Electronic, optical, and chemical interrogation of neural circuits with multifunctional fibers (Conference Presentation)

Despite recent advances in microfabrication and nanofabrication, integrating multiple modes of communication with the brain into a single biocompatible neural probe remains a challenge. These multifunctional neural probes may further our understanding of normal and disrupted functions of neural circuits manifested in neurological conditions, such as Parkinson’s disease. Here, we present a novel family of probes fabricated using a thermal drawing process. In this process, a macroscopic template (preform) containing the desired features is drawn by applying heat and tension into a fiber that conserves the original geometry of the preform but at a much smaller scale. Being composed of soft materials, such as polymers, conductive composites, and low melting temperature metals, fiber based neural probes minimize the damage to the surrounding tissue when implanted. Furthermore, fiber drawing enables straightforward integration features allowing for simultaneous electrical, optical and chemical interrogation of the brain. We demonstrate the utility of these probes for one-step optogenetics, in which a viral vector carrying opsin genes is injected through the same device then used to optically stimulate neurons and record their response as electrical activity. With these probes, we also show, for the first time, recordings of electrical activity in the spinal cord of freely moving mice.