Recent Advances in Encapsulation of Flexible Bioelectronic Implants: Materials, Technologies, and Characterization Methods

Abstract

Bioelectronic implantable systems (BIS) targeting biomedical and clinical research should combine long‐term performance and biointegration in vivo. Here, recent advances in novel encapsulations to protect flexible versions of such systems from the surrounding biological environment are reviewed, focusing on material strategies and synthesis techniques. Considerable effort is put on thin‐film encapsulation (TFE), and specifically organic–inorganic multilayer architectures as a flexible and conformal alternative to conventional rigid cans. TFE is in direct contact with the biological medium and thus must exhibit not only biocompatibility, inertness, and hermeticity but also mechanical robustness, conformability, and compatibility with the manufacturing of microfabricated devices. Quantitative characterization methods of the barrier and mechanical performance of the TFE are reviewed with a particular emphasis on water‐vapor transmission rate through electrical, optical, or electrochemical principles. The integrability and functionalization of TFE into functional bioelectronic interfaces are also discussed. TFE represents a must‐have component for the next‐generation bioelectronic implants with diagnostic or therapeutic functions in human healthcare and precision medicine.

Liquid metal-based soft, hermetic, and wireless-communicable seals for stretchable systems

“…With the low gas permeability and soft mechanical properties, EGaIn opens possible design space to achieve stretchable and hermetic seals, which will help enable the practical long-term applications of stretchable and soft systems that are sensitive to the permeation of various gases, including flexible electronics systems, wearable systems, energy generation and storage systems, heat transfer systems, sensing systems, and biomedical systems (18)(19)(20)(21)(22)(23)(24)(25). In this work, we demonstrated the design and fabrication of LM-based seals with the integration of spacers for stretchable batteries-specifically, lithium-ion batteries (LIBs) with a water-based electrolyte.…”

Materials and Biomedical Applications of Implantable Electronic Devices

“…[161] The encapsulation are important components for the packaging of implantable electronics, by isolating these electronics from hash in vivo environments containing different biofluids, water-based ionic solutions, and strict geometrical and size constraints. [162] The hermeticity is the most essential property for evaluating these packages to the reliability and longevity of implantable electronics. When the O 2 and water solutions diffuse through packages, these electronics would be delaminated, dissolved, hydrolyzed, blistered, or eroded, greatly affecting the [144] Copyright 2015, Elsevier Advanced Technology.…”

Assessment of AF4 Parylene Cohesion/Adhesion on Si and SiO2 Substrates by Means of Pull-Off Energy

“…Poly(p-xylylene) or parylene is a thermoplastic polymer with a semicrystalline structure, which was introduced in the 1960s [1]. It has found applicability in different industries through the years, such as in the automotive, medical and electronics industries [2][3][4][5],…”