Stretchable Encapsulation Materials with High Dynamic Water Resistivity and Tissue-Matching Elasticity

Abstract

Flexible implantable medical devices (IMDs) are an emerging technology that may substantially improve the disease treatment efficacy and quality of life of patients. While many advancements have been achieved in IMDs, the constantly straining application conditions impose extra requirements for the packaging material, which needs to retain both high stretchability and high water resistivity under dynamic strains in a physiological environment. This work reports a polyisobutylene (PIB) blendbased elastomer that simultaneously offers a tissue-like elastic modulus and excellent water resistivity under dynamic strains. The PIB blend is a homogeneous mixture of two types of PIB molecules with distinct molecular weights. The blend achieved an optimal Young's modulus of 62 kPa, matching those of soft biological tissues. The PIB blend film also exhibited an extremely low water permittivity of 1.6−2.9 g m −2 day −1 , from unstrained to 50% strain states. The combination of high flexibility and dynamic water resistivity was tested using triboelectric nanogenerators (TENGs). The PIB blendpackaged TENG was able to stably operate in water for 2 weeks, substantially surpassing the protection offered by Ecoflex. This work offered a promising material solution for packaging flexible IMDs to achieve stable performance in a strained physiological environment.

Continuously Quantifying Oral Chemicals Based on Flexible Hybrid Electronics for Clinical Diagnosis and Pathogenetic Study

“…However, behaviors such as chewing and grinding when eating solid food may wear down the encapsulation layer of the system, leading to acid corrosion, electrical shorts, and even battery leakage. Better biocompatibility may be achieved by introducing adaptively deformable encapsulations, such as cellular microstructures [ 42 ], microfluidic suspensions [ 43 ], and tissue-like materials [ 44 , 45 ] to minimize package degradation. Thereafter, the mean values of the corresponding parameters during sleep and wakefulness were calculated ( Figure 5(d) ).…”

Reliability of printed stretchable electronics based on nano/micro materials for practical applications

“…181 As a result, less free space is available for small molecules to transfer through the film. Butyl rubbers have been applied to protect stretchable organic electronic materials, 182,183 triboelectric nanogenerators, 184 alternating current electroluminescence devices 185 and iongels. 186 However, few of the aforementioned strategies have been applied to printed stretchable electronics.…”

Materials and Biomedical Applications of Implantable Electronic Devices

“…Reproduced with permission. [ 179 ] Copyright 2022, ACS. f) The image of Ti6Al4V based encapsulation with optical window (top) and SEM image of titanium–glass interface (bottom).…”

“…Shao et al reported a polyisobutylene blend-based elastomer with high stretchability and high water resistivity, which could potentially be used for packing materials of implantable electrodes (Figure 5e). [179] However, the permeability of many elastomers is higher in comparison with metal and/or non-stretchable polymers, and the issue could be solved by increasing the thickness of the elastomer layer. [180] Natural materials, such as collagen, are conventional materials as the membrane for the implantable electrode.…”

“…e) Illustrations of the polyisobutylene (PIB) blendbased elastomer encapsulated triboelectric nanogenerators. Reproduced with permission [179]. Copyright 2022, ACS.…”