Replicating the Bright-Light Therapy of Seasonal Affective Disorder Using Dual-Gate Dielectric Synaptic Transistors: An Exploration of Neuromorphic Computing Approaches

A synaptic device is fabricated using a TiO 2 channel that is highly responsive to optical stimuli and incorporates a dual-gate dielectric, facilitating charge trapping at the interface. Unlike conventional synaptic transistors that only respond to a single type of stimulus, such as optical or electrical, the fabricated device can emulate synaptic behavior by integrating both optical and electrical stimuli. These distinctive attributes enable the device to induce excitatory postsynaptic currents via optical and inhibitory postsynaptic currents following electrical stimulation. The lifetime of the optical synaptic behaviors is approximately 12 times longer than that of the electrical stimulation. In addition, by employing the paired-pulse facilitation index, distinct time constants corresponding to rapid and slow phases are computed, mirroring a pattern similar to that observed in a biosynapse. A nonlinearity factor v = 7.21 × 10 –4 is defined based on the short- to long-term plasticity transition, demonstrating outstanding linearity responses. In particular, 2048 analogue states are achieved, characterized by an exceptional linear response. Human depression, which is a seasonal affective disorder, is emulated by employing electrical stimulation to emulate melancholic feelings. Subsequently, light therapy is emulated for seasonal affective disorder by incorporating light stimulation. The findings signify a promising pathway to emulate human brain activities.