Cellulose Fiber Tortuosity as a Bioinspired Design Strategy for Light-Driven, Self-Powered Ionotronic Synapses.

Area of Science:

• Materials Science
• Neuroscience
• Electrical Engineering

Background:

• The pursuit of energy-efficient, brain-inspired computing necessitates advanced neuromorphic devices.
• Ionotronic synapses, mimicking neuronal ionic signaling, are crucial for artificial learning and memory.
• Existing light-driven synaptic devices often neglect the impact of ion transport architecture, unlike biological systems.

Purpose of the Study:

• To investigate the role of ion transport architecture in ionotronic synapses.
• To develop a flexible, light-responsive ionotronic synaptic device using cellulose fiber substrates.
• To explore the potential of tunable substrate tortuosity for modulating synaptic behavior and enabling optical communication.

Main Methods:

• Fabrication of a two-terminal ionotronic synaptic device on cellulose fibers (thread, cloth, paper) with carbon electrodes.
• Incorporation of lanthanum hexaboride (LaB₆) nanoparticles for light-to-heat conversion and ionic liquid (EMIM:OAc) for ion transport.
• Characterization of device performance under varying substrate tortuosity and optical stimuli (light wavelength, frequency, intensity, duration).

Main Results:

• The device operates in a self-powered mode, exhibiting light-modulated synaptic responses.
• Increased substrate tortuosity significantly reduced excitatory post-synaptic potential (EPSP) amplitude and enhanced retention time.
• The device successfully emulated paired-pulse facilitation (PPF) and spike-dependent plasticity, demonstrating optical data encryption and Morse code transmission.

Conclusions:

• Fiber tortuosity is a critical, previously underexplored design parameter for ionotronic synapses.
• Cellulose fiber substrates offer a versatile platform for creating flexible, tunable ionotronic devices.
• This work paves the way for advanced neuromorphic vision and secure optical communication technologies.