The viability of a new biophotonic alternative to conventional prescription-drug-based treatments is explored for inflammatory disease and mental health disorders using a non-invasive drug-free optogeneticsbased therapy to treat patients by optically stimulating selected afferent branches of the auricular vagus nerve transcutaneously via the outer ear using a high-resolution, addressable array of organic light emitting diodes (OLED) manufactured on a flexible plastic substrate. Preliminary analysis and optical measurements indicate that our 620 nm flexible red OLED display technology is bright enough to induce therapeutic optical stimulation in optogenetically modified neural tissue.

Objective -There is a need for low power, scalable photoelectronic devices and systems for emerging optogenetic needs in neuromodulation. Conventional light emitting diodes (LEDs) are constrained by power and lead-counts necessary for scalability. Organic LEDs (OLEDs) offer an exciting approach to decrease power and lead-counts while achieving high channel counts on thin, flexible substrates that conform to brain surfaces or peripheral neuronal fibers. In this study, we investigate the potential for using OLEDs to modulate neuronal networks cultured in vitro on a transparent microelectrode array (MEA) and subsequently validate neurostimulation in vivo in a transgenic mouse model. Approach -Cultured mouse cortical neurons were transfected with light-sensitive opsins such as blue-light sensitive channel-rhodopsin (ChR2) and green-light sensitive chimeric channelrhodopsin (C1V1tt) and stimulated using blue and green OLEDs (with 455 and 520 nm peak emission spectra respectively) at a power of 1 mW/mm 2 under pulsed conditions.Main results -We demonstrate neuromodulation and optostimulus-locked, single unit-neuronal activity in neurons expressing stimulating and inhibiting opsins (n=4 MEAs, each with 16 recordable channels). We also validated the optostimulus-locked response in a channelrhodopsin expressing transgenic mouse model, where at least three isolatable single neuronal cortical units respond to OLED stimulation. Significance -The above results indicate the feasibility of generating sufficient luminance fromOLEDs to perform neuromodulation both in vitro and in vivo. This opens up the possibility of developing thin, flexible OLED films with multiple stimulation sites that can conform to the shape of the neuronal targets in the brain or the peripheral nervous system. However, stability of these OLEDs under chronic conditions still needs to be carefully assessed with appropriate packaging approaches.

In this paper a four-mirror tunable micro electro-mechanical systems (MEMS) Fabry Perot Interferometer (FPI) concept is proposed with the mathematical model. The spectral range of the proposed FPI lies in the infrared spectrum ranging from 2400 to 4018 (nm). FPI can be finely tuned by deflecting the two middle mirrors (or by changing the three cavity lengths). Two different cases were separately considered for the tuning. In case one, tuning was achieved by deflecting mirror 2 only and in case two, both mirrors 2 and 3 were deflected for the tuning of the FPI.

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