Soft infrared optoelectronic fibers for modulation and recording of neural activity

Due to their flexibility and robustness, polymer optical fibers represent a promising platform for the development of brain-compatible implantable devices with reduced risk of tissue inflammation. Furthermore, by combining different biocompatible materials it is possible to integrate multiple functionalities in a single hybrid optical fiber. This approach allows the fabrication of soft brain interfaces able to support multiple modalities of neural interrogation. Such interfaces capable of simultaneous light delivery and recording of neuronal activity with minimal tissue damage are currently lacking for infrared wavelengths in the strong water absorption region. This spectral region, in particular, is crucial for infrared neuromodulation, a promising technique for direct light-induced control of neural activity without genetic manipulation. Here we present novel infrared fiber-based neural interfaces developed by thermal drawing of soft, biocompatible optical polymers, which are able to simultaneously modulate and record neural activity, as validated experimentally in vivo.