Optical methods are becoming established in the fields of neuroscience, medical imaging and diagnostics, etc. Optogenetics, for example, despite being a nascent field of study, has been named the Method of the Year 2010 by Nature Methods. We propose to develop and test a novel device structure to facilitate three-dimensional deep-tissue light penetration and collection with capabilities for simultaneous spatiotemporal modulation of different wavelenghts to advance a broad range of applications in optical neural stimulation and recording. A 3D optrode array consisting of optically transparent needles can penetrate >1 mm directly into tissue, thereby creating multiple independent paths for light propagation that avoid attenuation due to tissue absorption and scattering. We will develop SiO2 arrays suitable for visible and even NIR applications. The intellectual merits of this research lie in the addressing the barrier for nearly all modes of optical excitation where penetration depth is determined by optrode length, not by wavelength. We propose to leverage off of the extensive body of microfabrication methods developed for penetrating electrodes to achieve the same advantages for optical delivery and reception as compared to external approaches. Broader Impact: Multiple, broadly enabling, and potentially transformative, impacts may emerge from this work. Although our focus is on optogenetic neural stimulation and recording, optrode array devices have application in basic neuroscience research, highly selective photodynamic therapy, and deep tissue imaging for diagnostics and therapy. From an applied neuroscience and neuroengineering perspective, the optrode array device will facilitate deeper access into neural tissue, such as axon bundles within the fasicles of central or peripheral nerves. Deeper access across multiple stimulation/recording sites may enable restoration of lost motor or sensory function after nervous system disorders or disease. Potential representative applications, among many, include restoration of hand grasp or stance after paralysis, and restoration of cutaneous and proprioceptive sensory feedback after limb loss. From an educational perspective, the inherently interdisciplinary and interactive nature of the proposed research will provide unique opportunities for training in biophotonics, microfabrication, neuroengineering, and basic neuroscience, and will interact synergistically with ongoing major research and educational initiatives at the University of Utah. From diversity and outreach perspectives, the established success of the Bioengineering Department (of which the PI is an adjunct-faculty member, and the co-PI a tenure-track member) in attracting and mentoring female engineers, along with recently enhanced College- and University-wide outreach and recruitment efforts, will help bring underrepresented populations into the emerging neuro-engineering growth area.
