Barrier properties of polymer encapsulation materials for implantable microsystems

Abstract

Biocompatible polymers utilized for flexible encapsulations of implantable microsystems provide many advantages compared to widely used rigid titanium or ceramic packages. However, polymers alter their properties due to interactions with their environment. As a result the protective function of these materials especially for long-term implants is not reliable. Therefore, we investigated barrier properties against water vapor of silicone and Parylene C membranes. And we combined these polymers to a multi-layer membrane to enhance the protective function of such an encapsulation system. Applying a bonding agent between two polymer layers increases the strength of the sample as well as the barrier properties significantly.

Atomic-Layer-Deposited SiOx/SnOx Nanolaminate Structure for Moisture and Hydrogen Gas Diffusion Barriers

“…Figure 3d shows the measured XRR results of the t-SnO x and p-SnO x that were 10 nm thick. The analyzed density at 10 nm thickness for p-SnO x (6.55 g/cm 3 ), which was close to the density of bulk SnO 2 (6.93 g/cm 3 ), showed a denser structure than t-SnO x (4.93 g/cm 3 ). The XRR result of the 10 nm p-SiO x is shown in Figure S2c, and the density value of p-SiO x was 2.24 g/cm 3 , which shows a lower value than t-SnO x and p-SnO x , which is a similar trend to the WVTR result (Figure 4).…”

“…The analyzed density at 10 nm thickness for p-SnO x (6.55 g/cm 3 ), which was close to the density of bulk SnO 2 (6.93 g/cm 3 ), showed a denser structure than t-SnO x (4.93 g/cm 3 ). The XRR result of the 10 nm p-SiO x is shown in Figure S2c, and the density value of p-SiO x was 2.24 g/cm 3 , which shows a lower value than t-SnO x and p-SnO x , which is a similar trend to the WVTR result (Figure 4). We calculated the porosity, which may be closely related to the barrier property of the film, using the experimentally obtained refractive index and density values.…”

“…Here, ρ f , ρ b , and p are the density of the film material, density of the bulk material without voids (6.93 g/cm 3 for SnO 2 bulk), and porosity, respectively. The calculated p values are 28.9 and 5.5% for t-SnO x and p-SnO x , respectively.…”

Non‐hermetic packaging of biomedical microsystems from a materials perspective: A review

“…Hermetic packages are conventionally made from glass, metal or ceramic materials whereby the gas and moisture permeability through the material is negligible (Madduri et al, 2008; Schuettler, Schatz, Ordonez, & Stieglitz, 2011). Hermetic materials have been successfully used to package devices for chronic applications, some of the most notable being cochlear implants and cardiac pacemakers (Kirsten, Wetterling, Uhlemann, Wolter, & Zigler, 2013). Titanium is the most commonly used metal for hermetic encapsulation because of its biocompatibility, low permeability for ions and moisture, mechanical durability and the ability to create viable hermetic seals by laser welding (Amanat, James, & McKenzie, 2010).…”

Implantable biomedical sensor array with biocompatible hermetic encapsulation

“…An inert barrier layer of parylene C was deposited onto the whole device surface except the ceramic membrane out of the vapor phase (First Sensor Microelectronic Packaging GmbH Dresden, Parylene Coating System 2000-150 LV) (Kirsten et al, 2013). All areas of the surface are uniformly coated by the gaseous parylene C.…”