Stretchable Electronics Based on Laser Structured, Vapor Phase Polymerized PEDOT/Tosylate

Bioelectronics for electrical stimulation: materials, devices and biomedical applications

Bioelectronics is a hot research topic, yet an important tool, as it facilitates the creation of advanced medical devices that interact with biological systems to effectively diagnose, monitor and treat a broad spectrum of health conditions. Electrical stimulation (ES) is a pivotal technique in bioelectronics, offering a precise, non-pharmacological means to modulate and control biological processes across molecular, cellular, tissue, and organ levels. This method holds the potential to restore or enhance physiological functions compromised by diseases or injuries by integrating sophisticated electrical signals, device interfaces, and designs tailored to specific biological mechanisms. This review explains the mechanisms by which ES influences cellular behaviors, introduces the essential stimulation principles, discusses the performance requirements for optimal ES systems, and highlights the representative applications. From this review, we can realize the potential of ES based bioelectronics in therapy, regenerative medicine and rehabilitation engineering technologies, ranging from tissue engineering to neurological technologies, and the modulation of cardiovascular and cognitive functions. This review underscores the versatility of ES in various biomedical contexts and emphasizes the need to adapt to complex biological and clinical landscapes it addresses.

Nanoscale Nickel-Based Thin Films as Highly Conductive Electrodes for Dielectric Elastomer Applications with Extremely High Stretchability up to 200

This paper presents on electromechanical characterization of thin film nickel-based wrinkled electrodes for dielectric elastomer (DE) applications. The investigation of a sandwich composed of a very soft and flexible elastomer carrying an ultrathin metallic electrode, together with its prestretch-dependent wrinkled structure of the electrode, facilitates the understanding of some of its interesting properties. Compared to conventional screen-printed carbon black electrodes, nickel-based thin film electrodes offer an ohmic resistance that is about 2 orders of magnitude lower. This remarkable feature makes it an advantageous electrode material alternative for the development of energy-efficient and high-frequency DE applications. Ultrathin (10-20 nm) layers are sputter deposited as electrodes onto either biaxially or, under pure-shear conditions, uniaxially prestretched silicone membranes. After the sputtering process, the membranes are allowed to relax whereby wrinkled out-of-plane buckled surfaces are obtained. With an initial resistance smaller than 400 Ω/square and a strong adhesion to the silicone, some electrode configurations are able to withstand strains up to 200% while remaining electrically conductive. A linear dependence of the capacitance on strain is revealed, as well as a long-term stability over 10 million cycles of mechanical stretching. All investigated thin film configurations of nickel and nickel-carbon films are suitable as compliant electrodes for DE actuators, as demonstrated by measuring the force characteristics with and without a high voltage. An increased level of prestretch shifts the resistance threshold of the electrode layers to even higher strain levels. In general, the best performance is achieved with pure metallic electrodes deposited on biaxially prestretched silicone membranes.

Stretchable, Fully Polymeric Electrode Arrays for Peripheral Nerve Stimulation

There is a critical need to transition research level flexible polymer bioelectronics toward the clinic by demonstrating both reliability in fabrication and stable device performance. Conductive elastomers (CEs) are composites of conductive polymers in elastomeric matrices that provide both flexibility and enhanced electrochemical properties compared to conventional metallic electrodes. This work focuses on the development of nerve cuff devices and the assessment of the device functionality at each development stage, from CE material to fully polymeric electrode arrays. Two device types are fabricated by laser machining of a thick and thin CE sheet variant on an insulative polydimethylsiloxane substrate and lamination into tubing to produce pre-curled cuffs. Device performance and stability following sterilization and mechanical loading are compared to a state-of-the-art stretchable metallic nerve cuff. The CE cuffs are found to be electrically and mechanically stable with improved charge transfer properties compared to the commercial cuff. All devices are applied to an ex vivo whole sciatic nerve and shown to be functional, with the CE cuffs demonstrating superior charge transfer and electrochemical safety in the biological environment.