Jonathan K. George

3D printing scaffold coupled with low level light therapy for neural tissue regeneration

3D printing has shown promise for neural regeneration by providing customized nerve scaffolds to structurally support and bridge the defect gap as well as deliver cells or various bioactive substances. Low-level light therapy (LLLT) exhibits positive effects on rehabiliation of degenerative nerves and neural disorders. With this in mind, we postulate that 3D printed neural scaffold coupling with LLLT will generate a new strategy to repair neural degeneration. To achieve this goal, we applied red laser light to stimualte neural stem cells on 3D printed scaffolds and investigated the subsequent cell response with respect to cell proliferation and differentiation. Here we show that cell prolifeartion rate and intracellular reactive oxgen species synthesis were significantly increased after 15 s laser stimulation follwed by 1 d culture. Over culturing time of 14 d in vitro, the laser stimulation promoted neuronal differentiation of neural stem cells, while the glial differentiation was suppressed based on results of both immunocytochemistry studies and real-time quantitative reverse transcription polymerase chain reaction testing. These findings suggest that integration of 3D printing and LLLT might provide a powerful methodology for neural tissue engineering.

Graphene-based solitons for spatial division multiplexed switching

Spatial division multiplexing utilizes the directionality of the lights propagating k-vector to separate it into distinct spatial directions. Here, we show that the anisotropy of orthogonal spatial solitons propagating in a single graphene monolayer results in phase-based multiplexing. We use the self-confinement properties of spatial solitons to increase the usable density of states (DOS) of this switching system. Furthermore, we show that crossing two orthogonal solitons exhibits a low (0.035 dB) mutual disturbance from another enabling independent k-vector switching. The efficient utilization of the DOS and multiplexing in real space enables data processing parallelism with applications in optical networking and computing.

Identifying mirror symmetry density with delay in spiking neural networks (Conference Presentation)

The ability to rapidly identify symmetry and anti-symmetry is an essential attribute of intelligence. Symmetry perception is a central process in human vision and may be key to human 3D visualization. While previous work in understanding neuron symmetry perception has concentrated on the neuron as an integrator, here we show how the coincidence detecting property of the spiking neuron can be used to reveal symmetry density in spatial data. We develop a method for synchronizing symmetry-identifying spiking artificial neural networks to enable layering and feedback in the network. We show a method for building a network capable of identifying symmetry density between sets of data and present a digital logic implementation demonstrating an 8x8 leaky-integrate-and-fire symmetry detector in a field programmable gate array. Our results show that the efficiencies of spiking neural networks can be harnessed to rapidly identify symmetry in spatial data with applications in image processing, 3D computer vision, and robotics.

Scattering and absorption control in biocompatible fibers towards equalized photobiomodulation

Transparent tissue scaffolds enable illumination of growing tissue to accelerate cell proliferation and improve other cell functions through photobiomodulation. The biphasic dose response of cells exposed to photobiomodulating light dictates that the illumination be evenly distributed across the scaffold such that the cells are neither under nor over exposed to light. However, equalized illumination has not been sufficiently addressed. Here we analyze and experimentally demonstrate spatially equalizing illumination by three methods, namely: engineered surface scattering, reflection by a gold mirror, and traveling-waves in a ring mesh. Our results show that nearly equalized illumination is achievable by controlling the light scattering-to-loss ratio. This demonstration furthers opportunities for dose-optimized photobiomodulation in tissue regeneration.

Polar synthetic imaging

In the search for low-cost wide spectrum imagers it may become necessary to sacrifice the expense of the focal plane array and revert to a scanning methodology. In many cases the sensor may be too unwieldy to physically scan and mirrors may have adverse effects on particular frequency bands. In these cases, photonic masks can be devised to modulate the incoming light field with a code over time. This is in essence code-division multiplexing of the light field into a lower dimension channel. In this paper a simple method for modulating the light field with masks of the Archimedes’ spiral is presented and a mathematical model of the two-dimensional mask set is developed.