Solution-Phase lighting-emitting devices for optogenetic control of the peripheral nervous system
Delivering light deep into tissue is an important open challenge in biomedical engineering, with particular relevance for optogenetics. One feasible solution is the application of miniaturized bio-implantable light-emitting devices. Such devices should be able to adapt to stimulate cells in tissues with different shapes, sizes, stiffness, and mechanical characteristics. OLED is the most successful light application in current display technologies with many advantages but it cannot adapt to the extreme requirement in three-dimensional structures. The limitations come from the multi-layered device architecture and manufacturing process of vacuum evaporation. Here, we propose a radically different device concept, a solution-phase light-emitting device (sol-LED) with a simple structure that can readily adapt various form factors and thus is of particular relevance to novel applications in the biomedical context. The sol-LED consists of electrodes and a solution that adopts the exciplex host-dye guest system. The fabrication is based on the process under liquid-state such as injection and capillary processes to fill the space in pre-formed devices. The proposed sol-LED will take advantage of existing state-of-the-art OLED materials and established OLED device physics and translate them to the liquid state by dissolving solid-state materials in suitable solvents. Apart from developing this entirely novel type of light source, the use of sol-LEDs as light-source for optogenetics will be developed and tested. Sol-LED with a needle-like shape will be produced by injection of the solution into a hollow microneedle. The resulting devices will be implanted into muscles of the posterior thighs of mice. The motor function will then be mimicked by alternating stimulation of the muscle cells responsible for contraction of the left and right legs. With this, we will test if the device can stimulate cells in vivo with constant intensity and frequency despite strong muscle movements.