Abstract
Human receives and transmits various information from the outside world
through different sensory systems. The sensory neurons integrate various
sensory inputs into a synthetical perception to monitor complex
environments, and this fundamentally determines the way how we perceive
the world. Developing multifunctional artificial sensory elements that
can integrate multisensory perception plays a vital role in future
intelligent perception systems, whereas prior spiking neurons reported
can only handle single-mode physical signals. Here, we present a
bio-inspired haptic-temperature fusion spiking neuron based upon a
serial connection of piezoresistive sensor and VO2volatile memristor. The artificial sensory neuron is capable of
detecting and encoding pressure and temperature inputs based on the
voltage dividing effect and the intrinsic thermal sensitivity of
metal-insulator transition in VO2. Recognition of
Braille characters is achieved through multiple piezoresistive sensors,
taking advantage of the spatial integration capabilities of such spiking
neurons. Notably, the traditionally separate haptic and temperature
signals can be fused physically in the sensory neuron when synchronizing
the two sensory cues, which is able to recognize multimodal
haptic/temperature patterns. The artificial multisensory neuron thus
provides a promising approach towards e-skin, neuro-robotics and
human-machine interaction technologies.
1. Introduction
The sensory system is a part of the nervous system that processes
sensory information, which includes receptors, neural pathways, and the
sensory center of the cerebral cortex. In the sensory neural network of
humankind, the sensory receptors convert environmental information into
potential changes and encode such potential changes into spike trains
with neural spike coding in the cell body. Subsequently, interneurons
convey the spike trains from the receptors to the cerebral cortex of the
brain, where the information is decoded into sensory perceptions for
further processing.[1-6] Such structure forms the
basis of sensing, pre-processing and encoding capabilities of the human
sensory system. This outperforms digital computers in dealing with a
large number of complex tasks, such as perception and real-time sensory
data processing. Therefore, it is of great significance to draw
inspiration from the human sensory system and develop artificial sensory
hardware that can efficiently realize the perception and encoding
capabilities, which will provide a promising approach towards e-skin,
neurorobotics and human-machine interaction technologies.
Traditional complementary metal
oxide semiconductor (CMOS) technology utilizes complex auxiliary
circuits and bulky capacitors to emulate sensors and bio-dynamics, which
takes up a large area and high computational
cost.[6-10] In recent years, many researchers have
devoted efforts to emulating the synaptic dynamics or neuronal behaviors
using emerging devices such as non-volatile
memristors,[11-13] volatile
memristors[14, 15] and synaptic
transistors.[16, 17] Meanwhile, there were recent
reports on emulation of biological sensing functions by integrating
functional sensors with synaptic and neuron
components.[18-28] One way is to use sensors
combined with artificial synapse devices,[19-27]and recently, volatile memristors have emerged as excellent candidates
for the construction of artificial sensory neurons due to their simple
two-terminal structure and dynamic threshold switching (TS)
characteristics.[18, 23, 28, 29, 32] However,
aiming at sensory neuron, these prior studies only focus on single-mode
sensory perception, but rarely achieves the integration of multiple
sensory inputs,[28-32] which is distant from the
efficient processing of cross-sensory information in biology. Therefore,
it is of great significance to construct an artificial sensory system
that not only senses and converts the physical information in real time,
but also directly fuse and integrate multisensory inputs in a
hardware-efficient manner.