No abstract

A polymer bulk heterojunction structure utilized as an active photosensitive platform to evoke neuronal activity in a blind retina. The features of the elicited action potentials correlate with the optoelectronic properties of the polymer/electrolyte interface, and resembles the natural response of the retina to light. The polymer interface can be used as an optoelectronic epiretinal interface for retinal prosthesis with no requirement for external power sources or connection cables.

Identifying the specific role of physical guidance cues in the growth of neurons is crucial for understanding the fundamental biology of brain development and for designing scaffolds for tissue engineering. Here, we investigate the structural significance of nanoscale topographies as physical cues for neurite outgrowth and circuit formation by growing neurons on semiconductor nanowires. We monitored neurite growth using optical and scanning electron microscopy and evaluated the spontaneous neuronal network activity using functional calcium imaging. We show, for the first time, that an isotropic arrangement of indium phosphide (InP) nanowires can serve as physical cues for guiding neurite growth and aid in forming a network with neighboring neurons. Most importantly, we confirm that multiple neurons, with neurites guided by the topography of the InP nanowire scaffolds, exhibit synchronized calcium activity, implying intercellular communications via synaptic connections. Our study imparts new fundamental insights on the role of nanotopographical cues in the formation of functional neuronal circuits in the brain and will therefore advance the development of neuroprosthetic scaffolds.

Color sensing procedures typically involve multiple active detectors or a photodetector coupled to a filter array. We demonstrate the possibility of using a single polymer layer based device structure for multicolor sensing. The device structure does not require any color filters or any subpixelation, and it distinguishes colors without any external bias. The color sensing relies on an appropriate thickness of the active polymer layer that results in a characteristic polarity and temporal profile of the photocurrent signal in response to various incident colors. The device characteristics reveal interesting similarities to the features observed in natural photosensitive systems including retinal cone cells.