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Sensors based on triboelectric nanogenerators have been widely used for energy harvesting and sensing applications, however, the applications of multidimensional information perception and interactive control are insufficient. In this paper, we present an ultra-stretchable triboelectric strip sensor (TSS) using triboelectric mechanism for controlling the objects in three-dimensional space. This facile and low-cost TSS is mainly composed of a parallel structure including three symmetric sensor strips fixed on the base and a mobile stage connected with them. Based on the coupling effect of triboelectrification and electrostatic induction, the length changes of each strip with the same finger contacting point generate different signal output ratios from two terminal electrodes, functioning as the interactive interface for multi-dimensional sensing and controlling. Hence, the parallel sensor strips structure can realize the sensing and controlling in three degrees of freedom of linear motion and two degrees of freedom of rotational motion, and resultant sensing ranges are X, Y, Z, α and β (20 mm, 20 mm, 30 mm, 36°, and 36°). In terms of manipulation, this is simpler than the conventional controller with rigid structure and includes additional space dimensions. Furthermore, demonstration of the TSS as human-nanomachine terminal to control the nanomanipulator in scanning electron microscope (SEM) is successfully realized with the accuracy of 10 nm. The proposed TSS shows great potential for the applications in automated control, robotics control, and Internet of Things (IoT).

Triboelectric nanogenerators and sensors have been widely adopted for diversified energy harvesting and sensing applications, but the demonstrations of 3D information sensing and controlling are very limited. In this paper, we present a novel self-powered virtual reality 3D-control sensor (VR-3D-CS) based on triboelectric mechanism for controlling the attitude (both the position and rotation) of object in 3D virtual space. This innovative, cost-effective, simple-designed sensor has a symmetric 3D structure with eight separated sensing electrodes and two touching spheres as the interactive interface with human fingers for 3D force information sensing and VR controlling. Based on the coupling effect of triboelectrification and electrostatic induction, the VR-3D-CS generates different electric output signals in response to different operation manner that can be used to control the attitude of objects in 3D virtual space. The symmetrical 3D configuration design of the sensor enables the detection of 3D force from both the normal direction and shear direction. By employing vector properties of force and signal analysis from the eight sensing electrodes, detection of six-axis directions in 3D space is achieved by triboelectric mechanism for the first time. The VR-3D-CS has been demonstrated to be able to detect normal force in the range of 0–18 N. It can resolve the shear force direction with step resolution of at least 15°. Besides, due to the positive output voltage and low internal impedance, the VR-3D-CS is readily compatible with commercial portable signal processing system for signal analysis and controlling. Demonstration of the VR-3D-CS as interactive interface for Augmented Reality (AR) control is successfully realized. The robust structure, stable output performance and self-powered sensing property enable the device as an ideal human machine interface towards AR interface, batteryless and energy saving applications.

The application of CsPbI3 inorganic perovskite in carbon-based perovskite solar cells without hole transporter (C-PSCs) is expected to enhance device stability. However, due to the lower hole selectivity of carbon electrode than that of hole transporter, the efficiency of CsPbI3 C-PSCs is significantly suppressed. Herein, size mismatch-induced cation segregation in CsPbI3 is studied and employed to solve the problem. After treating CsPbI3 with CsX (X Br, Cl and F) ethanol solutions, the larger size mismatch between X- and I- ions would induce the more obvious cation segregation. The moderate size mismatch between I- and Cl- ions allows a partial substitution of I- ions with Cl- ions in CsPbI3 to form energy level gradient, and the CsCl residue on the surface tends to react with CsPbI3 to generate 2D Cs2PbI2Cl2 nanosheets, serving as an electron blocking layer. The synergistic effect of the energy level gradient and the electron blocking layer well improves hole selectivity at CsPbI3/carbon interface to reduce carrier recombination loss. As a result, the C-PSCs based on the CsCl-treated CsPbI3 achieve an efficiency of 15.23%, a record value for inorganic C-PSCs.

Soft robots have significant advantages in terms of flexibility and adaptability, leading to potential applications in the bionics field. Inspired by the caterpillars in nature, this work proposed a soft caterpillar robot (SCR) by integrating two types of ultra-stretchable bionic sensors on a dual air-chamber pneumatic network structure. In order to realize self-powered tactile sensing, four triboelectric nanogenerator tactile sensors (TTSs) based on functional liquid metal (FLM) with thorny-structured bionic whiskers are developed and attached on the SCR. Meanwhile, two ultra-stretchable resistive strain sensors (RSSs) by using FLM are covered as the bionic skin to sense self-body deformation of the SCR. The TTS has a fast response time of 0.03 s and a minimum perception of 0.05 kPa, which can be very sensitive to the unknown stimulus of various materials. The RSS with a relatively high sensitivity of 2.94 and small hysteresis of 1.42% possess the ultra-stretchable ability of 180% strain, which helps to adapt and adjust its own body bending and crawling. The biological perception capabilities of the SCR play a crucial role in mimicking bionic actions and response in an unknown environment, such as escaping from unexpected attacks as well as adaptive crawling through an unknown tunnel environment.

