Yaokun Pang

Arrays of Ordered Pb Nanowires and Their Optical Properties for Laminated Polarizers

A laminated micropolarizer of Pb nanowire arrays was fabricated within an anodic alumina membrane (AAM) by anodization of the pure Al foil and subsequent electrodeposition of Pb. X-ray diffraction, scanning electron microscopy, transmission electron microscopy, selected-area electron diffraction, and high-resolution electron microscopy investigations reveal that the ordered Pb nanowires are essentially single crystal, and have an average diameter of 40 nm. Spectrophotometry measurements show that the Pb nanowire arrays embedded in AAM can only transmit polarized light vertical to the wires. An extinction ratio of 17 to 18 dB and an average insertion loss of 0.4 dB cm–1 in the wavelength range of 1 to 2.2 μm were obtained, respectively. Therefore, these Pb nanowire/AAM composites can be used as a wire grid type micropolarizer.

Active micro-actuators for optical modulation based on a planar sliding triboelectric nanogenerator.

Based on a triboelectric nanogenerator (TENG), the first active micro-actuator for optical modulation driven by mechanical energy without external power or mechanical joint is presented. This demonstrates the enormous potential of TENGs for independent and sustainable self-powered micro/nano electromechanical systems, and opens up new -applications of TENGs in triboelectric-voltage-controlled devices.

p‐Type MoS2 and n‐Type ZnO Diode and Its Performance Enhancement by the Piezophototronic Effect

A plasma-induced p-type MoS2 flake and n-type ZnO film diode, which exhibits an excellent rectification ratio, is demonstrated. Under 365 nm optical irradiation, this p-n diode shows a strong photoresponse with an external quantum efficiency of 52.7% and a response time of 66 ms. By increasing the pressure on the junction to 23 MPa, the photocurrent can be enhanced by a factor of four through the piezophototronic effect.

Tribotronic Transistor Array as an Active Tactile Sensing System

Large-scale tactile sensor arrays are of great importance in flexible electronics, human-robot interaction, and medical monitoring. In this paper, a flexible 10 × 10 tribotronic transistor array (TTA) is developed as an active tactile sensing system by incorporating field-effect transistor units and triboelectric nanogenerators into a polyimide substrate. The drain-source current of each tribotronic transistor can be individually modulated by the corresponding external contact, which has induced a local electrostatic potential to act as the conventional gate voltage. By scaling down the pixel size from 5 × 5 to 0.5 × 0.5 mm2, the sensitivities of single pixels are systematically investigated. The pixels of the TTA show excellent durability, independence, and synchronicity, which are suitable for applications in real-time tactile sensing, motion monitoring, and spatial mapping. The integrated tribotronics provides an unconventional route to realize an active tactile sensing system, with prospective applications in wearable electronics, human-machine interfaces, fingerprint identification, and so on.

Transparent and Flexible Self-Charging Power Film and Its Application in a Sliding Unlock System in Touchpad Technology.

Portable and wearable personal electronics and smart security systems are accelerating the development of transparent, flexible, and thin-film electronic devices. Here, we report a transparent and flexible self-charging power film (SCPF) that functions either as a power generator integrated with an energy storage unit or as a self-powered information input matrix. The SCPF possesses the capability of harvesting mechanical energy from finger motions, based on the coupling between the contact electrification and electrostatic induction effects, and meanwhile storing the generated energy. Under the fast finger sliding, the film can be charged from 0 to 2.5 V within 2094 s and discharge at 1 μA for approximately 1630 s. Furthermore, the film is able to identify personal characteristics during a sliding motion by recording the electric signals related to the persons individual bioelectricity, applied pressing force, sliding speed, and so on, which shows its potential applications in security systems in touchpad technology.

Arrays of ordered Pb nanowires with different diameters in different areas embedded in one piece of anodic alumina membrane

Nanochannel arrays with constant nanochannel density but varying nanochannel diameters in different areas in one piece of anodic alumina membrane are achieved. Using this type of membrane as a template, ordered Pb nanowire arrays with constant nanowire density but diameters decreasing radially were obtained by electrodeposition. Scanning electron microscopy and transmission electron microscopy (TEM) images taken from different areas of the Pb nanowire arrays show that we can control the growth of aligned Pb nanowires with different diameters in a single process at one time. The individual Pb nanowires have been characterized using selected-area electron diffraction and high-resolution TEM. Nanometre-scale fibrils, rods, wires, and tubules of metal, semiconductor, carbon, and other materials with the same density but different diameters in different areas can be fabricated using this type of template, in combination with other fabrication techniques. The simultaneous integration of ordered nanowire structures with different diameters embedded in a single anodic alumina membrane could be useful in nanodevice manufacture as well as electronics, optoelectronics, and magnetics.

