ABSTRACT
Electrochemiluminescence (ECL) holds significant promise for the development of cost-effective light-emitting devices because of its simple structure. However, conventional ECL devices (ECLDs) have a major limitation of short operational lifetimes, rendering them impractical for real-world applications. Typically, the luminescence of these devices lasts no longer than a few minutes during operation. In the current study, a novel architecture is provided for ECLDs that addresses this luminescence lifespan issue. The device architecture features an ECL active layer between two coplanar driving electrodes and a third floating bipolar electrode. The inclusion of the floating bipolar electrode enables modulating the electrical-field distribution within the active layer when a bias is applied between the driving electrodes. This, in turn, enables the use of opaque yet electrochemically stable noble metals as the driving electrodes while allowing ECL light to escape through the transparent floating bipolar electrode. A significant extension on operational lifetime is achieved, defined as the time required for the initial luminance (>100 cd m-2) to decrease by 50%, surpassing 1 h. This starkly contrasts the short lifetime (<1 min) attained by ECLDs in a conventional sandwich-type architecture with two transparent electrodes. These results provide simple strategies for developing durable ECL-based light-emitting devices.
ABSTRACT
Neural interfaces play a major role in modulating neural signals for therapeutic purposes. To meet the demand of conformable neural interfaces for developing bioelectronic medicine, recent studies have focused on the performance of electrical neurostimulators employing soft conductors such as conducting polymers and electronic or ionic conductive hydrogels. However, faradaic charge injection at the interface of the electrode and nerve tissue causes irreversible gas evolution, oxidation of electrodes, and reduction of biological ions, thus causing undesired tissue damage and electrode degradation. Here we report a conformable neural interface engineering based on multicross-linked membrane-ionogel assembly (termed McMiA), which enables nonfaradaic neurostimulation without irreversible charge transfer reaction. The McMiA consists of a genipin-cross-linked biopolymeric ionogel coupled with a dopamine-cross-linked graphene oxide membrane to prevent ion exchange between biological and synthetic McMiA ions and to function as a bioadhesive forming covalent bonds with the target tissues. In addition, the demonstration of bioelectronic medicine via the McMiA-based neurostimulation of sciatic nerves shows the enhanced clinical utility in treating the overactive bladder syndrome. As the McMiA-based neural interface is soft, robust for bioadhesion, and stable in a physiological environment, it can offer significant advancement in biocompatibility and long-term operability for neural interface engineering.