The inorganic CsPbI3 perovskite obtained from dimethylammonium iodide (DMAI)-related strategies have greatly promoted the development of CsPbI3 perovskite solar cells (PSCs). However, deeper understandings are urgently needed to further enhance device performance. Herein, the crystallization processes of DMAI-based strategy are systematically studied and some new understandings are proposed. During annealing, β-phase-like CsPbI3 is first formed and then gradually transits to γ-phase-like structure. DMA ions tend more to form DMAPbI3 in the system, implying the amount of alloyed DMA ions in CsPbI3 would be very limited. In addition, the pre-generated Cs4PbI6 plays an important role in stabilizing CsPbI3 perovskite phase at low temperature. These findings help us to finely manipulate film composition, and the quality of CsPbI3 film is substantially improved after simultaneously suppressing the formation of δ-CsPbI3, minimizing DMAPbI3 residual and generating PbI2 passivator. More promisingly, the carbon-based CsPbI3 PSCs without hole transporter achieve a record efficiency of 14.6%.

The past few years have witnessed the rapid innovation of wearable chemical sensors that induce impacts on various areas of our daily life. As the emerging Internet of Thing (IoT), wearable chemical sensors hold considerable promise not only for healthcare and fitness applications but also for other diversified applications ranging from environment monitoring to security/forensic identification. With the vision of more versatile, convenient, communicating and integrated, this review provides a comprehensive overview of the recent progress of wearable chemical sensors and systems. First, in terms of healthcare application, the development of wearable chemical sensors for markers detection from sweat is reviewed in the aspect of transduction mechanism and structural configuration (i.e., soft/soft-hard integration patch, tattoo, and microfluidics). Then the evolution of wearable tear and saliva sensors from simple sensor design to integrated system (e.g., communication module and power supply integration) are reviewed. Next, treatment (i.e., drug delivery), as an indispensable part of close loop sensing-therapeutic system establishment, is reviewed via the representatives of microneedle technology. Additionally, the progress of wearable chemical sensors for environmental monitoring and security/forensic applications are presented, showing the development of self-sustainable/on-site testing systems. With this review, we believe the development trend of wearable chemical sensors is towards multifunctional, sensing-therapeutic, self-powered and integrated systems.

The power conversion efficiencies of organic-inorganic hybrid perovskite solar cells (PSCs) have been boosted from 3.8% to over 25% in about ten years. However, low device stability still impedes their practical applications. In the last few years, the inorganic PSCs based on carbon electrodes (C–PSCs) have gradually become one of the promising resolutions, and up to now, much progress has been made. Herein, recent developments in C–PSCs, including (1) device structure and working principles, (2) categorical progress of CsPbBr3, CsPbI3-xBrx, CsPbI3 and other inorganic C–PSCs, are reviewed. Promising research directions (e.g. developing suitable deposition methods, improving phase stability, tuning energy band structure, modifying perovskite/carbon interface and exploiting new inorganic perovskites) are then suggested to promote the development of inorganic C–PSCs.

There is abundance of low-frequency biomechanical and blue energy that can be harvested from our ambient environment. Utilization of these energy plays a significant role for the sustainability of the wearable devices and environmental monitoring devices. Here, we presented a rotational pendulum triboelectric-electromagnetic hybrid generator (RPHG) which is able to scavenge low-frequency ( 2 and 79.9 W/m 2 are obtained at a driving frequency of 2 Hz and amplitude of 14 cm by the TENG and EMG, respectively, which can charge a capacitor of 22μF to 7 V rapidly in 30 s. The RPHG can light up about more than hundreds of commercial lights emitting diodes (LEDs). Then, the RPHG was placed on human body and tested by running on treadmill and rope skipping. The open-circuit voltage of the EMG can be about 9 V and that of TENG can reach 150 V. Finally, the RPHG was tested on a homemade buoy in Tai Lake. When the wave frequency is about 1 Hz and the wave height is 20 cm, the open-circuit voltage of EMG can reach over 3 V and that of TENG can reach 80 V regardless of whether the RPHG is placed vertically or horizontally. Generally, the proposed device demonstrates the effectiveness towards energy harvesting from ambient environment of multidirectional and wide frequency range, i.e., human motion and blue energy, showing the great potential of being a sustainable power source for those wearable devices and monitoring devices in blue ocean.