Efficient Storing Energy Harvested by Triboelectric Nanogenerators Using a Safe and Durable All-Solid-State Sodium-Ion Battery

Storing energy harvested by triboelectric nanogenerators (TENGs) from ambient mechanical motion is still a great challenge for achieving low‐cost and environmental benign power sources. Here, an all‐solid‐state Na‐ion battery with safe and durable performance used for efficient storing pulsed energy harvested by the TENG is demonstrated. The solid‐state sodium‐ion batteries are charged by galvanostatic mode and pulse mode with the TENG, respectively. The all‐solid‐state sodium‐ion battery displays excellent cyclic performance up to 1000 cycles with a capacity retention of about 85% even at a high charge and discharge current density of 48 mA g−1. When charged by the TENG, an energy conversion efficiency of 62.3% is demonstrated. The integration of TENGs with the safe and durable all‐solid‐state sodium‐ion batteries is potential for providing more stable power output for self‐powered systems.

Tribotronic Tuning Diode for Active Analog Signal Modulation

Realizing active interaction with external environment/stimuli is a great challenge for current electronics. In this paper, a tribotronic tuning diode (TTD) is proposed by coupling a variable capacitance diode and a triboelectric nanogenerator in free-standing sliding mode. When the friction layer is sliding on the device surface for electrification, a reverse bias voltage is created and applied to the diode for tuning the junction capacitance. When the sliding distance increases from 0 to 25 mm, the capacitance of the TTD decreases from about 39 to 8 pF. The proposed TTD has been integrated into analog circuits and exhibited excellent performances in frequency modulation, phase shift, and filtering by sliding a finger. This work has demonstrated tunable diode and active analog signal modulation by tribotronics, which has great potential to replace ordinary variable capacitance diodes in various practical applications such as signal processing, electronic tuning circuits, precise tuning circuits, active sensor networks, electronic communications, remote controls, flexible electronics, etc.

Stretchable Triboelectric–Photonic Smart Skin for Tactile and Gesture Sensing

Smart skin is expected to be stretchable and tactile for bionic robots as the medium with the ambient environment. Here, a stretchable triboelectric-photonic smart skin (STPS) is reported that enables multidimensional tactile and gesture sensing for a robotic hand. With a grating-structured metal film as the bioinspired skin stripe, the STPS exhibits a tunable aggregation-induced emission in a lateral tensile range of 0-160%. Moreover, the STPS can be used as a triboelectric nanogenerator for vertical pressure sensing with a maximum sensitivity of 34 mV Pa-1 . The pressure sensing characteristics can remain stable in different stretching conditions, which demonstrates a synchronous and independent sensing property for external stimuli with great durability. By integrating on a robotic hand as a conformal covering, the STPS shows multidimensional mechanical sensing abilities for external touch and different gestures with joints bending. This work has first demonstrated a triboelectric-photonic coupled multifunctional sensing terminal, which may have great applications in human-machine interaction, soft robots, and artificial intelligence.

Tribotronic transistor sensor for enhanced hydrogen detection

Hydrogen detection with a high sensitivity is necessary for preventing potential explosions and fire. In this study, a novel ZnO tribotronic transistor is developed by coupling a ZnO field effect transistor (FET) and triboelectric nanogenerator in free-standing mode and is used as a sensor for hydrogen detection at room temperature. Tribotronic modulated performances of the hydrogen sensor are demonstrated by investigating its output characteristics at different sliding distances and hydrogen concentrations. By applying an external mechanical force to the device for sliding electrification, the detection sensitivity of the ZnO tribotronic transistor sensor is improved, with a significant enhancement achieved in output current by 62 times at 500 ppm hydrogen and 1 V bias voltage. This study demonstrates an extension of the applications of emerging tribotronics for gas detection and a prospective approach to improve the performance of the hydrogen sensor via human-interfacing.