through the discrimination of multiple mechanical stimuli. [3] Therefore, the ideal artificial electronic skin can discriminate external loads from various types of input and can also detect intensity.Furthermore, the electronic skin must have properties that satisfy corresponding requirements for tactile sensing. For example, there are several relevant para meters that electronic skin sensors must measure, such as sensitivity, working range, detection time, and hysteresis. The measurement of these is important in order to realize the tactile sensing of human activities or motions. To demon strate electronic skin with the capabili ties of humanskinlike tactile sensing, many researchers have studied novel materials with improved sensing perfor mance, including carbon nanotubes, [6][7][8][9][10][11][12] flexible elastomers, [3,4,6,[13][14][15][16][17] conducting polymers, [14,18,19] ionic gels, [5,7,[20][21][22][23] nanowires [24] or materials with the structure of nanoneedles, [25] hemispheres, [3,5,26,27] and pyramids. [10,14,[28][29][30][31] However, most of the previous studies have focused on the capability to perceive only a single type of mechanical stimulus, rendering previous attempts at designing an electronic skin incapable of sensing multiple forms of mechanical loads.Previous studies have reported sensors with different mate rials and structural approaches for the detection and discrimi nation of the perception of multiple mechanical stimuli. Yin et al. developed the fiber strain sensor for tensile, bending, and torsionsensitive properties using graphenebased composite fiber. [32] In the present study, a fiber strain sensor was fabri cated in a compression spring structure through a facile solu tion process with high reproducibility. Pang et al. presented an interlockingbased straingauge sensor for detecting multiple mechanical forces (including normal, tangential, and torsional forces) using Ptcoated microhair arrays. [33] This strain sensor allowed for a simple and robust sensing platform using the interlocking structure for largearea sensing. Despite the poten tial of devices such as these, the sensors presented in previous reports exhibited low sensitivity for the perception of external mechanical stimuli in a low sensing range with only small elec trical signal differences. They could also only detect a limited range of mechanical loadings.To improve the performance of tactile sensors, a new tac tile sensor should be designed by taking different approaches than the traditional approaches. In this study, we fabricated a tactile sensor composed of an ionic gel inspired by the ionic Sensors that detect and discriminate external mechanical forces are a principal component in the development of electronic tactile systems that can mimic the multifunctional properties of human skin. This study demonstrates a pyramid-plug structure for highly sensitive tactile sensors that enables them to detect pressure, shear force, and torsion. The device is composed of pyramidpatterned ionic gel inspired by neural mec...

The development of a highly sensitive artificial mechanotransducer that mimics the tactile sensing features of human skin has been a big challenge in electronic skin research. Here, we demonstrate an ultrasensitive, low-power oxide transistor-based mechanotransducer modulated by microstructured, deformable ionic dielectrics, which is consistently sensitive to a wide range of pressures from 1 to 50 kPa. To this end, we designed a viscoporoelastic and ionic thermoplastic polyurethane (i-TPU) with micropyramidal feature as a pressure-sensitive gate dielectric for the indium-gallium-zinc-oxide (IGZO) transistor-based mechanotransducer, which leads to an unprecedented sensitivity of 43.6 kPa, which is 23 times higher than that of a capacitive mechanotransducer. This is because the pressure-induced ion accumulation at the interface of the i-TPU dielectric and IGZO semiconductor effectively modulates the conducting channel, which contributed to the enhanced current level under pressure. We believe that the ionic transistor-type mechanotransducer suggested by us will be an effective way to perceive external tactile stimuli over a wide pressure range even under low power (<4 V), which might be one of the candidates to directly emulate the tactile sensing capability of human skin.

Self-powered triboelectric microfluidic system was developed for the simple and rapid liquid sensing with multiple methods such as triboelectric signal and resistance measurement.

The process of memory and learning in biological systems is multimodal, as several kinds of input signals cooperatively determine the weight of information transfer and storage. This study describes a peptide-based platform of materials and devices that can control the coupled conduction of protons and electrons and thus create distinct regions of synapse-like performance depending on the proton activity. We utilized tyrosine-rich peptide-based films and generalized our principles by demonstrating both memristor and synaptic devices. Interestingly, even memristive behavior can be controlled by both voltage and humidity inputs, learning and forgetting process in the device can be initiated and terminated by protons alone in peptide films. We believe that this work can help to understand the mechanism of biological memory and lay a foundation to realize a brain-like device based on ions and electrons.