical and design attributes throughout development. Performance properties like trackability and pushability were measured, providing unbiased insights for comparison independent of individual practitioner preferences.