Date of Award
Doctor of Philosophy (PhD)
The evolution of electronic skin (E-skin) technology in the past decade has resulted in a great variety of flexible electronic devices that mimic the physical and chemical sensing properties of skin for applications in advanced robotics, prosthetics, and health monitoring technologies. The further advancement of E-skin technology demands closer imitation of skin receptors' transduction mechanisms, simultaneous detection of multiple information from different sources, and the study of transmission, processing and memory of the signals among the neurons. Motivated by such demands, this thesis focuses on design, fabrication, characterization of novel flexible electronic devices and integration of individual devices to realize prototype biomimetic E-skin with neurological and multimodal sensing functions.
More specifically, we have studied flexible carbon nanotube thin-film transistors (CNT-TFTs) as control and signal processing units of E-skin and flexible ferroelectret nanogenerator (FENG) and triboelectric nanogenerator (TENG) as skin mechanoreceptors. Multiple fabrication methods, such as low-cost printing and conventional cleanroom-based microfabrication have been implemented to fabricate flexible CNT-TFTs with different structures and functions, especially the synaptic functions. Based on the research on individual devices, we have demonstrated a prototype force-sensing flexible neurological E-skin and its sensory nerve and synapse, with FENG serving as the sensory mechanoreceptor that generates action potentials (pulsed voltages) to be processed and transmitted by the flexible synaptic CNT-TFT. It allows for instantaneous detection of force stimuli and offers biological synapse-like behavior to store the stimulus information and relay the stimulus signals to the next stage. The force-sensing neurological E-skin was further augmented with visual and auditory sensing modalities by introducing phototransistor-based optical sensor and FENG-based acoustic sensor. Successful transduction of visual, auditory and tactile stimuli and synaptic processing and memory of those signals have all been demonstrated. Thanks to the multimodal sensing capability of the neurological E-skin, psychological associative learning experiment-“Pavlov’s dog's experiment”, was also successfully implemented electronically by synergizing actual visual and auditory signals in the synaptic transistor. Flexible electronics and prototype neurological E-skin system demonstrated in this thesis may offer an entry into novel multimodal, user-environment interactive soft E-skin system for soft robotic and diagnostic applications.
Chuan C. Wang
Shantanu S. Chakrabartty, Srikanth S. Singamaneni, Yong Y. Wang, Xuan X. Zhang,