Large-Area Soft e-Skin: The Challenges Beyond Sensor Designs

Abstract

This article presents the state of the field of large-area tactile sensing in robotics and prosthetics, particularly focusing on neural-like tactile data handling, energy autonomy, and advanced manufacturing based on printed electronics.

Soft eSkin: distributed touch sensing with harmonized energy and computing

“…The human skin therefore responds to both dynamic and static or quasi-static stimuli through FAs and SAs [2][3][4][5][6][7]. Since SAs continue to generate spikes throughout the static or quasistatic events (figure 1b), the neuromorphic approach in eSkin is fundamentally different from the event-driven approaches that are widely explored today in context with vision and other sensory modalities [2][3][4][8][9][10][11][12][13][14]. This neural computing aspect of human skin (hereafter referred to as 'skin' only) is discussed later in this section.…”

“…20 W, where energy required to pass one spike through a synapse is 10 fJ [22]) despite large tactile data coming from receptors distributed in the skin (figure 2). Therefore, the distributed computations make the skin inherently power-efficient and robust to noise [2,3,[11][12][13][14]21,23,24]. Clearly, the harmonized energy and computing in eSkin should be explored much like the distributed touch sensing has been.…”

“…This is because signal transfer in the nervous system is essentially aiming to maximize the fidelity with the time-continuous voltage signals (i.e. analogue signals) from receptors (or the neuron inside the brain) [12]. But the spike generation mechanism takes that signal as a probability density function and converts it into spikes (and 'discretizes' the signal).…”

“…The above issues with current engineered systems could possibly be resolved, just like in biology, by converting the signal into spikes, before it is transferred (figure 3b). With the network of sensors as local soft and flexible computing units, and sending partially computed tactile data to the higher perception levels, the parasitic losses (particularly the CV 2 F) are also minimized [12,27]. The CV 2 F losses arises as a result of transmitting huge amounts of data to higher perception levels using complex and longer interconnects in limited communication bandwidth, which may result the loss of useful information.…”

Monolayer MoSe₂-Based Tunneling Field Effect Transistor for Ultrasensitive Strain Sensing

“…HE flexible and stretchable electronics has attracted increasing attention due to the promise it holds for advances in various applications including health monitoring, robotics and e-skin [1]- [5] . Some of these applications demand high-performance and in this regard the modest performance of organic semiconductors based devices may be insufficient.…”