In fast and transient somatosensory processing, the relative timing of the selected spikes is more important than the spike frequency because the ensemble of the first spikes in the spike trains encodes the dynamic tactile information. Here, inspired by the functional effectiveness of the selected spikes, we propose an artificial dynamic sensory system based on position-encoded spike spectrum. We use a mixed ion-electron conductor to generate a potential spike signal. We design artificial receptors that have different ion relaxation times (τ); thus, a sequence of the spikes from the receptors creates a spike spectrum, providing the spatial information (position and motion trace) and the temporal information (speed and dynamic contact area). The artificial receptors can be incorporated by as much as 132/square centimeters by using only two global signal addressing lines for sensor operation. Structural simplicity of the device opens the possibility of scalable fabrication with dense receptor integration. With computational decoding of the position-encoded spike spectrum, the artificial sensory system can recognize complicated dynamic motions in real time. The high-resolution spatiotemporal tactile perception in the ionic artificial sensory system enables the real-time dynamic robotic manipulation.

Full advantage of stretchable electronic devices can be taken when utilizing an intrinsically stretchable power source. High-performance stretchable supercapacitors with a simple structure and solid-state operation are good power sources for stretchable electronics. This study suggests a new type of intrinsically stretchable, printable, electroactive ink consisting of 1T-MoS2 and a fluoroelastomer (FE). The active material (1T-MoS2/FE) is made by fluorinating the metallic-phase MoS2 (1T-MoS2) nanosheets with the FE under high-power ultrasonication. The MoS2 in the 1T-MoS2/FE has unconventional crystal structures in which the stable cubic (1T) and distorted 2H structures were mixed. The printed line of the 1T-MoS2/FE on the porous stretchable Au collector electrodes is intrinsically stretchable at more than ε = 50% and has good specific capacitance (28 mF cm–2 at 0.2 mA cm–2) and energy density (3.15 mWh cm–3). The in-plane all-solid-state stretchable supercapacitor is stretchable at ε = 40% and retains its relative capacity (C/C o) by 80%. This printable device platform potentially opens up the in-plane fabrication of stretchable micro-supercapacitor devices for wearable electronic applications.

On‐skin healthcare patch‐type devices have great technological challenges in monitoring full‐day activities and wearing for multiple days without detachment. These challenges can be overcome when the sensor is air permeable but waterproof. This study presents a light‐weight, highly stable, and stretchable Au electrode that is fabricated by sputtering on an imidized nanofiber mat. The contact surface of the electrode is hydro‐wetting and the outer surface of the electrode is hydrophobic, so the porous electrode simultaneously has excellent sweat permeability and waterproofing capabilities. The electrode is applied to the electrocardiogram sensor for monitoring the cardiac signals for five consecutive days without detaching while doing various full‐day activities such as relaxing, exercising, showering, and sleeping. This study suggests a modular setup of the electrodes and the cardiac signal processing unit for activating the device when cardiac monitoring is required.

Although ion gels are attractive sensing materials for deformable epidermal sensors or implantable devices, their sensing performances are highly affected by environmental humidity change, so that their sensing reliability cannot be secured. This study proposes a new concept of maintaining the high-precision temperature sensing performance of highly deformable ion gel sensors. In this approach, a hydrophobic ion gel sensing layer is kept water-saturated by attaching a hydrogel layer, rather than attempting to completely block water penetration. This study performs experimental and theoretical investigation on water concentration in the ion gel, using the analysis of mass transportation at the interface of the ion gel and the hydrogel. By using the charge relaxation time of the ionic molecules, the temperature sensor is not affected by environmental humidity in the extreme range of humidity (30%-100%). This study demonstrates a highly deformable on-skin temperature sensor which shows the same performance either in water or dry state and while exercising with large strains (𝝐 = 50%).

Wang et al. fabricated a 100 × 100 pressure sensor matrix with a resolution of 100 dpi that could detect a wide pressure range. [32] You et al. made a flexible pressure sensor array of 100 pixels cm −2 without having electrical crosstalks between the pixels. [33] Kim et al. have demonstrated a carbonbased piezocapacitive pressure sensor array which could perceive a low pressure (0.4 Pa). [34] Li et al. fabricated a 4 × 4 matrix of supercapacitive pressure sensors using the ion-electronic interface and showed a high pressure-to-capacitance sensitivity (114 nF kPa -1 ). [35] In contrast to the intensive studies on the pressure sensors, shear sensors have been rarely investigated. It is because of the structural complexity of the shear sensor required for detecting different horizontal shear directions and the angles to the normal direction. Another technological difficulty in shear sensor fabrication is the need for deformability requested to prevent the slip of an object.So far, tactile shear force recognition has proceeded in three approaches; i) fabrication of a unit shear sensor, ii) profiling relative strain distribution by analyzing strain distribution obtained from a strain sensor array, and iii) direct mapping of shear forces by using a shear sensor array. The unit sensors are relatively large and designed to detect the shear forces applied from four directions. Viry et al. made a three-axial force sensor by using fluorosilicone and air gap between top and bottom electrodes. [36] Although the sensor could quantitatively measure shear forces, it could not provide the shear force distribution over a large area. Hua et al. implemented a 10 × 10 strain sensor array showing the shear force distribution through the piezoresistive sensor network. [37] Unfortunately, the quantitative value of shear force was difficult to obtain through the strain distribution approach. A shear sensor array is expected to simultaneously provide the shear force distribution and the quantitative force values. Cheng et al. fabricated a shear sensor array based on capacitance change upon air gap deformation. [38] Because of the small capacitance of the air gap, this type of capacitive sensor requires a large sensing area to obtain reliable sensing signals, thus fabrication of a miniaturized array sensor is difficult through this approach.In this work, we propose a deformable shear sensor array (3 × 3) in 27 mm × 27 mm, in which each sensor can An array of shear sensors is essential in tactile sensation as well as the pressure sensors. Surprisingly, however, the shear sensor array is rarely investigated mainly due to the structural complexity to measure the horizontal forces from various directions and also due to the mechanical softness required for preventing the slip of an object. Here, an array of small shear sensors that can recognize both shear force and shear rotational angle is fabricated. All the device components are made of deformable materials to acquire the softness of the sensor. This work presents a novel design for the sm...